Pediatric cardiologist Dr. Sandra Mattos had been collecting data on 100,000 newborns in the Brazilian state of Paraiba as part of her work. The microcephaly fears linked to the Zika virus drove her team to check back into hospital records for ... more than 1,600 babies born in the state in the last four years. We were very, very surprised," Mattos said. Babies with mild microcephaly were present in the population dating back to at least 2012. Scientists think the original reports of 4,700 suspected cases were inflated by over-reporting that didn't stand up when specialists examined the babies. Lingering questions remain, including why more than 80 per cent of suspected microcephaly cases are confined to Brazil's northeast region. And why has microcephaly not appeared in other Latin American countries with similar climates, such as among the 2,100 pregnant women infected with Zika in Colombia? In Berlin, epidemiologist Dr. Christoph Zink has been charting publicly available data from the Zika virus outbreak in terms of when cases appeared, the geographic distribution and the continuous microcephaly epidemic. He proposes another potential explanation. "I would ask my toxicological colleagues in Brazil to please look very closely into the practical application of agrochemicals in their country," Zink said. Mattos said pesticides have been raised as a potential factor by her colleagues in Brazil.