WHO declares Zika virus a global health emergency

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WHO: Zika Virus 'Spreading Explosively'

GENEVA/LONDON (Reuters) -- The World Health Organization declared the mosquito-borne Zika virus to be an international public health emergency as the disease linked to thousands of suspected cases of birth defects in Brazil spreads rapidly.

WHO Director-General Margaret Chan told reporters on Monday an international coordinated response was needed to improve detection and speed work on a vaccine and better diagnostics, although curbs on travel or trade were not necessary.

READ MORE: What is the Zika virus? Your questions answered

The emergency designation was recommended by a committee of independent experts to the U.N. agency following criticism of a hesitant response so far. The move should help fast-track international action and research priorities.

"Members of the committee agreed that the situation meets the conditions for a public health emergency of international concern. I have accepted this advice," Chan said.

See more about the outbreak in the gallery below:

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Zika, health agents trying to eradicate Zika mosquitoes in South America, Central America
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WHO declares Zika virus a global health emergency
An Aedes aegypti mosquito is photographed through a microscope at the Fiocruz institute in Recife, Pernambuco state, Brazil, Wednesday, Jan. 27, 2016. The mosquito is a vector for the proliferation of the Zika virus currently spreading throughout Latin America. New figures from Brazil's Health Ministry show that the Zika virus outbreak has not caused as many confirmed cases of a rare brain defect as first feared. (AP Photo/Felipe Dana)
A Sucre municipal worker fumigates for Aedes aegypti mosquitoes that transmit the Zika virus in the Petare neighborhood of Caracas, Venezuela, Monday, Feb. 1, 2016. Venezuela is reporting a jump in cases of a rare, sometimes paralyzing syndrome that may be linked to the Zika virus. (AP Photo/Fernando Llano)
In this Wednesday, Jan. 27, 2016 photo, Aedes aegypti mosquitoes sit in a petri dish at the Fiocruz institute in Recife, Pernambuco state, Brazil. The mosquito is a vector for the proliferation of the Zika virus spreading throughout Latin America. New figures from Brazil's Health Ministry show that the Zika virus outbreak has not caused as many confirmed cases of a rare brain defect as first feared. (AP Photo/Felipe Dana)
RECIFE, BRAZIL - FEBRUARY 01: David Henrique Ferreira, 5 months, who was born with microcephaly, is examined by a doctor on February 1, 2016 in Recife, Pernambuco state, Brazil. Ferreira's mother says she spends up to eight hours per day in transit on buses, three days per week, to visit a litany of doctors with David. In the last four months, authorities have recorded thousands of cases in Brazil in which the mosquito-borne Zika virus may have led to microcephaly in infants. The ailment results in an abnormally small head in newborns and is associated with various disorders including decreased brain development. The World Health Organization (WHO) declared the Zika virus a 'public health emergency of international concern' today. (Photo by Mario Tama/Getty Images)
Health ministry personnel fumigate a classroom against the Aedes aegypti mosquito, vector of the dengue, Chikungunya and Zika viruses in Tegucigalpa, , on February 1, 2016. Honduran President Juan Orlando Hernandez on Friday declared the country on a preventive state of alert due to the Zika virus which in the last 44 days killed a person and infected some 1000. AFP PHOTO/Orlando SIERRA. / AFP / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images)
In this Thursday, Jan. 28, 2016 photo, Daniele Ferreira dos Santos holds her son Juan Pedro as he undergoes visual exams at the Altino Ventura foundation in Recife, Pernambuco state, Brazil. Santos was never diagnosed with Zika, but she blames the virus for her sonâs defect and for the terrible toll it has taken on her life. (AP Photo/Felipe Dana)
A man works on a fence amidst a cloud of insecticide as city workers fumigate to combat the Aedes Aegypti mosquitoes that transmits the Zika virus, at the San Judas Community in San Salvador, El Salvador, Tuesday, Jan. 26, 2016. Worries about the rapid spread of Zika through the hemisphere has prompted officials in El Salvador, Colombia and Brazil to suggest women stop getting pregnant until the crisis has passed. (AP Photo/Salvador Melendez)
A health worker stands in the Sambadrome as he sprays insecticide to combat the Aedes aegypti mosquitoes that transmits the Zika virus in Rio de Janeiro, Brazil, Tuesday, Jan. 26, 2016. Inspectors begin to spray insecticide around Sambadrome, the outdoor grounds where thousands of dancers and musicians will parade during the city's Feb. 5-10 Carnival celebrations. Brazil's health minister says the country will mobilize some 220,000 troops to battle the mosquito blamed for spreading a virus linked to birth defects. (AP Photo/Leo Correa)
