Human–Dromedary Camel Interactions and the Risk of Acquiring Zoonotic Middle East Respiratory Syndrome Coronavirus Infection

Abstract

Impact• Dromedary camels are the only animal species for which there is convincing evidence that it is a host species for MERS-CoV and hence a potential source of human infections.• Direct contact with dromedary camels can only explain a small proportion of the primary cases. Other possible sources and vehicles of infection include food-borne transmission through consumption of unpasteurized camel milk and raw meat, medicinal use of camel urine and zoonotic transmission from other species.• In the Arabian Peninsula, dromedary camel production has intensified and is nowadays concentrated around cities. This may have facilitated the zoonotic 'spillover' infections from camels to humans, explaining the emergence of the virus in the human population in the Arabian Peninsula. SummaryMiddle East respiratory syndrome coronavirus (MERS-CoV) cases without documented contact with another human MERS-CoV case make up 61% (517/853) of all reported cases. These primary cases are of particular interest for understanding the source(s) and route(s) of transmission and for designing long-term disease control measures. Dromedary camels are the only animal species for which there is convincing evidence that it is a host species for MERS-CoV and hence a potential source of human infections. However, only a small proportion of the primary cases have reported contact with camels. Other possible sources and vehicles of infection include food-borne transmission through consumption of unpasteurized camel milk and raw meat, medicinal use of camel urine and zoonotic transmission from other species. There are critical knowledge gaps around this new disease which can only be closed through traditional field epidemiological investigations and studies designed to test hypothesis regarding sources of infection and risk factors for disease. Since the 1960s, there has been a radical change in dromedary camel farming practices in the Arabian Peninsula with an intensification of the production and a concentration of the production around cities. It is possible that the recent intensification of camel herding in the Arabian Peninsula has increased the virus' reproductive number and attack rate in camel herds while the 'urbanization' of camel herding increased the frequency of zoonotic 'spillover' infections from camels to humans. It is reasonable to assume, although difficult to measure, that the sensitivity of public health surveillance to detect previously

A Comparative Review of Animal Models of Middle East Respiratory Syndrome Coronavirus Infection

“…10,29,43 Although the exact mode of transmission between camels and humans is unknown, it is speculated that transmission may occur through direct contact, ingestion of unpasteurized camel milk, or contact with respiratory droplets or nasal secretions, which have been shown to carry high viral loads. 1,9,27,44 Despite the high prevalence of MERS-CoV in camels, viral transmission from camels to humans appears to be limited, and multiple countries with seropositive camels have yet to detect MERSCoV infections in humans. 18,32,49 …”

MERS: an emerging disease of the 21st century

“…Thus, this might have paved the way for possible spillover events between camels and human being; which manifested as a zoonosis like MERS. 27 A review of the South Korean outbreak in 2015, by Majumder et al revealed findings similar to those generated in KSA, but the case-fatality rate as discussed earlier was nearly half that of the Saudi's. 28 Nevertheless, it is important to mention here the concept of -super spreaders‖, where the literature has established the 20/80 rule in which a small percentage of individuals in any community is noted to direct most transmission occurrences.…”

“…Furthermore, there is evidence regarding other causes of infection, such as consuming camel raw meat and unpasteurized milk, remedial utilization of camel urine, and zoonosis from other species. 24 Regarding the human host, an epidemiological study conducted by Alsahafi et al that included the total reported cases of MERS-CoV in KSA between 2012 and 2015, has revealed that two-thirds of patients were males and that one third of them were elderly (>60 years old). Interestingly, the gender difference was reversed when considering the healthcare workers, where about 60% of the affected were females.…”

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“…The majority of primary cases do not report contact with animals 76,77 . Dromedary camels are ubiquitously present in the Middle East and have been part of desert cultures for centuries with cultural and economic importance.…”