Researchers carry out unprecedented mapping of the incidence of gestational malaria in Brazil

Published in the journal Lancet Regional Health – Americasstudy helps to guide actions to combat this public health problem in the country (Image: Wikimedia Commons)

July 20, 2022

Thais Szego | FAPESP Agency – An unprecedented mapping of the incidence of malaria among Brazilian pregnant women was published by researchers from the University of São Paulo (USP) in the journal Lancet Regional Health – Americas.

The data indicate that, although gestational malaria still represents an important public health problem in the country, there was a reduction of approximately half of the cases over the period analyzed (2004 to 2018). According to the authors, this is due to the expansion of the diagnosis and treatment network, as well as the inclusion, as of 2006, of the drug artemisinin in the therapeutic regimen.

Also according to the researchers, the reduction was not greater, possibly because of the decentralization of public actions to combat malaria in the country. As municipalities have the autonomy to deal with cases, this can lead to losses with the alternation of teams linked to health agencies with each new election.

“Although there are several studies published on gestational malaria in the country, none of them presented an overview of the disease, as they were mostly carried out in specific locations or regions”, he tells FAPESP Agency Claudio Romero Farias Marinho, associate professor at the Laboratory of Experimental Immunoparasitology at the Institute of Biomedical Sciences (ICB-USP), who coordinated the work. “And that’s why we set out to explore the spatial and spatio-temporal patterns of malaria during pregnancy in Brazil, epidemiologically characterizing this population.”

Group of risk

As the researcher recalls, pregnant women constitute one of the main risk groups for malaria – a disease caused by protozoa of the genus plasmodium and transmitted by mosquito anopheles. Infected pregnant women are more at risk of severe anemia, premature birth, miscarriage and stillbirth. The fetus may have microcephaly or have its growth impaired in the uterus, with impacts that usually extend beyond the gestational period.

“Studies show that infection affects brain development and function causing cognitive and neurological deficits, a consequence of conditions such as cerebral palsy and epilepsy, is associated with respiratory problems in childhood and makes the child more prone to infections, in addition to the risk risk of developing chronic diseases in adulthood, such as diabetes and high blood pressure”, says Marinho.

For these reasons, pregnant women were the focus of the survey conducted by the postdoctoral student at the ICB-USP Jamille Dombrowski, FAPESP scholarship, in partnership with researchers from the Faculty of Public Health (FSP-USP). The group analyzed the historical series of the disease over a period of 15 years, involving data from 61,833 women with gestational malaria in Brazil obtained from the Malaria Epidemiological Surveillance System (Sivep-Malaria) of the Ministry of Health. The results showed municipalities in the states of Amazonas, Acre, Rondônia and Pará with a high incidence of the disease in pregnant women.

The survey also made it possible to point out the group at greatest risk, which are younger pregnant women, especially those between 15 and 24 years old. This is because it is in this age group that the largest number of primigravidae (women in their first pregnancy) are found. In such cases, specific immunity against the forms of plasmodium that settle in the placenta is lower, as it is acquired after successive pregnancies. “It is also important to remember that in the Northern Region of Brazil, primiparous pregnant women are very young and their time of exposure to the protozoan is shorter because of their short life span, making their body less protective against it”, explains the researcher.

The study also revealed evidence that the treatment regimen for these patients may not be being done correctly, as a high percentage of primaquine notification was noted. It is a drug that is contraindicated during pregnancy, as it can cause the destruction of the red blood cells of the fetus, responsible for transporting oxygen, and consequently cause a miscarriage.

All this information obtained by the team coordinated by Professor Marinho can help guide the Ministry of Health in the establishment of public policies to control malaria and also to offer better assistance to pregnant women in these cases. It will be possible to identify areas that may require greater vigilance or additional interventions, acting on specific strategies to protect pregnant women and their babies from the devastating consequences of the disease.

With the epidemiological aspect ready, the focus of the researchers becomes the early diagnosis of a complication of the disease, placental malaria. It is very important, as pregnant women usually do not have symptoms, but they may have the parasite in their placenta – a condition known as placental malaria – and the disease is only detected after the baby is born, without the possibility of intervention or treatment. .

For this reason, Dombrowski is working on a new project that aims to identify biomarkers of rapid measurement and affordable cost so that their analysis can be introduced into the routine of prenatal care.

The article Mapping and characterizing areas with high levels of malaria in pregnancy in Brazil: A spatiotemporal analysis can be read at: