Resistance profile of the Plasmodium falciparum dihydropteroate synthase gene in three hospitals in the city of Ndjamena, Chad

Why this matters for everyday life

Malaria remains a daily threat for millions of families across Africa, especially young children and pregnant women. Many prevention programs rely on long‑used medicines that keep infections at bay. This study from N’Djamena, the capital of Chad, looks at whether the malaria parasite is quietly changing its genetic makeup in ways that could undermine one of these key drugs. Understanding these early warning signs helps public health officials decide when it is time to adjust treatment strategies before more lives are put at risk.

Malaria, old medicines, and a new threat

The parasite that causes the most severe form of malaria in humans, Plasmodium falciparum, is usually treated and prevented with combinations of drugs. One long‑standing medicine, sulfadoxine–pyrimethamine (often called SP or Fansidar), is widely used to protect pregnant women and, in some regions, young children. But SP targets a specific step in the parasite’s internal chemistry. When the parasite’s genetic code mutates at that step, the drug can lose its power. The researchers focused on a parasite gene called Pfdhps, which helps the parasite make folate, a small molecule it needs to grow. Changes at two positions in this gene, known as A437G and A581G, are strongly linked to SP no longer working well.

Taking a snapshot in Chad’s capital

To see how common these genetic changes have become, the team carried out a cross‑sectional survey in three major health facilities in N’Djamena: a university hospital for mothers and children, a general hospital, and a health center. They enrolled 220 people who came for malaria testing and agreed to participate, excluding those who had recently taken antimalarial drugs or had conditions that made blood sampling risky. Malaria infection was first checked using standard rapid tests and microscope examination of thick blood smears. When Plasmodium falciparum was confirmed, small spots of blood were preserved on filter paper for later genetic analysis in the laboratory.

From blood spots to parasite genes

In the lab, the scientists extracted parasite DNA from the dried blood and used a sensitive technique called semi‑nested PCR to amplify the Pfdhps gene, making it easier to study. They then used restriction enzymes, molecular “scissors” that cut DNA at specific sequences, to distinguish normal from mutated versions of the gene. If the DNA fragments produced had particular sizes, this indicated whether the A437G or A581G mutation was present. Statistical tools were used to link the presence of these mutations to age, sex, marital status, occupation, and everyday malaria‑related habits, such as wearing protective clothing, bedtime, and which medicines people reported using.

What the team found in people and parasites

Among the 220 participants, 87 had P. falciparum malaria, giving an infection prevalence of about 40 percent—similar to recent national survey figures. Infection was especially common in very young children and in married adults. Of these 87 infected individuals, just under 38 percent carried parasites in which the Pfdhps gene could be successfully amplified, allowing detailed genetic study. Within this group, the more “classic” resistance marker A437G was relatively uncommon, appearing in about 9 percent of alleles. In contrast, the A581G mutation, a change known to boost resistance and linked to treatment failure, was detected in more than half of the alleles examined. The A581G mutation showed up more frequently in people aged 6–35 years, in married adults, in women, and in those who reported taking Fansidar. It was also more frequent among people who did not wear protective clothing and those with behaviors suggesting higher exposure to mosquito bites.

Implications for malaria control and next steps

To a non‑specialist, the key message is straightforward: in N’Djamena, many malaria parasites already carry genetic changes that can weaken an important prevention drug. While SP is still in use, the high frequency of the A581G mutation in particular signals that the parasite is adapting. The authors argue that Chad should reinforce genetic monitoring of malaria parasites so that health authorities can spot rising resistance early and adapt national guidelines in time. They also recommend expanding future work to include other genes tied to resistance against modern frontline drugs. In essence, this study functions as an early alarm, warning that some of the tools we rely on to prevent malaria are losing their edge and that careful, ongoing surveillance is essential to stay ahead of a shape‑shifting foe.

Citation: Cedric, Y., Djakbé, D.L., Ngaryedji, T. et al. Resistance profile of the Plasmodium falciparum dihydropteroate synthase gene in three hospitals in the city of Ndjamena, Chad. Sci Rep 16, 9452 (2026). https://doi.org/10.1038/s41598-026-39796-7

Keywords: malaria drug resistance, Plasmodium falciparum, sulfadoxine pyrimethamine, Chad N’Djamena, Pfdhps mutations