Emerging viral diseases in dromedary camels in the Southern Morocco.

During the last fifteen years, new viral diseases such Bluetongue (BT), West Nile (WN), African horse sickness (AHS), Epizootic hemorrhagic disease (EHD) and Peste des Petits Ruminants (PPR) have extended their geographic distribution and emerged in North Africa and in Europe. Camel (Camelus dromedarius) is considered as a potential vector in the transmission of some of these diseases while it is host-specific for Camelpox (CP). A serological survey was conducted on 1392 sera to estimate changes of these diseases prevalence in camels over two different time spans (2003 and 2009) and across different sites of South Morocco. Results indicate clearly that BT was circulating in camels before the first notified outbreak in Morocco (2004) with 42% positive sera in Guelmim in 2003. BT and WN prevalence's increased over time from 11 to 25% and from 10 to 13% respectively. Higher prevalence of both diseases was found in camels living in oases indicating an increased intensity of viral circulation in these sites. Camels have been tested negative for AHS, EHD and PPR viruses while higher CP prevalence has been detected in camels living in Smara, the most closed site to eastern borders (i.e. Mauritania). The seroprevalence of CP in camels at interval of 7 years increases from 23% to 37%. This survey could provide information on the possible use of camel as a sentinel animal for surveillance of emerging diseases such BT and WN.

Experimental infection of camels with bluetongue virus.

Three camels aged 4-5 years were experimentally infected with Bluetongue virus serotype 1 (BTV-1) and were observed for 75 days. No clinical signs of disease were observed throughout the experiment, however all three animals seroconverted and developed BTV-1 specific neutralising antibodies after challenge. All three camels developed a viraemia from 7 days post infection albeit at a lower level than that usually observed in experimental infections of sheep and cattle. Virus was isolated from the blood of all three animals suggesting that camels may act as a reservoir for BTV and play an important role in its transmission.