Hooo-Hooo Volume 11 Nr 1 - Page 14

WildLife Group of the SAVA PCR, and/or histopathology. Arboviral diseases – These are caused by a diverse group of vector-borne viruses (usually mosquitoes and midges). Viruses that have been reported in viruses include Shuni virus (Orthobunyavirus), Sindbis and Middelburg viruses (Alphaviruses), and West Nile virus (Flavivirus). Shuni, Sindbis and Middelburg viruses have been identified in rhinos with neurological signs; weakness, progressive paralysis and death within 24 hours of recumbency. West Nile virus (WNV) infection has been suspected in zoo rhinos, causing nonspecific signs such as lethargy. Rhinos in endemic areas commonly develop antibody titres (up to 1:640). Antibodies to other arboviruses have been found in rhinos, but not associated with disease; Wesselbron, African Horse Sickness, Bluetongue and Rift Valley Fever (high seroprevalence in some areas). Diagnosis is usually by serological tests (ELISA, plaque reduction neutralization test, etc.). Other available tests include PCR and immunohistochemistry for some viruses. Management requires good vector control and consideration of vaccination in captive rhino (for example WNV). FUNGAL DISEASE Aspergillosis – Fungal pneumonia caused by Aspergillus sp. has been identified primarily in captive black rhinos. These cases were usually associated with immunosuppressive diseases or therapy (e.g., steroid administration). All rhinos had concurrent disease such as anaemia, mucocutaneous ulcers or TB. Diagnosis is based on Aspergillosis serology, fungal culture, and/or histopathology. Treatment (e.g., itraconazole) is usually unsuccessful. PROTOZOAL AND PARASITIC DISEASES Tick-borne protozoal diseases – Babesia bicornis (piroplasm) has been reported to cause mortalities in black rhinos in Tanzania and RSA; the organism has also been found in healthy animals. Disease may be precipitated by stress. Theileria bicornis (piroplasm) has also been found in black and white rhinos in Kenya and RSA, but has not been associated with disease. Cowdria ruminantium (rickettsia) may infect black and 14 white rhinos, based on the presence of antibodies to heartwater found in animals in Zimbabwe. Neosposis (N. caninum) – N. caninum is a coccidian parasite of domestic dogs found worldwide. Transmission is faecal-oral or transplacental. Abortion, acute death (myocarditis) have been seen in white rhinos, and may also cause neurological signs. Diagnosis is based on serological tests (ELISA, IFAT, agglutination), immunohistochemistry, or PCR. Trypanosomosis (T. vivax, T. congolense, T. simiae, T. godfreyi, T. evansi) – Mortalities due to trypanosomosis have been associated with translocation of black and white rhinos from fly-free to tsetse areas. Animals exhibit loss of condition, weakness, and death associated with anaemia, leukopenia, thrombocytopenia, and hypoproteinaemia. There has been a fatal outbreak of T. evansi in Sumatran rhinos in a Malaysian sanctuary. Acquired immunity results in asymptomatic infection until an individual is subjected to stress. Diagnosis is based on blood smear, PCR, IHC, and ELISA. Management requires tsetse control and possibly strategic use of trypanocides (diminazene aceturate). Filarial skin disease – Stephanofilaria dinniki is a subcutaneous parasite of black rhinos that usually results in self-limiting skin disease. Clinical manifestation may be associated with environmental conditions and stress. There has been an outbreak of skin lesions in black and white rhinos in Meru Nationa Park. Although the parasites were not identified, lesions responded to treatment with ivermectin, amoxicillin and debridement. TOXIC, METABOLIC/NUTRITIONAL, NON- INFECTIOUS AND IDIOPATHIC DISEASES Cyanobacteria intoxication – Blue-green algae (Microcystis spp., others) release biotoxins that are hepato- and neurotoxic. Ingestion while drinking results in death of rhinos and other species due to liver and respiratory failure. On necropsy, the liver is enlarged and friable, with widespread areas of