Pregnant Women's Role in Malaria Surveillance and Monitoring
Pregnant women were found to have malaria infection in 60% of the identified hotspots detected through clinical cases, revealed research published in Nature Communications ().
Close monitoring of malaria trends in a community or region (i.e. whether it is increasing or decreasing) is essential to adjust interventions aimed at controlling or eliminating the disease. However, relying on clinical cases that arrive at health centres is not ideal, as there are many patients who do not seek care or are asymptomatic. On the other hand, cross-sectional studies (i.e. collecting data from many people at the same time) are expensive and can only be carried out every two to three years.
Active Participation of Pregnant Women in Malaria Surveillance
For Alfredo Mayor, researcher at ISGlobal and CISM, pregnant women attending antenatal care visits are an optimal group to monitor the prevalence of malaria and other infectious diseases. "In sub-Saharan Africa, 79% of pregnant women attend at least one antenatal care visit, which is a good representation of the total population," notes Mayor. "In addition, antenatal visits have the advantage of capturing asymptomatic infections because they are independent of whether the person feels unwell."‘P. falciparum infection in pregnant women during their initial antenatal care visit is a key indicator to estimate the malaria burden in children. #malaria #mosquitodiseases #pregnancymalaria’
In this study, Mayor and his team measured malaria prevalence in 6,471 pregnant women attending antenatal care visits in three areas of southern Mozambique with different levels of transmission (Manhi�a, Magude and Ilha Josina) and compared it with the prevalence estimated from clinical cases or from cross-sectional studies in children, in the same areas and over the same time period (2016-2019).
The analysis shows that infection rates in pregnant women closely reflect the rates in children from cross-sectional studies, especially when the parasite is detected by molecular tests (PCR). With rapid diagnostic tests, the correlation holds in low-transmission areas (Manhi�a or Magude), but is lost in high-transmission areas (Ilha Josina) when multigravid women (who have had more than one pregnancy) are included. Multigravid women had a lower prevalence than the children in the community. "This is because the immunity acquired during previous pregnancies allows them to maintain low parasite densities and evade detection by rapid tests, which are less sensitive than PCR," explains Arnau Pujol, co-first author of the study with Gloria Matambisso.
The results also show a good correlation over time between the declining infection rates in pregnant women and that of clinical cases, albeit with a lag of about three months (i.e. infection rates in pregnant women followed the same pattern as those in clinical cases, but with a delay of 2-3 months). This correlation was observed in all three sites, regardless of whether the woman was primigravida, multigravida or HIV-positive.
"Our study shows that screening for P. falciparum at the first antenatal care visit can be used to estimate disease burden in children," says Matambisso. However, the authors warn that it is important to consider the delay of about three months compared to clinical cases, as well as the need to exclude multigravid women in high-transmission areas or to use more sensitive tests.
Reference:
- Detecting temporal and spatial malaria patterns from first antenatal care visits - (https:www.nature.com/articles/s41467-023-39662-4)