Rapid entomological assessment in eight high malaria endemic regencies in Papua Province revealed the presence of indoor and outdoor malaria transmissions

Abstract

Abstract Background Malaria in eastern Indonesia remains high despite significant reduction and elimination in other parts of the country. A rapid entomological assessment was conducted in eight high malaria endemic regencies of Papua Province, Indonesia, to expedite malaria elimination efforts in this region. This study aims to characterize specific, actionable endpoints toward understanding where and when malaria transmission is happening, where interventions may function best, and identify gaps in protection that result in continued transmission. Methods The entomological assessment included identifying potential vectors through human landing catch (HLC), indoor morning and night resting collections, identification of larval sites through surveillance of water bodies, and vector incrimination toward understanding exposure to malaria transmission. Results Human landing catches (HLCs) and larval collections identified 10 Anopheles species, namely Anopheles koliensis, An. punctulatus, An. farauti, An. hinesorum, An. longirostris, An. peditaeniatus, An. tesselatus, An. vagus, An. subpictus and An. kochi. The most common and abundant species found overall were An. koliensis and An. punctulatus, while An. farauti was found in large numbers in the coastal areas of Mimika and Sarmi Regencies. Vector incrimination on Anopheles collected from HLCs and night indoor resting demonstrated that An. koliensis and An. punctulatus carried Plasmodium in Keerom, Jayapura, and Sarmi Regencies. Analysis of HLCs for the most common species revealed the An. koliensis, An. punctulatus and An. farauti, bite indoors and outdoors at equal rates. Larval surveillance demonstrated that most water bodies in and surrounding residential areas contained Anopheles larvae. Conclusions This study demonstrated indoor and outdoor exposure to mosquito bites and gaps in protection, enabling exposure to infectious bites in all regencies. This may explain why current malaria control efforts focusing on indoor protection have failed to reduce malaria incidence in the region substantially. Optimization of insecticide-treated bed nets (ITNs), as well as installment of mosquito screens in houses, may further reduce indoor transmission. For outdoor transmission, the use of community-centric approaches to reduce or eliminate larval sources within and surrounding the village through the guidance of locally stationed entomologists, along with Social and Behavior Change Communication (SBCC) mediated health education towards the local adoption of mosquito protection tools during outdoor activities, may reduce malaria transmission.