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Original Research
1.
Epidemiological investigation of bovine blindness
syndrome in local and improved herds in Mkinga
district of Tanzania -
Emanuel Senyael Swai, Esron Daniel Karimuribo, Paul
Yohana Kisaka, Benedeta N. Mwawado
Vet World. 2012; 5(10): 581-589
doi:
10.5455/vetworld.2012.581-589
Abstract
Aim: A demand-driven epidemiological field
and laboratory investigation of a 'bovine blindness
syndrome, BBS' was conducted in Mkinga district of
Tanzania during the period of June through August,
2009.
Materials and methods: Participatory
epidemiological (PE) methods including focus group
discussion (FGD), proportional piling and matrix
scoring were used to characterize clinical signs,
disease impact and risk factors for BBS as perceived
by livestock keepers. PE investigation was
complimented by microbiological culture of ocular
discharges (n = 96 swab samples), clinical
examination of animals and entomological
investigation of the 'butterfly insects like' that
were suspected by livestock keepers to be associated
with BBS.
Results: Matrix scoring showed
moderate to good agreement between informant groups
on the clinical signs, risk factors, disease impact
and occurrence which coincides with rainy season.
Clinical examination of cattle (n=177) from six
villages revealed that 72 (40.7%) presented
discharges from eyes, of which the majority had
serous discharges (n=35; 48.6%) while muco-purulent
and dried discharges were recorded in 19.2% and
32.2% of the animals, respectively. Of the 37 cattle
that were found to be blind (based on obstacle
test), most were affected in the right eye and the
prevalence of blindness was significantly higher in
indigenous than in cross-bred cattle (26.1% vs 5.4%,
p=0.0027). Entomological examination of insect
specimens identified the suspected 'butterfly
insects' to be moths that belong to the species
Arcyophora longivalvis, reported to serve as
mechanical carriers for Moraxella bovis, a bacterium
that causes Infectious Bovine Keratoconjuctivitis (IBK
or Pinkeye) which among others, it causes blindness
in cattle. M. bovis was isolated from 83.7% of 96
samples cultured.
Conclusion: It is concluded
that blindness in cattle in the area under study
district was due to M. bovis infection. To the best
of our knowledge, this is the first study in East
Africa which has associated A. longivalvis moths
with transmission of IBK. Appropriate disease
prevention and control measures for pinkeye should
be adopted in order to safeguard animal health in
Mkinga.
Keywords: Arcyophora longivalvis,
Cattle, Moraxella bovis, Tanga, Tanzania
