Rift Valley Fever Virus Infection in African Buffalo (Syncerus caffer) Herds in Rural South Africa: Evidence of Interepidemic Transmission

Abstract

Abstract. Rift Valley fever virus (RVFV) is an emerging biodefense pathogen that poses significant threats to human and livestock health. To date, the interepidemic reservoirs of RVFV are not well defined. In a longitudinal survey of infectious diseases among African buffalo during [2000][2001][2002][2003][2004][2005][2006], 550 buffalo were tested for antibodies against RVFV in 820 capture events in 302 georeferenced locations in Kruger National Park, South Africa. Overall, 115 buffalo (21%) were seropositive. Seroprevalence of RVFV was highest (32%) in the first study year, and decreased progressively in subsequent years, but had no detectable impact on survival. Nine (7%) of 126 resampled, initially seronegative animals seroconverted during periods outside any reported regional RVFV outbreaks. Seroconversions for RVFV were detected in significant temporal clusters during 2001-2003 and in 2004. These findings highlight the potential importance of wildlife as reservoirs for RVFV and interepidemic RVFV transmission in perpetuating regional RVFV transmission risk. Sabie (2003Sabie ( -2006 regions of the park ( Figure 1 ). Briefly, from a defined sub-region of Kruger National Park having a buffalo population of approximately 3,000, 593 buffalo were captured at 302 georeferenced locations by using aerial or ground darting techniques, working in close collaboration with veterinarians in Kruger National Park.Captured animals were tested for exposure to infections and uniquely branded and given subcutaneous insertion of microchip tags for later identification. A subset (n = 167) were fitted with either radio collars or global positioning system collars for tracking and weekly to monthly follow-up. Because male and female buffalo have horns, it was impossible for a radio collar to come off an animal without tearing through the belting. We identified mortality events by the belting still being intact and the remains of a carcass. We assumed that a radio collar had fallen off if the belting was severed and no carcass was present after an extensive search of the area. 18 We estimated time since death (0-30 days) using the extent of carcass remains.18 During the study, there were 288 live repeat captures among the 593 buffalo studied and 55 documented deaths among the 167 tracked animals.Ethical approval. Institutional Animal Care and Use Committee approval was through University of California Berkeley #R217-0402 to Wayne M. Getz. This protocol was also reviewed and approved by the Animal Care and Use Committee for the South Africa National Parks.Animal assessment. Animals < 5 years of age were assigned to an age group on the basis of physical examination for incisor eruption pattern.19 Age of animals ≥ 5 years of age at the time of first examination was determined by visual comparison of horn development and body size to a calibrated photographic reference collection. 17,20 Four age groups were considered: youngest = 1-3 years, mid-low = 3-5 years, mid-high = 5-8 years, highest = more than 8 years.Testing for antibodies ...

High seroprevalence of Rift Valley fever phlebovirus in domestic ruminants and African Buffaloes in Mozambique shows need for intensified surveillance

“…A high seroprevalence in buffaloes has been demonstrated by many researchers mainly in sub-Saharan Africa especially in South Africa [59,60] and Kenya [61]. In our study, seroprevalence was also high.…”

“…In our study, seroprevalence was also high. African buffaloes are known to be a common host of RVFPV [60]. Other study performed in African buffaloes reported lower seroprevalence, 7.5% (34/541) in Zimbabwe [6], compared to this study.…”

Cross-Sectional Survey of Rift Valley Fever Virus Exposure in Bodhei Village Located in a Transitional Coastal Forest Habitat in Lamu County, Kenya

“…12,21,22 Effective surveillance and prevention (livestock vaccination) will require inclusion of border areas, such as the transitional coastal forests of Kenya, as risk zones during future periods of El Niñ o/Southern Oscillation (ENSO) excess rainfall in the Horn of Africa. 23 Improved warning systems through more detailed mapping combined with early intervention should aid in preventing recurrence of the severe RVF outbreaks of the past.…”

Seroprevalence of Rift Valley fever virus in livestock during inter-epidemic period in Egypt, 2014/15

“…Antibodies against RVFV were detected in several studies in different African countries during inter-epidemic times (e.g. prevalence rates of 21, 15.6 and 12.5% in South Africa, Kenya and Botswana respectively [37–39]).…”