Increasing role of Anopheles funestus and Anopheles arabiensis in malaria transmission in the Kilombero Valley, Tanzania

Malaria Journal

Research

Caroline Harris¹  Stefan Dongus²  Samson S Kiware³  Silas Majambere⁴  Dickson W Lwetoijera⁴  Gregor J Devine⁵  Philip J McCall⁶ 

[1] Division of Biomedical and Life Sciences, Lancaster University, LA1 4YW, Bailrigg, Lancaster, UK;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania;Department of Epidemiology and Public Health, Swiss Tropical and Public Health Institute, PO Box, CH-4002, Socintr 57, Basel, Switzerland;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania;Department of Mathematics, Statistics and Computer Science, Marquette University, 53201-1881, Milwaukee, WI, USA;Environmental Health and Ecological Sciences Thematic Group, Ifakara Health Institute, PO Box 53, Ifakara, Tanzania;Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK;QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia;Vector Biology Department, Liverpool School of Tropical Medicine, Pembroke Place, L3 5QA, Liverpool, UK;

关键词: Malaria;    Anopheles;    Transmission;    Vector;    Surveillance;    Gambiae;    Arabiensis;    Funestus;    Season;    Insecticide;    Susceptibility;    EIR;    Kilombero;    Tanzania;   

DOI  :  10.1186/1475-2875-13-331

 received in 2014-07-04, accepted in 2014-08-22,  发布年份 2014

来源: Springer

【 摘 要 】

BackgroundIn order to sustain the gains achieved by current malaria control strategies, robust surveillance systems that monitor dynamics of vectors and their roles in malaria transmission over time are essential. This longitudinal study demonstrates the trends in malaria vector dynamics and their relative contribution to malaria transmission in hyperendemic transmission settings in Tanzania.MethodsThe study was conducted in two villages within the Kilombero Valley, in rural Tanzania for five consecutive years (2008–2012). Seventy-two houses were selected per village and each house was sampled for mosquitoes monthly using a CDC light trap. Collected mosquitoes were assessed for species identity and sporozoite infection status using PCR and ELISA, respectively. Anopheles funestus and Anopheles arabiensis susceptibility to insecticides was assessed using WHO guidelines.ResultsA total of 100,810 malaria vectors were collected, of which 76% were Anopheles gambiae s. l. and 24% were An. funestus. Of all An. funestus samples that amplified with PCR (n = 2,737), 97% were An. funestus s.s., 2% were Anopheles rivorulum and 1% Anopheles leesoni. Whereas for An. gambiae s.l. (n = 8,117), 93% were An. arabiensis and 7% were Anopheles gambiae s.s. The proportion of An. gambiae s.s. identified by PCR (2,924) declined from 0.2% in the year 2008 to undetectable levels in 2012. Malaria transmission intensity significantly decreased from an EIR of 78.14 infectious bites/person/year in 2008 to 35 ib/p/yr in 2011 but rebounded to 226 ib/p/yr in 2012 coinciding with an increased role of An. funestus in malaria transmission. Insecticide susceptibility tests indicated high levels of resistance in An. funestus against deltamethrin (87%), permethrin (65%), lambda cyhalothrin (74%), bendiocarb (65%), and DDT (66%). Similarly, An. arabiensis showed insecticide resistance to deltamethrin (64%), permethrin (77%) and lambda cyhalothrin (42%) in 2014.ConclusionThe results indicate the continuing role of An. arabiensis and the increasing importance of An. funestus in malaria transmission, and pyrethroid resistance development in both species. Complementary vector control and surveillance tools are needed that target the ecology, behaviour and insecticide resistance management of these vector species, in order to preserve the efficacy of LLINs.

【 授权许可】

CC BY   
© Lwetoijera et al.; licensee BioMed Central Ltd. 2014