Carmen Chicas Mejia, 82, covers her mouth and nose while city workers fumigate her home to combat the Aedes Aegypti mosquitoes that transmit the Zika virus, at the San Judas Community in San Salvador, El Salvador, Tuesday, Jan. 26, 2016. Worries about the rapid spread of Zika through the hemisphere has prompted officials in El Salvador, Colombia and Brazil to suggest women stop getting pregnant until the crisis has passed. (AP Photo/Salvador Melendez)
Dead insects and larvae float in an empty vase at a cemetery in Cartagena, Colombia, Tuesday, Jan. 26, 2016. Local health workers emptied vases during a campaign to destroy potential hatcheries of Aedes aegypti mosquitoes that transmits the Zika virus at a the cemetery as part of a prevention campaign that according to the health ministry has already infected more than 16,000 people in Colombia, and could hit more than half a million. (AP Photo/Reinaldo Reyes)
A woman covers her mouth while city workers fumigate insecticide to help combat the Aedes Aegypti mosquitoes that transmit the Zika virus, at the San Judas Community in San Salvador, El Salvador, Tuesday, Jan. 26, 2016. Worries about the rapid spread of Zika through the hemisphere has prompted officials in El Salvador, Colombia and Brazil to suggest women stop getting pregnant until the crisis has passed. (AP Photo/Salvador Melendez)
A health worker stands in the Sambadrome as he sprays insecticide to combat the Aedes aegypti mosquitoes that transmit the Zika virus, in Rio de Janeiro, Brazil, Tuesday, Jan. 26, 2016. Inspectors began to spray insecticide around the Sambadrome, the outdoor grounds where thousands of dancers and musicians will parade during the city's Feb. 5-10 Carnival celebrations. Brazil's health minister says the country will mobilize some 220,000 troops to battle the mosquito blamed for spreading a virus linked to birth defects. (AP Photo/Leo Correa)
Members of the Migente foundation check mosquito traps in the Paris neighborhood, Bello municipality, Antioquia department, Colombia on January 26, 2016. The Study and Control of Tropical Diseases Program (PECET) of Antioquia's University released one year ago Aedes aegypti mosquitos carrying the Wolbachia pipientis bacteria, which prevents them from transmitting the Zika and dengue viruses, as part of project to fight dengue. The Zika virus, a mosquito-borne disease suspected of causing serious birth defects, is expected to spread to all countries in the Americas except Canada and Chile, the World Health Organization said. AFP PHOTO /Raul ARBOLEDA / AFP / -- / RAUL ARBOLEDA (Photo credit should read RAUL ARBOLEDA/AFP/Getty Images)
A photographer walks through the fumes as Health Ministry employee fumigate against the Aedes aegypti mosquito to prevent the spread of the Zika virus in Soyapango, six km east of San Salvador, on January 21, 2016. Health authorities have issued a national alert against the Aedes Aegypti mosquito, because of the link between the Zika virus and microcephaly and Guillain-Barré Syndrome in fetuses. AFP PHOTO/Marvin RECINOS / AFP / Marvin RECINOS (Photo credit should read MARVIN RECINOS/AFP/Getty Images)
Army soldiers check for Aedes aegypti mosquito larvae during a clean-up operation against the insect, which transmits the Zika virus, in Sao Paulo, Brazil on January 22, 2016. AFP PHOTO/Miguel SCHINCARIOL / AFP / Miguel Schincariol (Photo credit should read MIGUEL SCHINCARIOL/AFP/Getty Images)
Army soldiers check for Aedes aegypti mosquito larvae during a clean-up operation against the insect, which transmits the Zika virus, in Sao Paulo, Brazil on January 22, 2016. AFP PHOTO/Miguel SCHINCARIOL / AFP / Miguel Schincariol (Photo credit should read MIGUEL SCHINCARIOL/AFP/Getty Images)
Army soldiers check for Aedes aegypti mosquito larvae during a clean-up operation against the insect, which transmits the Zika virus, in Sao Paulo, Brazil on January 22, 2016. AFP PHOTO/Miguel SCHINCARIOL / AFP / Miguel Schincariol (Photo credit should read MIGUEL SCHINCARIOL/AFP/Getty Images)
A health agent from the Sao Paulo secretariat of public health and army soldiers check for Aedes aegypti mosquito larvae during a clean-up operation against the insect, which transmits the Zika virus, in Sao Paulo, Brazil on January 22, 2016. AFP PHOTO/Miguel SCHINCARIOL / AFP / Miguel Schincariol (Photo credit should read MIGUEL SCHINCARIOL/AFP/Getty Images)
A Health Ministry employee fumigates a home against the Aedes aegypti mosquito to prevent the spread of the Zika virus in Soyapango, six km east of San Salvador, on January 21, 2016. Health authorities have issued a national alert against the Aedes Aegypti mosquito, because of the link between the Zika virus and microcephaly and Guillain-Barré Syndrome in fetuses. AFP PHOTO/Marvin RECINOS / AFP / Marvin RECINOS (Photo credit should read MARVIN RECINOS/AFP/Getty Images)
A Health Ministry employee fumigates a home against the Aedes aegypti mosquito to prevent the spread of the Zika virus in Soyapango, six km east of San Salvador, on January 21, 2016. Health authorities have issued a national alert against the Aedes Aegypti mosquito, because of the link between the Zika virus and microcephaly and Guillain-Barré Syndrome in fetuses. AFP PHOTO/Marvin RECINOS / AFP / Marvin RECINOS (Photo credit should read MARVIN RECINOS/AFP/Getty Images)
