Virus / Flaviviridae / West Nile Virus / Detailed Viral Descriptions:

Ý ß  INTERMEDIATE HOSTS AND VECTOR SPECIES with literature reports for West Nile Virus:

Intermediate Hosts and Vector Species

Editorial Summary (Editorial Overview Text Replicated on Overall Virus page - West Nile virus)

A large number of mosquito species (Culicidae - Mosquitoes (Family)) have been found infected with West Nile virus and/or have been shown capable of transmitting the disease in the laboratory. Several species of ticks (Argasidae - Soft ticks (Family) and Ixodidae - Hard ticks (Family) ) have also been shown to be potential vectors of the virus. The virus has been detected in blooded louse flies (Hippoboscidae - Keds, Louse-flies etc.(Family)) taken from a WN virus-positive bird and it is possible that there is a role for bird-feeding hemipteran bugs, mites, and ticks in transmission of WNV between birds. Other species of arthropods have been infected experimentally.

(References are available in detailed literature reports below)

Data Source Information Arthropod families affected (detailed information available below):
INSECTS CHELICERATA

The following list indicates the arthropod species in which West Nile virus has been detected:

INSECTS

Mosquitoes: (Culicidae - Mosquitoes (Family))

Aedeomyia africana: (Aedeomyia (Genus))

  • Senegal (Barkedji area), 1990. WN virus isolated from 2/14 pools containing a total of 962 mosquitoes. (J110.31.w1)
  • Senegal (Barkedji area), 1990. WN virus isolated from female mosquitoes (963 mosquitoes collected, one WN virus isolate). (J110.38.w1)

Aedes aegypti - Yellow fever mosquito:

  • Madagascar (1975-88). Natural infection. Virus isolated once. (J95.69.w1, J124.141.w1)
  • Madagascar. Virus isolated (one isolate); virus transmission demonstrated and low rate transovarial transmission. (J84.5.w2)
  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)
  • Infection on several occasions following engorgement on viraemic lemurs (Eulemur (Lemur) fulvus - Brown lemur (Lemuridae - Large lemurs (Family))) infected with the Malagasy Mg An 798 strain WN virus. (J91.34.w1)
  • Vertical transmission demonstrated: WN virus isolated from adults of the generation after the mosquitoes which were inoculated by intrathoracic injection of WN virus. (J91.48.w1)
  • Experimental infection by allowing the mosquitoes to imbibe a suspension of WN virus through a membrane. Considered "an efficient host" for WN virus. (J11.52.w1) 
  • Transmission: Mouse to mosquito to mouse transmission demonstrated. (B241.49.w49)
  • Experimental infection by feeding on viraemic chicks. Of 19 mosquitoes tested, 16% became infected and 16% developed disseminated infection. Considered "relatively refractory" to infection. (J110.38.w3)

Aedes africanus: (Aedes (Genus))

  • Central African Republic. Virus isolated (one isolate). (J84.5.w2)

Aedes albocephalus: (Aedes (Genus))

  • Madagascar. (J124.141.w1)
  • Madagascar. Virus isolated (35 isolates). (J84.5.w2)
  • Experimental infection by feeding on hamsters infected with WN virus and (following an incubation period) transmission of WN virus to hamsters by biting demonstrated. (J122.53.w1)

Aedes albopictus - Asian tiger mosquito:

  • USA, 2000. WN virus detected in a total of one mosquito pool. (J214.267.w11)
  • USA (Pennsylvania), 2000. WN virus detected by RT-PCR in a pool of two mosquitoes. (J218.18.w1)
  • USA, 2001. WN virus detected in a total of five pools. (P39.3.w4)
  • USA (Maryland), 2002.  Natural infection detected. (W27.15Aug02.wnv1)
  • USA, 2002. WN virus detected in 63 positive pools (1% of the total of positive mosquito pools) with 18,328 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • Vertical transmission demonstrated: WN virus isolated from adults of the generation after the mosquitoes which were inoculated by intrathoracic injection of WN virus. (J91.48.w1)
  • Experimental transmission demonstrated and low-rate transovarial transmission. (J84.5.w2)
  • Experimental transmission hamster-mosquito-hamster and chick-mosquito-chick  by feeding demonstrated. (B241.49.w49)
  • Experimental infection by feeding on viraemic chicks. Of 61 mosquitoes tested, 90% became infected and 85% developed disseminated infection. Considered "highly susceptible" to infection. (J110.38.w3)
  • Estimation of potential for acting as a vector for WN virus in North America. Efficient experimental vector competence, few field isolations of WN virus in the USA, potentially could be important as a bridge vector, also may (less likely) act as an enzootic vector. (J214.267.w12)
  • Experimental infection by feeding on viraemic chicks demonstrated infection rates of up to 96% and transmission rates (by feeding on uninfected chicks, 13 days after infection of the mosquitoes) of up to 92%. There were significant variations between strains of mosquitoes from different locations in the percentage of mosquitoes becoming infected, although the percentage which developed disseminated infection and the percentage with disseminated infection which successfully transmitted the virus were not significantly different between strains. The extrinsic incubation period for WN virus in this mosquito species was estimated to be 10 days at 26°C. It was considered that, based on the efficacy of experimental viral transmission together with evidence of natural infection, bionomics, and distribution, this species could act as an important bridge vector for WN virus in the southeastern USA. (J218.18.w2)

Aedes albothorax: (Aedes (Genus))

  • Kenya. Virus isolated (one isolate). (J84.5.w2)

Aedes cantans: (Aedes (Genus))

  • Slovakia, Ukraine, Bulgaria. Virus isolated (seven isolates) (in Bulgaria detected within mosquitoes by immunofluorescence assay). (J84.5.w2)
  • West Slovakia (Malacky), 1972. Virus isolated. (J88.42.w1)

Aedes cinereus:

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Aedes circumluteolus: (Aedes (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated once. (J95.69.w1, J124.141.w1)
  • South Africa, Madagascar. Virus isolated (two isolates). (J84.5.w2)
  • Southern Africa (lowland coastal Natal), 1965-1980: One isolation made from 201,427 Aedes circumluteolus. No further details. (P33.3.w1)

Aedes excrucians: (Aedes (Genus))

  • Ukraine. Virus isolated (one isolate). (J84.5.w2)

Aedes geniculatus: (Aedes (Genus))

  • Experimental transmission: chick-mosquito-chick transmission demonstrated. (B241.49.w49) 

Aedes juppi + caballus: (Aedes (Genus))

  • South Africa. Virus isolated (one isolate). (J84.5.w2)

Aedes madagascarensis: (Aedes (Genus))

  • Madagascar. Virus isolated. (J124.141.w1)
  • Madagascar. Virus isolated (one isolate). (J84.5.w2)

Aedes vexans - Inland floodwater mosquito:

  • Senegal (Barkedji area), 1993. WN virus isolated from female mosquitoes (4,174 mosquitoes collected, two WN virus isolates). (J110.38.w1)
  • Senegal, Russia. Virus isolated (three isolates). (J84.5.w2)
  • Ukraine (western). (J116.5.w1)
  • USA (Connecticut), 1999. WN virus isolated from a pool of six mosquitoes. (J22.286.w1)
  • USA (New York State), 2000. WN virus detected by RT-PCR in 10/761 pools containing a total of 21,486 mosquitoes in the epicenter area and 0/422 pools containing a total of 13,490 mosquitoes outside the epicenter area. Virus was isolated from 1 pool. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in four pools from a total of 5,712 mosquitoes. (J84.7.w21)
  • USA  (New York State) May 13- November 4, 2000. 10/1,181 pools of mosquitoes (0.8%) positive by PCR. (J84.7.w7) 
  • USA, 2000. WN virus detected in a total of 16 mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of five pools. (P39.3.w4)
  • USA, 2002. WN virus detected in 62 positive pools (1% of the total of positive mosquito pools) with 173,479 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • Estimation of potential for acting as a vector for WN virus in North America. Inefficient experimental vector competence, several field isolations of WN virus in the USA, potentially could act as a bridge vector, unlikely to act as an enzootic vector. (J214.267.w12)
  • Experimental infection by feeding on viraemic chicks. Of 13 mosquitoes tested, 46% became infected and 8% developed disseminated infection. Considered "relatively refractory" to infection. (J110.38.w3)
  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 14 mosquitoes of 32% (considered "moderate"), transmission rate 23% at 14 days after infection  (considered "moderate"). Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)

