Epidemiology and Control of Infectious Bursal Disease (Gumboro) in Kenya

1. EpidemiologyandControlofInfectiousBursalDisease(Gumboro)in Kenya
JaneW. K.Githinji1
; FrancescaStomeo2
; NicholasSvitek3
;PhilipKitala4
;Lily Bebora4
; Lucy Njagi4
1-DirectorateofVeterinaryServices,Kenya 2-BiosciencesEasternandCentralAfrica-InternationalLivestockResearchInstituteHub
3- VaccinesBiosciences,InternationalLivestockResearchInstitute,Nairobi,Kenya 4-UniversityofNairobi,Kenya
Introduction
Poultry production is a growing and economically important activity among the Kenyan rural small-scale holder families. Poul-
try is mainly owned by women and youth. Infectious diseases are the key limiting factors to increasing poultry production in
most developing countries, including Kenya. Infectious Bursal Disease (IBD), also known as Gumboro disease, is among the
prevalent viral diseases diagnosed in Kenyan chicken. The disease is caused by the IBD virus, a double stranded bi-segmented
RNA virus. The virus multiplies primarily in the immature B-lymphocytes in the Bursa of Fabricius, the main organ responsible
for production of B-lymphocytes in young chicken, causing severe damage to the bursa. Damage to the Bursa of Fabricius is
characterized by immunosuppression and subsequent increased susceptibility to other infectious diseases, as well as interfer-
ence with effective vaccination for control of other infectious diseases. Adequate levels of maternally derived IBD antibodies
protect young chicks under 2wks old from IBD. Infectious bursal disease occurs worldwide. In Kenya, imported commercial
vaccines are available for prevention of IBD and are used by most farmers, usually from 2wks of age. The disease has been
detected among vaccinated and unvaccinated chicken. Effective vaccination against IBD should be based on the epidemiologic
characteristics of IBD in Kenya, including virus strains responsible for the disease. For instance, mild or intermediate vaccines
will not be effective against very virulent IBD virus strains which are able to break through the vaccines. The disease causes
major economic losses due to deaths, vaccination costs and reduced production.
Acknowledgements
Directorate of Veterinary Services, Kenya ISPC SF-2016
The research
The current study will determine the epidemiology
of IBD in poultry, mainly chicken, in Kenya, as a
prerequisite to the development of an effective
IBD control strategy.
Justification
The epidemiology of IBD in Kenya has not been
studied. Controlling IBD supports control of all
other infectious diseases. Many poultry farmers
have had to give up poultry farming after incurring
heavy losses caused by occurrence of infectious
diseases, and this despite spending heavily on
vaccines and antimicrobial drugs.
Objectives
 Determine the epidemiology of infectious
bursal disease in Kenya
 Compare genetic characteristics of IBD
viruses circulating in Kenya with currently
used vaccines
 Determine the role of maternally derived
IBD antibody levels, in the epidemiology of
IBD in Kenya
Materials and Methods
Bursal tissues, or spleen tissues where the bursa
has regressed, will be collected from poultry cases
submitted at the veterinary laboratories, strategi-
cally spread across the country. Two specimens
will be collected, one in RNA later (for molecular
work) and the other stored frozen ( for future
virus isolation, if needed). The tissue samples will
be used for RNA extraction, RTPCR, gene se-
quencing and phylogenetic analysis. Epidemiologi-
cal data will be collected, preferably through the
study specific questionnaire or through the rou-
tine Laboratory Specimen Submission Form. Infor-
mation on vaccines currently in use will be ob-
tained from the farmers, the Directorate of Veter-
inary Services and from the Agrovet supply cen-
tres. Serum specimens will be collected from day
old chicks from at least 50% top hatcheries supply-
ing farmers with day-old chicks. The sera will be
tested for protective levels of IBD antibodies in
day-old chicks supplied to farmers., using antibody
ELISA tests
Expected outputs
 Information on the epidemiology of IBD in
Kenya
 Molecular characteristics of IBD viruses circu-
lating in Kenya will be available
 Risk factors for IBD will be available
 Role of hatcheries in the control of IBD in
Kenya will be assessed.
 Scientific based information for development
of an IBD control policy for Kenya will be
available
 Scientific information on which to base spe-
cific vaccination schedules will be available
 Potential for locally manufactured and more
appropriate vaccine (s)
 Potential for improvement of molecular
diagnostic tests for Kenyan IBD virus strains
Expected Outcomes
 Job creation and economic empowerment
for women and youth
 Poverty alleviation and
 nutritional improvement
 Sustainable livelihoods especially for the
rural poor and small scale farmers
 Increased poultry production
 Improved poultry health
 More profitable poultry production business-
es
Some Preliminary Sequence Results
Category
Num-
ber
%
(n=12)
average %
Identity)
Total speci-
mens tested 12 100%
No. of IBDV
Positive 12 100%
97.6 (10
NCIB hits
No. of vvIBD
virus strains 12 100%
97.6(10
NCIB hits)
No. of vvIBD-
Attenuated-
reassortant
strains 9 75%
97.3
(AB368968)
No. of vvIBD,-
non-
reassortant
(KJ621061) 3 25%
98.8
(KJ621061)