The Zika virus spread in Brazil between 2015 and 2016, a situation that led the country to declare a state of emergency. As a result, thousands of children were born with abnormalities of the nervous system. Microcephaly, transmitted from mother to child, is one of the best-known consequences of the infection, which not only reduces quality of life, but also life expectancy. To examine the effects of Zika on pregnant women and their babies, one study conducted one of the largest analyzes on the subject.
How was the study that evaluated the effects of Zika conducted?
Published in The Lancet Regional Health – Americas, the article combines 13 national studies with data from 1,548 pregnant women. As a result of a robust analysis, episodes of microcephaly, neurological and ocular abnormalities, and neuroimaging, abnormalities were found in 31.5% of the children, almost a third of the sample.
Though harmful to the health of young people, the findings will enable stronger public policy, better care, and even new research to monitor and control the disease.
When the cases and effects of the Zika virus broke out in Brazil, there was not much response for long-term action against the problem.
“Faced with this, there was no time for a great national expression and different groups carried out independent studies,” recalls epidemiologist Ricardo Arais de Alencar Ximenes, one of the authors of the article and a professor at UFPE.
Thus, this spraying resulted in smaller patient samples, protocols with variable criteria, and variability in results, which added to the uncertainty of the results.
“But really in 2016 we started talking to these groups to harmonize protocols and, since then, integrate data from different studies. Brazilian science has demonstrated its maturity and capacity in the face of this pandemic”, Ximenes stresses.
From these interactions emerged the Brazilian Federation of Zika Cohorts, which today includes scientists from 26 institutions. “The great value of the article, which is the first of its kind in the Federation, is the unification of forces, allowing more reliable results to be reached”, highlights the specialist.
To be included in a meta-analysis, studies must confirm a diagnosis of Zika infection in pregnant women through RT-PCR assays, before fetal abnormalities are detected. They also needed to accompany women until the end of their pregnancy, exclusively in Brazil.
Thus, the surveys covered the four regions most affected by the epidemic – Northeast, North, Midwest and Southeast. The data of each participant received an individual analysis, under a series of possible effects that Zika causes in children.
They ranged from low birth weight to microcephaly and eye and neurological problems, for example, seizures.
Microcephaly is one of the effects of congenital Zika
Ximenes points out that with the Zika epidemic caught up in the increase in microcephaly cases, part of the population still believes that this is the only abnormality associated with the infection. However, he reiterates that the congenital syndrome associated with the virus can present itself in various ways, including vision difficulties and motor deficits, among others.
It is possible, for example, that the abnormality in the brain was asymptomatic or caused only mild symptoms. “Regardless of that, one third of children infected is a very impressive number, indicating the possibility of contracting Zika,” he adds.
Furthermore, Ximenes argues that even the smallest manifestations can lead to problems over the years.
According to the meta-analysis, 2.6% of the children of affected mothers had microcephaly at the first medical evaluation. On the other hand, other children received the same diagnosis over time; overall, 4% developed the condition during the first years of life.
“Our results indicate that among children with microcephaly, the fraction of late diagnosis is not negligible,” say the paper’s authors. The risk of Zika-associated postpartum microcephaly has not been previously documented. They concluded that this illustrates the importance of monitoring head growth for all babies exposed to the virus before birth, even those with normal skull circumference.
By the way, children with microcephaly caused by Zika often have different disorders at the same time. “So this has led to the belief that Zika-associated congenital syndrome is generally characterized by a number of problems,” says Ximenes. “But that doesn’t actually happen in most cases.”
According to a meta-analysis, less than 1% of infants with maternal infection had more than one malformation. “That is, we found that the manifestations tend to occur in isolation,” repeats the epidemiologist.
The finding serves as a warning even to professionals, who can sometimes not associate a condition with Zika, or even let it run its course, because it’s an isolated symptom. “An early diagnosis of the syndrome allows for early interventions that benefit patients,” says Ximenes.