Zika: where are we now and where is it going?

I’ve previously written to give a brief general overview of the Zika virus and to tell the story of where it came from. In this article I’ll described where the virus is now and what we expect it to do next.

Zika: where is it now?

There’s been less fuss about Zika in the news since 2016, partly because our improved understanding of the virus means there’s less of a threat from the ‘unknown’ and partly because the number of new cases already seems to be dwindling away as the populations exposed to it have developed ‘herd immunity’.

In November last year, the WHO dropped their classification of Zika as a ‘public health emergency of international concern,’ and transferred responsibility for response to the outbreak from an ’emergency committee’ to a committee with a more long-term outlook. Just last week, Brazil also announced the end of an official ‘state of emergency’ in their country,

According to the WHO, as of March 2017 there were 61 countries with ongoing transmission of Zika (50 of which are in the Americas or Caribbean). There were no new countries with Zika since their previous report in February 2017 and a total of 23 countries which were involved in the Zika outbreak over the past two years now no longer have any evidence for transmission – so the spread of the virus seems to be slowing down, even regressing.

Will Zika start to affect new areas?

To give you a feel of just how widespread Zika could become, here’s a map of the regions which scientists have determined may be suitable for Zika transmission. It’s possible that the virus may spread more in a few more areas which haven’t yet been heavily affected, such as southern USA and South-East Asia, but the majority of the countries which are suitable for Zika transmission have already been affected by the virus.

elife-15272-fig2-v2-download.jpg
A map of the areas which Zika virus could potentially affect, based on clmate and the presence of the right type of mosquitos (source). Hopefully this gives a feel of just how widespread Zika could become.

What will happen to Zika in the Latin America and the Caribbean?

One prediction is that the virus will continue to affect people here at low, ‘background’ levels, with larger outbreaks only occurring every few years once the level of herd immunity in the population wears off.

This is more or less what happens with another similar virus called ‘dengue’ in the Americas. For example, in the Caribbean, there’s been an established pattern of an outbreak of a different dengue virus sub-type every 3 or 4 years.

In fact, this may have been what Zika’s been doing in Africa all along. New research suggests Zika may have been much more widespread in Africa than we initially realised. Therefore, Zika in the Americas may copy what Zika has been dowing in Africa over the last half-century, with sporadic outbreaks every few years of varying sizes, but no more huge outbreaks like the one seen in 2015-16.

Does this mean that we can relax and forget about Zika?

No! For reasons that I’ve previously explained, I feel passionately that further research on this virus is vital for global health security!

Other articles I’ve written on Zika:

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