If the finding of MERS in Kenyan camels sounds a little familiar, it is because a little over a year ago – in EID Journal: MERS Antibodies In Camels – Kenya 1992-2013 - we saw a study using archived camel blood samples going back 20 years that found MERS-like antibodies were circulating in Kenya as early as 1992.
What Corman et al. found last year was that the camel density appeared to influence the rate of seropositivity. Camels from the sparsely populated Laikipia County in southern Kenya only coming in with about a 10% positive rate, while seropositivity in the more populous Northern and Eastern counties ran as high as 78%.
Today’s report (based on recently obtained blood samples) shows a marked increase, to roughly 47% positive among 335 camels – sampled from 9 different camels herds - in Laikipia county. The authors write:
Although Laikipia County camel density is low relative to more northern regions of Kenya, our study suggests the population is sufficient to maintain high rates of viral transmission and that camels may be constantly re-infected and serve as long term carriers of the virus .
This lack of lasting immunity has come up before (see EID Journal: MERS Coronavirus In A Saudi Dromedary Herd), and while work is being done on a vaccine, a big unanswered question is how protective it would be for camels.
But the real $64 question is: Why have we not seen any human infections with the MERS virus in places like Kenya, Somalia, and Sudan, even though camels there have been shown to carry the virus?
The authors suggest this may be due to a lack of surveillance and testing in the region, or perhaps the virus in the Middle East has recently evolved to make the zoonotic jump to man, while the virus in Northern Africa has not. It is hoped that genetic sequencing and side-by-side comparison of these viruses will provide some badly needed answers.
Below you’ll find a press release from the University of Liverpool on today’s findings, followed by a link to the (open access) study.
Public Release: 16-Oct-2015
University of Liverpool
A new study has found that nearly half of camels in parts of Kenya have been infected by the virus that causes Middle East Respiratory Syndrome (MERS) and calls for further research into the role they might play in the transmission of this emerging disease to humans.
MERS was first identified in Saudi Arabia in 2012 and there is currently no vaccine or specific treatment available. To date, it has infected 1,595 people in more than 20 countries and caused 571 deaths. Although the majority of human cases of MERS have been attributed to human-to-human infections, camels are likely to be a major reservoir host for the virus and an animal source of MERS infection in humans.
A team of scientists from the University of Liverpool and institutions in the USA, Kenya and Europe, surveyed 335 dromedary - single humped - camels from nine herds in Laikipia County, Kenya and found that 47% tested positive for MERS antibodies, showing they had been exposed to the virus.
Professor Eric Fèvre, Chair of Veterinary Infectious Diseases at the University's Institute of Infection and Global Health said: "Although Laikipia County camel density is low relative to more northern regions of Kenya, our study suggests the population is sufficient to maintain high rates of viral transmission and that camels may be constantly re-infected and serve as long term carriers of the virus. MERS in camels, it seems, is much like being infected by the common cold.
"The significance of this is not yet clear, because we don't know if the virus is universally zoonotic. While the risk of these camels spreading MERS to humans cannot yet be discounted, it appears to be, for now, very low as there have been no human cases diagnosed in Kenya.
"It might be that the mutations required to make this virus zoonotic have only evolved recently in the Middle East, where the human outbreaks have so far been concentrated."
Lead author Dr Sharon Deem, Director of the Saint Louis Zoo Institute for Conservation Medicine, said: "Demand for livestock products, such as meat and milk, is rising across the globe and could offer poor farmers a route out of poverty as markets expand, but zoonotic disease remains a major obstacle to this goal.
"Further research to determine whether the MERS virus is dangerous to humans in Kenya and other sub-Saharan countries is critical."
The full study is published in PLOS ONE.
Published: October 16, 2015
Middle East respiratory syndrome coronavirus (MERS-CoV) is a recently identified virus causing severe viral respiratory illness in people. Little is known about the reservoir in the Horn of Africa. In Kenya, where no human MERS cases have been reported, our survey of 335 dromedary camels, representing nine herds in Laikipia County, showed a high seroprevalence (46.9%) to MERS-CoV antibodies. Between herd differences were present (14.3%– 82.9%), but was not related to management type or herd isolation. Further research should focus on identifying similarity between MERS-CoV viral isolates in Kenya and clinical isolates from the Middle East and elsewhere.