K?rber G
K?rber G. 200 000 people and resulting in over 600 deaths, and in Kenya and Somalia (1997C1998) affecting over 89 000 people and resulting in more than 450 deaths [5, 6]. During epidemics, the virus devastates livestock, including cattle, sheep, goats, and camels, with mortality rates reaching 30% in adult animals and up to 100% in young animals [7C9]. Abortions occur in up to 100% of pregnant cattle, sheep, and goats [8, 9]. The virus causes periodic epidemics in both Eastern Africa (Kenya, Somalia and Tanzania) as well as other African countries including Zimbabwe, South Africa, Egypt, Mauritania, Senegal, The Gambia, and Madagascar [5, 9, 10C12]. Of these countries, severe outbreaks of RVFV involving both humans and livestock have been most frequent in Kenya. In 2000, the virus was introduced into the Arabian Peninsula following a severe outbreak in Saudi Arabia and Yemen associated with importation of livestock from East Africa in 2000C2001 [13C15]. An intriguing aspect of RVF epidemiology in Kenya is the periodicity of the outbreaks, between which inter-epidemic periods (IEPs) occur with low or no activity. Retrospective analysis of available livestock data collected through passive surveillance at the Kenya Ministry of Livestock and Fisheries Development starting from 1975 indicates that the increased numbers of RVFV cases were reported in 1990, 1997C1998, and recently in 2006C2007. In contrast, no cases were recorded between 1991 and 1996, and only one case was recorded between 2000 and mid-2006 [16]. Cryptic maintenance and transmission cycles of RVFV have been postulated but the exact mechanism remains poorly understood. The prevailing hypothesis is that RVFV is maintained in the eggs of floodwater mosquitoes belonging to the subgenera and [17, 18]. When the flood during heavy rainy seasons, transovarially infected mosquitoes hatch and the subsequent infected adult mosquitoes transmit the virus to domestic animals including sheep, goats, cattle, and camels. The and other flooded areas also serve as a habitat for mosquito species, which also utilize the habitat after the floodwater have rapidly disappeared [18C20]. The IL6 antibody domestic animals amplify the virus to high titres and provide a source of infection for the and other species that are capable of transmitting the virus beyond the habitat to additional livestock and humans. The involvement of wildife species during epidemics Cevipabulin (TTI-237) and the existence of sylvatic cycles involving wildlife and mosquitoes in maintenance and perpetuation of the virus during IEPs have never been investigated. The wildlife-mosquito cycling of RVFV could maintain the virus at low levels and might be difficult to detect if the wildlife reservoirs undergo mild or asymptomatic infections. When flooding occurs, the proliferation of the competent mosquito vectors Cevipabulin (TTI-237) results in the transmission of the virus possibly because more livestock animals are infected and have higher Cevipabulin (TTI-237) viraemias. This is followed by transmission from livestock to humans. It has been suggested that mosquitoes can transmit the virus to wild animals, particularly buffalo which can develop low viraemia with high survival, and possibly low abortion rates [17]. This wildlife-mosquito cycling may involve low-level livestock infections since limited data in countries where RVFV outbreaks occur suggest that between 25% and 23% of livestock may have been infected by RVFV during an IEP [21, 22]. Available data on the prevalence of RVFV antibodies in wildlife are limited and conflicting. A study of 281 black and white rhinos taken from Kenya, Namibia and South Africa between 1987 and 1997 found no antibodies by enzyme-linked immunosorbent assay (ELISA) against RVFV, whereas another study reported high levels of RVFV antibodies in black and white rhino, buffalo, and waterbuck taken from Zimbabwe [23, 24]. In this study, we investigated the presence of RVFV-neutralizing antibodies in diverse species of wildlife in Kenya collected from various regions, including regions where RVFV outbreaks have been documented in the past, during the 1999C2005 IEP. We also tested a limited number of wildlife specimens collected during the recent severe outbreak of 2006C2007 [25, 26]..