![\"Grey](\"http:\/\/ichef.bbci.co.uk\/news\/624\/media\/images\/77207000\/jpg\/_77207535_464x2.jpg\")
<\/span><\/figure>\nWhat are the symptoms of Zika?<\/h2>\n
Deaths are rare and only one-in-five people infected is thought to develop symptoms.<\/p>\n
These include:<\/p>\n
- \n
- mild fever<\/li>\n
- conjunctivitis (red, sore eyes)<\/li>\n
- headache<\/li>\n
- joint pain<\/li>\n
- a rash<\/li>\n<\/ul>\n
A rare nervous system disorder, Guillain-Barr\u00e9 syndrome, that can cause temporary paralysis has been linked to the infection.<\/p>\n
There is no vaccine or drug treatment so patients are advised to rest and drink plenty of fluids.<\/p>\n
But the biggest concern is the impact it could have on babies developing in the womb and the surge in microcephaly.<\/p>\n
![\"Grey](\"http:\/\/ichef-1.bbci.co.uk\/news\/624\/media\/images\/77207000\/jpg\/_77207535_464x2.jpg\")
<\/span><\/figure>\nWhat is microcephaly?<\/h2>\n
![\"Graphic](\"http:\/\/ichef-1.bbci.co.uk\/news\/624\/cpsprodpb\/179A5\/production\/_87877669_zikagfx.jpg\")
<\/span><\/figure>\nIt is when a baby is born with an abnormally small head, as their brain has not developed properly.<\/p>\n
The severity varies, but it can be deadly if the brain is so underdeveloped that it cannot regulate the functions vital to life.<\/p>\n
Children that do survive face intellectual disability and development delays.<\/p>\n
It can be caused by infections such as rubella, substance abuse during pregnancy or genetic abnormalities.<\/p>\n
Case study: ‘It’s not the end of the world’<\/a><\/p>\n
The WHO says there is “scientific consensus” <\/a>that Zika causes microcephaly as well as Guillain-Barre syndrome.<\/p>\n
Some babies who died had the virus in their brain and it has been detected in placenta and amniotic fluid too.<\/p>\n
<\/span><\/figure>\nIs it safe to try for a baby?<\/h2>\n
Some governments have advised women to delay getting pregnant until more is known.<\/p>\n
Experts now believe Zika is linked to a broader set of complications in pregnancy, including miscarriage, stillbirth, premature birth and eye problems.<\/p>\n
The US Centres for Disease Control says Zika lingers in the blood for about a week and can be spread by sexual intercourse.<\/p>\n
“The virus will not cause infections in a baby that is conceived after the virus is cleared from the blood,” it says.<\/p>\n
“There is currently no evidence that Zika-virus infection poses a risk of birth defects in future pregnancies.”<\/p>\n
The WHO advises couples practice safer sex or abstain for at least eight weeks if they are returning from Zika-affected areas. If the man in the couple planning a pregnancy develops Zika symptoms, then this period of abstinence or safe sex should be extended to six months.<\/p>\n
<\/span><\/figure>\nWhy is it a public health emergency?<\/h2>\n
The WHO is worried that Zika is spreading far and fast, with devastating consequences.<\/p>\n
Declaring Zika as a “public health emergency of international concern” singles the disease out as a serious global threat. It puts it in the same category of importance as Ebola.<\/p>\n
Unlike Ebola, where the focus was on boots on the ground, with Zika the attention will be on understanding the link with microcephaly.<\/p>\n
The WHO will co-ordinate countries’ health agencies to conduct trials to determine the risk.<\/p>\n
It will also encourage efforts to stop the mosquito that spreads the disease as well as finding a treatment or a vaccine to stop the virus.<\/p>\n
The work will depend on money donated by countries.<\/p>\n
![\"World](\"http:\/\/ichef-1.bbci.co.uk\/news\/624\/cpsprodpb\/15EF1\/production\/_90614898_zika_virus_past_present_map624_02_08_16.png\")
<\/span><\/figure>\n<\/span><\/figure>\nWhere did Zika come from?<\/h2>\n
It was first identified in monkeys in Uganda in 1947.<\/p>\n
The first human case was detected in Nigeria in 1954 and there have been further outbreaks in Africa, South East Asia and the Pacific Islands.<\/p>\n
![\"Zika](\"http:\/\/ichef.bbci.co.uk\/news\/624\/cpsprodpb\/8C55\/production\/_87952953_zika_virus_spread_624.png\")
<\/span><\/figure>\nMost were small and Zika has not previously been considered a major threat to human health.<\/p>\n
But in May 2015 it was reported in Brazil<\/a> and has since spread rapidly.<\/p>\n
“Its current explosive pandemic re-emergence is, therefore, truly remarkable,” the US National Institutes of Health said<\/a>.<\/p>\n
![\"Grey](\"http:\/\/ichef.bbci.co.uk\/news\/624\/cpsprodpb\/11923\/production\/_87917917_464x2.jpg\")
<\/span><\/figure>\nHow does it spread?<\/h2>\n
![\"Aedes](\"http:\/\/ichef.bbci.co.uk\/news\/624\/cpsprodpb\/F516\/production\/_87824726_504021244.jpg\")
<\/span><\/figure>\nIt is spread by Aedes <\/i>mosquitoes. They are the same insects that spread dengue and chikungunya virus.<\/p>\n
They are found throughout the Americas except for Canada and Chile where it is too cold for them to survive, and across Asia.<\/p>\n
![\"Map](\"http:\/\/ichef.bbci.co.uk\/news\/624\/cpsprodpb\/63C7\/production\/_87934552_spread_of_aedes_mosquitoes_624.png\")
<\/span><\/figure>\n![\"Zika](\"http:\/\/ichef.bbci.co.uk\/news\/624\/cpsprodpb\/0288\/production\/_90484600_zika_virus_cycle_624_9.png\")
<\/span><\/figure>\nAnd, unlike the mosquitoes that spread malaria, they are mostly active during the day, so bed nets offer limited protection.<\/p>\n
If they drink the blood of an infected person they can then infect subsequent people they bite.<\/p>\n
The WHO says sexual transmission is also possible.<\/p>\n
<\/span><\/figure>\nHow long are people infectious?<\/h2>\n
The best evidence so far suggests that people can spread the virus via mosquitoes for a week after being infected.<\/p>\n
In semen it may persist for two weeks.<\/p>\n
Countries have advised safe sex and a ban on blood donations for a month after just visiting such countries and for longer if they developed symptoms.<\/p>\n
<\/span><\/figure>\nWhat can people do?<\/h2>\n
As there is no treatment, the only option is to reduce the risk of being bitten.<\/p>\n
Health officials advise people to:<\/p>\n
- \n
- use insect repellents<\/li>\n
- cover up with long-sleeved clothes<\/li>\n
- keep windows and doors closed<\/li>\n<\/ul>\n
The mosquitoes lay their eggs in standing water, so people are also being told to empty buckets and flower pots.<\/p>\n
The US Centers for Disease Control has advised pregnant women not to travel<\/a> to affected areas.<\/p>\n
<\/span><\/figure>\nWhat is being done?<\/h2>\n
![\"Fumigation\"](\"http:\/\/ichef.bbci.co.uk\/news\/624\/cpsprodpb\/E858\/production\/_87908495_gettyimages-506091002.jpg\")
<\/span><\/figure>\nBrazilian Health Minister Marcelo Castro has said a new testing kit is being developed to identify infections quickly.<\/p>\n
He also said more money was being put into the development of a vaccine.<\/p>\n