ZIKA: WHAT YOU NEED TO KNOW
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. The Pan American Health Organisation (PAHO) said Aedes mosquitoes are found in all countries in the Americas except Canada and continental Chile.
There is no treatment or vaccine available for Zika infection. Companies and scientists are racing to develop a safe and effective vaccine for Zika, but one is not expected to be ready for months or years.
The PAHO said there is no evidence that Zika can cause death, but some cases have been reported with more serious complications in patients with pre-existing medical conditions.
The virus has been linked to microcephaly, a condition in newborns marked by abnormally small heads and brains that have not developed properly. It also has been associated with Guillain-Barre syndrome, a rare disorder in which the body's immune system attacks part of the nervous system.
Health officials have yet to establish a direct causal relationship between Zika virus infection and birth defects, but it is strongly suspected. Brazil has reported more than 4000 cases of suspected microcephaly that may be linked to Zika. Researchers have identified evidence of Zika infection in 17 of these cases, either in the baby or in the mother.
People who get Zika virus disease typically have a mild fever, skin rash, conjunctivitis, muscle and joint pain and fatigue that can last for two to seven days. But as many as 80 per cent of people infected never develop symptoms.
Efforts to control the spread of the virus focus on eliminating mosquito breeding sites and taking precautions against mosquito bites such as using insect repellent and mosquito nets. US health officials have advised pregnant women to avoid travel to Latin American and Caribbean countries.
Health officials said Zika outbreaks have been reported in at least 26 countries in the Americas. Brazil has been the nation most affected. Other nations and territories include Barbados, Bolivia, Colombia, Costa Rica, Curacao, Dominican Republic, Ecuador, El Salvador, French Guiana, Guadeloupe, Guatemala, Guyana, Haiti, Honduras, Jamaica, Martinique, Mexico, Nicaragua, Panama, Paraguay, Puerto Rico, Saint Martin, Suriname, Venezuela and the US Virgin Islands.
The 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 the 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.
Two cases of possible person-to-person sexual transmission has been described, but the PAHO said more evidence is needed to confirm whether sexual contact is a means of Zika transmission.
The WHO says because no big Zika outbreaks were recorded before 2007, little is known about complications caused by infection. During an outbreak of Zika from 2013-2014 in French Polynesia, national health authorities reported an unusual increase in Guillain-Barre syndrome. Health authorities in Brazil have also reported an increase in Guillain-Barre syndrome.