Aedes spp. (Aedes (Genus))

  • USA  (New York State) May 13- November 4, 2000. 1/73 pools of mosquitoes (1.4%) positive by PCR. (J84.7.w7) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 1/72 pools containing a total of 1,340 mosquitoes in the epicenter area. Virus was isolated from 0 pools. (J84.7.w15)
  • USA, 2000. WN virus detected in a total of one mosquito pool. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of two pools. (P39.3.w4)

Anopheles atropos:

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Anopheles barberi:

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Anopheles brunnipes: (Anopheles (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1, J124.141.w1)
  • Madagascar. Virus isolated (one isolate). (J84.5.w2)

Anopheles coustani: (Anopheles (Genus))

  • Israel. Virus isolated (one isolate). (J84.5.w2)

Anopheles crucians / Anopheles bradleyi:

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Anopheles maculipalpis: (Anopheles (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated once. (J95.69.w1, J124.141.w1)
  • Madagascar. Virus isolated (one isolate). (J84.5.w2)

Anopheles maculipennis: (Anopheles (Genus))

  • Portugal, Ukraine. Virus isolated (one isolate). (J84.5.w2)

Anopheles pharoensis: (Anopheles (Genus))

  • Egypt 1950's. WN virus probably isolated once in July from a pool of mosquitoes, but the isolation could not be repeated. (J91.5.w1)

Anopheles plumbeus: (Anopheles (Genus))

  • Experimental transmission: chick-mosquito-chick transmission demonstrated. (B241.49.w49) 

Anopheles punctipennis:

  • USA  (New York State) May 13- November 4, 2000. 1/54 pools of mosquitoes (1.8%) positive by PCR. (J84.7.w7) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 1/37 pools containing a total of 165 mosquitoes in the epicenter area and 0/17 pools containing a total of 291 mosquitoes outside the epicenter area. Virus was isolated from 0 pools. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in one pool from a total of 50 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of one mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of three pools. (P39.3.w4)

Anopheles quadrimaculatus - Common malaria mosquito:

  • USA, 2001. WN virus detected in a total of five pools. (P39.3.w4)

Anopheles subpictus: (Anopheles (Genus))

  • India (1957). Virus isolated from a pool of 40 mosquitoes. (J91.20.w1)
  • India. Virus isolated (one isolate). (J84.5.w2)

Anopheles walkeri:

  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)

Anopheles sp.: (Anopheles (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1)
  • Madagascar. Virus isolated (one isolate). (J84.5.w2)

Coquillettidia metallica: (Coquillettidia (Genus))

  • Uganda. Virus isolated (one isolate). (J84.5.w2)

Coquillettidia microannulata: (Coquillettidia (Genus))

  • Southern Africa (lowland coastal Natal), 1965-1980. One isolation made from 254 Coquillettidia microannulata. No further details. (P33.3.w1)

Coquillettidia perturbans - Irritating mosquito:

  • USA, 2001. WN virus detected in a total of five pools. (P39.3.w4)
  • USA 2001: Experimental infection following feeding of mosquitoes on chicks (Gallus gallus) which had been inoculated with WN virus 1-2 days earlier (and following intrathoracic inoculation), development of disseminated infection and transmission to naive chicks by bite (feeding). Considered an "inefficient" laboratory vector, based on percentage development of disseminated infection and percentage transmission to naive chicks  by mosquitoes with disseminated infection.(J84.7.w36)

Coquillettidia richiardii: (Coquillettidia (Genus))

  • South Russia, Bulgaria. Virus isolated (one isolate) (in Bulgaria detected within mosquitoes by immunofluorescence assay). (J84.5.w2)

Culex antennatus: (Culex (Genus))

  • Egypt 1950's. WN virus isolated five times from 485 pools of mosquitoes (average 72 mosquitoes per pool). (J91.5.w1)
  • Egypt 1950's. Successful artificial inoculation of mosquitoes with viral persistence and multiplication. (J91.5.w1)
  • Egypt. Experimental infection by parenteral injection and by ingestion of blood containing virus. (J91.5.w2)
  • Egypt, 1993. Five isolates of Flavivirus of the Japanese encephalitis complex, considered to be most probably West Nile virus, collected from a total of 2,691 mosquitoes. Minimum field infection rate (MFIR) calculated as 1.9 per 1,000 specimens tested. (J110.39.w3)
  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1, J124.141.w1)
  • Egypt, Madagascar. Virus isolated (six isolates). (J84.5.w2)
  • Experimental transmission baby mouse-mosquito-baby mouse and wild birds-mosquito-mouse demonstrated. (B241.49.w49) 
  • Virus has been isolated from specimens collected in the field, the mosquitoes have been shown able to acquire the infection by bite and transmit it by bite after a suitable incubation period, and the species is found in close association with naturally infected vertebrate hosts. (J129.42.w1)

Culex bitaeniorhynchus: (Culex (Genus))

  • Experimental transmission demonstrated. (J84.5.w2)

Culex decens group: (Culex (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1, J124.141.w1)
  • Madagascar. Virus isolated (eight isolates). (J84.5.w2)

Culex erraticus:

  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)

Culex erythrothorax:

  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 15 mosquitoes of 100%, transmission rate 33% at 7 days after infection.  Infection rate for 25 mosquitoes of 100%, transmission rate 64% at 14 days after infection . Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)

Culex ethiopicus: (Culex (Genus))

  • Ethiopia. Virus isolated (one isolate). (J84.5.w2)
  • Senegal (Barkedji area), 1991, 1993. WN virus isolated from female mosquitoes (1991, 641 mosquitoes collected, one WN virus isolate; 1993 1,669 mosquitoes collected, two WN virus isolates). (J110.38.w1)

Culex fatigans: (Culex (Genus))

  • India and Pakistan: suspected as a vector of WN virus. (B241.49.w49) 
  • Experimental transmission: chick-mosquito-chick transmission and blood/virus suspension-mosquito-chick transmission demonstrated. (B241.49.w49) 

Culex guiarti: (Culex (Genus))

  • Cote d'Ivoire. Virus isolated (one isolate). (J84.5.w2)

Culex melanura:  (Culex (Genus))

  • USA, 2001. WN virus detected in a total of 26 pools. (P39.3.w4)

Culex neavei:: (Culex (Genus))

  • Senegal (Barkedji area), 1990. WN virus isolated from 3/10 pools containing a total of 199 mosquitoes (J110.31.w1)
  • Senegal, South Africa. Virus isolated (four isolates). (J84.5.w2)
  • Senegal (Barkedji area), 1991-1994. WN virus isolated from female mosquitoes (1990: 199 mosquitoes collected, three WN virus isolates; 1991: 756 mosquitoes collected, one WV virus isolate; 1992: 1,946 mosquitoes collected, three WN virus isolates; 1993: 3,602 mosquitoes collected, seven WN virus isolates; 1994: 950 mosquitoes collected, two WN virus isolates). (J110.38.w1)
  • Southern Africa (lowland coastal Natal), 1965-1980. One isolation made from 57,559 Culex neavei. Considered to be a moderate vector for West Nile virus but with a higher infectivity threshold than Culex univittatus. (P33.3.w1)
  • Experimental transmission of WN virus to hamster demonstrated following feeding of mosquitoes on chicken or pigeon. (B241.49.w49) 

Culex nigripalpus:

