Zika hasn’t been in the news much, but that doesn’t mean it’s gone

From Science News
October 30, 2017

Less than a year after the World Health Organization declared Zika is no longer a public health emergency, the virus seems to have fallen from public consciousness, at least outside of heavily affected areas. The mosquito-borne virus staged a massive assault on the Western Hemisphere in 2015 and 2016(SN: 12/24/16, p. 19), but this year, Zika appears to be in retreat.

In the hardest-hit countries, data from each country’s department of health shows a striking drop in locally acquired cases, that is, ones caused by bites from local, infected mosquitoes. For instance:

  • Brazil had over 216,000 probable cases in 2016; as of early September, the new cases for 2017 were around 15,500.
  • Colombia tallied more than 106,000 suspected and confirmed cases from 2015 to the end of 2016. This year, new cases have plummeted, with around 1,700 by mid-October.
  • Mexico went from about 8,500 confirmed cases in 2015 and 2016 combined to around 1,800 by early October of this year.

The numbers have also dropped in the United States and its territories. In Puerto Rico, Zika cases hit nearly 35,000 in 2016, the U.S. Centers for Disease Control and Prevention reports. But this year, less than 500 cases have been tallied as of mid-October. In the 50 states, the CDC counted about 5,100 cases in 2016. Most were in travelers who had been to places where Zika was active, although 224 were locally acquired in Florida and Texas. So far in 2017, only about 300 cases have been reported as of mid-October, mostly from travelers. Local transmission seems to have come to a standstill, with one suspected case in Texas and one case confirmed in Florida.

That doesn’t mean Zika’s days are numbered. If Zika behaves like other arboviruses, such as chikungunya and dengue, it will probably stick around. Arbovirus diseases tend to be cyclical, says public health researcher Ernesto Marques of the University of Pittsburgh. “You have big booms, then they drop. Then a few years later, they come back again.”

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