Three weeks ago, I mentioned in this blog that the Zika virus had been found in Brazil, and some of the possible consequences. Although it’s not definitively proven, there is evidence that women who are infected with the virus during pregnancy have a higher risk of giving birth to children with the serious condition known as microcephaly, in which the brain is underdeveloped.
Since then, more details have emerged. At the time, citing the figure being reported by major news outlets, I said that Brazil had about 2,700 cases of microcephaly in 2015 (up from only 147 cases the previous year, before the Zika virus arrived in the country). Now more than 3,800 cases have been reported. In the areas of the country hardest hit by the virus, babies born with microcephaly number 114 in 10,000 live births, or more than 1%.
By comparison, about 25,000 children with microcephaly are born each year in the US (where the virus has not yet spread); that’s about 0.6% of births. (The US-based nonprofit organization Foundation for Children With Microcephaly, however, puts the percentage higher, saying it affects from 2% to 2.5% of the population.) The condition can be fatal, or it can result in anything from mild developmental delays to extremely severe disability.
Three weeks ago, some doctors in Brazil were advising women to postpone pregnancy during the outbreak of the virus, which could last for months. The governments of several other countries—Columbia, El Salvador, Ecuador, and Jamaica—are now joining in that recommendation. The US Centers for Disease Control is advising pregnant women to avoid traveling to more than 20 countries where the Zika virus is prevalent; late last week it added to its list Barbados, Bolivia, Ecuador, Guadaloupe, St. Martin, Guyana, and Samoa.
The Aedes aegypti mosquito, which transmits the Zika virus, is present in all countries in the Americas except Canada and Chile. In Brazil and elsewhere, officials are trying to eliminate areas of standing water that can serve as breeding grounds for mosquitoes, including poorly maintained drainage structures and small ponds or containers where residents have been storing up water because of the recent drought.
Brazil is dedicating funding to finding a vaccine against the Zika virus. Until now it has not been a priority, because in most people the virus causes only mild symptoms—headache, fever, rash—or no symptoms at all.
The country is also experimenting with releasing genetically modified mosquitoes into the environment to try to reduce the mosquito population. A company called Oxitec has set up a facility in Piracicaba, Brazil, and is releasing altered male mosquitos; they can successfully mate with female mosquitoes, and the fertilized eggs will hatch, but the offspring die before they’re able to fly. The company is reporting a better-than-80% reduction in the mosquito population in areas where the modified mosquitoes have been released. This article from 2012 explains the genetic modification in more detail.
Janice Kaspersen
Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines.
