Page 551 - The Veterinary Laboratory and Field Manual 3rd Edition

488 Susan C. Cork

Control. Isolate sick animals. Streptomycin- to humans. Humans become infected when bit-
penicillin in large doses may be effective in ten by infected fleas, this is more likely when
treating cases although some animals become living in crowded rat-infested accommodation.
persistent carriers. If Leptospira sp. induced The epidemic plagues (like the black death in
abortion is confirmed then all stock (including the middle ages) are now rare although the
pigs) should be tested for leptospirosis (using disease still occurs sporadically in Asia and
molecular methods or serology) to identify the the Americas. Wildlife biologists working with
source of infection. In some countries vaccina- ground squirrels have been infected. The pneu-
tion is available for livestock. monic form of the disease is transmitted from
human to human by aerosol.
Signs in animals and humans: Infected rodents
Meliodosis
develop septicaemia and die; the fleas leave the
Cause: Burkholeria pseudomallei dead host to infect a new one. Humans and other
animals may develop the bubonic form of the
Epidemiology: This organism is common in the disease which is named due to the formation of
environment of rice paddies and wet areas. It buboes (enlarged lymph nodes) in the axillae
is a species of bacteria that is carried by many and groin. The bubonic form can be fatal within
wildlife species, especially rodents, as well as a few days if not treated with antibiotics. Fever
domestic stock and may be passed in the faeces and malaise, enlarged spleen, vomiting and so
of healthy animals. Signs in animals: There may on also occur as the disease develops. The pneu-
be none. In horses, there may be a ‘glanders-like monic form in humans is initially respiratory
disease’ with mild respiratory signs or systemic and later becomes systemic. In cats and dogs the
disease with fever and occulonasal discharges. disease is more frequently localized and pres-
Recovery is often complete. Diagnosis: The ents itself as a skin lesion and enlarged regional
Mallein skin test is available to diagnose the dis- lymph node.
ease in horses. Nasal discharge and/or tissues
may be submitted for culture/microscopy/PCR Diagnosis: Fixed and fresh tissues for micros-
screening. copy and culture. PCR can also be used. In the
live animal culture of blood may allow isolation
Control: Isolation of clinical cases. Handlers of the organism. Whole blood, serum and spu-
should wash hands after handling sick animals tum samples from clinical cases and skin lesion
and before handling healthy animals, equipment biopsy from affected cats or dogs may be useful.
should not be shared between animals. Note
that Glanders in horses is caused by B. mallei, Control: Control rodents and fleas. Large doses
this disease is also zoonotic. of streptomycin-penicillin combinations may be
used to treat cases. Vaccines are available for
humans.
Plague

Cause: Yersinia pestis (Pasteurella pestis) rabies
Epidemiology: This bacterium can survive in the Cause: Lyssavirus
environment for prolonged periods. The typical
urban cycle for bubonic plague involves rodents Epidemiology: Sylvatic (wild) and urban cycles
and the rodent flea with accidental transmission exist. The virus is usually transmitted via the

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