The seasonal dynamics and biting behavior of potential Anopheles vectors of Plasmodium knowlesi in Palawan, Philippines

Parasites & Vectors

Kristelle Mae R. Valle¹  Brian A. Bacay¹  Richard Paul B. Malijan¹  Wilfredo E. Aure¹  Jessie C. Braganza¹  Ferdinand V. Salazar¹  Majhalia M. Torno²  Fe Esperanza Espino³  Frank Mechan⁴  Stephen J. Torr⁴  Kimberly M. Fornace⁵  Chris Drakeley⁵  Heather M. Ferguson⁶ 

[1] Department of Medical Entomology, Research Institute for Tropical Medicine, Alabang, 1781, Muntinlupa City, Metro Manila, Philippines;Department of Medical Entomology, Research Institute for Tropical Medicine, Alabang, 1781, Muntinlupa City, Metro Manila, Philippines;Taxonomy & Pesticide Efficacy Branch, Vector Biology & Control Division, Environment Health Institute, National Environment Agency, Ministry of Sustainability and the Environment, 11 Biopolis Way, 138667, Singapore, Singapore;Department of Parasitology, Research Institute for Tropical Medicine, Alabang, 1781, Muntinlupa City, Ma, Metro Manila, Philippines;Department of Vector Biology, Liverpool School of Tropical Medicine, L3 5Q4, Liverpool, UK;Faculty of Infectious and Tropical Diseases, London School of Tropical Medicine and Hygiene, WC1E 7HT, London, UK;Institute of Biodiversity, Animal Health and Comparative Medicine, University of Glasgow, G12 8QQ, Glasgow, UK;

关键词: Anopheles balabacensis;    Anopheles flavirostris;    Plasmodium knowlesi;    Vector behavior;    Philippines;   

DOI  :  10.1186/s13071-021-04853-9

来源: Springer

【 摘 要 】

BackgroundA small number of human cases of the zoonotic malaria Plasmodium knowlesi have been reported in Palawan Island, the Philippines. Identification of potential vector species and their bionomics is crucial for understanding human exposure risk in this setting. Here, we combined longitudinal surveillance with a trap-evaluation study to address knowledge gaps about the ecology and potential for zoonotic spillover of this macaque malaria in Palawan Island.MethodsThe abundance, diversity and biting behavior of human-biting Anopheles mosquitoes were assessed through monthly outdoor human landing catches (HLC) in three ecotypes representing different land use (forest edge, forest and agricultural area) across 8 months. Additionally, the host preference and biting activity of potential Anopheles vectors were assessed through comparison of their abundance and capture time in traps baited with humans (HLC, human-baited electrocuting net—HEN) or macaques (monkey-baited trap—MBT, monkey-baited electrocuting net—MEN). All female Anopheles mosquitoes were tested for the presence of Plasmodium parasites by PCR.ResultsPreviously incriminated vectors Anopheles balabacensis and An. flavirostris accounted for > 95% of anophelines caught in longitudinal surveillance. However, human biting densities were relatively low (An. balabacensis: 0.34–1.20 per night, An. flavirostris: 0–2 bites per night). Biting densities of An. balabacensis were highest in the forest edge, while An. flavirostris was most abundant in the agricultural area. The abundance of An. balabacensis and An. flavirostris was significantly higher in HLC than in MBT. None of the 357 female Anopheles mosquitoes tested for Plasmodium infection were positive.ConclusionsThe relatively low density and lack of malaria infection in Anopheles mosquitoes sampled here indicates that exposure to P. knowlesi in this setting is considerably lower than in neighboring countries (i.e. Malaysia), where it is now the primary cause of malaria in humans. Although anophelines had lower abundance in MBTs than in HLCs, An. balabacensis and An. flavirostris were caught by both methods, suggesting they could act as bridge vectors between humans and macaques. These species bite primarily outdoors during the early evening, confirming that insecticide-treated nets are unlikely to provide protection against P. knowlesi vectors.Graphical abstract

【 授权许可】

CC BY