Baby camels identified as key factor in animal to human MERS virus transmission 

Research led by the Royal Veterinary College in collaboration with colleagues in London, the USA and Jordan revealed that affectionate treatment of the animals increases the risk of catching Middle East Respiratory Syndrome (MERS) after contracting the virus.

Kissing and petting highly prized young animals is common practice among many camel-owning communities in the Middle East. Their size means their muzzles are close to human head height, with feeding and watering crowds of camels also a high risk, as individuals come into close proximity with the animals’ breath and mouth secretions.

MERS-CoV forms one of a small number of zoonotic beta-coronaviruses to emerge with global implications since the start of the century. While camels themselves suffer only mild symptoms, for humans the virus can prove fatal; although the number of human cases reported is relatively small with 2,600 identified in 27 countries, there have been nearly 1,000 deaths.

The research published in Lancet Microbe, also revealed the occurrence of secondary or human-to-human transmission, in households where some members had had no direct camel contact. Diabetes sufferers were deemed particularly at risk of infection. 

Camel races were also found to be a high risk environment for infection, with potential for both primary (camel-to-human) and secondary transmission.

RVC scientists worked with peers from the London School of Hygiene & Tropical Medicine, the US Rocky Mountain Laboratories, as well as the government of Jordan and the country’s University of Science and Technology and Yarmouk University. The original research based in the Middle Eastern state consisted of a cross-sectional study from September 2017 to October 2018 and included 879 individuals from 204 livestock-owning households in southern Jordan.

RVC professor of veterinary public health Javier Guitian said the UK Research and Innovation-funded study was one of the largest epidemiological investigations of MERS-CoV among high-risk populations since the discovery of the virus in Saudi Arabia in 2012. 

He said: “Our findings highlight the role of contact with juvenile dromedary camels and attendance at camel races in zoonotic transmission. Additionally, we provide evidence in support of within-household transmission among camel-owning communities. Effective surveillance among these high-risk groups remains a global health priority. 

He urged that when camel vaccines under development become available, young camels should be prioritised for vaccination.

LSHTM professor in epidemiology Punam Mangtani added: 

“Although we were aware that young camels shed high viral loads, we have now shown that these animals also pose a higher risk of viral transmission to humans. We have, in addition, shown in this serosurvey of camel-owning compared to other livestock-owning households, that antibodies giving an indication of past infections were also present in household members not in direct contact with camels.

“This indirect evidence suggests the occurrence of asymptomatic transmission to household members, some of whom may be frailer and more susceptible to severe disease from MERS-CoV infection.”

Pic: RVS