Absence of MERS-CoV antibodies in feral camels in Australia: Implications for the pathogen's origin and spread

Crameri, Gary; Durr, Peter A.; Barr, Jennifer; Yu, Meng; Graham, Kerryne; Williams, Owen J.; Kayali, Ghazi; Smith, David; Peiris, Malik; Mackenzie, John S.; Wang, Lin-Fa

It is impossible to know for certain if the camels imported over 100 years ago from Pakistan carried MERS-CoV. Even if they did, it is possible that it was extinguished during the sea voyage. Alternatively, if the virus did manage to infect the Australian camel population, it is also plausible that it failed to establish long term sustained transmission due to the low population density of the camels when they were released into central Australia in the 1920s. Nevertheless, we propose that a careful collation of all the virological and ecological evidence will enable a reasoned assessment of the most probable status of the ancestors of the feral camels at the time of importation. Specifically, we suggest that investigations in Pakistan (as well as neighbouring Afghanistan and Iran) will provide an important piece of evidence, as to date there have not been any published reports of the MERS-CoV sero-status of these camel populations. Following on from this, if sampling in these countries show that MERS-CoV is not present in the current population, then the most probable explanation is that the virus was unlikely to have ever been introduced into Australia. By contrast, if the virus is found to be present, genetic studies of the virus may be able to partially resolve when it entered into the population, and thus if the camels exported to Australia might have been infected.