Source of MERS infections in humans not known
ROME - Further investigation, analysis and study is needed to understand the potential role of animals in the emergence and spread of Middle Eastern Respiratory Syndrome (MERS), the Food and Agriculture of the United Nations (FAO) said today. Current evidence is not sufficient to identify the specific source, whether animal or otherwise, of the coronavirus that is causing MERS in humans.
FAO explains that coronaviruses are a family of viruses that affect primarily birds and mammals. Some strains cause mild disease, while a limited number are more harmful (e.g. the Severe Acute Respiratory Syndrome [SARS] coronavirus). The MERS coronavirus has been shown to cause acute respiratory illness in humans. It hasn’t yet been shown to cause disease in animals.
"It is not yet clear how people are becoming infected, or where the virus might come from," stated Juan Lubroth, FAO chief veterinary officer. "We do not have enough information to identify with certainty the virus's origin. Confirming the source and mechanisms of transmission and spread are key to developing ways to reduce the risks posed by this virus to humans or other countries."
A study led by the National Institute for Public Health and the Environment of the Netherlands and just published in The Lancet Infectious Diseases Journal provides more information. It found antibodies for the MERS coronavirus or a similar virus in camel blood samples. The samples were taken in areas where human cases have not been reported. In some cases, the tested camels have been isolated from other camels for many years.
These antibody findings indicate that the MERS virus, or a similar coronavirus, occurs in some camels and potentially other species. However, the only way to know with any certainty if the virus affecting humans is the same as the virus possibly affecting camels (or any other animal) is to isolate the virus in different species and compare them genetically.
So far, the MERS coronavirus has only been isolated in humans. Investigation and research in animal species must continue to shed light on potential animal sources. If and once identified, veterinary and public health authorities could better communicate how to prevent infection or institute specific control measures.
Authorities in the affected region continue to investigate the situation. FAO is in close communication with national authorities as well as the World Health Organization (WHO) and the World Organization for Animal Health (OIE). FAO and its partners stand ready to support national and regional efforts to identify the environment and context or which animal species might serve as a reservoir and to address the virus in animals in order to protect human health, animal health and animal-related livelihoods.
Meanwhile, FAO is urging countries to invest in efforts to better understand virus sources and mechanisms of transmission and spread. This information can be employed to help people and animals avoid exposure in order to reduce the risks viruses pose to health and trade.