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The Zika virus, a mosquito-borne illness, has been linked to a dramatic rise in birth defects in Brazil and neighboring countries. The World Health Organization (WHO) declared it a Public Health Emergency of International Concern in February 2016, and by mid-2016, sixty countries were reporting active transmission of the virus. Health officials confirmed that the Zika virus is behind a dramatic increase in cases of microcephaly, a condition in which infants are born with unusually small heads and brains that usually results in developmental disabilities. The U.S. Centers for Disease Control and Prevention (CDC) has said pregnant women, or women who may become pregnant, should consider postponing travel to the nearly thirty countries where the Zika virus has been transmitted. Some governments, including those of Colombia, Ecuador, and El Salvador, have advised women against becoming pregnant in the near future.
What is the Zika virus?
The Zika virus is a mosquito-borne illness carried by Aedes aegypti mosquitoes. Most people who are infected do not become ill, but an estimated 20 percent experience symptoms including rash, fever, joint pain, red eyes, muscle pain, and headaches. The incubation period—the time between exposure to exhibiting symptoms—is unknown, but, according to the CDC, it is likely between a few days and a week. In most cases symptoms are mild and last up to a week.
The virus was first discovered in 1947 in the Zika forest in central Uganda, but until 2007, there had only been fourteen documented cases in humans. Experts say the disease likely did not spread among humans in Uganda because the Aedes africanus mosquitoes that transmit the virus there are poorly adapted to human environments, and therefore preferred to prey on monkeys. Researchers found evidence of infections elsewhere in Africa, as well as in Asia, but local populations there appear to have developed some resistance to the virus, preventing large-scale outbreaks.
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