Published: 26 Jul 2024 | Last Updated: 16 Aug 2024 17:40:01

New research led by the Royal Veterinary College (RVC) into the spread of MERS-CoV, the virus carried by camels which causes Middle East Respiratory Syndrome (MERS), has found that young camels present a high risk for human exposure to the virus, with kissing and petting young camels found to be an important route of viral transmission.

Like SARS-CoV-2, MERS-CoV is a respiratory virus and one of a small group of deadly zoonotic beta-coronaviruses to have emerged with global impact over the past two decades. Infection in camels causes only minor cold or flu symptoms, but infection in humans can be fatal. There have been more than 2,600 human cases identified to date, and 940 deaths reported across 27 countries.

Despite the high fatality rate among reported cases, zoonotic transmission pathways and camel subpopulations posing the highest risk have been poorly understood. However, this groundbreaking research identifies activities involving frequent close-quarter exposure to camel breath and nasal secretions as being high risk.

Young camels are known to shed high volumes of the virus when infected, due to lack of previous immunity, and kissing and petting is common practice among many camel-owning communities in the Middle East – where the animals are highly revered and cherished, above other livestock. The physical size of camels places their muzzles at human head height and activities such as feeding and watering, where camels crowd around individuals carrying feed sacks of filling troughs, were also found to be high risk.

Study findings, recently published in the journal Lancet Microbe, demonstrated that human-to-human transmission of the virus also appears to be happening in family household settings, with household members without camel contact showing evidence of viral exposure if sharing the household with other members who are positive, particularly those with camel contact. Diabetic household members were found to be 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 (human-to-human) transmission to occur.

The research was conducted by the RVC alongside experts from the London School of Hygiene & Tropical Medicine (LSHTM), Rocky Mountain Laboratories (NIH), Jordan University of Science and Technology (JUST), Yarmouk University and the Jordanian government. The research was a cross-sectional study between September 2017 and October 2018 and encompassed 879 people comprising 204 livestock-owning households in southern Jordan.

Findings highlight the importance of effective surveillance activities for the virus across the Arabian Peninsula and help identify which groups of humans and camels should be prioritised when vaccines currently in development become available.

Javier Guitian, Professor of Veterinary Public Health at the RVC, said:

“This study represents one of the largest epidemiological investigations of MERS-CoV among high-risk populations since the virus was first identified in Saudi Arabia in 2012. 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.

“When camel vaccines currently under development become available, young camels should be prioritised for vaccination. Public health education in camel-owning communities should aim to raise awareness and reduce the risk of zoonotic exposure, particularly through young camels’ nasal secretions.

“We are very grateful for all the support we’ve received from project partners and funders. This has allowed us to establish a multidisciplinary research team and build a relationship of trust with communities in Southern Jordan, which are central in confronting the global challenge posed by MERS-CoV.”

Professor Punam Mangtani, at LSHTM said:

“I am pleased to see our combined veterinary and human epidemiological research with Jordanian and US experts has been able to successfully investigate factors involved in the transmission of MERS-CoV across the animal-human interface.

“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 addtion, 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.

“The findings give greater urgency to co-create with affected communities, effective and acceptable interventions in to reduce spillover infections from camels, the reservoir for MERS-CoV, to humans.” 

The study was funded by UK Research and Innovation (UKRI). This work builds upon the long-standing relationship that exists between the RVC and partners at LSHTM, NIH and JUST – the relationship with JUST being first initiated through a World Organisation for Animal Health twinning initiative, with support from the UK International Biosecurity Programme (IBSP) and British Embassy in Jordan.

Notes to Editors

The key findings included:

• Eight per cent of household members were positive on blood tests showing evidence of previous exposure to the virus
• Ten per cent of households that owned camels contained at least one member showing evidence of a past infection on blood tests
• Positive blood test results were associated with frequent (more than weekly) interactions with young camels (less than a year old)
• Risk of transmission activities were identified as frequent kissing, petting, feeding and watering of young camels
• Attending camel races and elevated blood glucose were also associated with positive results for previous MERS-CoV exposure
• Older and diabetic individuals were more likely to be positive on blood tests showing an immunological response to the virus.
• Among individuals without any history of camel contact, a positive blood test result (showing evidence of past exposure to the virus) was associated with sharing a household with a member with camel contact, and positive on the same test, suggesting secondary human-to-human transmission of the virus is also occurring, alongside primary camel-to-human transmission.

Reference

Holloway P, Gibson M, Holloway T, Van Doremalen N, Munster N, Al–Omari, Letko M, Nash S, Cardwell J, Abu-Basha E, Hayajneh W, Mangtani P, Guitian J MERS-CoV exposure and risk factors for MERS-CoV ELISA seropositivity among members of livestock-owning households in southern Jordan: a population based cross-sectional study, Lancet Microbe, 2024.

The article can be accessed here: https://www.thelancet.com/journals/lanmic/article/PIIS2666-5247(24)00082-X/fulltext

For media enquiries, please contact:

• Jasmin De Vivo jasmin.devivo@plmr.co.uk or rvc@plmr.co.uk
• Press Line: 0800 368 9520

About the RVC

• The Royal Veterinary College (RVC) is the UK's largest and longest established independent veterinary school and is a Member Institution of the University of London. 
• It is one of the few veterinary schools in the world that hold accreditations from the RCVS in the UK (with reciprocal recognition from the AVBC for Australasia, the VCI for Ireland and the SAVC for South Africa), the EAEVE in the EU, and the AVMA in the USA and Canada. 
• The RVC is ranked as the top veterinary school in the world in the QS World University Rankings by subject, 2024. 
• The RVC offers undergraduate and postgraduate programmes in veterinary medicine, veterinary nursing and biological sciences. 
• The RVC is a research-led institution, with 88% of its research rated as internationally excellent or world class in the Research Excellence Framework 2021. 
• The RVC provides animal owners and the veterinary profession with access to expert veterinary care and advice through its teaching hospitals and first opinion practices in London and Hertfordshire.