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The World Health Organisation announced on Thursday that it will convene an emergency meeting to try to find ways to stop the transmission of the Zika virus - which officials said is "spreading explosively" across the Americas.
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Researchers take fight to Zika mosquito
Researchers have announced plans to deploy a modified male mosquito that could render the females infertile after four people in New York state tested positive for the Zika virus which is linked to birth defects.
"The level of alarm is extremely high, as is the level of uncertainty. Questions abound. We need to get some answers quickly, " Margaret Chan, the director-general of the WHO, said in Geneva in a briefing to member countries.
Chan said that the situation today is dramatically different from last year because of the multiplying number of cases and the severity of the symptoms and that "the level of alarm is extremely high."
Health officials said 23 countries are affected by mosquitoes that are spreading the virus locally. The Centres for Disease Control and Prevention said the United States has 31 confirmed cases in 11 states and the District of Columbia. All are travel-related, the CDC's Lyle Petersen said, and "this number is increasing rapidly." The country also has 20 additional cases because of local transmission in US territories - 19 in Puerto Rico and one in the US Virgin Islands.
Brazil is the epicenter of Zika, and public health officials are investigating a link between the virus and a rare brain defect called microcephaly in infants, as well as a nervous system syndrome known as Guillain-Barre that can lead to paralysis.
During a briefing to the WHO executive board on Thursday, Brazil's health minister, Claudio Maierovitch, said the country is investigating 12 confirmed deaths of babies born with microcephaly for potential linkage with Zika virus infection. The country has more than 4000 suspected cases of microcephaly. Some of those have turned out not to be microcephaly, but many of them have been confirmed through ultrasound, he said. He did not provide a figure. Pregnant women who tested positive for the Zika virus have had a rash and fever during the "first and second parts of their pregnancy," he said.
Several countries, such as El Salvador, have been so shaken by the reports that they have taken extreme measures by advising women of childbearing age to wait six months to two years before trying to become pregnant. Bruce Aylward, assistant director-general of the WHO, said the group's position is that women who are pregnant should engage in "an abundance of caution" to avoid being bitten by mosquitoes.
Marcos Espinal, director of communicable diseases and health analysis for the Pan American Health Organisation, said Zika is likely to spread to the same areas where dengue exists and predicted that "we can expect 3 to 4 million cases of Zika virus disease."
That reach includes parts of the southern United States, according to a map he presented at the briefing.
The WHO said the reason Zika appears to be spreading so rapidly is two-fold: One, because it is a new disease to the region, the population does not have immunity and two, the Zika virus is primarily transmitted by a mosquito species known as Aedes aegypti, which lives in every country in North and South America except for Canada and Chile.
WHO officials said that this type of mosquito also has been simultaneously carrying a host of other viruses - dengue, Chikungunya, yellow fever, West Nile - to those regions in recent years. Among the hypotheses scientists are looking are whether the recent severe reactions may be related to co-infection with Zika and another virus, or previous exposure to one.
Aylward said that some of the women who gave birth to children with microcephaly had been tested and some of them had other infections and some did not.
"We don't have an answer as to what is actually going on," he said.
Part of the challenge with Zika is that it is often "silent" with up to 75 per cent of patients who are infected having no symptoms, said Sylvain Aldighieri, who works in epidemic alert and response for the WHO/PAHO.
Representatives from several countries raised concerns about whether we're seeing a potentially more virulent mutated virus in the Americas, but WHO officials said that tests so far show that it's "very similar" to what was circulating in the Pacific region several years ago.
WHO officials that better diagnostic tests are in the works as well as possible antiviral therapies and vaccines but that any of these could take months to develop. Meanwhile, efforts are focused on controlling the spread of the virus by eliminating mosquito populations. In some countries health officials have been going door to door to spray for mosquito breeding grounds and have launched public education campaigns to urge people to wear repellent clothing or use sprays. In a controversial experiment, a British company has announced it would release genetically modified mosquitoes whose larvae die to see if they can help stop the spread of the virus.
The WHO's Chan urged "every community, every family and individual" to do their part by doing things like taking care not to leave stagnant collections of water on their properties and emphasised that every person in the world could be vulnerable to the virus.
"The mosquito is ubiquitous," she said. "You don't need to travel to get the disease."
The WHO emergency session on Zika is scheduled to take place on Monday.