Page 548 - The Veterinary Laboratory and Field Manual 3rd Edition

Important zoonotic diseases 485

species. People considered ‘at risk’, for example, appropriate samples for the laboratory. In some
animal handlers should be vaccinated against countries vaccination for cattle (and goats/
human strains of influenza to prevent co-infec- sheep) is recommended.
tion and subsequent genetic reassortment

cutaneous larva migrans
brucellosis
Cause: Hookworm (Uncinaria spp., Ancyclostoma
Cause: There are many species of Brucellae. The braziliense, A. caninum) Epidemiology: When
species of greatest importance for humans are there is a large population of dogs the environ-
Brucella abortus (from cattle) and Brucella meliten- ment soon becomes heavily contaminated with
sis (from goats and sheep). Brucella canis occurs dog faeces. Dog to dog transmission of canine
in dogs and Brucella suis in pigs (also reported parasites is rapid although older dogs usually
in other species including deer and occasion- have a degree of immunity which stops clini-
ally dogs). In some countries Brucella ovis is an cal parasitism becoming apparent. Humans and
important cause of infertility in sheep. puppies become infected when hookworm larvae
penetrate the skin and migrate through the tis-
Epidemiology: Brucellae are obligate intracel-
lular bacteria with a tendency to infect the sues. In humans A. braziliense is most commonly
reproductive system of animals. Most are fairly implicated.
host adapted although cross infections can and Signs in animals: There may be few signs
do occur. The greatest source of environmental although hookworm is more pathogenic than
contamination is following a Brucella induced Toxocara. In pups, there may be severe anaemia
abortion. Humans may become infected with Br. and sometimes death. In both puppies and dogs
abortus or Br. melitensis from abortion fluids or by there may be signs of dermatitis on the feet and
drinking infected milk as well as from discharges legs due to larval migration.
and fluids from apparently normal births.
Diagnosis: Parasite eggs in dog faeces.
Signs in animals: There may be no signs. The Control: Routine worming of dogs as outlined
organism can remain dormant in the tissues of for Toxocara sp.
a young cow or nanny goat until she becomes
pregnant. Abortion often occurs at about the
sixth month of gestation.
Hydatids
Diagnosis: Serum samples (preferably paired,
that is, a repeat sample taken 2–4 weeks after the Cause: Echinoccocus granulosus
first), milk, placenta, foetal stomach contents,
foetal liver/spleen. PCR or culture may also be Epidemiology: E. multilocularis is fairly wide-
performed where feasible. spread in Africa, Asia, South America and the
Middle East. It is a small tapeworm of dogs
Control: Cattle, especially milking cows (blood which has the intermediate stages of the life
and/or milk), should be tested for Brucella anti- cycle in sheep, cattle, goats, yaks and, occasion-
bodies. Infected animals should be isolated. ally, humans. Humans act as a dead-end host in
Milk should be boiled before consumption. this cycle but dogs become re-infected by inges-
Isolate animals which have aborted and bury tion of cysts in un-cooked infected meat and offal
any contaminated material after collecting the from meat animals (for example, ruminants).

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