Intestinal Fluke Infection in Lagomorphs

• This parasite was first collected in 1892. (B614.11.w11)
• Life cycle: Adult flukes inhabit the small intestine. Eggs are passed in the faeces and ingested by small land snails, e.g. Vertigo ventricosa. Miracidia hatch and penetrate the intestine. Sporocysts are then established in and around the snail's digestive gland. The development to the infective stage (metacercaria that develop within the snail) takes twelve weeks. Infection of a susceptible host occurs when it ingests an infected snail. (B614.11.w11)
• Patency: 21 to 25 days. (B614.11.w11)
• Survival of adult flukes: at least 260 days in the host. (B614.11.w11)

Hasstilesia texensis 

• This parasite is also found in lagomorphs and is morphologically very similar to Hasstilesia tricolor. (B614.11.w11)

• Hasstilesia tricolor 
• Hasstilesia texensis 

Clinical signs

• In Sylvilagus floridanus - Eastern cottontail:
  • Emaciation and death soon after capture and transfer to outdoor enclosures. (J1.10.w6)

Pathological findings

Gross pathology

• In Sylvilagus floridanus - Eastern cottontail:
  • Often no associated pathology reported. (J1.10.w6)
  • GIT: 
    • In the small intestines, enteritis and heavy infection with flukes. (J1.10.w6)
    • Severe catarrhal enteritis. (J40.4.w1)

Histopathology

• In Sylvilagus floridanus - Eastern cottontail:
  • Small intestines: extensive destruction of villi next to flukes, also fluke-to-fluke attachment.. (J1.10.w6)

Occurrence

• Hasstilesia tricolor is found in wild lagomorphs in the USA. Oryctolagus cuniculus - European rabbit is also reported to be susceptible. (B614.11.w11)
• Hasstilesia tricolor Stiles and Hassel 1894 in Lepus americanus - Snowshoe hare "and related species." (B272.8.w8)
• High prevalence of infection with Hasstilesia tricolor in Sylvilagus floridanus - Eastern cottontail in Virginia, USA. (J1.10.w6)
• Hasstilesia tricolor were found in Sylvilagus floridanus - Eastern cottontail in central Pennsylvania; ova were found in 14.6% of faeces examined as well as adults being found in the stomachs/small intestines. (J1.16.w18)
• Hasstilesia tricolor were found in 37% of 260 Sylvilagus floridanus - Eastern cottontail in the southeastern USA. (J1.16.w19)
• Hasstilesia tricolor were found in the small intestines of 16% of 45 Sylvilagus floridanus - Eastern cottontail in western Kentucky, USA, over a period of 15 months starting winter 1979. (J1.19.w15)
• Hasstilesia tricolor is found in wild lagomorphs in the USA including Sylvilagus floridanus - Eastern cottontail and Lepus americanus - Snowshoe hare. (J515.78.w1)
• Hasstilesia texensis has been found in Oklahoma cottontail Sylvilagus floridanus alacer (Sylvilagus floridanus - Eastern cottontail), Texas jackrabbit Lepus texianus (Lepus californicus - Black-tailed jackrabbit), and Sylvilagus aquaticus - Swamp rabbit. (J515.78.w1)
• Hasstilesia tricolor was found during a study of Sylvilagus floridanus - Eastern Cottontail in Virginia. (J524.60.w1) 
• Hasstilesia tricolor was found in 3% of rabbits In a study of Sylvilagus floridanus - Eastern Cottontail in a high density population on Fishers Island, New York, where they had been introduced. (J40.8.w1)
• In 210 Sylvilagus floridanus - Eastern cottontails from Iowa, Hasstilesia tricolor was found in 11 individuals (5.2%); in one rabbit amore than 10,000 flukes were estimated to be present. These flukes were usually found in the first 50 cm of the small intestine. In eight individuals with heavy infections, a severe catarrhal enteritis was noted. (J40.4.w3)
• In a study of cottontails [probably Sylvilagus floridanus - Eastern Cottontail] in the eastern USA, Hasstilesia tricolor was found in the intestines of 41% of 27 rabbits. (J40.7.w1)
• In a study of Sylvilagus floridanus - Eastern Cottontail (Sylvilagus floridanus mearnsi) from southern Minnesota, USA, 1932-1945, Hasstilesia tricolor was detected in one of 97 rabbits. (J40.11.w1)
• In Sylvilagus aquaticus - Swamp rabbit, Hasstilesia tricolor and Hasstilesia texensis. (J469.151.w1)
• In Sylvilagus floridanus - Eastern cottontail in Alabama, 1939,found in 10/50 rabbits (20%), with always at least 30 flukes present and some having heavy infections in the upper third of the small intestines. Mostly they were free in the gut lumen but some were attached to or embedded in the mucosa. (J332.28.w3)
• Hastilesia tricolor found in Sylvilagus floridanus - Eastern Cottontail. (J469.136.w1)
• A fluke, Ogmocotyle sp. was found was found in the small intestines of 1/3 Pentalagus furnessi - Amami rabbit. (J469.782.w1)

• Environmental Assessment
• History & Documentation
• Physical Examination of Mammals
• Necropsy of Mammals
• Imaging in Lagomorph Diagnosis and Treatment
• Clinical Pathology of Lagomorphs
• Treatment and Care
• Environmental and Population Management
• Preventative Medicine for Mammals
• Chapter 2 - B36 Field Manual of Wildlife Diseases - Specimen Collection and Preservation
• Chapter 3 - B36 Field Manual of Wildlife Diseases - Specimen shipment
• Appendix A - B36 Field Manual of Wildlife Diseases - Sample specimen history form

• Lepus americanus - Snowshoe hare
• Lepus californicus - Black-tailed jackrabbit
• Oryctolagus cuniculus - European rabbit
• Pentalagus furnessi - Amami rabbit
• Sylvilagus aquaticus - Swamp rabbit
• Sylvilagus floridanus - Eastern cottontail