Phylogeography of Rift Valley Fever Virus in Africa Reveals Multiple Introductions in Senegal and Mauritania

Abstract

Rift Valley Fever (RVF) virus (Family Bunyaviridae) is an arthropod-borne RNA virus that infects primarily domestic ruminants and occasionally humans. RVF epizootics are characterized by numerous abortions and mortality among young animals. In humans, the illness is usually characterized by a mild self-limited febrile illness, which could progress to more serious complications. RVF virus is widespread and endemic in many regions of Africa. In Western Africa, several outbreaks have been reported since 1987 when the first major one occurred at the frontier of Senegal and Mauritania. Aiming to evaluate the spreading and molecular epidemiology in these countries, RVFV isolates from 1944 to 2008 obtained from 18 localities in Senegal and Mauritania and 15 other countries were investigated. Our results suggest that a more intense viral activity possibly took place during the last century compared to the recent past and that at least 5 introductions of RVFV took place in Senegal and Mauritania from distant African regions. Moreover, Barkedji in Senegal was possibly a hub associated with the three distinct entries of RVFV in West Africa.

Severe Human Illness Caused by Rift Valley Fever Virus in Mauritania, 2015

“…Males were more likely to be affected, as previously observed in 2015 [4, 7, 24]. This result can be explained by the fact that men tend to occupy the high risk occupations, such as shepherds and breeders [4, 14–16].…”

“…As a consequence of this outbreak, a surveillance system was developed to detect animal cases in Mauritania, Senegal, and other West African countries [24]. As in previous epidemics of RVF [3, 9–13], an outbreak of abortions and perinatal mortality in herds (sheep, goats, cattle, and camels) preceded the human epidemic in 2015.…”

Enquête d’investigation sur des cas de fièvre de la vallée du Rift au Tagant, Mauritanie

“…La fièvre de la vallée du Rift (FVR) est une zoonose due à un virus à ARN appartenant au genre Phlebovirus, de la famille des Bunyaviridae [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16]. Cette zoonose est transmise par les moustiques.…”

“…Toutefois, des complications graves, telles que des hémorragies peuvent survenir [1,16]. La FVR a été isolée pour la première fois au Kenya en 1930, [1,15,16] et la majorité des foyers de FVR ont été décrits dans des pays africains : en Afrique de l'Est où des flambées de FVR ont été signalées de 1977 à 2007, en Égypte, au Kenya, en Somalie, en Tanzanie, en Somalie et au Soudan [15]. En Afrique australe, plusieurs épidémies à grande échelle ont été observées depuis 2010 en Afrique du Sud, au Botswana et en Namibie [12].…”

Comprehensive Phylogenetic Reconstructions of Rift Valley Fever Virus: The 2010 Northern Mauritania Outbreak in the Camelus dromedarius Species

“…In autumn of 1987, a major RVF epizootic was observed in ruminants of the Senegal River Valley, followed by human outbreaks (Digoutte et al 1989). Subsequent RVF epizootics associated with human cases occurred in 1993, 1998, and 2003(Soumaré et al 2012. Favorable environmental conditions, mainly rainfall, are the key factors causing unusual viral emergence of mosquito vectors, leading to a larger number of infected domestic animals being considered as amplifying hosts.…”