Species/Taxa Recorded and Diagnostic Method used for Confirmation

WN virus has been isolated from frogs (Rana ridibunda - Marsh frog) and haemagglutination inhibition antibodies have been detected in a wetland snake species (Natrix natrix - Grass snake) and a pond turtle Clemmys caspica (Emydidae - Pond turtles (Family)). More recently WNV infection has been confirmed in the USA associated with clinical signs and mortality in Florida Alligators (Alligator mississippiensis - American alligator (Alligatoridae - Alligators & Caimans (Family)) and associated with neurological signs in a Crocodile monitor (Varana salvidorii) (Varanidae - Monitors (Family), and antibodies have been recorded in crocodiles Crocodilus niloticus: Crocodile (Crocodylidae - Crocodiles (Family)) in Israel. It has been shown experimentally that infected frogs can act as a source of virus to infect mosquitoes, and virus loads in serum of alligators have been shown to rise above those at which mammals are considered to be able to act as amplification hosts.

(J84.9.w8, J84.9.w12, J91.18.w1, J114.3.w1, J114.6.w1, J115.13.w3, P39.3.w8, P39.4.w16, P48.1.w4, W27.14Nov02.wnv1, W27.15Nov02.wnv1, W27.20Nov03.wnv1)

Anura - Frogs and toads (Order)

Rana ridibunda - Marsh frog:

• Tajikistan (River Kafiringan), 1985. Natural infection without apparent clinical disease. West Nile virus (three strains) isolated from blood and internal organs of frogs. (J114.3.w1)
• Tajikistan (River Kafiringan), 1985. Experimental infection. West Nile virus transmitted frog to Culex pipiens mosquitoes to frog, and from frog to mosquitoes and then from the mosquitoes to 1-2-day-old mice. (J114.6.w1)

Squamata - Scaled reptiles (Order)

Natrix natrix - Grass snake:

• Austria [no date stated]. Natural infection. Haemagglutination inhibition (HI) antibodies reported in 24/25 individuals. (J115.13.w3)

Crocodile monitor (Varana salvidorii) (Varanidae - Monitors (Family))):

• USA (Zoo), 1st August 2001-28th February 2002. Natural infection with neurological clinical signs. Infection confirmed by presence of WN virus antibodies by PRNT. (P39.3.w8)

Crocodylia - Alligators & Crocodiles (Order)

Florida Alligators (Alligator mississippiensis - American alligator (Alligatoridae - Alligators & Caimans (Family))):

• USA (Florida), 2002: Natural infection confirmed in three farm-raised alligators. Positive PCR and immunohistochemistry, also virus isolation. (W27.14Nov02.wnv1, W27.15Nov02.wnv1)
• USA (Georgia) 2001, 2002: Natural infection confirmed by RT-PCR and virus isolation following epizootics in farmed alligators in the fall of 2001 and the fall of 2002. Death of about 250 individuals November to December 2001 and more than 1,000 individuals in 2002. A variety of bacterial infections were noted also. (J84.9.w8)
• USA (Florida) 2002: Natural infection in farm-reared alligators, with extremely high viraemia detected. (P48.1.w4)
• USA (Florida) 2002: Natural infection, epizootic characterised by neurological disease at an alligator farm in Florida. Death of about 300 of 9,000 animals. Virus detected, reaching 10^8.9 log₁₀ pfu/0.5cm³ in liver but lower in brain and spinal cord at 10^6.6 log₁₀ pfu/0.5cm³. Plasma contained 10^3.6 to 10^6.5 log₁₀ pfu/0.5cm³ (P39.4.w16)
• USA (Louisiana) 2003: Natural infection in alligators on three separate farms, mainly hatchlings eight to nine inches long but also some individuals, 14-18 inches long, from the previous year's hatching. About 10% to 50% of individuals dies per affected building. (W27.20Nov03.wnv1)

Crocodilus niloticus: Crocodile (Crocodylidae - Crocodiles (Family)):

• A survey of 20 healthy farmed crocodiles in the Negev Desert, southern Israel, found 14/20 (70%) to be seropositive for WNV, titres ranging from 1:20 to 1:320. It was not possible to state whether they had been exposed at their present location or at their breeding farms, although infection at the present site would be compatible with the lack of difference in seroprevalence between individuals originating from two different farms. (J84.9.w12)

Testudines - Turtles and Tortoises (Order)

Clemmys caspica (Emydidae - Pond turtles (Family)):

• Israel, 1965-1966: Natural infection. Group B arbovirus (probably WN virus) haemagglutination inhibition antibodies detected in 2/18 individuals (11%). (J91.18.w1) 

• Anura - frogs and toads (Order)
• Squamata - Scaled reptiles (Order)
• Crocodylia - Alligators & Crocodiles (Order)
• Testudines - Turtles and Tortoises (Order)