  • USA, 2001. WN virus detected in a total of five pools. (P39.3.w4)
  • USA 2001: Experimental infection following feeding of mosquitoes on chicks (Gallus gallus) which had been inoculated with WN virus 1-2 days earlier (and following intrathoracic inoculation), development of disseminated infection and transmission to naive chicks by bite (feeding). Considered a "competent but only moderately efficient" laboratory vector, based on percentage development of disseminated infection and percentage transmission to naive chicks  by mosquitoes with disseminated infection.(J84.7.w36)
  • Estimation of potential for acting as a vector for WN virus in North America. Relatively inefficient experimental vector competence, no field isolations of WN virus in the USA, potentially (not likely) could act as a bridge vector, also may (not likely) act as an enzootic vector. (J214.267.w12)

Culex nigripes: (Culex (Genus))

  • Central African Republic. Virus isolated (one isolate). (J84.5.w2)

Culex pallens: (Culex (Genus))

  • Experimental transmission: Transmission to mice by mosquitoes following infection of the mosquitoes by feeding on a blood/virus suspension demonstrated. (B241.49.w49) 

Culex perexiguus: (Culex (Genus))

  • Egypt, 1993. Twenty three isolates of Flavivirus of the Japanese encephalitis complex, considered to be most probably West Nile virus, collected from a total of 9,011 mosquitoes. Minimum field infection rate (MFIR) calculated as 2.6 per 1,000 specimens tested. (J110.39.w3)
  • Israel. Virus isolated (one isolate). (J84.5.w2)
  • Israel. One of two mosquito species incriminated as vectors of WN virus in Israel. (W27.20May02.wnv1)

Culex perfuscus group: (Culex (Genus))

  • Central African Republic, Senegal. Virus isolated (one isolate). (J84.5.w2)
  • Senegal (Barkedji area), 1993. WN virus isolated from female mosquitoes (330 mosquitoes collected, two WN virus isolates). (J110.38.w1)

Culex pipiens complex - Northern house mosquito

(Culex modestus (Culex pipiens modestus)/Culex molestus:

  • France. Identified as an enzootic vector of WN virus in southern France. (P31.6.w1)
  • France, Russia. Virus isolated (three isolates). (J84.5.w2)
  • Israel, 1951-52. Virus isolated in Israel (near Maayan Zvi), 1951/52. (J100.93.w1)
  • "The ornithophilic mosquito biotype Culex modestus is of great importance for circulation of West Nile virus in natural foci of bird colonies in the Volga Delta and in populated areas". (J84.6.w3)
  • Experimental transmission  to baby mouse demonstrated following feeding of mosquitoes on a blood/virus suspension. (B241.49.w49) 

(Culex pipiens):

  • Czechland (South Moravia) 1997. One strain isolated from a total of 232 mosquitoes in four pools, during investigations following flooding of the Morava River when the mosquito population was exceptionally high. (J115.13.w4)
  • Czechland (South Moravia) 1999. One strain isolated from a total of 3546 mosquitoes in 56 pools; the infection rate was significantly lower than in 1997. (J115.13.w4)
  • Czech Republic (Lanzhot), 1997. WN virus isolated from a pool of 57 Culex pipiens pipiens. (J88.42.w1, J84.5.w3).
  • Egypt 1950's. WN virus probably isolated once in January from a pool of mosquitoes, but the isolation could not be repeated. (J91.5.w1)
  • Egypt 1950's. Successful artificial inoculation of mosquitoes with viral persistence and multiplication. Successful transmission of virus  after being maintained at 12-23°C (mean daily winter temperatures).(J91.5.w1)
  • Egypt. Experimental infection by parenteral injection and by ingestion of blood containing virus. Successful transmission of virus  after being maintained at 12-23°C (mean daily winter temperatures). (J91.5.w2)
  • Egypt, 1993. Two isolates of Flavivirus of the Japanese encephalitis complex, considered to be most probably West Nile virus, collected from a total of 26,982 mosquitoes. Minimum field infection rate (MFIR) calculated as 0.3 per 1,000 specimens tested. (J110.39.w3)
  • Israel. Culex pipiens group is one of two mosquito species incriminated as vectors of WN virus in Israel. (W27.20May02.wnv1)
  • Southern Africa (high plateau of South Africa). (1965-1980). Natural infection. WN virus isolated once from 128,967 Culex pipiens mosquitoes. No further details. (P33.3.w1)
  • Romania (Bucharest), 1996. WN virus isolated from a pool of 30 female Culex pipiens pipiens collected from the walls and ceiling of a blockhouse. Basements of such buildings, flooded with a mixture of water and raw sewage, provide favourable breeding conditions for Culex pipiens. (J91.61.w2, J98.352.w1)
  • South Africa, Egypt, Israel, Romania, Czechland, Bulgaria. Virus isolated (one isolate) (in Bulgaria detected within mosquitoes by immunofluorescence assay). (J84.5.w2)
  • USA (Connecticut), 1999. WN virus isolated from a pool of 12 mosquitoes. (J22.286.w1)
  • USA (Connecticut), June 1- October 26, 2000. WN virus isolated  from five pools of 1-50 mosquitoes from densely populated suburban areas. (J84.7.w13)
  • USA, 2000. "Virus isolation data suggest the 1999 outbreak was transmitted by Culex species mosquitoes, principally Culex pipiens. Overwintering mosquitoes of this species collected in January and February 2000 were found to be positive for WN virus". (J84.7.w33)
  • USA  (New York State) May 13- November 4, 2000. 79/1,119 pools of mosquitoes (7.1%) positive by PCR and 212/3,746 (5.7%) of mixed Culex pipiens/Culex restuans pools. (J84.7.w7) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 78/831 pools containing a total of 22,120 mosquitoes in the epicenter area and 1/188 pools containing a total of 8,698 mosquitoes outside the epicenter area. Virus was isolated from 25 pools. Virus was also detected in 211/3,208 pools containing both Culex pipiens and Culex restuans (Culex restuans - White dotted mosquito) mosquitoes, but no WN virus was detected in any pools containing only Culex restuans. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in 74 pools from a total of 20,051 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of 226 mosquito pools of Culex pipiens/Culex restuans mosquitoes. (J214.267.w11)
  • USA  (New York and New Jersey), 1999. Six isolations from pools of exclusively Culex pipiens, one from mixed Culex pipiens/Culex restuans (Culex restuans - White dotted mosquito) pools, two from mixed Culex pipiens/Culex restuans/Culex salinarius  pools. (J84.7.w4) 
  • USA (New York City) January to February 2000. WN virus RNA detected by TaqMan RT-PCR assay from three pools of mosquitoes (two pools confirmed by PCR as Culex pipiens) and virus was isolated from one pool, indicating overwintering of WN virus within infected, hibernating Culex pipiens mosquitoes. (N7.49.w1, N7.49.w2, J84.7.w26)
  • USA, 2000. WN virus detected in a total of 132 mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of 349 pools and in a further 118 Culex pipiens-restuans pools. (P39.3.w4)
  • USA, 2002. WN virus detected during surveillance activities. (N7.51.w6)
  • USA, 2002. WN virus detected in 1,139 positive pools (19% of the total of positive mosquito pools) with 180,565 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • USA, 2002. Culex pipiens/Culex restuans: WN virus detected in 857 positive pools (14% of the total of positive mosquito pools) with 170,232 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • USA. Experimental infection.  Infection rate in mosquitoes of  > 70% following feeding on 1-4 day old chickens inoculated with WN virus 1-3 days previously but development of disseminated infection in less than 20%. Following intrathoracic inoculation and development of disseminated infection, shown able to transmit infection by bite to susceptible chicks. (P32.1.w5)
  • Culex pipiens var. pallens. Experimental infection by engorgement on virus-containing solution. Infection and multiplication in the mosquito confirmed, also transmission to mice by biting. (J126.2.w1)
  • Experimental transmission baby mouse-mosquito-baby mouse, mouse-mosquito-mouse and wild birds-mosquito-mouse demonstrated. (B241.49.w49) 
  • [No location or date provided] Virus has been isolated from specimens collected in the field, the mosquitoes have been shown able to acquire the infection by bite and transmit it by bite after a suitable incubation period, and the species is found in close association with naturally infected vertebrate hosts. (J129.42.w1)
  • Experimental infection: Vertical transmission demonstrated following intrathoracic inoculation of Culex pipiens mosquitoes with WN virus. Virus isolated by cell culture from 2/1,417 F1 adult progeny after rearing at 18°C (minimum filial infection rate of about 1.4 per 1000) and from 4/1,873 F1 adult progeny reared at 26°C (minimum filial infection rate of 2.1 per 1000). Temperature was not considered to affect the filial infection rate.(J110.39.w4)
  • Experimental infection by feeding on viraemic chicks. Of 95 mosquitoes tested, 81% became infected and 23% developed disseminated infection. Considered "moderately susceptible" to infection. No virus detected in 641 F1 adult progeny of infected mosquitoes reared at 18°C nor in 933 adult progeny reared at 26°C, but virus was recovered (105.3 PFU) from one pool of seven F1 larvae. (J110.38.w3)
  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 17 mosquitoes of 100%, transmission rate 0% at 7 days after infection.  Infection rate for 31 mosquitoes of 100%, transmission rate 71% at 14 days after infection . Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)
  • Estimation of potential for acting as a vector for WN virus in North America. Reasonably efficient experimental vector competence, many field isolations of WN virus in the USA, potentially could act as a bridge vector, also may (extremely likely) act as an enzootic vector. (J214.267.w12)

