Impact of ENSO 2016-17 on regional climate and malaria vector dynamics in Tanzania

Kreppel, K., Caminade, C., Govella, N., Morse, A. P., Ferguson, H. M. and Baylis, M. (2019) Impact of ENSO 2016-17 on regional climate and malaria vector dynamics in Tanzania. Environmental Research Letters, 14(7), 075009. (doi: 10.1088/1748-9326/ab26c7)

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Abstract

Large scale modes of climate variability, including the El Niño Southern Oscillation (ENSO) and the Indian Ocean Dipole (IOD), have been shown to significantly impact mosquito-borne diseases in the Tropics, including malaria. However, the mechanistic cascade from ENSO and the IOD, to induced changes in regional climate and ultimately mosquito abundance and behaviour is poorly understood. Mosquito population dynamics, behaviour and their potential to transmit disease are all sensitive to micro-climatic conditions. The warm phase of ENSO (El Niño) tends to be associated with increased precipitation and outbreaks of various vector-borne diseases, while the cold phase (La Niña) can cause drought during the short rains over East Africa. The sensitivity of Anopheles mosquito population dynamics and host-seeking behaviour to ENSO and to the resulting micro-climatic conditions, were investigated in the Kilombero Valley in Tanzania. From June 2016 to September 2017, changes in the timing and intensity of the rainy seasons and temperature due to the ENSO 2016–17 were observed. Mosquitoes were collected using Centres for Disease Control and Prevention (CDC) light traps indoors and mosquito electrocuting traps in- and outdoors. Changes in abundance and biting behaviour of Anopheles arabiensis and Anopheles funestus were correlated with climate and micro-climate. The impacts of El Niño on climate and mosquito abundance were not clear. However, the study area experienced a drought due to La Niña during which both vector species declined significantly. An. arabiensis densities stayed more stable at higher temperatures and were found in higher numbers outdoors with respect to An. funestus. For both species, indoor temperature and season determined their host-seeking location, with higher temperatures and the wet season driving them outside. The study confirmed the influence of ENSO and micro-climate on malaria vector abundance and host-seeking behaviour, generating hypotheses for predicting the impact of future ENSO on malaria risk and vector control. Our observation of higher outdoor biting during warmer conditions indicates that indoor vector control strategies may become proportionally less effective during this time.

Item Type:Articles
Status:Published
Refereed:Yes
Glasgow Author(s) Enlighten ID:Kreppel, Dr Katharina and Ferguson, Professor Heather and Govella, Dr Nico
Authors: Kreppel, K., Caminade, C., Govella, N., Morse, A. P., Ferguson, H. M., and Baylis, M.
College/School:College of Medical Veterinary and Life Sciences > Institute of Biodiversity Animal Health and Comparative Medicine
Journal Name:Environmental Research Letters
Publisher:IOP Publishing
ISSN:1748-9326
ISSN (Online):1748-9326
Published Online:16 July 2019
Copyright Holders:Copyright © 2019 The Authors
First Published:First published in Environmental Research Letters 14(7): 075009
Publisher Policy:Reproduced under a Creative Commons License
Data DOI:10.5285/89406b06-d0aa-4120-84db-a5f91b616053

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Project CodeAward NoProject NamePrincipal InvestigatorFunder's NameFunder RefLead Dept
731911Impact of El Nino of malaria vector dynamics in Tanzania and MalawiHeather FergusonNatural Environment Research Council (NERC)NE/P004407/1RI BIODIVERSITY ANIMAL HEALTH & COMPMED