Pf41 serological profiling reveals potential malaria exposure in low transmission setting in the Menoreh Hills, Central Java, Indonesia.

BACKGROUND

Pf41 serological profiling may serve as an additional sero-epidemiological tool to characterize past malaria exposure, particularly in low-transmission settings where routine parasitological methods have limited capacity to detect historical exposure. In the Menoreh Hills, Central Java, where malaria transmission is low and unstable, such profiling can reveal exposure history that are not captured by conventional parasitological methods. This study evaluates the utility of Pf41 antibody responses as an exposure marker in a low-transmission context, with the Menoreh Hills serving as an epidemiologically relevant field site.

METHODS

A cross-sectional seroepidemiological study was conducted from January to June 2025 in four malaria-endemic villages: Sedayu, Kemejing, Kembaran, and Wadas. Serum samples from 120 individuals in malaria endemic villages and 24 healthy non-exposed controls were analyzed for anti-Pf41 IgG antibodies using a protein microarray. Demographic and behavioral data were collected through structured questionnaires, and statistical analyses were performed to assess differences in antibody responses and their associations with demographic and exposure-related factors.

RESULTS

The results revealed a high overall Pf41 seropositivity rate of 71% (85/120) among individuals in malaria endemic villages, with marked heterogeneity across villages: Kembaran 93%, Sedayu 83%, Wadas 60%, and Kemejing 47%. Mean standardized MFI was significantly higher in all exposed groups compared to controls (p < 0.001). At the individual level, Pf41 antibody responses were significantly associated with selected behavioral factors in a site-specific manner. In Sedayu, behavioral factors showed a site-specific pattern, with frequent mosquito bites during outdoor activities at night being associated with higher Pf41 antibody levels. In Kemejing, higher antibody levels were observed among individuals who fed livestock at night. In the pooled analysis across all study sites, nighttime livestock feeding and the use of repellent was significantly associated with increased Pf41 antibody levels.

CONCLUSIONS

These findings indicate that serological evidence of past malaria exposure remains detectable in the Menoreh Hills despite a decline in reported clinical cases, with antibody responses varying across villages and reflecting differences in behavioral risk profiles. The integration of Pf41 serology into malaria surveillance systems could complement existing approaches by contributing to the identification of populations or areas with serological evidence of prior malaria exposure in low-transmission settings.