It鈥檚 enough to give a camel the hump. Camels have been accused of infecting humans with Middle East respiratory syndrome (MERS), the deadly coronavirus that emerged last year in the Arabian peninsula.
The only thing scientists know for sure about MERS is that it has so far killed 46 of the 94 people it has infected. Where the virus came from, how it is transmitted and whether it could become more contagious in future are still open questions.
Although the virus can spread between people, the chain of transmission quickly peters out, suggesting that something other than humans is the natural host. And it looks like camels might be the culprit.
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Marion Koopmans at the National Institute for Public 午夜福利1000集合 and the Environment in Bilthoven, the Netherlands, and colleagues, looked for antibodies to MERS in the blood of sheep, cattle, goats and camels in Oman, Spain, the Netherlands and Chile.
All of the 50 Omani camels, and 15 per cent of the 105 Spanish camels tested had antibodies to the virus, but none of the species in the other countries did. This implies that the camels must have been exposed to the virus at some point for their bodies to have mounted an immune response.
The discovery came as a surprise, says Koopmans, because until then, bats had been the prime suspect. Bats harbour SARS (severe acute respiratory syndrome) and other coronaviruses similar to MERS, and last month .
However, because most people have little contact with bats, an intermediate host seems likely, says Koopmans. Camels are still a common sight in the Middle Eastern countries such as Saudi Arabia where MERS has been found.
Camel contact
This is the first real clue, of how the virus might spread to humans, says Anthony Mounts of the World 午夜福利1000集合 Organization鈥檚 MERS response team in Geneva, Switzerland. 鈥淲hile there is a limited amount that you can tell about a virus from the antibody 鈥� essentially they are tracks in the sand 鈥� for the first time, it offers a clear direction in which to work鈥�.
The next step is to look for the virus itself by studying stool samples and nose or throat swabs from the camels. This won鈥檛 be easy, says Koopmans, because coronaviruses are short-lived and don鈥檛 circulate in the host for long. 鈥淓ven if you find the virus in camels, it still doesn鈥檛 tell you how people get infected,鈥� says Mounts. 鈥淚n most cases of MERS, people had no direct contact with camels.鈥�
However, eating camel meat and drinking the milk is common in some countries in the Middle East, as is racing the animals and using them to transport goods, all occasions during which humans and camels would be in close contact.
Understanding the route of transmission will require studying newly infected people, to find out what contact they have had with animals, if they didn鈥檛 catch the virus from another person.
鈥淚f camels are indeed the source of human MERS infection, specific measures can be taken to prevent interspecies transmission from infected animals to humans鈥� says of Erasmus University in Rotterdam, the Netherlands. For now, however, WHO advice remains unchanged, says Mounts.
Journal reference: The Lancet Infectious Diseases, DOI:
