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Rift Valley fever (RVF) is an acute zoonotic viral disease of domestic ruminants
in mainland Africa and Madagascar. The disease may exist in non-clinical form
in apparently health animals. This study was designed to investigate the existence
and spatial distribution of non-clinical form of RVF virus (RVFV) activity in
wild and domestic animals in six districts in northern Tanzania. A retrospective
cross-sectional study involved testing a total of 285 and 100 serum samples
from domestic ruminants and wildlife species, respectively. The samples were
subjected to IgG and IgM enzyme-linked immunosorbent assay (ELISA) as well
as to the Real-time Polymerase Chain Reaction (RT-PCR). Based on ELISA test,
the seroprevalence of RVF-specific IgG antibodies was: African buffalo (40.9%,
n=22), African elephant (33.3%, n=3), cattle (11.8%, n=93), sheep (11.3%, n=97)
and goats (8.4%, n=95). Two serum samples from goats tested positive for IgM.
All samples tested were RVFV-negative based on RT-PCR test. The highest intravillage
sero-prevalence of IgG was observed in two villages (Kimotorok and
Lormorije) of Simanjiro district. Domestic ruminants from herds that were located at an elevation below 1000m were at higher risk (OR=2.32, 95% CI 1.05 – 5.16,
p=0.04) of RVFV infection. Findings of the current study indicate existence of a
wide range of domestic and wildlife hosts which could serve as potential reservoirs
of RVFV during inter-epidemic period. This calls for adoption of one health
approach in responding to RVF epidemics as well as during implementation of
RVF controlling measures with the ultimate goal of eradicating RVF in Tanzania. |
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