TOPSHOT - A Health Ministry employee fumigates a home against the Aedes aegypti mosquito to prevent the spread of the Zika virus in Soyapango, six km east of San Salvador, on January 21, 2016. Health authorities have issued a national alert against the Aedes Aegypti mosquito, because of the link between the Zika virus and microcephaly and Guillain-Barré Syndrome in fetuses. AFP PHOTO/Marvin RECINOS / AFP / Marvin RECINOS (Photo credit should read MARVIN RECINOS/AFP/Getty Images)
Health ministry employees spray to eliminate breeding sites of the Aedes Aegypti mosquito, which transmits diseases such as the dengue, chicunguna and Zica viruses, in a Tegucigalpa cemetery on January 21, 2016. The medical school at the National Autonomous University of Honduras (UNAH) recommended that women in the country avoid getting pregnant for the time being due to the presence of the Zika virus. If a pregnant woman is infected by the virus, the baby could be born with microcephaly. AFP PHOTO/Orlando SIERRA / AFP / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images)
A specialist fumigates the Nueva Esperanza graveyard in the outskirts of Lima on January 15, 2016. Health officials fumigated the largest cementery in Peru and second largest in the world to prevent Chikunguya and Zika virus, which affect several South American countries. AFP PHOTO/ERNESTO BENAVIDES / AFP / ERNESTO BENAVIDES (Photo credit should read ERNESTO BENAVIDES/AFP/Getty Images)
View of the Nueva Esperanza graveyard as it is fumigated in the outskirts of Lima on January 15, 2016. Health officials fumigated the largest cemetery in Peru and second largest in the world to prevent Chikunguya and Zika virus, which affect several South American countries. AFP PHOTO/ERNESTO BENAVIDES / AFP / ERNESTO BENAVIDES (Photo credit should read ERNESTO BENAVIDES/AFP/Getty Images)
A pregnant woman is attended at the Maternal and Children's Hospital in Tegucigalpa on January 21, 2016. The medical school at the National Autonomous University of Honduras (UNAH) recommended that women in the country avoid getting pregnant for the time being due to the presence of the Zika virus. If a pregnant woman is infected by the virus, the baby could be born with microcephaly. AFP PHOTO/Orlando SIERRA / AFP / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images)
A pregnant woman waits to be attended at the Maternal and Children's Hospital in Tegucigalpa on January 21, 2016. The medical school at the National Autonomous University of Honduras (UNAH) recommended that women in the country avoid getting pregnant for the time being due to the presence of the Zika virus. If a pregnant woman is infected by the virus, the baby could be born with microcephaly. AFP PHOTO/Orlando SIERRA / AFP / ORLANDO SIERRA (Photo credit should read ORLANDO SIERRA/AFP/Getty Images)
Aedes aegypti mosquito larvae sit in a petri dish at the Fiocruz institute in Recife, Pernambuco state, Brazil, Wednesday, Jan. 27, 2016. The mosquito is a vector for the proliferation of the Zika virus currently spreading throughout Latin America. New figures from Brazil's Health Ministry show that the Zika virus outbreak has not caused as many confirmed cases of a rare brain defect as first feared. (AP Photo/Felipe Dana)
A technician of the Fiocruz institue stores Aedes aegypti mosquitoes to be used in research, in Recife, Pernambuco state, Brazil, Wednesday, Jan. 27, 2016. The mosquito is a vector for the proliferation of the Zika virus currently spreading throughout Latin America. New figures from Brazil's Health Ministry show that the Zika virus outbreak has not caused as many confirmed cases of a rare brain defect as first feared. (AP Photo/Felipe Dana)
CORRECTS CDC IS INVESTIGATING WHETHER AEDES ALBOPICTUS SPREADS THE ZIKA VIRUS, NOT DEFINITIVE - This 2003 photo provided by the Centers for Disease Control and Prevention shows a female Aedes albopictus mosquito acquiring a blood meal from a human host. On Friday, Jan. 15, 2016, U.S. health officials are telling pregnant women to avoid travel to Latin America and Caribbean countries with outbreaks of a tropical illness linked to birth defects. The Zika virus is spread through mosquito bites from Aedes aegypti and the CDC is investigating whether it is also spread by Aedes albopictus. The disease causes only a mild illness in most people. But thereâs been mounting evidence linking the virus to a surge of a rare birth defect in Brazil. (James Gathany/Centers for Disease Control and Prevention via AP)
Aedes aegypti mosquitos are seen in containers at a lab of the Institute of Biomedical Sciences of the Sao Paulo University, on January 8, 2016 in Sao Paulo, Brazil. Researchers at the Pasteur Institute in Dakar, Senegal are in Brazil to train local researchers to combat the Zika virus epidemic. / AFP / NELSON ALMEIDA (Photo credit should read NELSON ALMEIDA/AFP/Getty Images)
Aedes aegypti mosquitos are seen in containers at a lab of the Institute of Biomedical Sciences of the Sao Paulo University, on January 8, 2016 in Sao Paulo, Brazil. Researchers at the Pasteur Institute in Dakar, Senegal are in Brazil to train local researchers to combat the Zika virus epidemic. / AFP / NELSON ALMEIDA (Photo credit should read NELSON ALMEIDA/AFP/Getty Images)
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The WHO said last week the Zika virus was "spreading explosively" and could infect as many as 4 million people in the Americas. Brazil is due to host the Olympic Games in Rio de Janeiro in August.

