Arboviruses pose a major threat to pregnant women and babies in Brazil.

Arboviruses—diseases transmitted by arthropods, such as mosquitoes and ticks—continue to pose a threat to pregnant women and newborns in Brazil. A study published in August in the journal Nature Communications reveals that infections with Zika, dengue, and chikungunya viruses, all transmitted by the Aedes aegypti mosquito , are associated with a significant increase in perinatal complications, including premature birth, low birth weight, and congenital anomalies.

Conducted by researchers from the Center for Data and Knowledge Integration for Health (Cidacs/Fiocruz Bahia), the study analyzed 6.9 million births that occurred in Brazil between 2015 and 2020, cross-referencing information from three national databases: the birth registry (SINASC), the registry of notifiable diseases (SINAN), and the mortality registry (SIM). The objective was to measure the impact of arbovirus infections during pregnancy on the health of newborns, observing outcomes such as birth weight, gestational age, and risk of death in the first weeks of life.

Among mothers of live-born babies, 19,000 (0.3%) had dengue fever, 8,300 (0.1%) were diagnosed with Zika, and just over 6,000 (less than 0.1%) with chikungunya during pregnancy. Although the numbers seem small compared to the total number of births, the authors emphasize that the effects were significant.

Women with chikungunya presented a higher risk of premature birth, low Apgar score (an indicator that assesses the baby's vital signs immediately after birth), and neonatal death, especially when the infection occurred in the second or third trimester of pregnancy. “Chikungunya can be transmitted at the time of delivery when there is a high viral load in the mother's blood. In these cases, the baby may develop serious neurological complications, such as seizures, meningoencephalitis, and hemorrhages, requiring admission to a neonatal ICU,” warns gynecologist and obstetrician Rômulo Negrini, maternal-infant coordinator at Einstein Hospital Israelita. “The virus has an affinity for the central nervous system and can cause brain inflammation, with a risk of developmental sequelae.”

The pattern of complications observed for dengue was similar. In pregnant women infected with the virus, especially at the end of pregnancy, there were more premature births and babies with low birth weight or low Apgar scores. “Dengue causes high fever, dehydration, changes in coagulation, and a drop in platelets. These factors can lead to fetal distress and premature delivery,” explains Negrini.

Systemic inflammation and placental damage also help explain the higher rate of prematurity in babies born to women diagnosed with dengue. In laboratory-confirmed analyses, the risk of neonatal death also increased, reinforcing the severity of the infection when it occurs late in pregnancy.

Zika infection, in turn, remained the most concerning arboviral disease. The study confirmed the link between maternal infection and a higher incidence of congenital malformations, as well as low birth weight and increased neonatal mortality. “Zika has strong neurotropism [the ability to preferentially infect and multiply in cells of the nervous system] . This means that it infects the neural progenitor cells of the fetus, which give rise to the brain and spinal cord, leading to cell death and interrupting brain development,” explains Negrini. “Therefore, infection in the first trimester, when the nervous system is forming, tends to cause microcephaly, calcifications, limb deformities, and ocular and auditory abnormalities.”

And it's not just in early pregnancy that Zika is a concern—the study results point to malformations even in late infections, in the third trimester, something considered uncommon until then. "Generally, the more advanced the gestational period, the greater the risk of premature birth and low Apgar scores. Infections in the early stages, especially Zika, are more associated with fetal malformations," notes the specialist from Einstein Hospital. Hence the importance of medical monitoring throughout the pregnancy.

Targeted prenatal care

The study reinforces the importance of surveillance and prenatal care protocols targeted at pregnant women with suspected or confirmed cases of these infections. “Ideally, the diagnosis should be confirmed, the fetus monitored with serial ultrasounds, and maternal warning signs assessed, including persistent fever, low platelet count, and bleeding,” advises Rômulo Negrini. “Pregnant women with severe dengue, for example, should be monitored in a unit with obstetric and neonatal support. In cases of Zika, detailed morphological ultrasound and follow-up with a specialist in fetal medicine are essential.”

There is no specific antiviral treatment for any of the three infections. Management aims to alleviate symptoms, including hydration, fever control, and monitoring of the mother and baby. "Most infected pregnant women live in regions with lower levels of education and poor infrastructure. The mosquito continues to proliferate where sanitation and access to health services are lacking," warns the doctor.

Treating arboviruses as a maternal and child health issue, and not just an infectious one, would reduce the impact on mothers and babies. "With adequate surveillance, early diagnosis, and obstetric care, it is possible to drastically reduce serious outcomes," she concludes.

Source: Einstein Agency

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