Culex poicilipes Theobold: (Culex (Genus))

  • Senegal (Barkedji area), 1990. WN virus isolated from 29/221 pools containing a total of 21,668 mosquitoes. (J110.31.w1, J84.5.w2)
  • Senegal (Barkedji area), 199-1994. WN virus isolated from female mosquitoes (1990: 21,668 mosquitoes collected, 23 WN virus isolates; 1991 7,363 mosquitoes collected, one WN virus isolate; 1993 2863 mosquitoes collected, 10 WN virus isolates; 1994 7,014 mosquitoes collected, four WN virus isolates). (J110.38.w1)

Culex pruina: (Culex (Genus))

  • Central African Republic. Virus isolated (one isolate). (J84.5.w2)

Culex pseudovishnui: (Culex (Genus))

  • Pakistan: Virus isolations suggest this mosquito species may serve as a vector in Pakistan. (J96.76.w2)

Culex quinquefasciatus - Southern house mosquito:

  • India, Pakistan, Madagascar. Virus isolated (seven isolates); virus transmission demonstrated. (J84.5.w2)
  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1, J124.141.w1)
  • South Africa. Culex pipiens quinquefasciatus: Experimental infection by feeding on experimentally infected mice, domestic and wild birds. (J94.31.w1)
  • USA, 2001. WN virus detected in a total of 13 pools. (P39.3.w4)
  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)
  • USA 2001: Experimental infection following feeding of mosquitoes on chicks (Gallus gallus) [Gallus gallus domesticus - Domestic chicken (Phasianidae - Grouse, Turkeys, Pheasants, Partridges, etc. (Family))] which had been inoculated with WN virus 1-2 days earlier (and following intrathoracic inoculation), development of disseminated infection and transmission to naive chicks by bite (feeding). Considered a "competent but only moderately efficient" laboratory vector, based on percentage development of disseminated infection and percentage transmission to naive chicks by mosquitoes with disseminated infection. Feeds on avian hosts and mammals and may play a role in transmission in the USA when the geographical spread of the virus brings it into areas where this mosquito is found. (J84.7.w36)
  • USA, 2002. WN virus detected in 625 positive pools (10% of the total of positive mosquito pools) with 27,451 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • USA (Georgia) 2002. This was the only species of mosquito to test positive. (P48.1.w5)
  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 215 mosquitoes (four groups from three different locations) of 8-86%, transmission rate 0-9% at 7 days after infection (poor).  Infection rate for 158 mosquitoes  (three groups from different locations) of 28-66%, transmission rate 19-52% at 14 days after infection (poor to moderate). Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)
  • Estimation of potential for acting as a vector for WN virus in North America. Reasonable experimental vector competence, no field isolations of WN virus in the USA, potentially could act (not very likely) important as a bridge vector, also may (more likely) act as an enzootic vector. (J214.267.w12)
  • Experimental infection. Vertical transmission demonstrated following intrathoracic inoculation. In offspring, 2/15 male and 0/13 female pools tested were WN virus-positive. (P39.4.w13)

Culex restuans - White dotted mosquito:

  • USA (Connecticut), June 1- October 26, 2000. WN virus isolated  from four pools of 3-18 mosquitoes from densely populated suburban areas. (J84.7.w13)
  • USA  (New York State) May 13- November 4, 2000. 0/238 pools of Culex restuans mosquitoes (0%) positive by PCR, but 212/3,746 (5.7%) of mixed Culex pipiens/Culex restuans pools. (J84.7.w7)
  • USA  (New York and New Jersey), 1999. Four isolations from pools of Culex restuans/Culex salinarius, one from mixed Culex pipiens/Culex restuans pool, two from mixed Culex pipiens/Culex restuans/Culex salinarius pools. (J84.7.w4) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 211/3,208 pools containing both Culex pipiens and Culex restuans mosquitoes, but no WN virus was detected in any pools containing only Culex restuans. (J84.7.w15)
  • USA, 2000. WN virus detected in a total of 11 mosquito pools. (J214.267.w11)
  • USA, 2000. WN virus detected in a total of 226 mosquito pools of Culex pipiens/Culex restuans mosquitoes. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of 76 pools and in a further 118 Culex pipiens-restuans pools. (P39.3.w4)
  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)
  • USA, 2002. WN virus detected in 289 positive pools (5% of the total of positive mosquito pools) with 173,688  individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • USA, 2002. Culex pipiens/Culex restuans: WN virus detected in 857 positive pools (14% of the total of positive mosquito pools) with 170,232 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • USA 2001: Experimental infection following feeding of mosquitoes on chicks (Gallus gallus) which had been inoculated with WN virus 1-2 days earlier (and following intrathoracic inoculation), development of disseminated infection and transmission to naive chicks by bite (feeding). Considered an "efficient" laboratory vector, based on percentage development of disseminated infection following feeding on chicks and percentage transmission of infection to naive chicks by mosquitoes with disseminated infection.(J84.7.w36)
  • Estimation of potential for acting as a vector for WN virus in North America. Efficient experimental vector competence, several field isolations of WN virus in the USA, potentially could act (not very likely) as a bridge vector, also may (very likely) act as an enzootic vector. (J214.267.w12)

Culex salinarius - Unbanded saltmarsh mosquito:

  • USA (Connecticut), June 1- October 26, 2000. WN virus isolated  from two pools of five and six mosquitoes from densely populated suburban areas. (J84.7.w13)
  • USA  (New York State) May 13- November 4, 2000. 31/501 pools of mosquitoes (6.2%) positive by PCR. (J84.7.w7) 
  • USA  (New York and New Jersey), 1999. Four isolations from pools of Culex restuans [(Culex restuans - White dotted mosquito]/Culex salinarius, two from mixed Culex pipiens [(Culex pipiens complex - Northern and Southern house mosquitoes)]/Culex restuans [(Culex restuans - White dotted mosquito]/Culex salinarius pools. (J84.7.w4) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 31/483 pools containing a total of 19,541 mosquitoes in the epicenter area and 10/17 pools containing a total of 704 mosquitoes outside the epicenter area. Virus was isolated from 13 pools.  (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in 32 pools from a total of 17,744 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of 36 mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of 184 pools. (P39.3.w4)
  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)
  • USA, 2002. WN virus detected in 102 positive pools (2% of the total of positive mosquito pools) with 1188,814 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • USA 2001: Experimental infection following feeding of mosquitoes on chicks (Gallus gallus) [Gallus gallus domesticus - Domestic chicken (Phasianidae - Grouse, Turkeys, Pheasants, Partridges, etc. (Family))] which had been inoculated with WN virus 1-2 days earlier (and following intrathoracic inoculation), development of disseminated infection and transmission to naive chicks by bite (feeding). Considered an "efficient" laboratory vector, based on percentage development of disseminated infection following feeding of chicks and percentage transmission to naive chicks  by mosquitoes with disseminated infection. "May be an ideal bridge vector between the enzootic avian cycle of WN and mammalian host"(J84.7.w36)
  • Estimation of potential for acting as a vector for WN virus in North America. Efficient experimental vector competence, few field isolations of WN virus in the USA, potentially could be important as a bridge vector, also may (not likely) act as an enzootic vector. (J214.267.w12)

