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Biting patterns of malaria vectors of the lower Shire valley, southern Malawi.
Acta Trop. 2019 Sep; 197:105059.AT

Abstract

Assessing the biting behaviour of malaria vectors plays an integral role in understanding the dynamics of malaria transmission in a region. Biting times and preference for biting indoors or outdoors varies among mosquito species and across regions. These behaviours may also change over time in response to vector control measures such as long-lasting insecticidal nets (LLINs). Data on these parameters can provide the sites and times at which different interventions would be effective for vector control. This study assessed the biting patterns of malaria vectors in Chikwawa district, southern Malawi. The study was conducted during the dry and wet seasons in 2016 and 2017, respectively. In each season, mosquitoes were collected indoors and outdoors for 24 nights in six houses per night using the human landing catch. Volunteers were organized into six teams of two individuals, whereby three teams collected mosquitoes indoors and the other three collected mosquitoes outdoors each night, and the teams were rotated among twelve houses. All data were analyzed using Poisson log-linear models. The most abundant species were Anopheles gambiae sensu lato (primarily An. arabiensis) and An. funestus s.l. (exclusively An. funestus s.s.). During the dry season, the biting activity of An. gambiaes.l. was constant outdoors across the categorized hours (18:00 h to 08:45 h), but highest in the late evening hours (21:00 h to 23:45 h) during the wet season. The biting activity of An. funestus s.l. was highest in the late evening hours (21:00 h to 23:45 h) during the dry season and in the late night hours (03:00 h to 05:45 h) during the wet season. Whereas the number of An. funestuss.l. biting was constant (P = 0.662) in both seasons, that of An. gambiaes.l. was higher during the wet season than in the dry season (P = 0.001). Anopheles gambiae s.l. was more likely to bite outdoors than indoors in both seasons. During the wet season, An. funestus s.l. was more likely to bite indoors than outdoors but during the dry season, the bites were similar both indoors and outdoors. The biting activity that occurred in the early and late evening hours, both indoors and outdoors coincides with the times at which individuals may still be awake and physically active, and therefore unprotected by LLINs. Additionally, a substantial number of anopheline bites occurred outdoors. These findings imply that LLINs would only provide partial protection from malaria vectors, which would affect malaria transmission in this area. Therefore, protection against bites by malaria mosquitoes in the early and late evening hours is essential and can be achieved by designing interventions that reduce vector-host contacts during this period.

Authors+Show Affiliations

School of Public Health and Family Medicine, College of Medicine, University of Malawi, Malawi; Laboratory of Entomology, Wageningen University and Research, the Netherlands. Electronic address: monicahmirai@yahoo.com.School of Public Health and Family Medicine, College of Medicine, University of Malawi, Malawi; MAC Communicable Diseases Action Centre, Blantyre, Malawi. Electronic address: tmzilahowa@mac.medcol.mw.Centre for Health Informatics, Computing and Statistics (CHICAS), Lancaster Medical School, Lancaster University, United Kingdom. Electronic address: b.amoah@lancaster.ac.uk.School of Public Health and Family Medicine, College of Medicine, University of Malawi, Malawi. Electronic address: dusterchifundo@gmail.com.School of Public Health and Family Medicine, College of Medicine, University of Malawi, Malawi. Electronic address: kphiri@medcol.mw.Laboratory of Entomology, Wageningen University and Research, the Netherlands. Electronic address: henk.vandenberg@wur.nl.Laboratory of Entomology, Wageningen University and Research, the Netherlands. Electronic address: willem.takken@wur.nl.School of Public Health and Family Medicine, College of Medicine, University of Malawi, Malawi; Laboratory of Entomology, Wageningen University and Research, the Netherlands. Electronic address: robert.mccann@wur.nl.

