Fascioloidosis is an allochthonous parasitic disease in Europe caused by the digenean trematode
Fascioloides magna
. The final hosts of
F. magna
in Europe are defined as definitive, aberrant and dead-end. Roe deer are aberrant hosts in which juvenile flukes permanently migrate through the liver parenchyma. Failure in pseudocysts formation leads to the death of both the host and the parasite. In this paper we present gross and histological findings of
F. magna
infection in 34 roe deer. The special emphasis is on the pseudocyst formation accompanied with new fluke's migratory channels observed in 7 animals, suggesting reinfection and prolonged survival of roe deer. No
F. magna
eggs were recovered from the faeces of the infected animals. These findings indicate that pseudocyst formation is essential for roe deer survival, but also point out the potential beginning of adaptation processes in roe deer, altering otherwise acute and fatal disease into a chronic one.
A serologic survey of the blacktail jackrabbit ( Lepus californicus ) for infections with 10 arboviruses was conducted from 1971 through 1974 along the Sacramento River in Butte County, California. Of 325 animals captured and bled a total of 493 times, 40% were found positive for hemagglutination-inhibiting (HI) antibody to California encephalitis (CE) virus, 34% to western equine encephalomyelitis (WEE) virus, 20% to Buttonwillow virus, 15% to St. Louis encephalitis (SLE) virus and 12% to Main Drain virus. Only 5 and 2% of the animals had HI antibodies to Lokern and Turlock (TUR) viruses, respectively. There was no serologic evidence for infection of animals with Powassan, Modoc and Rio Bravo viruses. Differenles in monthly and yearly activities of some viruses were found by analyses of lata on antibody prevalence rates and immunologic conversions in recaptured animals. Experimental studies revealed that subadult jackrabbits were highly susceptible by subcutaneous inoculation to infection with CE, WEE and SLE viruses but were refractory to infection with TUR virus. All animals infected with CE and WEE viruses developed viremia that persisted for 2 or 3 days after inoculation and then developed antibodies that were detectable from 7 through at least 56 days after infection. In contrast, only 2 of 7 animals that developed HI antibodies to SLE virus had viremia, and at barely detectable levels; and HI antibodies were undetectable in 3 of the 7 animals at 56 days after infection.
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