MERS remains prevalent in camels in Saudi Arabia

A survey of slaughterhouses in Riyadh reveals continued risk of zoonotic transmission

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The virus responsible for Middle East respiratory syndrome (MERS), is prevalent in camels slaughtered for meat in Saudi Arabia, according to a new study. 

Dromedaries, the intermediate host, are the only known source of human MERS infections. The virus was first detected in Saudi Arabia in 2012, and  has infected approximately 2,900 people in 27 countries and caused 858 deaths.  With a mortality rate of 34.4%, MERS-CoV is considered to be among the deadliest of the three recently emerged human coronaviruses. 

To assess the risk of future zoonotic transmission, the team surveyed the three main slaughterhouses in Riyadh in the winter of 2019, collecting nasal swabs and blood from  171  young and healthy camels. The nasal swabs were examined using RT-PCR to detect the infection and serum samples were tested using ELISA to detect the neutralizing antibodies. Genetic diversity of positive isolates was determined through the amplification and sequencing of the spike gene.

The team reported a high prevalence (38.6%) and seropositivity (70.8%) of MERS-CoV. This indicates ongoing circulation of MERS-CoV infection in camels in these slaughterhouses. Efforts should be made to protect people in close contact with camels including veterinarians, slaughterhouse and camel workers. 

“The greatest concern is a spillover event that would end up in an outbreak in humans,” says Naif Alharbi, the director of the Vaccine Development Unit at KAIMRC and co-author of the study. “That could happen at any point.”

The researchers also analysed the spike gene of the virus in their samples, and revealed high genetic stability. According to Alharbi, this indicates “that the virus is circulating in camels and getting accustomed to camels as a host without a biological or immunological pressure that would push the virus to change its genetic makeup.” 

Although public health measures such as strict hygiene and moving camel markets to the periphery of cities were introduced in the Kingdom, Saudi Arabia still experiences the highest caseload of MERS. This highlights the urgent need for further action to prevent zoonotic transmissions and outbreaks. 

The authors conclude more research is needed to assess the impact of the virus on public health and potential infection control measures. They also highlight the value of developing a vaccine targeting the spike protein to help combat the virus in camels.

References

  1. Alharbi, N.K. et al, High Rate of Circulating MERS-CoV in Dromedary Camels at Slaughterhouses in Riyadh, 2019. Viruses, 12, 1-10 (2020). | article

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