Eco-epidemiological characteristics of the 2006 – 2007 Rift Valley
fever outbreak in Tanzania: A retrospective analysis
Abstract
Tanzania was one of the countries that were heavily affected by the
2006/07 Rift Valley fever (RVF) epizootic that affected the entire
Eastern Africa region. In this study we used information on the
geographical locations of the reported cases (abortions and serological
data) to explore the eco-epidemiologic characteristics of the 2006/07
RVF outbreak in the north-eastern Tanzania. A total of 3819 small
ruminant serological samples were investigated, of which 68.40% (2614)
had serological results on IgM antibodies, and positive history of
abortions. Of the 2614 data, 1826 (69.9%), and 1135 (43.4%) had
information on abortion and IgM positive status respectively.
Suitability analysis showed that 80% of the study area favours the
occurrence of RVF. While a pair wise comparison of the risk difference
indicated short distances (≤ 15Km) to the points of livestock
congregations such auctions (Z = 20.32; P < 0.00001), dip
tanks (Z = 7.997; P < 0.00001), water bodies (Z = 19.209; P
< 0.00001), and transport network (Z = 13.589; P <
0.00001) were highly associated with the IgM seropositivity. Also,
proximity (≤ 30 Km) to the wildlife reservoirs was significantly (Z =
14.51; P < 0.00001) associated with the occurrence of RVF. The
same risk factors were highly (P < 0.00001) associated with
the occurrence of RVF related abortions. This work could have future
implications in informing a collaborative approach to develop and adapt
prevention and control strategies that will help manage the disease
risks, and the associated socio-economic and public health impacts.