2016 Volume 67 Issue 3 Pages 159-166
Zika virus (Flaviviridae) is an emerging arbovirus. It was first isolated from rhesus monkeys in Zika forest in Uganda in 1947 and was isolated from Aedes africanus mosquitoes collected from the canopy of Zika forest in 1948. The first human case was reported in Nigeria in 1954. For half a century, the virus was reported to cause sporadic human infections in Africa and Asia, with mild symptoms comparable to dengue. In 2007, a Zika disease epidemic occurred in the Yap Islands, Micronesia. In 2013 a large epidemic was reported in French Polynesia with more than 70 cases of Guillain-Barre syndrome and other neurological conditions, and 333 confirmed Zika cases. There were more than 30,000 cases of suspected Zika infection in French Polynesia in 2013. Following this, a Zika outbreak on the Cook Islands of New Caledonia was reported, with 932 suspected and 50 confirmed cases, and 51 confirmed cases were reported on Easter Island in 2014. In early 2015, several patients presenting symptoms of mild fever, rash, conjunctivitis and arthralgia were reported in northeastern Brazil. It seems there were more than 1.5 million cases of Zika disease in Brazil. The Brazilian epidemic of microcephaly in newborn infants is of greater concern. In the northeastern states, a greater than 20-fold increase in the incidence of microcephaly was observed from 2014 to 2015. Some public health officials believe that there is a strong relationship between Zika virus infection in pregnant women and microcephaly. Microcephaly and other fetal malformations that are potentially associated with Zika virus infection or suggestive of congenital infection have been reported in Brazil, Cabo Verde, Colombia, French Polynesia, Martinique and Panama, although the incidence of microcephaly was different in each endemic country. Scientists at the Centers for Disease Control and Prevention (CDC) reviewed the existing evidence and concluded that Zika virus is a cause of microcephaly and other severe fetal brain defects.
The vector mosquitoes belong to the genus Aedes. It is known that the vector species differ in each epidemic areas. In the Yap Islands, Ae. hensilli seems to be the vector, while the vectors in French Polynesia were apparently Ae. polynesiensis and Ae. aegypti; however, the virus has not been isolated from these species. In Brazil, Zika virus might be transmitted by Aedes aegypti and Ae. albopictus. The possibility that Zika virus has become highly adapted to Ae. albopictus should be cause for concern, even in temperate countries in Asia, Europe and North and South America.
