Genomic analysis of the Middle East respiratory syndrome coronavirus (MERS-CoV) first identified last year has provided important new information about transmission.
MERS-CoV causes severe acute respiratory illness with a high fatality rate; there have been 130 confirmed cases to date, nearly all of them in Saudi Arabia and mostly sporadic cases with no obvious source of infection, although infection between humans has also been observed. There have been 58 deaths.
With any new human pathogen, understanding issues such as how it is transmitted and causes disease are very important for public health preparedness. A new study published in the Lancet reports on the largest number of different isolates sequenced so far (21). Linked with information on the location of five different outbreaks within in Saudi Arabia and the date of infection, this has allowed researchers to track changes in the viral genome over time.
Some of the genomic changes were too great to be the result of normal mutations during passage between human hosts. The pattern of transmission revealed that it could not be solely transmitted between humans, and must therefore also involve movement of an animal reservoir or infected animal products. Possible animal species that may be acting as hosts for the virus include bats or camels.
The researchers conclude that identification of the animal reservoirs and how the virus is transmitted from them to humans is now ‘urgently needed to provide the necessary information to interrupt transmission and contain the virus’.
Comment: This is a useful demonstration of the potential value of rapid genome sequencing for the monitoring and control of infectious diseases; hopefully, such applications will be embedded in public health and clinical systems before the emergence of any major new threat. The priority for MERS-CoV now is to find out how to prevent further infections from the unknown animal source, and combine this knowledge with current measures to limit spread from infected humans.