Latin American health ministers were meeting in Montevideo on Wednesday for a regional crisis summit to discuss the public health emergency declared by the World Health Organization (WHO) over the rapid spread of the Zika virus, according to dpa. Ministers from 10 South American countries were joined in the Uruguayan capital by their counterparts from Mexico, Costa Rica and the Dominican Republic, as well as Director of the Pan-American Health Organisation (PAHO), Carissa Etienne. The conference was called a week earlier by Brazilian President Dilma Rousseff, whose country is most affected by the Zika virus with an estimated 1.5 million infections. The virus, which is transmitted by Aedes aegypti mosquitos, is suspected of causing birth defects through mother-to-child transmission but the link has not yet been proven. The number of confirmed cases of babies born with microcephaly, in which the newborn has an abnormally small head, has risen significantly in Brazil in the past week. The number of cases of microcephaly has risen from 270 a week ago to 404, the Health Ministry said Tuesday. Health authorities in the US state of Texas on Tuesday announced the first known case of the virus being sexual transmitted. While WHO spokesman Gregory Haertl acknowledged the transmission "raises concerns," he said that "almost a 100 per cent" of the cases are caused by mosquitos and emphasized the focus should be on limiting exposure to the insect.