Long-Run Relative Importance of Temperature as the Main Driver to Malaria Transmission in Limpopo Province, South Africa: A Simple Econometric Approach

Abstract

Malaria in Limpopo Province of South Africa is shifting and now observed in originally non-malaria districts and it is unclear whether climate change drives this shift. This study examines the distribution of malaria at district level in the province; determines direction and strength of the linear relationship and causality between malaria with the meteorological variables (rainfall and temperature) and ascertains their short and long run variations. Spatio-temporal method, Correlation analysis and econometric methods are applied. Time series monthly meteorological data (1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007) were obtained from South Africa Weather Services while clinical malaria data came from Malaria Control Centre in Tzaneen (Limpopo Province) and South African Department of Health. We find that malaria changes and pressures vary in different districts with a strong positive correlation between temperature with malaria, r = 0.5212, and a weak positive relationship for rainfall, r= 0.2810. Strong unidirectional causality runs from rainfall and temperature to malaria cases (and not vice versa): F (1, 117) = 3.89, and a bi-directional causality exists between rainfall and temperature and temperature to rainfall and from rainfall to temperature, F (1, 117) = 19.80; F (1,117) = 17.14 with 001 . 0   respectively in both cases. Results show evidence of strong existence of a long-run relationship between climate variables and malaria, with temperature maintaining very high level of significance than rainfall. Temperature, therefore, is more important in influencing malaria transmission in Limpopo Province.

Seasonally lagged effects of climatic factors on malaria incidence in South Africa

“…28 showed that incidence rates in Limpopo were related to both temperature and rainfall. However, they also showed that temperature plays a more important role in influencing malaria transmission compared to rainfall 28 . Precipitation and temperature are the most commonly tested climate variables.…”

Climate change, public health and COP21 – a South African perspective

“…Diarrhoeal infections were linked in one study to anomalously dry seasons and increases in monthly average maximum temperatures in sub-Saharan Africa. [6] Malaria in Limpopo is more significantly associated with temperature than rainfall, [7] and models suggest a possible expansion in malaria zones in Africa, including SA in the future. [8] Schistosoma worms, the cause of schistosomiasis (including bilharzia), may thrive in warmer water and emergent transmission in previously unaffected areas may occur.…”

Climate change is catchy – but when will it really hurt?

“…Lazenby et al [13] have considered the prediction skill of temperature variability at the seasonal time scale for various time frames (in months) and various lead times and show the utility (and current limitations) of these predictabilities in respect of health applications. This is the approach adopted in a study currently underway in the Mopani district of Limpopo Province which aims to link climate and disease models for malaria, diarrhoea and pneumonia ( Fig.…”

“…Lazenby et al [13] considered the application of improved seasonal climate forecasting techniques in predicting extreme seasonal temperature in the northern parts of SA, and the direct impact on health. They conclude that the skill of these forecasts is good enough to develop a heat-health warning system for the country.…”