Exploring the Influence of Daily Climate Variables on Malaria Transmission and Abundance of Anopheles arabiensis over Nkomazi Local Municipality, Mpumalanga Province, South Africa

Abstract

The recent resurgence of malaria incidence across epidemic regions in South Africa has been linked to climatic and environmental factors. An in-depth investigation of the impact of climate variability and mosquito abundance on malaria parasite incidence may therefore offer useful insight towards the control of this life-threatening disease. In this study, we investigate the influence of climatic factors on malaria transmission over Nkomazi Municipality. The variability and interconnectedness between the variables were analyzed using wavelet coherence analysis. Time-series analyses revealed that malaria cases significantly declined after the outbreak in early 2000, but with a slight increase from 2015. Furthermore, the wavelet coherence and time-lagged correlation analyses identified rainfall and abundance of Anopheles arabiensis as the major variables responsible for malaria transmission over the study region. The analysis further highlights a high malaria intensity with the variables from 1998–2002, 2004–2006, and 2010–2013 and a noticeable periodicity value of 256–512 days. Also, malaria transmission shows a time lag between one month and three months with respect to mosquito abundance and the different climatic variables. The findings from this study offer a better understanding of the importance of climatic factors on the transmission of malaria. The study further highlights the significant roles of An. arabiensis on malaria occurrence over Nkomazi. Implementing the mosquito model to predict mosquito abundance could provide more insight into malaria elimination or control in Africa.

Investigating the Resurgence of Malaria Prevalence in South Africa Between 2015 and 2018: A Scoping Review

“…For example, using climate-based mathematical models, the impact of mosquito (mainly An. arabiensis) population dynamics on malaria transmission was investigated over 26,28,40,43], Limpopo [28] and Mpumalanga provinces [11]. Other studies also confirm that the vector population correlates with the resurgence [5,42,44].…”

“…In addition, Behera et al [30] attributed malaria resurgence over the province to El Niño/La Niña and sea surface temperature (SST) from the south-western Indian Ocean. We found only three studies [5,11,31] linking the resurgence to the climate in Mpumalanga province over the study period. Kapwata and Gebreselassie [31] and Adeola et al [5] believe that transmission over the province is associated with surface land temperature and other non-climatic factors, while Abiodun et al [11] found that rainfall and relative humidity are more significant.…”

“…We found only three studies [5,11,31] linking the resurgence to the climate in Mpumalanga province over the study period. Kapwata and Gebreselassie [31] and Adeola et al [5] believe that transmission over the province is associated with surface land temperature and other non-climatic factors, while Abiodun et al [11] found that rainfall and relative humidity are more significant. It is established that rainfall contributes to the proliferation of mosquito breeding sites, while temperature contributes to the development of the sporogonic stages of the malaria parasite within the mosquito's body.…”

“…The biting rate and gonotrophic processes are also temperature-dependent [8 -10]. For these reasons, a qualitative relationship between the vector abundance and the climate variables could help identify the peaks of the vector population through meteorological monitoring and forecast [11,12]. As part of the Malaria Elimination Strategic Plan (MESP), South Africa and a few other African countries are working towards the eradication of malaria since the major outbreak in 2000 across all the epidemic provinces [3,4].…”

Investigating the resurgence of malaria prevalence in South Africa between 2015 and 2018: A scoping review

“…Although, these activities significantly reduced malaria transmission in 2004 through 2014. The nation recently experienced a noticeable resurgence between 2015 and 2018 across the three epidemic provinces [5][6][7][8].…”