Culex scottii: (Culex (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated from "Culex sp. close to scottii". (J95.69.w1)
  • Madagascar. Virus isolated (one isolate). (J84.5.w2)

Culex stigmatosoma:

  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 15 mosquitoes of 67%, transmission rate 0% at 7 days after infection.  Infection rate for 48 mosquitoes of 77%, transmission rate 19% at 14 days after infection . Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)

Culex tarsalis:

  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)
  • USA, 2002. WN virus detected in 249 positive pools (4% of the total of positive mosquito pools) with 129,056 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 94 mosquitoes (three groups from different locations) of 87-94%, transmission rate 10-60% at 7 days after infection.  Infection rate for 91 mosquitoes  (three groups from different locations) of 74-100%, transmission rate 60-100% at 14 days after infection . Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)
  • Experimental infection. Vertical transmission demonstrated following intrathoracic inoculation. In offspring, 10/44 male and 5/42 female pools tested were WN virus-positive. However 0no transmission occurred following intrathoracic inoculation in a different batch. (P39.4.w13)
  • Experimental infection by feeding on two to three-day-old infected chickens demonstrated that specimens of this species collected in Orange County, California, were competent vectors for WNV. The mosquitoes were efficient laboratory vectors for the virus. All six WN-inoculated mosquitoes which fed on uninfected chickens transmitted the virus to the chickens by bite, infection rates were 94-97%, dissemination rates  81-83% and estimated transmission rates of 81% for mosquitoes ingesting 106.5 PFU WN virus/ml blood, and 91% for mosquitoes ingesting 107.3 PFU/ml blood. It was considered, based on this transmission data and the known role of this mosquito species in transmission of St. Louis encephalitis virus, that this mosquito should be considered as a potentially important vector, both as a maintenance vector and a bridge vector, for WN virus transmission in the western USA. (J279.2.w2)

Culex territans:

  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)

Culex theileri Theobald: (Culex (Genus))

  • South Africa, (Upington) 1974. Infection with WN virus demonstrated. Four isolates from 53 pools totalling 4889 mosquitoes, April 1974, but low natural infection rate (0.83 per 1,000 mosquitoes in this study i.e. one infected mosquito per 1,204 mosquitoes), and has been shown to be a poor vector. Transmission rate of 25% for an infecting dose of 5.4 logs and 0% for an infecting dose of 4.5 logs. (J111.72.w1).
  • South Africa, (Olifantsvlei) 1961-1965. Natural infection. Virus isolated once from Culex theileri mosquitoes in the summer months. (J94.32.w1)
  • Southern Africa  (high plateau of South Africa).(1965-1980). Natural infection. Virus isolated once from 82,995 Culex theileri. No further details. (P33.3.w1)  
  • South Africa. Virus isolated (one isolate); virus transmission demonstrated (J84.5.w2)
  • Experimental transmission blood/virus suspension-mosquito-chick demonstrated. (B241.49.w49) 

Culex tritaeniorhynchus: (Culex (Genus))

  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1, J124.141.w1)
  • Pakistan. Virus isolations suggest this mosquito species may serve as a vector in Pakistan. (J96.76.w2)
  • Pakistan (Karachi), 1986.  Four strains of WN virus isolated from Culex tritaeniorhynchus mosquitoes. (J117.26.w1)
  • Pakistan, India, Madagascar. Virus isolated (three isolates); virus transmission demonstrated and low rate transovarial transmission. (J84.5.w2)
  • Experimental infection: Vertical transmission demonstrated: WN virus isolated from adults of the generation after the mosquitoes which were inoculated by intrathoracic injection of WN virus. (J91.48.w1)
  • Experimental studies on susceptibility of different strains to ingestion of WN virus; replication of WN virus following ingestion of virus suspension through a membrane. (J91.33.w1). 
  • Experimental transmission  to mouse demonstrated following feeding of mosquitoes on a blood/virus suspension. (B241.49.w49) 
  • Virus has been isolated from specimens collected in the field, the mosquitoes have been shown able to acquire the infection by bite and transmit it by bite after a suitable incubation period, and the species is found in close association with naturally infected vertebrate hosts. (J129.42.w1)

Culex univittatus: (Culex (Genus))

  • "Studies in Egypt, Israel and South Africa , have implicated Cx. univittatus as the main species transmitting WN virus in all three countries based on field isolation rates." (B241.49.w49) 
  • Egypt 1950's. WN virus isolated nine times from 160 pools of mosquitoes (average 40 mosquitoes per pool). Probably isolated a further three times, in July, August and September, but isolation could not be repeated. (J91.5.w1)
  • Considered to be an effective vector for  West Nile virus and the most effective vector (main viral maintenance vector) on the South African plateau.(P33.3.w1)
  • Egypt, Nile Delta. Culex univittatus  is the principle vector (J107.36.w1)
  • Egypt 1950's. Successful artificial inoculation of mosquitoes with viral persistence and multiplication. Successful transmission of virus as early as five days after infection when maintained at 28-32°C and after being maintained at 12-23°C (mean daily winter temperatures).(J91.5.w1)
  • Egypt. Experimental infection by parenteral injection and by ingestion of blood containing virus. Successful transmission of virus  after being maintained at 12-23°C (mean daily winter temperatures). Transmission by biting as early as five days after infection and for at least 33 days after maintenance at 28-32°C.(J91.5.w2)
  • Egypt, Israel, South Africa, Madagascar. Virus isolated (51 isolates); virus transmission demonstrated. (J84.5.w2)
  • Kenya, 1998. WN virus was isolated from male Culex univittatus complex mosquitoes. This first field isolation of WN virus from male mosquitoes indicates natural vertical transmission of the virus in this species of mosquito. (J91.62.w1)
  • Madagascar (1975-88). Natural infection. Virus isolated. (J95.69.w1, J124.141.w1)
  • Senegal (Barkedji area), 1993. WN virus isolated from female mosquitoes (602 mosquitoes collected, five WN virus isolates). (J110.38.w1)
  • South Africa (Olifantsvlei, Lake Chrissie), summers 1962-1965. Natural infection. Virus detected from pools of mosquitoes in the months of November to April. Isolated at up to 8.9 isolates per 1000 mosquitoes but generally at 0.2 to 1.0 isolates per 1000.  This species appeared to be the primary vector in the feral transmission cycle of WN virus and the main vector causing WN virus infection in sentinel chickens.  (J94.32.w1)
  • South Africa, 1974 (approx.). Experimental infection. 
    • Mosquitoes infected  by feeding on viraemic two-day-old chicks (inoculated intramuscularly at one day old) were able to transmit WN virus to 89-100% of two- to four-day-old chicks at seven to eight, 41 and 49 days after feeding; infectivity of mosquitoes at 81 days remained at 100%. 
    • Transmission rate was reduced to 48% when mosquitoes held at 18°C, compared with 97% transmission rate at 26°C.
    • Transmission rate was reduced from 89% to 33% when mosquitoes were fed a lower virus dose (2.6 logs versus 5.0 logs virus). (J110.11.w1)
  • South Africa (Upington), 1974. Infection with WN virus demonstrated. Thirty three isolates from 52 pools totalling 1325 mosquitoes giving an infection rate of 39 per 1,000 mosquitoes (one infected mosquito per 26 mosquitoes). Shown to be "almost certainly the main vector of both WN and SIN [Sindbis] viruses in human infections" in this area. Mainly ornithophilic, but also feeds readily on man, at least when abundant. (J111.72.w1)
  • South Africa. Experimental infection by allowing feeding on infected, viraemic chicks, followed by transmission after maintenance at various temperatures. Experiments indicated that once infected with WN virus, these mosquitoes remained infected for life. Transmission from mosquitoes to a pigeon ((Columba - (Genus))- species not stated) and from the pigeon to further mosquitoes by feeding was also demonstrated. (J110.30.w1)
  • South Africa (Witwatersrand, three locations), 1984. Virus isolated 23 times from 135 pools of mosquitoes. (J125.70.w1)
  • Southern Africa (high plateau of South Africa). (1965-1980). Natural infection. Virus isolated 128 times from 70,037 Culex univittatus. No further details. (P33.3.w1)
  • Experimental transmission: mouse-mosquito-mouse, blood/virus suspension-mosquito-chick, chick-mosquito-chick and wild birds-mosquito-mouse transmission demonstrated. (B241.49.w49) 
  • Virus has been isolated from specimens collected in the field, the mosquitoes have been shown able to acquire the infection by bite and transmit it by bite after a suitable incubation period, and the species is found in close association with naturally infected vertebrate hosts. (J129.42.w1)

