New Research on Zika Virus Demonstrates Lingering Challenges

School of Public Health professor Marcia C. de Castro presented preliminary research on Wednesday that found that birth rates in Latin America have not fallen in the months following the Zika epidemic.

The seminar, hosted by the Brazil Studies Seminar Series and called “Impact of the Zika Virus Outbreak on Brazilian Fertility,” looked at abortion, historical birth rates, access to contraceptives, and the spread of the virus itself to show why birth rates failed to fall, despite the known risk of having a child while infected with the virus.

Castro attributed the constant birth rate to ineffectiveness in Brazil’s birth control program. Although 87 percent of women have access to contraception, a high rate of contraceptive misuse means that 40 percent of Brazilian pregnancies are unwanted, Castro claimed.


“To have a decline in the unwanted pregnancy, that means that women should have control of it in the first place. Access to contraception doesn’t seem to be the problem. Using it correctly is still a problem in Brazil,” Castro said.

She adds that Zika is often asymptomatic. “We have several records of women who delivered babies with congenital Zika syndrome and they never had symptoms during pregnancy,” Castro said.


Castro also shared developments showing that the Zika virus can have a diverse range of effects—beyond microcephaly, which causes babies to have smaller heads—on fetuses. Many children thought to be healthy at birth were later discovered to have Zika-based impairments. According to Castro, 20 percent of children with brain damage had “perfectly normal head sizes.”

Instead of trying to lower birth rates, Castro argued that the Brazilian government might reduce incidence of Zika by improving infrastructure to reduce standing water. She cited one survey showing that 85 percent of mosquito breeding habitats are domestic water containers.

However, while Castro found the Brazilian government’s infrastructure improvements to be virtually non-existent, some attendees were still impressed by her description of how the government tried to combat Zika.

“All the information they gave, all the help they gave to women, to everyone...dealing with the problem.” said Patricia C. McCormick, a seminar attendee. “It’s amazing. Hats off.”

While Zika transmission rates have fallen, Castro emphasized that the virus was down but not out.

“Infections do have a cycle and they peak and they come down,” she said. “If you look at [mosquito-borne viral illness] dengue, every three years or so it’s epidemic, and then it comes down. Most likely [Zika] is going to have the same pattern.”


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