Academics Dr Cameron Webb and Nigel Beebe offer their thoughts on the threat Zika virus poses to us here in Australia.
The Zika virus is certainly topical and with the possible connection with birth defects, it has certainly captured the public’s attention.
The Zika virus has been spreading rapidly through the Americas and illustrating how quickly diseases can move with global travel, the first cases have now been confirmed in Australia. In two separate cases, tourists returning to the Gold Coast from overseas (one a pregnant woman) have been tested positive for Zika virus. However, experts believe that Australia is well placed to contain any outbreak.
While dozens of mosquito species in Australia are capable of spreading viruses such as Ross River, only one – the Aedes aegypti or yellow fever mosquito in far north Queensland (main picture, above) – is capable of transmitting Zika.
Despite fears Zika can also be spread through sex and the bite of an infected monkey (rare isolated cases have been reported), Dr Cameron Webb, an expert on mosquito-borne viruses, said the yellow fever mosquito would play the most important role in its transmission if it does arrive here this year.
Dr Webb said that for Australia’s yellow fever mosquito to spread Zika, one of the insects would have to bite an infected traveller shortly after that person returned from a country where the virus is circulating. The same mosquito could then bite other people who have never left the country. This is the same process that occurs with dengue fever outbreaks in far north Queensland.
Dr Webb, of Sydney University, said if there was an outbreak, local health authorities would try to kill the mosquitoes and their eggs in the affected area quickly, while infected people would be isolated to limit the spread of their blood through other mosquitoes.
Local transmission of the virus through Aedes aegypti mosquitoes is occurring in 23 countries in the Americas, where there are fears it can cause potentially fatal birth defects.
While the virus does not usually cause symptoms for 80 per cent of people (and when it does, the symptoms are mild), Brazilian health authorities are investigating links between the virus and a rare brain condition called microcephaly in infants, as well as a nervous system syndrome known as Guillain-Barre that can cause paralysis.
Based on the possible association of microcephaly in babies (neurodevelopment disorder resulting in underdeveloped brain and small head) and other neurological disorders with the outbreak of Zika virus, the World Health Organisation (WHO) has advised that this outbreak constitutes a Public Health Emergency of International Concern (PHEIC). With officials referring to the virus as “spreading explosively” across the Americas, there is concern that four million people could be infected with the virus this year.
Dr Webb said the outbreak highlighted the importance of Australia’s efforts to keep exotic mosquitoes out of the country, particularly Aedes albopictus or the Asian tiger mosquito, which is also capable of transmitting Zika.
He said that while the yellow fever mosquito was unlikely to become established in southern cities of Australia, even with a warming climate, there was great potential for the Asian tiger mosquito to establish itself in such cities as Melbourne and Sydney.
The species, which can also carry dengue and chikungunya viruses, is found in the Torres Strait.
Associate Professor Nigel Beebe, of the University of Queensland, said that to prevent this species and others from entering Australia, there were traps designed to catch them within 400m of every Australian port.
He said these foreign species occasionally “popped in” and hit the traps after travelling on airplanes and ships. When this happens, researchers examine them and their eggs to see where they have come from. This information is then used to inform health, agriculture and travel authorities.
Associate Professor Beebe said given that Zika had been in French Polynesia and the Western Pacific in recent years, it was “probably more due to luck” that Australia had been spared local transmission of the virus so far.
However, he said Australia’s health system was well equipped to diagnose it and contain it quickly.
“If you can diagnose it early, you can go in and suppress it,” he said.
The Department of Foreign Affairs and Trade is advising pregnant women to avoid travel in areas where Zika is active.
The federal government is also asking Australian doctors to look out for signs of Zika infection in travellers returning from affected areas. A spokeswoman said Australian laboratories could diagnose the virus if required.
Article based on information published in the Sydney Morning Herald on January 30, 2016, written by Julia Medew.