Changes in the malaria transmission profile in a low-endemic area of the Brazilian Amazon: a cause for concern

Abstract

Since 2015, there has been a renewed global commitment to malaria elimination. Understanding the dynamics of the disease in regions with declining cases is essential to prevent reintroduction. This study aims to analyze the epidemiological indicators of malaria in Maranhao, a Brazilian state with a significant decline in cases. This is a descriptive, retrospective, and ecological study, with data from the malaria surveillance system, from 2003 to 2022. Demographic, spatial, temporal, and parasitological variables were analyzed. During this period, 83,517 malaria cases were reported, of which 67.8% were autochthonous, and among these, 83.1% occurred in rural areas. The Annual Parasitic Incidence (API) has recently been considered low risk in most municipalities. The analysis of seasonality was important at the beginning of the series, but with the reduction of cases, it lost relevance. The epidemiological profile has shifted, with an increase in imported cases initially from abroad and more recently from other Brazilian states. There was also a significant reduction in the proportion of P. falciparum, from 17.7% in 2003 to 6.01% in 2022. Most infected individuals were male, predominantly aged 15 to 45 years, of which increased from 59.1% to 70.5%. Although the overall trend is downward, recent changes in the disease profile are concerning, as they could reverse progress and cause a new rise in cases in a state close to elimination. Surveillance must be strengthened and adapted to prevent the reintroduction and resurgence of endemic transmission.