Nakouné Emmanuel, Kamgang Basile, Berthet Nicolas, Manirakiza Alexandre, Kazanji Mirdad
Laboratoire de Virologie, Institut Pasteur de Bangui, Bangui, Central African Republic.
Research Unit Liverpool School of Tropical Medicine, Organisation de Coordination pour la lutte contre les Endémies en Afrique Centrale, Yaoundé, Cameroon.
PLoS Negl Trop Dis. 2016 Oct 19;10(10):e0005082. doi: 10.1371/journal.pntd.0005082. eCollection 2016 Oct.
Rift Valley fever virus (RVFV) causes a viral zoonosis, with discontinuous epizootics and sporadic epidemics, essentially in East Africa. Infection with this virus causes severe illness and abortion in sheep, goats, and cattle as well as other domestic animals. Humans can also be exposed through close contact with infectious tissues or by bites from infected mosquitoes, primarily of the Aedes and Culex genuses. Although the cycle of RVFV infection in savannah regions is well documented, its distribution in forest areas in central Africa has been poorly investigated.
METHODOLOGY/PRINCIPAL FINDINGS: To evaluate current circulation of RVFV among livestock and humans living in the Central African Republic (CAR), blood samples were collected from sheep, cattle, and goats and from people at risk, such as stock breeders and workers in slaughterhouses and livestock markets. The samples were tested for anti-RVFV immunoglobulin M (IgM) and immunoglobulin G (IgG) antibodies. We also sequenced the complete genomes of two local strains, one isolated in 1969 from mosquitoes and one isolated in 1985 from humans living in forested areas. The 1271 animals sampled comprised 727 cattle, 325 sheep, and 219 goats at three sites. The overall seroprevalence of anti-RVFV IgM antibodies was 1.9% and that of IgG antibodies was 8.6%. IgM antibodies were found only during the rainy season, but the frequency of IgG antibodies did not differ significantly by season. No evidence of recent RVFV infection was found in 335 people considered at risk; however, 16.7% had evidence of past infection. Comparison of the nucleotide sequences of the strains isolated in the CAR with those isolated in other African countries showed that they belonged to the East/Central African cluster.
This study confirms current circulation of RVFV in CAR. Further studies are needed to determine the potential vectors involved and the virus reservoirs.
裂谷热病毒（RVFV）引发一种病毒性人畜共患病，在东非基本上呈现间断性动物流行病和散发性疫情。感染该病毒会导致绵羊、山羊、牛以及其他家畜患上严重疾病并流产。人类也可能通过与感染性组织密切接触或被主要为伊蚊属和库蚊属的受感染蚊子叮咬而接触到病毒。尽管在稀树草原地区RVFV的感染循环已有充分记录，但对其在中非森林地区的分布情况研究甚少。
方法/主要发现：为评估RVFV在中非共和国（CAR）生活的家畜和人类中的当前传播情况，采集了绵羊、牛和山羊以及有风险人群（如饲养员、屠宰场工人和牲畜市场工作人员）的血样。对样本进行了抗RVFV免疫球蛋白M（IgM）和免疫球蛋白G（IgG）抗体检测。我们还对两个本地毒株的完整基因组进行了测序，一个于1969年从蚊子中分离出来，另一个于1985年从生活在森林地区的人类中分离出来。在三个地点采集的1271只动物样本包括727头牛、325只绵羊和219只山羊。抗RVFV IgM抗体的总体血清阳性率为1.9%，IgG抗体的总体血清阳性率为8.6%。仅在雨季发现了IgM抗体，但IgG抗体的频率在不同季节没有显著差异。在335名被认为有风险的人群中未发现近期RVFV感染的证据；然而，16.7%的人有既往感染的证据。将在CAR分离的毒株的核苷酸序列与在其他非洲国家分离的毒株的核苷酸序列进行比较，结果表明它们属于东非/中非簇。
本研究证实了RVFV在CAR的当前传播情况。需要进一步研究以确定潜在的传播媒介和病毒宿主。
