The so-called Middle East respiratory syndrome (MERS) coronavirus was first found in June 2012 in a patient from Saudi Arabia, who suffered from severe pneumonia. Since this time more than 300 persons have developed an infection, of whom about a third died. The fact that the Arabian camel is the origin of the infectious disease has been confirmed recently. The transmission pathways of the viruses, however, have not been clear until now.
Viruses in humans and camels from one region are identical
Virologists Norbert Nowotny and Jolanta Kolodziejek from the Institute of Virology are investigating the transmission pathways of the MERS coronavirus. They found that viruses from infected humans and Arabian camels from the same geographical region have nearly identical RNA sequences. "This indicates transmission between animals and man. The process is referred to as zoonosis. With this knowledge we can specifically react to the spread of the virus. Vaccinations of camels are currently being discussed. We will thus be able to halt the spread of the virus," said Nowotny.
Virus RNA differs from region to region
The scientists investigated nasal and conjunctival swabs, taken from 76 camels in Oman. In five camels they found the MERS coronavirus and compared its RNA with those of MERS coronavirus from Qatar and Egypt. The analysis showed that the viruses differ from region to region. "This means that there is no specific 'camel MERS coronavirus strain', but that one virus infects both, camels and humans," says study coordinator Norbert Nowotny.
Transmission pathway through nose and eyes
Virus levels were surprisingly high in the nasal mucosa and conjunctiva of camels. Therefore the scientists presume that the transmission pathway from animals to humans most likely occurs through these contact sites, especially through nasal discharge.
In man the virus causes severe pneumonia and renal failure while camels show no or very little symptoms (in some cases nasal discharge). So far all infections in humans have occurred in the Arabian Peninsula. However, some developed the disease after they returned to their native country, of whom eleven were from Europe. MERS coronavirus is also transmitted from one human to another, for instance in families, in the community, or through contact between patients and medical staff.
MERS and SARS coronaviruses are relatives
MERS coronavirus is closely related to SARS coronavirus. SARS originated in China and claimed 800 lives worldwide in 2002 and 2003. "While the SARS coronavirus probably crossed the species barrier only once by passing from bats to humans, we may presume that the MERS coronavirus is being constantly transmitted from camels to humans," explains Nowotny.
The fact that MERS coronaviruses infect camels was shown by Nowotny and his colleagues in an earlier study, in which the scientists detected antibodies against the virus in the animals. The current genetic analysis of MERS coronarviruses permits more exact conclusions.
- Chantal BEM Reusken, Bart L Haagmans, Marcel A Müller, Carlos Gutierrez, Gert-Jan Godeke, Benjamin Meyer, Doreen Muth, V Stalin Raj, Laura Smits-De Vries, Victor M Corman, Jan-Felix Drexler, Saskia L Smits, Yasmin E El Tahir, Rita De Sousa, Janko van Beek, Norbert Nowotny, Kees van Maanen, Ezequiel Hidalgo-Hermoso, Berend-Jan Bosch, Peter Rottier, Albert Osterhaus, Christian Gortázar-Schmidt, Christian Drosten, Marion PG Koopmans. Middle East respiratory syndrome coronavirus neutralising serum antibodies in dromedary camels: a comparative serological study. The Lancet Infectious Diseases, 2013; 13 (10): 859 DOI: 10.1016/S1473-3099(13)70164-6
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