Climate change and malaria: some recent trends of malaria incidence rates and average annual temperature in selected sub-Saharan African countries from 2000 to 2018

Abstract

Background: Malaria is still a disease of massive burden in Africa, also influenced by climate change. The fluctuations and trends of the temperature and precipitation are well-known determinant factors influencing the disease's vectors and incidence rates. This study provides a concise account of malaria trends. It describes the association between average temperature and malaria incidence rates (IR) in nine sub-Saharan African countries: Nigeria, Ethiopia, South Africa, Kenya, Uganda, Ghana, Mozambique, Zambia and Zimbabwe. The incidence of malaria can vary both in areas where the disease is already present, and in regions where it is present in low numbers or absent. The increased vulnerability to the disease under increasing average temperatures and humidity is due to the new optimal level for vector breeding in areas where vector populations and transmission are low, and populations are sensitive due to low acquired immunity.

Methods: A second source trend analysis was carried out of malaria cases and incidence rates (the number of new malaria cases per 1000 population at risk per year) with data from the World Health Organization (WHO) and average annual mean temperature from 2000 to 2018 from the World Bank's Climate Change Knowledge Portal (CCKP). Additionally, descriptive epidemiological methods were used to describe the development and trends in the selected countries. Furthermore, MS Excel was chosen for data analysis and visualization.

Results: Findings obtained from this article align with the recent literature, highlighting a declining trend (20-80%) of malaria IR (incidence rate) from 2000 to 2018. However, malaria IR varies considerably, with high values in Uganda, Mozambique, Nigeria and Zambia, moderate values in Ghana, Zimbabwe, and Kenya, and low values in South Africa and Ethiopia in 2018. Evidence suggests varying IRs after average temperature fluctuations in several countries (e.g., Zimbabwe, Ethiopia). Also, an inverse temperature-IR relationship occurs, the sharp decrease of IR during 2012-2014 and 2000-2003, respectively, occurred with increasing average temperatures in Ghana and Nigeria. The decreasing trends and fluctuations, partly accompanying the temperature, should result from the intervention programmes and rainfall variability. The vulnerability and changing climate could arrest the recent trends of falling IR.

Conclusion: Thus, malaria is still a crucial public health issue in sub-Saharan Africa, although a robust decreasing IR occurred in most studied countries.

Keywords: 2000–2018; Climate vulnerability; Malaria incidence rates; Public Health; Temperature; sub-Saharan countries.

Fig. 1

Occurrence and prevalence of malaria in West Africa (Source: Mapping Malaria Risk in Africa (MARA/ARMA) database)

Fig. 2

Illustrates the nine selected African countries in this study sample. Schematic map of Africa showing the nine studied countries: Nigeria, Ethiopia, South Africa, Kenya, Uganda, Ghana, Mozambique, Zambia, Zimbabwe

Fig. 3

Incidence rates of malaria in nine sub-Saharan African countries from the World Health Organization (WHO) [11] and the average annual mean temperature from the World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 4

Annual incidence rates of malaria per 1000 population at risk and temperature in Uganda from the World Health Organization (WHO) [11] and the average annual mean temperature from World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 5

Annual incidence rates of malaria per 1000 population at risk in Mozambique from the World Health Organization (WHO) [11] and the average annual mean temperature from the World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 6

Annual incidence rates of malaria per 1000 population at risk and temperature in Nigeria from the World Health Organization (WHO) [11] and the average annual mean temperature from World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 7

Annual incidence rates of malaria per 1000 population at risk and temperature in South Africa from the World Health Organization (WHO) [11] and the average annual mean temperature from the World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 8

Annual incidence rates of malaria per 1000 population at risk in Zimbabwe from the World Health Organization (WHO) [11] and the average annual mean temperature from the World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 9

Annual incidence rates of malaria per 1000 population at risk and temperature in Kenya from the World Health Organization (WHO) [11] and the average annual mean temperature from World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 10

Annual incidence rates of malaria per 1000 population at risk and temperature in Zambia from the World Health Organization (WHO) [11] and the average annual mean temperature from World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 11

Annual incidence rates of malaria per 1000 population at risk and temperature in Ethiopia from the World Health Organization (WHO) [11] and the average annual mean temperature from the World Bank’s Climate Change Knowledge Portal (CCKP) [13]

Fig. 12

Annual incidence rates of malaria per 1000 population at risk and temperature in Ghana from the World Health Organization (WHO) [11] and the average annual mean temperature from World Bank’s Climate Change Knowledge Portal (CCKP) [13]