Zika virus global spread risk low – for now, says CQUni Immunology Professor

Published:13 October 2016

Professor Andrew Taylor-Robinson

Although the outbreak of the Zika virus in South America has not spread rapidly to other parts of the globe, developing countries where public health provisions are not as well-established could still be at risk in years to come.

That’s according to CQUniversity Immunology Professor Andrew Taylor-Robinson, who has discussed the potential of Zika’s impact upon global health in an article on the Atlas of Science website.

The Zika virus, which is spread by the infectious bite of the Aedes aegypti mosquito, emerged 18 months ago in South America, with the primary impact being babies born with microcephaly, a serious neurological defect.

Prof Taylor-Robinson said the world became concerned about the risks of a pandemic mainly because of the massive publicity surrounding the Rio de Janeiro Olympic Games.

“As events transpired, there was not a single case of Zika. So, was this a massive fuss about nothing or was the hullaballoo at all justified? Well, both yes and no,” he wrote.

“The impact of Zika was very real but may not have impacted on the Olympics irrespective of any vector control measures that were carried out. The fact is August is the driest month of the year in Brazil, a time when it is highly unlikely to see a mosquito on the Copacabana, let alone be bitten by one.

“This begs the question: are people in places far away and which are currently Zika-free zones right to be concerned by its potential global spread? The answer depends on where you live – with respect to both the region and the country. Cases of introduced infection, brought into a country by an infected traveller returning from a Zika-endemic territory, could happen almost anywhere, thanks to the pervasive nature of international air travel. For there to be a local outbreak, however, requires the presence of those Aedes mosquitoes. Since these do not fly at all far, maybe only 500 hundred metres in a lifetime, high population densities of mosquitoes and humans would have to coincide in order for the spread of infection to be sustained. Moreover, they inhabit tropical and subtropical regions, so you are pretty safe if you reside in a more temperate climate.

“In spite of appreciable anxiety among the general public in response to media speculation, in regions where Zika has not gained a foothold, such as North America, Europe and Australia, right now it is extremely probable that any outbreak would be contained locally. This is especially true of industrialised nations for which there is an established public health infrastructure and excellent resources provided for disease surveillance and mosquito control programs. In contrast, in developing countries it is feasible that a Zika outbreak may not be restricted so readily.

Prof Taylor-Robinson offered a warning for the future. "Due to the effect of global warming, the geographical range of Aedes mosquitoes may be predicted to expand in the coming decades. As a consequence, the worldwide distribution of Zika may also change beyond the pattern that becomes established over the next couple of years. Thus, countries which are not affected at present or in the near future should not be complacent that they will always remain free of Zika.

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