Assessment of interactions between African swine fever virus, bushpigs (<em>Potamochoerus larvatus</em>), <em>Ornithodoros</em> ticks and domestic pigs in north-western Madagascar

International audienceP>Since its introduction in Madagascar in 1998, African swine fever (ASF) has severely affected national pig production and persists as a common disease in that country. Two of its natural hosts in the African continent, the bushpig (Potamochoerus larvatus) and tick vectors of the Ornithodoros moubata complex, are reported in west and central regions of the island. However, their role in the maintenance and transmission of the virus has been insufficiently studied. In this work, we tried to assess their potential role in the epidemiology of the disease in Madagascar, by assessing the levels of interaction between (i) ASF virus (ASFV) and bushpigs and (ii) between soft ticks and domestic and wild suids in north-western Madagascar. Twenty-seven sera and 35 tissue samples from bushpigs were collected and analysed for the presence of anti-ASF antibodies and viral DNA. In addition, the sera from 27 bushpigs and 126 domestic pigs were analysed with an ELISA test for the detection of antibodies against salivary antigens from Ornithodoros ticks. No circulation of ASFV or anti-ASFV antibodies nor anti-tick antibodies were detected in bushpigs. However, seven of the domestic pig sera (5.6% of the total sample population) were antibody positive for O. moubata antigens. The probability of freedom from ASFV in the bushpig population using Bayesian statistical methods ranged between 73% and 84%. The probabilities of absence of anti-tick antibodies in domestic and wild pigs were estimated at 63% and 71%, respectively. These preliminary results suggest that bushpigs are unlikely to play a significant role in the maintenance and transmission of ASFV in Madagascar. Nevertheless, further ASFV surveys are needed on that species to confirm this assumption. In addition, the presence of antibodies against O. moubata in domestic pigs suggests that soft ticks may be able to maintain ASFV within a domestic pig cycle in areas of Madagascar where they remain present

West Nile virus infection in horses, Indian ocean

International audienceThe circulation of West Nile virus (WNV) in horses was investigated in the Southwest Indian ocean. In 2010, blood samples were collected from a total of 303 horses originating from Madagascar, Mauritius, Reunion and the Seychelles and tested for WNV-specific antibodies. An overall seroprevalence of 27.39% was detected in the Indian Ocean with the highest WNV antibody prevalence of 46.22% (95% CI: [37.4–55.2%]) in Madagascar. The age and origin of the horses were found to be associated with the WNV infection risk. This paper presents the first seroprevalence study investigating WN fever in horses in the Southwest Indian Ocean area and indicates a potential risk of infection for humans and animals. In order to gain a better understanding of WN transmission cycles, WNV surveillance needs to be implemented in each of the countries

Le réseau régional AnimalRisk : de la surveillance à la recherche dans l'Océan Indien

National audienceThe Animal Risk regional network: surveillance and research in the Indian Ocean. To meet the challenges of emerging diseases in the Indian Ocean region, in 2009 animal health stakeholders set up the Animal Risk-OI network, designed to provide technicaland scientific support to surveillance systems and to suggest ways of improving health risk control in the area. The network is supported by OIE referring bodies for the Indian Ocean—veterinary services and animal health research organizations. Animal Risk-OI is not intended to replace current monitoring systems but to help consider arising issues through bimonthly webconferences, annual meetings and quarterly newsletters, and to provide information for research aiming to clarify theepidemiology of certain diseases and recommend suitable control measures. This paper presents the preliminary findings following the monitoring and investigation of diseases considered by network partners to be of top priority. Apart from pursuing synergy between surveillance and research activities, the network aims to bridge the gap between animal and human health to instigate ajoint, standardized approach to the assessment and control of health risks in the Indian Ocean region.Pour répondre aux défis lancés par les maladies émergentes dans l’Océan Indien, les acteurs de la santé animale ont mis en place depuis début 2009 le réseau AnimalRisk-OI. Ce réseau a pour objectif d’apporter un soutien technique et scientifique aux systèmes de surveillance et de proposer des réponses pour une meilleure gestion des risques sanitaires dans la zone. Les partenaires sont les référents de l’OIE dans l’Océan Indien, à savoir les services vétérinaires ainsi que les structures de recherché impliquées en santé animale. Le réseau AnimalRisk-OI n’a pas pour vocation de se substituer aux systèmes de surveillance existants, mais il est chargé d’animer une réflexion autour des problématiques observées par des téléweb conférences bimensuelles, des réunions annuelles et des bulletins d’information trimestriels et de nourrir des actions de recherche qui visent à mieux comprendre l’épidémiologie de certaines maladies et donc de proposer des mesures de gestion adéquates pour mieux les maîtriser. Les premiers résultats de la surveillance et des investigations sur certaines maladies considérées prioritaires par les partenaires sont présentés ici. Les orientations envisagées, outre la poursuite de la synergie entre les actions de surveillance et de recherche, sont un rapprochement avec la santé humaine pour permettre une approche commune et harmonisée de l’appréciation et de la gestion des risques sanitaires dans l’Océan Indien