Lymphatic filariasis (LF) is a parasitic infection causing chronic disability and disfigurement, commonly affecting tropical countries like Indonesia. Although Bengkulu Province, particularly Central Bengkulu District, has been classified as non-endemic after mass drug administration (MDA) campaigns, the presence of chronic cases suggests the need for continued surveillance. This study aimed to explore the presence of hidden or subclinical LF transmission in a non-endemic area by assessing eosinophil levels as a potential early indicator of filarial infection, particularly when microfilariae are undetectable by microscopy. A cross-sectional study was conducted from August to October 2022 in three villages of Central Bengkulu. A total of 262 finger-prick blood samples were examined for microfilariae using Giemsa-stained smears, while 82 venous blood samples from Tiambang Village were analyzed for eosinophil levels using a Neubauer hemocytometer and Dunger’s solution. Sociodemographic data were also recorded. No microfilariae were detected in any of the samples. However, eosinophilia (>350 cells/mm³) was observed in a significant portion of participants in Tiambang Village, with an average eosinophil count of 436 cells/mm³. Elevated eosinophil levels were more common among females and individuals aged 26–45 years, who are typically more exposed to mosquito bites due to outdoor activities. Although microfilariae were not detected, elevated eosinophil levels may suggest hidden LF transmission or residual immune responses in the population. These findings highlight the importance of integrating eosinophil profiling as a complementary surveillance tool for early detection of LF in post-MDA or low-prevalence settings.

Lymphatic Filariasis, Eosinophil Count, Microfilarie Detection, Post-MDA Surveillance, Central Bengkulu