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
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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