A review of zoonotic viral pathogens in dromedary camels (Camelus dromedarius)

Dromedary, or one-humped camel Camelus dromedarius, is an almost exclusively domesticated species, common in arid areas as both beasts of burden and production animals for meat and milk. Approximately 30 million dromedary camels have the highest numbers in Africa and the Middle East. The hardiness of camels in arid regions has made humans more dependent on them, especially as a stable protein source. Camels also carry and may transmit disease-causing agents to humans and other animals. The ability of camels to act as a point source or vector for the disease is a concern due to increasing human demands for meat, lack of biosafety and biosecurity protocols in many regions, and growth in the interface with wildlife, where camel herds become sympatric with non-domestic species. We conducted a literature review of camel-borne zoonotic diseases and found that most publications (65%) focused on the Middle East respiratory syndrome (MERS) and Rift Valley fever. The high mortality from MERS outbreaks from 2012 to 2016 elicited an immediate response from the research community, as demonstrated by a surge of MERS-related publications. However, we contend that other camel-borne diseases such as Crimean–Congo hemorrhagic fever are essential to include in surveillance efforts. Camel populations, particularly in sub-Saharan Africa, are increasing exponentially in response to prolonged droughts, and thus, the risk of zoonoses increases as well. This review provides an overview of the major zoonotic diseases present in dromedary camels, their risk to humans, and recommendations to minimize spillover events