General information

 

Cowpox virus infections (see EAZWV fact sheet info) have been reported as a cause of a severe, sometimes fatal disease in Asian elephants in European zoos. African elephants can be affected as well, but usually the lesions in this species are restricted to the skin and they tend to heal quickly. The causative virus is an orthopox virus, affecting rodents (endemic hosts), elephants, (wild felids), tapirs, okapis, antelopes, rhinoceros, primates (including humans).

It causes local or generalized vesicular lesions of the skin and mucous membranes and can develop into a systemic disease, affecting the lungs and GI-tract. Intra-uterine infection in an Asian elephant has been reported.

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Pox infection in elephants is a zoonotic disease and has been reported in human caretakers after contact with affected elephants.

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Although the direct source of pox virus infections in elephants has never been found, it is generally accepted that infection takes place by consumption of roughage that has been contaminated with urine from affected rodents.

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Pox lesions in elephants occur on the skin (predominantly the trunk and the legs) and mucous membranes (tongue oral cavity). Lesions on the foot soles can result in complete sole detachments. 

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One still birth case has been reported in an Asian elephant in a European zoo, that had been vaccinated twice with Modified Vaccina Ankara strain on days 293 and 322 of its pregnancy. A full-grown calf (117 kg)  was born a-term with generalized pox lesions on the skin, air ways and gastro-intestinal track as  well as the spleen and liver. The dam nor any of the other (vaccinated) elpehants in the same herd were affected. 

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Treatment

Treatment of a pox virus infection is symptomatic. Antibiotic treatment should be considered as a prevention of a secondary bacterial infection.

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Prevention

Vaccination is strongly recommended for elephants living in European zoos.

First injection injections (s.c. or i.m.) of 4 ml MVA at the age of 12-16 weeks. Second injection injections (s.c. or i.m.) of 4 ml MVA 4 weeks after the first injection. The producer of the vaccine advices and offers titer measurement before the vaccination and 3-4 weeks after second vaccination). In young and untrained elephants this may be not possible, and vaccination should be practiced without titer control. Booster vaccinations: generally once every 2-3 years, depending on the titer. Vaccination during pregnancy: following this vaccination advice, elephants should be immune before they become pregnant. There are no sound studies about the possible side effects of vaccination on the fetus. New non-vaccinated imports or elephants with unknown vaccination status should not be bred before they are properly vaccinated.

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Contact with rodents worldwide should be avoided.