Rabies Virus Neutralizing Antibodies in Unvaccinated Rabies Occupational Risk Groups in Niger State, Nigeria | Chapter 13 | Current Trends in Disease and Health Vol. 1
Aims:
To determine the presence of rabies virus neutralizing antibodies (rVNA) as
well the potency of the rVNA in rabies occupational risk humans in Niger State
of Nigeria.
Study
Design: Cross-sectional study.
Place
and Duration: Research was conducted at the
Department of Veterinary Public Health, Ahmadu Bello University, Zaria, Nigeria
and Rabies Unit, Centers for Disease Control and Prevention, CDC, Atlanta, USA,
between May, 2012 and March, 2013.
Materials
and Methods: A total of 185 human volunteers were
recruited from rabies risk occupational groups who filled a structured
questionnaire on their previous bite history and vaccination status, between
May and July, 2012. A 2 ml each of blood from volunteers was collected and centrifuged
at 3000 rpm for 10 minutes and sera separated into pre-labeled vacutainers.
Standard Rapid fluorescent focus inhibition test (RFFIT) was used to detect the
presence of rVNA in the sera. Further end point titration of the rVNA positive
human sera was conducted to determine the potency.
Results:
The results indicated that, detectable titre of rVNA was recorded in 16.4% (23
of 140) viable human sera screened. Although from the questionnaire survey,
21.7% (5 out of the 23 positives) responded to have been vaccinated over ten
years prior. At least 3 of the respondents (1 dog butcher and 2 dog meat
consumers) who responded not previously vaccinated had some neutralizing
antibody titre range of 0.65 – 0.7 IU/ml which is above the minimum protective
titre (0.5IU/ml) recommended by WHO. Similarly, 3 respondents (2 veterinarians
and 1 animal health personnel) who responded to have been previously vaccinated
(> 10 years earlier) yet had a high titre range of 0.5 – 5.4IU/ml. The
highest specific rate for rVNA of 25% each was seen amongst the dog butchers
and pet owners followed by hunters (20%) and dog meat consumers (14.8%). Up to
125 (67.6%) of the volunteers do consume dog meat with only 12 (9.6%) of them
being dog butchers who source dogs for slaughter from households within and
outside their territories.
Conclusion:
Although the WHO minimum protective titre of rVNA is 0.5 IU/ml, the presence of
relatively high titres amongst these risk groups in this report is an
indication of a serious public health threat. This study recommends the
vaccination of rabies high risk groups and further screening of rabies
occupational risk and non risk groups in the study area and Nigeria at large.
This study concludes that there is serological evidence of rVNA in the serum of
vaccinated and unvaccinated rabies occupational risk groups in Nigeria. Rabies
occupational risk groups are at risk of contracting rabies without overt
symptoms of rabies, but serological response with some reasonable titres that
may or may not be protective.
Author(s) Details
Dr. A. Garba
Diagnostics and Extension
Department, National Veterinary Research Institute, Vom, Nigeria.
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