Page 549 - The Veterinary Laboratory and Field Manual 3rd Edition

486 Susan C. Cork

Humans become infected by accidental ingestion A note on Echinococcus multilocularis
of tapeworm eggs in food contaminated with
dog faeces and other animals become infected The life cycle of E. multilocularis involves a
by ingesting contaminated pasture. Humans are definitive host (for example, foxes, coyotes
not infected by eating infected meat unlike the and domestic dogs) and an intermediate host
situation with the human tapeworms (for exam- (for example, wild rodents). The life cycle is
ple, Taenia saginata). completed after the definitive host consumes
a rodent infected with cysts. Humans can
Signs in animals: There may be no signs in ani- become infected by handling infected animals
mals or localized signs due to the location of or by ingesting contaminated food, vegetables,
a cyst. In dogs, there are no clinical signs and and water. The parasite causes alveolar
diagnosis often requires administration of a pur- echinococcosis (AE) in humans and it is hard
gative to find the eggs in the faeces (for example, to diagnose and treat. Lesions can be found in
arecholine). In humans, the cysts develop slowly the liver and lungs and can metastasize to other
but may form huge balloon sized fluid filled cysts organs. As with E. granulosis, humans are a dead-
in the liver and lungs. If cysts occur in the brain end or incidental host. The incidence of human
there may be clinical signs of headaches fairly infestation with E. multilocularis is increasing in
early on but if cysts occur in other organs the urban areas, as wild canids migrate to urban and
disease may not be apparent for several years. suburban areas and gaining closer contact with
human populations. The disease has extended its
Diagnosis: Cysts are seen in the intermedi-
ate host at post-mortem and meat inspection. range in North America and Europe in the last
Hydatid eggs may be seen (under the micro- few decades although remains fairly uncommon
scope) in the faeces of purged dogs. Dog faecal in humans. Disease prevention includes basic
samples should be handled with care, note that hygiene and preventing domestic dogs catch-
Taeniad eggs look similar to hydatid eggs and so ing and ingesting wild rodents. Where possible,
treatment should be inclusive for all dog tape- food crops should be fenced off to prevent wild
worms. CAT (computerized axial tomography) and domestic canids contaminating produce.
scans, ultrasound and radiography along with
exploratory surgery may be required to diagnose
the disease in humans. japanese b encephalitis

Control: Routine treatment of dogs with a suit- Cause: Flavivirus, related to West Nile Virus
able anthelmintic. Dosing should take place
every 6 months of all dogs in the area. Routine Epidemiology: The virus cycles naturally and
meat inspection is important to allow monitor- silently between marsh birds (for example, night
ing of the disease in intermediate hosts. Hygiene herons) and mosquitoes (for example, Culex
and careful handling of dog faecal samples. spp.). More common in marshlands. Accidental
Burial of dog faeces. Wash hands, after handling mosquito borne infection of humans and horses
any dog, and before eating food. Wash fresh pro- may occur. Transplacental infection occurs in
duce well if there is a risk of contamination with pigs and newborn piglets may act as amplifier
carnivore faeces. Never feed raw offal to dogs hosts.
unless it is known to be free of hydatids.
Signs in animals: Horses: Sweating, dementia,
aimless wandering, photophobia, muscle trem-
ors, ataxia. Mortality rate 5%. Recovery may be

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