Culex vishnui group: (Culex (Genus))

  • Asia: Members of this complex (Culex tritaeniorhynchus, Culex vishnui and Culex pseudovishnui) have been implicated as vectors of WN virus in southwestern Asia. (B241.49.w49) 
  • India (1955). Virus isolated from a pool of 100 mosquitoes. (J91.20.w1)
  • India (1955). Virus isolated from a pool of 74 mosquitoes. (J91.20.w1)
  • India (1956). Virus isolated from a pool of 12 mosquitoes. (J91.20.w1)
  • India (1957). Virus isolated from a pool of 150 mosquitoes. (J91.20.w1)
  • India (1957). Virus isolated from a pool of 140 mosquitoes. (J91.20.w1)
  • India (Madras State) 1955. Virus isolated. (J88.17.w1)
  • India (Madras State) 1958. Virus isolated. (J88.17.w1)
  • India, Pakistan. Virus isolated (six isolates); virus transmission demonstrated. (J84.5.w2)

Culex weschei: (Culex (Genus))

  • Central African Republic. Virus isolated (one isolate); virus transmission demonstrated. (J84.5.w2)

Culex sp. (Culex (Genus))

  • Egypt, Algeria, Central African Republic. Virus isolated (three isolates). (J84.5.w2)
  • USA  (New York State) May 13- November 4, 2000. 19/232 pools of mosquitoes (8.2%) positive by PCR. (J84.7.w7) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 19/200 pools containing a total of 5,358 mosquitoes in the epicenter area and 0/32 pools containing a total of 1,108 mosquitoes outside the epicenter area. Virus was isolated from nine pools. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in 20 pools from a total of 5,744 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of 25 mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of 184 pools. (P39.3.w4)
  • USA, 2002. WN virus detected in 2,381 positive pools (39% of the total of positive mosquito pools) with 72,986 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)

Culiseta inornata:

  • USA 2002. WN virus reported during surveillance activities. (N7.51.w6)
  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 28 mosquitoes of 75%, transmission rate 21% at 14 days after infection  (considered "moderate"). Study of Californian mosquitoes as possible vectors of WN virus; this species is active during winter. (J84.8.w13)

Culiseta longiareolata: (Culiseta (Genus))

  • Egypt 1950's. Successful artificial inoculation of mosquitoes with viral persistence and multiplication. (J91.5.w1)

Culiseta melanura:

  • USA (Connecticut), June 1- October 26, 2000. WN virus isolated from three pools of 7-50 mosquitoes from semi-permanent swamp habitats. (J84.7.w13)
  • USA, 2000. WN virus detected in a total of three mosquito pools. (J214.267.w11)

Culiseta sp.  (Culiseta (Genus))

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Deinocerites cancer:

  • USA, 2001. WN virus detected in a total of two pools. (P39.3.w4)

Mansonia africana:  (Mansonia (Genus))

  • Senegal (Barkedji area), 1993. WN virus isolated from female mosquitoes (4,634 mosquitoes collected, one WN virus isolate). (J110.38.w1)

Mansonia (Coquillettidia) metallica: (Mansonia (Genus))

  • Uganda, 1959.  Virus isolated by mouse inoculation from a pool of 405 female mosquitoes. (J86.55.w1)

Mansonia uniformis: (Mansonia (Genus))

  • Ethiopia. Virus isolated (one isolate). (J84.5.w2)
  • Senegal (Barkedji area), 1993. WN virus isolated from female mosquitoes (925 mosquitoes collected, one WN virus isolate). (J110.38.w1)

Mimomyia hispida: (Mimomyia (Genus)) 

  • Senegal (Barkedji area), 1990. WN virus isolated from 8/14 pools totaling 1,195 mosquitoes. (J110.31.w1, J84.5.w2)
  • Senegal (Barkedji area), 1990. WN virus isolated from female mosquitoes (1,195 mosquitoes collected, nine WN virus isolates). (J110.38.w1)

Mimomyia lacustris: (Mimomyia (Genus)) 

  • Senegal (Barkedji area), 1990. WN virus isolated from 4/10 pools totaling 767 mosquitoes. (J110.31.w1, J84.5.w2)
  • Senegal (Barkedji area), 1990. WN virus isolated from female mosquitoes (767 mosquitoes collected, four WN virus isolates). (J110.38.w1)

Mimomyia splendens: (Mimomyia (Genus)) 

  • Senegal (Barkedji area), 1990. WN virus isolated from 6/43 pools totaling 3,789 mosquitoes. (J110.31.w1, J84.5.w2)
  • Senegal (Barkedji area), 1990, 1991. WN virus isolated from female mosquitoes (1990:3,789 mosquitoes collected, three WN virus isolates; 1991: 705 mosquitoes collected, one WN virus isolate). (J110.38.w1)

Mimomyia spp. (Mimomyia (Genus))

  • Senegal (Barkedji area), 1990. WN virus isolated from 2/2 pools totaling 136 mosquitoes. (J110.31.w1, J84.5.w2)
  • Senegal (Barkedji area), 1990. WN virus isolated from female mosquitoes (136 mosquitoes collected, two WN virus isolates). (J110.38.w1)

Ochlerotatus atlanticus / Ochlerotatus tormentor :

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Ochlerotatus atropalpus:

  • Experimental infection by feeding on viraemic chicks. Of 12 mosquitoes tested, 92% became infected and 92% developed disseminated infection. Considered "highly susceptible" to infection. (J110.38.w3)
  • Estimation of potential for acting as a vector for WN virus in North America. Efficient experimental vector competence, few field isolations of WN virus in the USA, potentially could be important as a bridge vector, also may (not likely) act as an enzootic vector. (J214.267.w12)

Ochlerotatus canadensis - Woodland pool mosquito:

  • USA, 2001. WN virus detected in a total of five pools. (P39.3.w4)
  • Estimation of potential for acting as a vector for WN virus in North America. Inefficient experimental vector competence, no field isolations of WN virus in the USA, potentially could act (not likely) as a bridge vector, unlikely to act as an enzootic vector. (J214.267.w12)

Ochlerotatus cantator - Brown saltmarsh mosquito:

