RIO DE JANEIRO (Reuters) - Brazil's Health Ministry said on Wednesday that most of the 508 confirmed cases of microcephaly reported in the country are likely related to the ongoing outbreak of Zika virus, and called its previous count too conservative.
Earlier on Wednesday, the ministry reported a total of 4,443 suspected and confirmed cases of the rare defect, up from 4,314 a week earlier. It did not, however, update its total of 41 cases in which it said that microcephaly had been linked by laboratory tests to Zika infections.
Microcephaly is marked by abnormally small head size that can result in developmental problems. Brazil is investigating a surge in the number of cases across the country in conjunction with the outbreak of Zika, but it has not yet been proven that the virus can cause microcephaly.
To clarify, the ministry said in an e-mailed statement that the government would cease to update the confirmed number of linked cases because "the Health Ministry considers that there were Zika virus infections in most of the mothers whose babies have been diagnosed" with the condition.
The previous counts, the ministry said, "did not adequately represent the number of cases observed."
Of the total reported on Wednesday, Brazil said 508 cases of microcephaly have been confirmed, while 3,935 were still being investigated. Very few of the microcephaly cases can be attributed to causes other than Zika, after extensive analyses and testing, the health ministry said.
Zika has proven to be extremely difficult to diagnosis. The virus still confounds blood tests and scientists have been tracking Zika with genetic tests and clinical symptoms.
Zika has now spread to more than 30 countries and has led the World Health Organization to declare a global health emergency.
Reporting by Paulo Prada; Additional reporting by Caroline Stauffer; Editing by Toni Reinhold