Pub Type(s)

Journal Article

Language

eng

PubMed ID

31194960

Citation

Mburu, Monicah M., et al. "Biting Patterns of Malaria Vectors of the Lower Shire Valley, Southern Malawi." Acta Tropica, vol. 197, 2019, p. 105059.
Mburu MM, Mzilahowa T, Amoah B, et al. Biting patterns of malaria vectors of the lower Shire valley, southern Malawi. Acta Trop. 2019;197:105059.
Mburu, M. M., Mzilahowa, T., Amoah, B., Chifundo, D., Phiri, K. S., van den Berg, H., Takken, W., & McCann, R. S. (2019). Biting patterns of malaria vectors of the lower Shire valley, southern Malawi. Acta Tropica, 197, 105059. https://doi.org/10.1016/j.actatropica.2019.105059
Mburu MM, et al. Biting Patterns of Malaria Vectors of the Lower Shire Valley, Southern Malawi. Acta Trop. 2019;197:105059. PubMed PMID: 31194960.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Biting patterns of malaria vectors of the lower Shire valley, southern Malawi. AU - Mburu,Monicah M, AU - Mzilahowa,Themba, AU - Amoah,Benjamin, AU - Chifundo,Duster, AU - Phiri,Kamija S, AU - van den Berg,Henk, AU - Takken,Willem, AU - McCann,Robert S, Y1 - 2019/06/10/ PY - 2019/02/26/received PY - 2019/06/06/revised PY - 2019/06/07/accepted PY - 2019/6/14/pubmed PY - 2019/11/23/medline PY - 2019/6/14/entrez KW - Anophelines KW - Biting KW - Culicines KW - HLC KW - Indoors KW - Malawi KW - Outdoors SP - 105059 EP - 105059 JF - Acta tropica JO - Acta Trop VL - 197 N2 - Assessing the biting behaviour of malaria vectors plays an integral role in understanding the dynamics of malaria transmission in a region. Biting times and preference for biting indoors or outdoors varies among mosquito species and across regions. These behaviours may also change over time in response to vector control measures such as long-lasting insecticidal nets (LLINs). Data on these parameters can provide the sites and times at which different interventions would be effective for vector control. This study assessed the biting patterns of malaria vectors in Chikwawa district, southern Malawi. The study was conducted during the dry and wet seasons in 2016 and 2017, respectively. In each season, mosquitoes were collected indoors and outdoors for 24 nights in six houses per night using the human landing catch. Volunteers were organized into six teams of two individuals, whereby three teams collected mosquitoes indoors and the other three collected mosquitoes outdoors each night, and the teams were rotated among twelve houses. All data were analyzed using Poisson log-linear models. The most abundant species were Anopheles gambiae sensu lato (primarily An. arabiensis) and An. funestus s.l. (exclusively An. funestus s.s.). During the dry season, the biting activity of An. gambiaes.l. was constant outdoors across the categorized hours (18:00 h to 08:45 h), but highest in the late evening hours (21:00 h to 23:45 h) during the wet season. The biting activity of An. funestus s.l. was highest in the late evening hours (21:00 h to 23:45 h) during the dry season and in the late night hours (03:00 h to 05:45 h) during the wet season. Whereas the number of An. funestuss.l. biting was constant (P = 0.662) in both seasons, that of An. gambiaes.l. was higher during the wet season than in the dry season (P = 0.001). Anopheles gambiae s.l. was more likely to bite outdoors than indoors in both seasons. During the wet season, An. funestus s.l. was more likely to bite indoors than outdoors but during the dry season, the bites were similar both indoors and outdoors. The biting activity that occurred in the early and late evening hours, both indoors and outdoors coincides with the times at which individuals may still be awake and physically active, and therefore unprotected by LLINs. Additionally, a substantial number of anopheline bites occurred outdoors. These findings imply that LLINs would only provide partial protection from malaria vectors, which would affect malaria transmission in this area. Therefore, protection against bites by malaria mosquitoes in the early and late evening hours is essential and can be achieved by designing interventions that reduce vector-host contacts during this period. SN - 1873-6254 UR - https://www.unboundmedicine.com/medline/citation/31194960/Biting_patterns_of_malaria_vectors_of_the_lower_Shire_valley_southern_Malawi_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0001-706X(19)30258-X DB - PRIME DP - Unbound Medicine ER -