In August 2016, the World Health Organisation declared the Zika outbreak a global health emergency after the virus that began causing infections and microcephaly among babies in South America started spreading to other parts of the world, even Africa and Asia. In 2014-‘15 the big global health scare was the Ebola epidemic in that killed more than 11,000 people but remained confined to west African countries. Public health researchers are now asking what the next global epidemic might be and a team of Australian scientists thinks it could be caused by the Ross River virus.

Ross River Virus is a mosquito-borne pathogen harboured by marsupial animals like kangaroos and wallabies. So far, it has been restricted largely to Australia and Papua New Guinea. But scientists from the University of Adelaide and the Australian National University have now found that the virus has been silently circulating in the South Pacific. The area saw an outbreak of Ross River Virus fever in 1979-’80 with more than 5,00,000 cases and is thought to have been started by an infected Australian tourist who travelled to Fiji.

Ross River Virus infections symptoms include fever, chills, muscle aches, rash, fatigue, headaches and joint aches. Although an infection has never killed anyone, it can be severely debilitating for months, sometimes years.

According to a study published in the International Journal of Infectious Diseases, the Australian research team found that the virus circulating in the South Pacific has escaped its marsupial reservoir and can been able to survive in other mammals. The researchers tested blood samples of American Samoan born after the 1979-1980 epidemic and had lived in American Samoa their whole lives. Among these subjects, a massive 63% had antibodies to the Ross River Virus, suggesting local transmission of the virus after 1980.

They conclude that if the virus can circulate in non-marsupials in the South Pacific than it can spread and survive in any part of the world. Given the right conditions, the research team warns, an outbreak of Ross River Virus can take off in the same way that Zika did.