BRASILIA (Reuters) - Two U.S.-Brazilian studies on whether the Zika virus spreading through the Americas is causing birth defects and other neurological disorders will yield initial results by May, a senior U.S. public health official said on Friday.
The studies seek to confirm the theory that the mosquito-borne virus is responsible for an unprecedented surge in Brazil of cases of babies born with abnormally small heads, a condition called microcephaly, and that it can cause Guillain-Barré syndrome, a temporary paralysis in adults.
Since it appeared in Brazil last year, the virus first detected in monkeys in Africa in 1947 has spread to more than 26 countries in the Americas, and to several countries elsewhere. Zika had previously been viewed as a relatively mild illness, but concern over the possible links to birth defects prompted the World Health Organization to declare the outbreak an international health emergency on Feb. 1.
Preliminary results of the two case control studies conducted by the U.S. Centers for Disease Control and Prevention and Brazilian biomedical research centres in the northeastern states of Bahia and Paraiba should be ready “this spring,” said CDC principal deputy director Anne Schuchat.
“Scientists are increasingly confident that Zika is causing microcephaly, but people may have different judgements about how much proof is enough,” Schuchat told reporters during a two-day meeting in the Brazilian capital on how to deal with the virus, which is borne by the same mosquito that transmits dengue and yellow fever.
“The epidemiologic studies ongoing here in Brazil and some being initiated in Colombia should help cement the link,” she said.
The WHO said on Friday it could take four to six months to prove the link.
Brazil has said it has confirmed more than 500 cases of microcephaly, and considers most of them to be related to Zika infections in the mothers. Brazil is investigating more than 3,900 additional suspected cases of microcephaly. But the causal link with Zika has not been proven.
Schuchat said the U.S. government is “very concerned” about a surge of the mosquito-borne virus in the U.S. Caribbean territory of Puerto Rico when the weather warms up in mid-year, and “extremely concerned” about the impact Zika can have on Haiti, where dengue is endemic.
Brazil is scrambling to contain the Zika outbreak that threatens attendance at the Olympic Games in Rio de Janeiro in August. The United States and other countries are recommending that pregnant women stay away.
The meeting between U.S. and Brazilian public health experts helped pool scientific information, remove hurdles and make sure “we are putting our best minds together” to advance research on Zika and its consequences, said U.S. delegation head, Assistant Secretary of Health and Human Services Jimmy Kolker.
He said he was confident Brazil’s government has removed legal obstacles to sending blood samples abroad, which has hindered international research into the virus by public institutions and private companies seeking a vaccine.
The U.S. experts said Brazil was quick to recognise it had a problem and alert the world. “A new disease or syndrome like this is a global problem, and we are lucky that the Brazilians were very prompt and open with their experience,” Schuchat said.
Reporting by Anthony Boadle; Editing by Frances Kerry