Cases of Zika virus could rise to 4 million across the Americas within a year

The WHO said the virus was “spreading explosively”and that it would hold an emergency meeting on Monday to decide if the outbreak should be declared an international health emergency.

Three-month-old Alice Vitoria Gomes Bezerra, who has microcephaly, is held by her father Joao Batista Bezerra on January 27, 2016 in Recife, Brazil. Mario Tama/Getty Images

GENEVA // There could be four million cases of the Zika virus across the Americas within the next year, a World Health Organisation official warned on Thursday.

The WHO said the virus, which has been linked to birth defects and neurological problems, was “spreading explosively”and that it would hold an emergency meeting on Monday to decide if the outbreak should be declared an international health emergency.

At a special meeting on Thursday in Geneva, WHO director general Dr Margaret Chan said Zika was becoming much more of a threat.

She said that although there was no definitive proof the Zika virus was responsible for a spike in the number of babies being born with abnormally small heads – microcephaly – in Brazil, “the level of alarm is extremely high”.

According to the US Centres for Disease Control, the Zika virus was now in more than 20 countries, mostly in Central and South America. It is spread by the same mosquito that spreads dengue and yellow fever.

Earlier this month, the CDC said pregnant women should consider postponing trips to more than a dozen countries where Zika has been recorded.

The CDC also advised women trying to get pregnant, or thinking of getting pregnant, to speak to their doctor before travelling and to take extra precautions to avoid mosquito bites.

Sylvain Aldighieri, head of WHO’s epidemic response team in the Americas, estimated that there could be three to four million Zika infections in the region over the next year.

He said the United Nations agency expected “huge numbers” of infections because of the widespread presence of the Aedes mosquitoes that spread Zika, and because people in the region have no natural immunity.

The WHO also warned China and all other countries that have dengue fever to be on the lookout for Zika infections.

The agency said it could be many years before a vaccine was available. Dr Chan also noted a possible relationship between Zika infections and Guillain-Barre syndrome, which can cause temporary paralysis.

“The possible links, only recently suspected, have rapidly changed the risk profile of Zika from a mild threat to one of alarming proportions,” Dr Chan said. “The increased incidence of microcephaly is particularly alarming, as it places a heartbreaking burden on families and communities.”

On Wednesday Brazil released new figures for cases of microcephaly, apparently showing fewer instances in the country than first feared.

Health experts had been looking at 4,180 suspected cases of microcephaly reported since October in Brazil. But health ministry officials said they had done a more intense analysis of more than 700 of those cases, confirming 270 cases and ruling out 462 others.

What this means is hard to say, according to some experts. It does not answer whether the tropical Zika virus is causing the babies to have unusually small heads. Nor does it really tell how big the problem is.

“I don’t think we should lower our alarm over the Zika outbreak,” said Paul Roepe, co-director of Georgetown University’s Centre for Infectious Disease.

The Zika virus was first detected in 1947 and for decades only caused mild disease. But Dr Chan said on Thursday that “the situation today is dramatically different”.

Independent experts will attend Monday’s emergency meeting, which will determine whether Zika should be declared a global emergency.

Such a declaration is akin to an international SOS signal and usually brings more money and action to address an outbreak. The last such emergency was announced for the devastating 2014 Ebola outbreak in West Africa, which eventually ended up killing more than 11,000 people. Polio was declared a similar emergency the year before.

Still, convening an emergency committee does not guarantee that a global emergency will be declared – WHO has held 10 such meetings to assess the Middle Eastern respiratory syndrome coronavirus and no emergency has been announced.

One reason why WHO is examining the Zika virus so quickly may be because the agency was criticised for its slow response to Ebola. Nearly 1,000 people had died before WHO declared it to be an international emergency. Senior agency officials resisted the Ebola declaration for two months, citing political and economic reasons.

* Associated Press