More than 2000 dromedaries -- Arabian camels -- have died since August 10 in Saudi Arabia. Various theories have been put forward to explain the numerous deaths. For several years, the Sahel and the Horn of Africa have also seen similar numbers of deaths. In 1995-1996, CIRAD worked on a fatal epizootic disease affecting dromedaries in Ethiopia.
Analyses are being conducted to confirm or rule out the hypothesis of food intoxication in the countries concerned. Poisoning caused by the ingestion of toxic plants, mycotoxins (microscopic fungi), or mineral deficiencies has also been suggested. The deaths are probably due to a multitude of factors, which have a detrimental effect on the immune system, including some viruses which could increase the severity of infections or parasitic infestations in animals.
As Bernard Faye, head of the animal resources department at CIRAD, explains: "For years, we have been witnessing new pathologies in camels. There is nothing to suggest that the causes of these diseases are identical because the symptoms are not always the same."
The morbillivirus of small ruminants
The morbillivirus, which affects small ruminants, is found in Africa, the Arab Peninsula, the Middle East and India. It affects sheep and goats, in particular, but can affect other species. The disease is characterised by a high temperature, body lesions, pneumonia and death within 8 days.
In Ethiopia, during 1995-1996 and in Kenya and Sudan at the start of 2000, the virus PPR (small ruminant virus), was identified as being the potential cause of the death of hundreds of dromedaries. The clinical and epidemiological observations combined with the laboratory results (serology tests, viral detection), would suggest that this virus plays a role in the emergence of an enzootic disease among camel populations in the Horn of Africa. Other pathogens have been isolated but their presence could be due to the fact that the animals’ immuno-defence systems are depressed because of the presence of this virus.
"Additional research is required in order to determine the causes of this disease and to identify whether or not the PPR virus has a role to play, such as continued virology diagnoses, epidemiological studies to measure the respective roles of the virus, other pathogenic agents and environmental risk factors ", according to Franηois Roger, Head of CIRAD’s research unit (UPR) Epidemiology and ecology of animal diseases. " In this way, we could contribute to understanding the causes of the emergence of this disease and its socio-economic impact."
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