Spread of Brazil’s Mosquito-Borne Virus Is Growing, but at Slower Pace

Despite deceleration, number of new cases in recent days is greater than all of 2014

SÃO PAULO—The spread of the mosquito-borne Zika virus, which some Brazilian health officials have linked to thousands of cases of infant brain damage, is slowing but still growing in South America’s largest country.

Figures released Tuesday by Brazil’s Health Ministry showed a 7% one-week increase in the number of suspected Zika-related cases of microcephaly, or brain and skull underdevelopment in newborns. Many Brazilian and international health authorities say there is substantial evidence—although no conclusive proof yet—that the virus is being transmitted to the infants by mothers who have been bitten by infected mosquitoes.

There were 193 new cases of suspected Zika-related microcephaly in the week of Dec. 19-26. Tuesday’s figures mark a slower rate of increase than was recorded the previous week, when suspected cases shot up 16%. But it brings the total number of suspected cases to 2,975, which have been found in 656 municipalities in 20 of Brazil’s 27 states. There was no increase in the number of Zika-related deaths, which held steady at 40.

Despite the slowdown, the number of new cases in recent days is greater than the 147 cases registered in all of 2014.