The WHO was lambasted for reacting too slowly to the Ebola epidemic in West Africa which killed more than 10,000 people, and has promised to do better in future global health crises.

U.S. Centers for Disease Control and Prevention head Thomas Frieden said the declaration "calls the world to action" on Zika.

"The WHO faced heavy criticism for waiting too long to declare the Ebola outbreak a public health emergency and they should be congratulated for being far more proactive this time," said Jeremy Farrar, director of the Wellcome Trust medical charity.

Derek Gatherer, a lecturer at Lancaster University, said the WHO's move was "like a declaration of war, in this case on Zika virus."

The WHO's International Health Regulations emergency committee brings together experts in epidemiology, public health and infectious diseases from the Americas, Europe, Asia and Africa.

UNDERDEVELOPED BRAINS

Brazil has reported nearly 4,000 suspected cases of microcephaly, in which infants are born with smaller-than-usual brains. The Health Ministry has linked the condition to Zika, although the connection is not yet definitive.

Chan said the causal link was "strongly suspected but not yet scientifically proven."

Brazilian Health Minister Marcelo Castro told Reuters that the epidemic was worse than believed because in 80 percent of the cases the infected people had no symptoms.

As the virus spreads from Brazil, other countries in the Americas are also likely to see cases of babies with Zika-linked birth defects, experts believe.

The Pan American Health Organization says that Zika has now spread in 24 nations and territories in the Americas. In addition, the Zika virus infection was also reported late last year in Cape Verde.

The Zika virus has raised questions worldwide about whether pregnant women should avoid infected countries.

Chan said delaying travel was something pregnant women "can consider," adding that if they needed to travel they should take personal protective measures by covering up and using mosquito repellant.

The clinical symptoms of Zika are usually mild and often similar to dengue, a fever which is transmitted by the same Aedes aegypti mosquito, leading to fears that Zika will spread into all parts of the world where dengue is commonplace.

More than a third of the world's population lives in areas at risk of dengue infection, in a band stretching through Africa, India, Southeast Asia and Latin America.

Zika's rapid spread through Latin America is put down to the prevalence of Aedes aegypti and a lack of immunity among the population.

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Brazilian Health Minister Marcelo Castro told Reuters that the epidemic was worse than believed because in 80 percent of the cases the infected people had no symptoms.

As the virus spreads from Brazil, other countries in the Americas are also likely to see cases of babies with Zika-linked birth defects, experts believe.

The Pan American Health Organization says that Zika has now spread in 24 nations and territories in the Americas.

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