RIO DE JANEIRO/QUITO – Brazil’s Health Ministry said Wednesday that in recent months it has recorded 4,180 suspected cases of a rare brain defect in babies that officials fear may be linked to the spread of the mosquito-borne Zika virus.
But so far, only 270 of the cases have been confirmed by lab tests as microcephaly involving brain damage, and the defect was ruled out in 462 cases, the ministry said. Researchers are still investigating 3,448 of the cases, which were recorded from Oct. 22 to Jan. 23.
The ministry said laboratories are trying to determine a link between the Zika virus and microcephaly, which also can be caused by factors such as herpes, rubella and syphilis. The rare birth defect causes babies to be born with unusually small heads and can cause lasting developmental problems.
Brazilian health officials estimate they had 150 cases of microcephaly in all of 2014 and the surge in suspected cases and the possible link to Zika have caused worries across Latin America’s biggest nation and in other countries in the Western Hemisphere.
On Tuesday, Brazil’s health minister, Marcelo Castro, announced that 220,000 military personnel were being deployed to bolster efforts to eradicate the Aedes aegypti mosquito that transmits Zika, dengue, chikungunya and yellow fever.
Castro said the government also would distribute mosquito repellent to some 400,000 pregnant women who receive cash-transfer benefits.
The arrival of Zika in Brazil last year initially caused little alarm as the virus’ symptoms are generally much milder than those of dengue. Then late last year, Brazilian researchers reported they suspected Zika was linked to the dramatic increase in reported cases of microcephaly.
The World Health Organization has stressed that a link remains circumstantial and is not yet proven scientifically.
The U.S. Centers for Disease Control and Prevention is advising pregnant women to reconsider travel to Brazil and 21 other countries and territories with Zika outbreaks. Officials in El Salvador, Colombia and Brazil have suggested women stop getting pregnant until the crisis has passed.
Brazilian President Dilma Rousseff meanwhile called Wednesday for Latin America to launch a region-wide fight against the Zika virus, blamed for causing a surge in brain-damaged babies.
Rousseff said she had asked a summit of the 33-member Community of Latin American and Caribbean States (CELAC) to launch “cooperative action in the fight against the Zika virus,” which originated in Africa and arrived in Latin America last year.
Since the outbreak of the mosquito-borne virus began, Latin American health officials have reported a surge in babies born with microcephaly, or abnormally small heads.
Brazil has been the hardest hit, just months before it welcomes hundreds of thousands of travelers from around the world for the Olympic Games in Rio de Janeiro.
Cases of microcephaly, which can cause brain damage or death, have risen from 163 per year on average in Brazil to some 4,000 suspected cases since the Zika outbreak began.
Forty-nine of the babies have died.
Rousseff announced a meeting of regional health ministers Tuesday in the Uruguayan capital Montevideo to address the outbreak.
The meeting will be held under the auspices of South American regional bloc MERCOSUR, but will be open to all Latin American and Caribbean countries, she said.
CELAC will later organize its own health ministers’ meeting, she added.
Zika has so far been detected in about 20 countries in the region.
But the World Health Organization has warned it is expected to spread to every country in the Americas except Canada and Chile.
Rousseff vowed to wage a “house-by-house fight” against Zika, echoing an announcement by her health minister Monday that 200,000 soldiers would be deployed to go house to house in a mosquito control campaign to wipe out breeding grounds.
“Most countries are adopting a model similar to ours of using the armed forces as one of the organizational vectors in the fight to physically eradicate breeding grounds and eliminate standing water,” Rousseff said.