Clif CleavelandBefore last year, the Zika virus was thought to cause only mild symptoms limited to inhabitants of parts of Asia and Africa. In November 2015, however Brazil reported a number of severe birth defects attributable to Zika infection. Worldwide travel advisories for pregnant women have followed.
Zika belongs to a group of viruses that cause yellow fever, dengue and West Nile fever. It was first detected in rhesus monkeys in the Zika Forest in Uganda in 1964, then was found in the Aedes mosquito species. From there, the insects carried it to Nigeria and on to people of all ages in Central Africa, Egypt, India and the Philippines.
Symptoms of Zika infection commonly include fever, headache, a rash and achy joints. Victims usually recover within a day or two, and 80 percent of infected persons don’t show any symptoms at all.
Zika became a major threat to public health when Brazilian public health officials reported 1,248 cases of abnormally small heads and various degrees of mental retardation in Brazilian children. The condition is known as microcephaly and is considered a rare disorder.
It was determined that, following infection of the mother by mosquito bite, the virus crossed the placenta in maternal blood and affected the fetus. Some Zika infections resulted in miscarriages, and the virus was discovered in the dead newborns’ brain tissue.