  • USA (New York State), 2000. WN virus detected by RT-PCR in 1/65 pools containing a total of 1,615 mosquitoes in the epicenter area and 0/22 pools containing a total of 993 mosquitoes outside the epicenter area. Virus was isolated from 0 pools. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in one pool from a total of 111 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of one mosquito pool. (J214.267.w11)
  • USA  (New York State) May 13- November 4, 2000. 1/87 pools of mosquitoes (1.1%) positive by PCR. (J84.7.w7) 
  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)
  • Estimation of potential for acting as a vector for WN virus in North America. Inefficient experimental vector competence, few field isolations of WN virus in the USA, potentially could act (not likely) as a bridge vector, unlikely to act as an enzootic vector. (J214.267.w12)

Ochlerotatus caspius: (Ochlerotatus (Genus))

  • Egypt 1950's. Successful artificial inoculation of mosquitoes with viral persistence and multiplication. (J91.5.w1)
  • Ukraine. Virus isolated (one isolate); virus transmission demonstrated. (J84.5.w2)

Ochlerotatus dorsalis:

  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 30 mosquitoes of 50%, transmission rate 13% at seven days after infection.  Infection rate for 29 mosquitoes of 41%, transmission rate 23% at 14 days after infection  (considered "moderate"). Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)

Ochlerotatus japonicus:

  • USA (New York State), 2000. WN virus detected by RT-PCR in 2/257 pools containing a total of 3,342 mosquitoes in the epicenter area and 3/271 pools containing a total of 3,871 mosquitoes outside the epicenter area. Virus was isolated from 0 pools. (J84.7.w15)
  • USA, 2000. WN virus detected in a total of nine mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of eight pools. (P39.3.w4)
  • USA. Experimental infection.  Infection rate in mosquitoes of  > 70% following feeding on 1-4 day old chickens inoculated with WN virus 1-3 days previously but development of disseminated infection in less than 20%. Following intrathoracic inoculation and development of disseminated infection, shown able to transmit infection by bite to susceptible chicks. (P32.1.w5)
  • Ochlerotatus japonicus USA  (New York State) May 13- November 4, 2000. 5/526 pools of mosquitoes (1.0%) positive by PCR. (J84.7.w7) 
  • Experimental infection by feeding on viraemic chicks. Of 36 mosquitoes tested, 69% became infected and 64% developed disseminated infection. Considered "highly susceptible" to infection. (J110.38.w3)
  • Estimation of potential for acting as a vector for WN virus in North America. Oechlerotatus japonicus japonicus. Efficient experimental vector competence, several field isolations of WN virus in the USA, potentially could be important as a bridge vector, also may (not very likely) act as an enzootic vector. (J214.267.w12)

Ochlerotatus melanimon:

  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 50 mosquitoes of 46%, transmission rate 13% at 7 days after infection.  Infection rate for 29 mosquitoes of 41% (considered "moderate"), transmission rate 23% at 14 days after infection  (considered "moderate"). Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)

Ochlerotatus punctor:

  • Experimental transmission:  chick-mosquito-chick transmission demonstrated. (B241.49.w49) 

Ochlerotatus sierrensis:

  • Experimental infection by feeding on hanging blood droplets (defibrinated blood) (at approximately 107.1 PFU/ml) and sampling of saliva ("transmission") seven or 14 days later. Infection rate for 40 mosquitoes of 5%, transmission rate 3% at 7 days after infection.  Infection rate for 50 mosquitoes of 14%, transmission rate 6% at 14 days after infection  (considered "poor vector"). Study of Californian mosquitoes as possible vectors of WN virus. (J84.8.w13)

Ochlerotatus sollicitans - Saltmarsh mosquito:

  • USA, 2001. WN virus detected in a total of six pools. (P39.3.w4)
  • USA. Experimental infection.  Infection rate in mosquitoes of  > 70% following feeding on 1-4 day old chickens inoculated with WN virus 1-3 days previously but development of disseminated infection in less than 20%. Following intrathoracic inoculation and development of disseminated infection, shown able to transmit infection by bite. (P32.1.w5)
  • Experimental infection by feeding on viraemic chicks. Of 50 mosquitoes tested, 70% became infected and 16% developed disseminated infection. Considered "moderately susceptible" to infection. (J110.38.w3)
  • Estimation of potential for acting as a vector for WN virus in North America. Inefficient experimental vector competence, no field isolations of WN virus in the USA, potentially could act (not very likely) as a bridge vector, also unlikely to act as an enzootic vector. (J214.267.w12)

Ochlerotatus taeniorhynchus - Black Saltmarsh Mosquito:

  • USA, 2001. WN virus detected in a total of four pools. (P39.3.w4)
  • Experimental infection by feeding on viraemic chicks. Of 75 mosquitoes tested, 12% became infected and 3% developed disseminated infection. Considered "relatively refractory" to infection. (J110.38.w3)
  • Estimation of potential for acting as a vector for WN virus in North America. Inefficient experimental vector competence, no field isolations of WN virus in the USA, potentially could act (not very likely) as a bridge vector, also unlikely to act as an enzootic vector. (J214.267.w12)

Ochlerotatus triseriatus - Eastern treehole mosquito

  • USA (New York State), 2000. WN virus detected by RT-PCR in 3/203 pools containing a total of 2,956 mosquitoes in the epicenter area and 0/206 pools containing a total of 6,335 mosquitoes outside the epicenter area. Virus was isolated from 1 pool. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in three pools from a total of 772 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of nine mosquito pools. (J214.267.w11)
  • (Ochleotatus triseriatus) USA  (New York State) May 13- November 4, 2000. 3/407 pools of mosquitoes (0.7%) positive by PCR. (J84.7.w7)
  • USA, 2001. WN virus detected in a total of 13 pools. (P39.3.w4)
  • USA, 2002. WN virus detected in 63 positive pools (1% of the total of positive mosquito pools) with 55,942 individual mosquitoes tested [Data as of 21 Jan 2003]. (P39.4.w1)
  • Estimation of potential for acting as a vector for WN virus in North America. Estimation of potential for acting as a vector for WN virus. Fairly efficient experimental vector competence, few field isolations of WN virus in the USA, potentially could be of some important as a bridge vector, unlikely to act as an enzootic vector. (J214.267.w12)

Ochlerotatus trivitattus:

  • USA, 2000. WN virus detected in a total of nine mosquito pools. (J214.267.w11)
  • USA, 2001. WN virus detected in a total of three pools. (P39.3.w4)

Orthopodomyia signifera:

  • USA, 2001. WN virus detected in a total of two pools. (P39.3.w4)

Psorophora ciliata - Gallinipper:

  • USA 2002. WN virus detected during surveillance activities. (N7.51.w6)

Psorophora columbiae - Dark rice field mosquito:

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Psorophora ferox - White-footed woods mosquito:

  • USA  (New York State) May 13- November 4, 2000. 1/16 pools of mosquitoes (6.2%) positive by PCR. (J84.7.w7) 
  • USA (New York State), 2000. WN virus detected by RT-PCR in 1/10 pools containing a total of 63 mosquitoes in the epicenter area and 0/6 pools containing a total of 162 mosquitoes outside the epicenter area. Virus was isolated from 1 pool. (J84.7.w15)
  • USA (New York State), 2000. WN virus detected by RT-PCR in one pool from a total of 58 mosquitoes. (J84.7.w21)
  • USA, 2000. WN virus detected in a total of one mosquito pool. (J214.267.w11)

Uranotaenia sapphirinia:

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

"Unidentified mosquitoes":

  • USA, 2001. WN virus detected in a total of one pool. (P39.3.w4)

Mosquitoes:

  • USA 1999 - 2007. WN virus detected in 1999 in 18 mosquito pools, in 2000 in 515 mosquito pools, in 2001 in 919 mosquito pools, in 2002 in 6604 mosquito pools, in 2003 in 8384 mosquito pools, in 2004 in 8759 mosquito pools, in 2005 in 11816 mosquito pools, in 2006 in 11898 mosquito pools, in 2007 in 8215 mosquito pools. (V.w118 - data from CDC-ArboNET)

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Lice: (Pediculidae - (Family))

Pediculus humanus corporis - Human body louse: (Pediculidae - (Family))

