Epidemiology of Rabies in Ethiopia and Evaluation of the Rapid Immunodiagnostic Test Kit for Rabies Diadnosis
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Date
2011-12-01
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Addis Ababa University
Abstract
The aims of this study were to investigate the epidemiology of rabies in humans and animals and
to evaluate the diagnostic performances of the Anigen Rapid Rabies Ag Test Kit. Retrospective
data of 2008-20 II and 20091l 0 were used to analyze rabies in animals and humans, respectively,
mainly in and around Addis Ababa. A questionnaire was developed and used to get additional
epidemiological information during the study period (March to September, 2011). A total of 935
brain samples were examined during 2008-20 II. Of this total number, 77.6% (N=726) samples
were positive for rabies. The highest proportion, 87.2% (N=633) of the positive cases was
recorded in dogs followed by cats, 5.1 % (N=37). The frequencies of occurrence of rabies in other
species were very limited. This showed that dogs remain the dominant species in maintenance
and transmission of rabies to humans and other animals in Ethiopia. Further analysis of
characteristics of rabid dogs showed that owned, adult, non-vaccinated, male dogs were most
frequently diagnosed positive for rabies virus. Furious form of rabies was the most commonly
reported form of the disease in rabid dogs. Rabies cases were reported throughout the year with
slight variations among the months of the year. Its occurrence showed variation among
administrative regions depending on their distance from the laboratory. A total of 2345 people
received post-exposure prophylaxis in 20 I 0/20 II against rabies due to exposure to rabid or rabies
suspected animals and humans. The greater proportion of post-exposure prophylaxis was given to
humans exposed to rabid or rabies suspected dogs. Fermi type vaccine was the most common,
81% (1887/2337), vaccine type used for post-exposure prophylaxis. The majority, 72.3%
(165312286), of the post- exposure prophylaxis was given to humans bitten by animals with an
unknown rabies status. The mean number of exposed humans per rabid animal was about 3 with
a range of 0 to 15 persons. The gold standard test for rabies diagnosis is the fluorescent antibody
test, requiring a fluorescent microscope and additional laboratory equipment. Recently, a rapid
and easy immunodiagnostic test was developed which needs no specialized laboratory equipment
and needs less expertise. Anigen Rapid Rabies Ag Test Kit was evaluated using 115 brain
samples collected from dogs, cats and bovines. The sensitivity and specificity of the rapid
immunodiagnostic test were 96.5 (95% CI: 90.0 - 99.3%) and 100% (95% CI: 88.4 - 100%),
respectively compared to the fluorescent antibody test. This test could be useful for field use
particularly in rabies surveillance and also for targeted post-exposure prophylaxis where the
standard test is not available. Strategy for control and elimination of rabies should be in place and
implemented in Ethiopia. Furthermore, the rapid immunodiagnostic test kit should be evaluated
at larger scale using samples from different species of animals. Strategies for the application of
the rapid immunodiagnostic test for the improvement of rabies surveillance and subsequent post
exposure prophylaxis should also be studied
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Keywords
Anigen Rapid Rabies Ag Test Kit, Epidemiology, Ethiopia, Fluorescent antibody test, Rabies