Zika transmitted through female Aedes

Some facts about the virus and the current outbreak

The virus is transmitted to people through the bite of infected female Aedes mosquitoes, the same type of mosquito that spreads dengue, chikungunya and yellow fever. Efforts to controlthe spread of the virus include eliminating mosquito breeding sites and taking precautions against mosquito bites such as using insect repellent and mosquito nets.

There is no treatment or vaccine available for Zika infection. People who get Zika virus disease typically have a mild fever, skin rash, conjunctivitis, muscle and joint pain and fatigue, with symptoms normally lasting for two to seven days. Most people never develop symptoms.

The virus has been linked to a devastating birth defect called microcephaly in which babies are born with abnormally small heads and brains that have not developed properly. The WHO said a direct causal relationship between Zika virus infection and birth defects has not yet been established but is strongly suspected.

The WHO said Zika cases have been reported in 23 countries and territories in the Americas in the current outbreak. Brazil has been the nation most affected.

Zika virus is found in tropical locales with large mosquito populations. Outbreaks of Zika virus disease have been recorded in Africa, the Americas, Southern Asia and Western Pacific. The virus was first identified in Uganda in 1947 in rhesus monkeys and was first identified in people in 1952 in Uganda and Tanzania, according to the WHO.

The WHO says that because no big Zika outbreaks were recorded before 2007, little is known about complications caused by infection. Long-term health consequences remain unclear. It is uncertain whether in pregnant women the virus crosses the placenta and causes microcephaly. Other uncertainties surround the incubation period of the virus.