  • Egypt. Experimental infection by parenteral injection; positive titre after four days of incubation, considered "probably" susceptible to infection (experiment not repeated). (J91.5.w2)

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Flies: (Muscidae - (Family))

Musca domestica vicina - House fly: (Muscidae - (Family))

  • Egypt. Experimental infection by parenteral injection; positive titre after four days of incubation, considered susceptible to infection. (J91.5.w2)

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Hippoboscid Flies: (Hippoboscidae - Keds, Louse-flies etc.(Family))

Louse flies: (Hippoboscidae - Keds, Louse-flies etc.(Family))

  • USA (Pennsylvania) WN virus has been detected by PCR and by virus isolation in a pool of five louse flies from a Bubo virginianus - Great horned owl with clinical signs of WNV infection. The flies had obviously (visibly) taken a blood meal therefore the finding of the virus was "not surprising". It is not yet known whether these insects are able to transmit WN virus (i.e. act as a vector for the virus).(W27.25Sept02.wnv1)

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CHELICERATA

Ticks: (Acarina - Mites and Ticks (Order))

Soft ticks:(Argasidae - Soft ticks (Family))

Argas hermanni: (Argas (Genus))

  • Egypt. Virus isolated (three isolates); virus transmission demonstrated. (J84.5.w2)
  • Egypt. (Argas reflexus hermanni) virus recovered from field-collected ticks in February . (J129.42.w1)

Argas arboreus: (Argasus [sic.]) (Argas (Genus))

  • Experimental infection by feeding on known concentrations of virus through a membrane. Virus detectable for 50 days after feeding. Successful transmission of virus to chickens by feeding on chickens 20 days after infection. Larvae from experimentally infected females were able to transmit virus to chickens. (J91.48.w2)

Argas hermanni: (Argasus [sic.]) (Argas (Genus))

  • Experimental infection by feeding on known concentrations of virus through a membrane. Virus detectable only for four days after feeding, increasing to eight days with a higher concentration of virus. (J91.48.w2)

Argas persicus: (Argas persicus - Fowl tick)

  • Egypt 1950's. Successful artificial inoculation with viral persistence and multiplication. (J91.5.w1)
  • Egypt. Experimental infection by parenteral injection; positive titre after 25 days of incubation, but no transmission to infant mice by biting. (J91.5.w2)
  • Experimental infection by feeding on known concentrations of virus through a membrane. Virus detectable only for three days after feeding, increasing to six days with a higher concentration of virus. (J91.48.w2)

Ornithodoros capensis: (Ornithodoros - Tampan ticks (Genus))

  • Azerbaijan. Virus isolated (five isolates); virus transmission demonstrated. (J84.5.w2); Glinyanyi Island, Baku archipelago (J116.5.w1); isolation was from ticks collected from herring gull (Larus argentatus - Herring gull) nesting areas on islands on the Caspian sea, without any mosquitoes present, which suggests the possibility of bird-tick-bird maintenance. (B224.w1)

Ornithodoros erraticus:  (Ornithodoros - Tampan ticks (Genus))

  • Egypt 1950's. Successful artificial inoculation with viral persistence and multiplication. Infection of ticks also acquired by feeding on infected mice but no transmission of infection to adult mice by feeding on them. (J91.5.w1)
  • Egypt. Experimental infection by parenteral injection; positive titre after 28 and 30 days of incubation, but no transmission to infant mice by biting. (J91.5.w2)
  • Experimental transmission demonstrated. (J84.5.w2)
  • Experimental infection by feeding on viraemic hosts with subsequent transmission; transmission by feeding on mice following infection of nymphs and subsequent moulting to adults demonstrated. (B241.49.w49) 

Ornithodoros maritimus (Ornithodoros coniceps): (Ornithodoros - Tampan ticks (Genus))

  • Experimental transmission demonstrated. (J84.5.w2)
  • Experimental infection by feeding on viraemic hosts with subsequent transmission; transmission by feeding on mice following infection of nymphs and subsequent moulting to adults demonstrated. (B241.49.w49) 

Ornithodoros moubata: (Ornithodoros - Tampan ticks (Genus))

  • Experimental transmission demonstrated. (J84.5.w2)
  • Experimental infection by engorging of first instar nymphs on viraemic infant mice. Peak titres in the body of the tick during the first seven days after infection with a decline over the next seven weeks. Transmission recorded to day-old chicks "only after mass feeding by five or more ticks". (B241.49.w49) 

Ornithodoros savigni: (Ornithodoros - Tampan ticks (Genus))

  • Egypt 1950's. Successful artificial inoculation with viral persistence and multiplication; one tick successfully transmitted WN virus by bite to infant mice. Infection of ticks also acquired by feeding on infected mice but no transmission of infection to adult mice by feeding on them. (J91.5.w1)
  • Egypt. Experimental infection by parenteral injection; positive titre after 12 days of incubation, transmission to infant mice by biting recorded. (J91.5.w2)
  • Experimental transmission demonstrated. (J84.5.w2)

Argasidae - Soft ticks (Family):

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Hard ticks: (Ixodidae - Hard ticks (Family))

Amblyomma variegatum:  (Amblyomma - Bont ticks (Genus))

  • Central African Republic. Virus isolated (one isolate). (J84.5.w2)

Dermacentor marginatus: (Dermacentor (Genus))

  • Moldavia. Virus isolated (one isolate); virus transmission demonstrated. (J84.5.w2)

Dermacentor reticulatus: (Dermacentor (Genus))

  • Experimental transmission demonstrated. (J84.5.w2)

Haemaphysalis leachii: (Haemaphysalis (Genus))

  • Experimental transmission demonstrated. (J84.5.w2)

Hyalomma marginatum: (Hyalomma - Bont-legged ticks (Genus))

  • Astrakhan, Azerbaijan. Virus isolated (five isolates). (J84.5.w2)
  • Russia (Volga Delta, Astrakhan region), 2001. Natural infection, virus isolated from nymphs. (J116.47.w1)

Hyalomma detritum: (Hyalomma - Bont-legged ticks (Genus))

  • Virus isolated (one isolate). (J84.5.w2)

Hyalomma plumbeum: (Hyeloma [sic.]) (Hyalomma - Bont-legged ticks (Genus))

  • USSR (Volga Delta), 1963. Virus isolated from Hyeloma plumbeum plumbeum. (J88.17.w1, B240.14.w14)
  • Astrakhan, former USSR. Isolation from ticks H. plumbeum. (J116.5.w1)

Ixodes ricinus: (Ixodes (Genus))

  • Ukraine (western). (J116.5.w1)

Rhipicephalus muhsamae: (Rhipicephalus (Genus))

  • Central African Republic. Virus isolated (one isolate). (J84.5.w2)

Rhipicephalus rossicus: (Rhipicephalus (Genus))

  • Experimental transmission demonstrated. (J84.5.w2)

Rhipicephalus s. sanguineus: (Rhipicephalus (Genus))

  • Egypt 1950's. Successful artificial inoculation with viral persistence and multiplication. (J91.5.w1)
  • Experimental transmission demonstrated. (J84.5.w2)

Rhipicephalus turanicus: (Rhipicephalus (Genus))

  • Azerbaijan. Virus isolated (one isolate). (J84.5.w2)

Ixodidae - Hard ticks (Family):

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Other Arthropods

Various species:

"Recent studies also suggest the involvement of nidiferous arthropods (bird-feeding hemipteran bugs, mites, and ticks) in WNV transmission cycles in the rookeries of colonial birds such as swallows, martins, and rooks [Corvus frugilegus - Rook]." (B244.w1)

Infection Type and Species/Taxa Affected
  • Free-ranging (naturally occurring)
  • Experimental
Taxa FAMILIES recorded as containing Intermediate Host / Vector  Species
  • Free-ranging (naturally occurring)
  • Experimental

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Authors & Referees

Authors Debra Bourne (V.w5)
Referee Suzanne I. Boardman (V.w6); Becki Lawson (V.w26)

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