Rift Valley Fever in Ruminants, Republic of Comoros, 2009

This work was supported with Fonds Européens de Développement Régional funds from the European Union within the Project “Programme de Coopération Scientifique sur les Maladies Animales Emergentes dans l’Océan Indien.”International audienceRift Valley fever (RVF) is caused by a Phlebovirus (family Bunyaviridae) transmitted by a wide range of mosquitoes (1). This zoonotic disease is present in Africa, the Middle East, and Madagascar. Infections by RVF virus (RVFV) in ruminants cause massive abortions in livestock and high death rates in young animals, which result in major economic consequences. Humans are infected by mosquito bites, contact, or inhalation of aerosols. RVF is frequently unapparent or mild for humans, inducing an influenza-like illness that occasionally leads to more serious complications such as hemorrhage, meningoencephalitis, retinopathy, or even death. The improvement of the Comorian veterinary services and the setting up of surveillance programs are essential to limit the risk of introducing devastating diseases in the area

Phylogeographic Reconstructions of a Rift Valley Fever Virus Strain Reveals Transboundary Animal Movements from Eastern Continental Africa to the Union of the Comoros

International audienceMajor explosive outbreaks of Rift Valley fever (RVF), an arthropod borne zoonotic disease, occur in humans and animals with significant mortality and economic impact across continental Africa and the Indian Ocean region (Madagascar, the Comoros archipelago). Recently, sporadic human cases have been reported in Mayotte and Grande Comore, two islands belonging to the Comoros archipelago. To identify the hypothetical source of virus introduction in an inter-epidemic or a post-epidemic period, a longitudinal survey of livestock was set up in Comorian ruminant populations, known to be susceptible hosts. The phylogeographic genomic analysis has shown that RVF virus (RVFV) detected in a zebu collected in Anjouan in August 2011 seems to be related to the last known epidemic of RVF which occurred in East Africa and Madagascar (2007–2009). This result highlights the fact that RVFV is maintained within local livestock populations and transboundary animal movements from eastern continental Africa to Indian Ocean islands likely result in RVFV crossover

Impact and Epidemiological Investigations into the Incursion and Spread of Peste des Petits Ruminants in the Comoros Archipelago: An Increased Threat to Surrounding Islands

International audienceLate October 2012, a great number of deaths of unknown origin occurred in goat herds in the suburbs of Ngazidja, located in the Comoros archipelago. Few weeks later, laboratory testing requested by the animal health authorities resulted in the identification of peste des petits ruminants (PPR) infection. Notably, the Index case could be attributed to a sick goat imported from Tanzania. Viral isolation was successful from the lungs leading to the whole N nucleoprotein gene sequencing. Phylogenetic analysis revealed that the strain belongs to the lineage III which includes strains of eastern African origin. In addition, to evaluate the impact of PPR on the Comorian indigenous domesticated ruminant population, a cross-sectional PPR serological survey was conducted between April and July 2013. A low overall PPRV antibody prevalence 2.24% (95% CI [1.38; 3.08]) was detected with a Grande Comore prevalence of 3.34% (IC = [2.09; 4.63]) with a limited spread of the disease mainly due to farm practices such as limited contacts between farm animals and rapid slaughtering of sick animals

Evidence for Circulation of the Rift Valley Fever Virus among Livestock in the Union of Comoros

Abstract Rift Valley fever virus (RVFV) is an arthropod-borne phlebovirus reported to be circulating in most parts of Africa. Since 2009, RVFV has been suspected of continuously circulating in the Union of Comoros. To estimate the incidence of RVFV antibody acquisition in the Comorian ruminant population, 191 young goats and cattle were selected in six distinct zones and sampled periodically from April 2010 to August 2011. We found an estimated incidence of RVFV antibody acquisition of 17.5% (95% confidence interval (CI): [8.9-26.1]) with a significant difference between islands (8.2% in Grande Comore, 72.3% in Moheli and 5.8% in Anjouan). Simultaneously, a longitudinal entomological survey was conducted and ruminant traderelated information was collected. No RVFV RNA was detected out of the 1,568 blood-sucking caught insects, including three potential vectors of RVFV mosquito species. Our trade survey suggests that there is a continuous flow of live animals from eastern Africa to the Union of Comoros and movements of ruminants between the three Comoro islands. Finally, a cross-sectional study was performed in August 2011 at the end of the follow-up. We found an estimated RVFV antibody prevalence of 19.3% (95% CI: [15.6%-23.0%]). Our findings suggest a complex RVFV epidemiological cycle in the Union of Comoros with probable inter-islands differences in RVFV circulation patterns. Moheli, and potentially Anjouan, appear to be acting as endemic reservoir of infection whereas RVFV persistence in Grande Comore could be correlated with trade in live animals with the eastern coast of Africa. More data are needed to estimate the real impact of the disease on human health and on the national economy

Evidence for Circulation of the Rift Valley Fever Virus among Livestock in the Union of Comoros

International audienceRift Valley fever virus (RVFV) is an arthropod-borne phlebovirus reported to be circulating in most parts of Africa. Since 2009, RVFV has been suspected of continuously circulating in the Union of Comoros. To estimate the incidence of RVFV antibody acquisition in the Comorian ruminant population, 191 young goats and cattle were selected in six distinct zones and sampled periodically from April 2010 to August 2011. We found an estimated incidence of RVFV antibody acquisition of 17.5% (95% confidence interval (CI): [8.9–26.1]) with a significant difference between islands (8.2% in Grande Comore, 72.3% in Moheli and 5.8% in Anjouan). Simultaneously, a longitudinal entomological survey was conducted and ruminant trade-related information was collected. No RVFV RNA was detected out of the 1,568 blood-sucking caught insects, including three potential vectors of RVFV mosquito species. Our trade survey suggests that there is a continuous flow of live animals from eastern Africa to the Union of Comoros and movements of ruminants between the three Comoro islands. Finally, a cross-sectional study was performed in August 2011 at the end of the follow-up. We found an estimated RVFV antibody prevalence of 19.3% (95% CI: [15.6%–23.0%]). Our findings suggest a complex RVFV epidemiological cycle in the Union of Comoros with probable inter-islands differences in RVFV circulation patterns. Moheli, and potentially Anjouan, appear to be acting as endemic reservoir of infection whereas RVFV persistence in Grande Comore could be correlated with trade in live animals with the eastern coast of Africa. More data are needed to estimate the real impact of the disease on human health and on the national economy., Rift Valley fever (RVF) is a viral disease transmitted by mosquitoes to ruminants. The disease may affect humans and has a great impact on the economy of the affected country. RVF occurs mostly in African countries, but epidemics have been reported in Madagascar and in the Arabian Peninsula. In the Union of Comoros, RVF virus (RVFV) has been suspected of continuously circulating since 2009 without any notifications of the typical clinical signs by the Comorian Animal Health Services. From April 2010 to August 2011, we conducted a livestock longitudinal survey in Grande Comore, Moheli and Anjouan. Our study aimed to detect RVFV-specific antibody acquisitions in cattle and goats. Simultaneously, a longitudinal entomological survey was conducted to describe the diversity of mosquitoes in the study zones and ruminant trade-related information was collected. Our investigations showed that Comoros ruminants acquired RVFV-specific antibodies all along the year and particularly in Moheli during the dry season. Our findings suggest a complex RVFV epidemiological cycle in the Union of Comoros with probable inter-islands differences in RVFV circulation patterns. The disease appears to be endemic in Moheli and potentially Anjouan, but the persistence of the disease in Grande Comore could be correlated with trade in live animals with the eastern coast of Africa