This document reports a case of African horse sickness virus (AHSV) detected in a captive zebra in Nigeria. The zebra presented with fever and loss of appetite and died a few days later. Samples were tested and found to weakly test positive for AHSV via PCR, though the virus could not be isolated due to the samples being frozen. This represents the first reported case of AHSV in zebras in Nigeria and calls into question previous understandings of AHSV epidemiology in equids in the region.

1. A REPORT OF AFRICAN HORSE
SICKNESS VIRUS IN A CAPTIVE ZEBRA
NIGERIAN VETERINARY MEDICAL ASSOCIATION, 47th ANNUAL
CONGRESS. “THE VETERINARIAN AND NATIONAL FOOD
SECURITY”. 4-8th Oct. 2010, MAKURDI, BENUE STATE.

2. NVMA 47TH ANNUAL CONGRESS
SCIENTIFIC
SESSION
Lazarus, D. D*., Atuman, Y. J., Adamu, S.
S., Mshelia, W. P., Shamaki, D., Fasina, F. O.

3. AFRICAN HORSE SICKNESS (AHS)
 African horse sickness is an infectious but non-
contagious, insect-borne viral disease affecting all
species of equids.
 It is transmitted in the field by at least two species
of Culiciodes.
 African horse sickness is an OIE reportable
disease.

4. AETIOLOGY
 African horse sickness is caused by an Orbivirus of
the family Reoviridae.
Viscerotropic virus
Family: Reoviridae, Genus: Orbivirus
Nine different serotypes of the virus have been
described.

5. SEROTYPES
 All serotypes of AHS virus occur in eastern and
southern Africa; this distribution reflects the
geographic pattern of zebra, which cycle the virus
asymptomatically and probably serves as a
reservoir for the virus.
 Only AHS virus serotypes 9 and 2 are found in
West Africa, where zebra population is not much in
distribution.

6. SEROTYPES
 Periodically, AHS virus spread, beyond sub-
Saharan Africa and the disease has caused major
epizootics extending as far as Pakistan and India in
the east and Morocco, Spain and Portugal in the
west.

7. VIRUS CHARACTERISTICS
 The virus can be inactivated by:
repeated freezing and thawing
treatment with acetic acid (pH, 6.3 or lower),
remaining for 2 weeks at 37°C, or being
placed for 5 minutes at 70°C.

8. HOST RANGE
In order of decreasing severity of the disease
 Horses
 Mules
 Donkeys
 Zebras
Approximately 70-95% of all horses developing
the disease will die.

9. ROLE OF ZEBRAS
 Not much is known about the role of zebras in the
epidemiology of AHS in West Africa.
 AHS virus over winters in zebras in Kruger National
Park in South Africa, from where it spreads
eastwards and southwards every year.
 AHS remains endemic in zebras populations across
East and South Africa.
 They harbour the virus and are often the source of
sudden outbreaks in Africa.

10. HOST RANGE
Dogs can also become infected by eating
Infected meat.
 1987-90 outbreak in Spain:
Dogs that did not consume infected meat
were found to be seropositive, suggesting
infection with by arthropod bites.

11. HOST RANGE
 There is no evidence that humans can be infected
by field strains of the virus.
 However, intranasal exposure to neurotrophic
vaccine strains has caused encephalitis and retinitis
in humans.

12. CASE HISTORY
 A captive zebra in a Game Reserve in
Bauchi, Nigeria was presented with symptoms of
Inappetance and fever.
 The zebra died after days of the onset of the
clinical symptoms.
 Samples were collected and sent to the Viral
Research Division, National Veterinary Research
Institute, Vom for AHS diagnosis.

13. LABORATORY ANALYSIS
 Samples of lymph nodes and pooled tissues was
submitted to the laboratory on ice.
 The samples were processed and packaged
according to International Standard for the
transportation of infectious materials affecting
animals (UN 2900) and shipped to the Equine
Research Centre, University of Pretoria,
Onderstepoort, South Africa.
 Virus isolation was attempted in vero cells.

14. LABORATORY ANALYSIS
 Real Time PCR was also attempted in the
diagnosis.

15. LABORATORY ANALYSIS

16. LABORATORY ANALYSIS

17. LABORATORY ANALYSIS

18. RESULTS
 No virus was isolated from the samples in cell
culture; as the sample was submitted frozen.
 AHS genome was detected in the samples (Weakly
positive) at RT-PCR using magnetic beads and
probes.
 By this assay, virus complexed with antibody will
yield a positive result on RT-PCR and be negative
on virus isolation.

19. RESULTS
 This assay can detect AHSV in equine blood for at
least three months after infection.
 It is a highly sensitive test that can pick up the virus
at incubatory stage.
 It also analyses 96 samples within a period of 3-4hr.
 The entire process of analyses is automated from
extraction to reading of results.

20. DISCUSSION
 African horse sickness outbreaks have occurred in
Nigeria since the case was first reported in the
1970’s.
 This has occurred mostly in exotic horses imported
for Polo tournaments.
 So far, serotypes 9 and more recently 2 have been
reported in the country.
 To date, there has been no report of AHS in the wild
equidae population in Nigeria; hence we present
the first report of African horse sickness diagnosis
in zebra in Nigeria.

21. DISCUSSION
 Repeated and intermittent outbreaks of African
horse sickness in Nigeria has always been reported
in horses; donkeys, mules and zebras have been
reported to be markedly resistant with no apparent
clinical signs, except mild pyrexia and extended
periods of viraemia.
 This report calls to question the previous
understanding of the epidemiology of the disease
and open new areas of research in equidae viral
infections.

22. DISCUSSION
 It will also be important to consider more critically
the epidemiologic relationships (spatial and
temporal) that exist between the wild, captive and
domesticated equidae.

23. ACKNOWLEDGEMENT
 The management of NVRI, Vom.
 The management of ERC, UP Onderstepoort, SA.
 Professor Alan Guthrie
 Associate Professor Melvyn Quan
 Chris Joone
 All laboratory staff at NVRI and ERC, UP.
 Field staff that contributed so much in sample
collection.

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