Climate Emergency Institute
Climate Science Library
Climate Change and Disease Prevalence in Africa
Robert Mburia, Kenya
Original Post: Jan. 12, 2012


Introduction

Impacts of global climate change on the environment and living beings are now more visible than ever before, as glaciers shrink, ice breaks up on lakes and rivers at faster rates, tree and animal populations and ranges shift irregularly, and natural and devastating calamities become a common occurrence, even in previously unaffected places. Scientists have a strong conviction that global temperatures will continue to rise for several decades to come, based on the levels of green house gases that human activities currently produce. The IPCC (Intergovernmental Panel on Climate Change) approximates an average rise of up to 2.5 to 10 degrees Fahrenheit over the next century, which calls for communities across the world to adapt mitigation measure to help them cope with these changes.

According to the IPCC, several negative impacts will be witnessed in various regions.
North America will experience increased intensity, duration and frequency of heat waves in cities that currently experience them, dwindling snow packs on mountains, and there will be an increase in the overall yields of rain- fed agriculture throughout the continent.

The Latin American region will experience a gradual reduction of tropical rain forests, and their replacement with Savannah vegetation; which poses a great risk of biodiversity reduction, extinction of some species, changes in levels and availability of water for domestic, agricultural, industrial and energy generation purposes. This will have adverse impacts on the health of the local people in the region and disruption of their livelihoods.

In Asia, availability of fresh water will be highly compromised in the central, south and eastern parts of the continent. Further, the region will most likely succumb to more floods (as witnessed this year), which will increase the occurrence of diseases and deaths in the region due to an increase in vulnerability and decrease in coping capabilities.

Europe is expected to have increased island flash floods, frequent coastal flooding, glacier retreat, reduced flooding, snow cover, and winter activities, extensive loss of species, reduced crop productivity and (in Western Europe) higher temperatures.

Diseases and Climate Change in Africa

Africa will be the continent most affected by these changes, because it has the lowest coping capacities due to underdevelopment and poverty. It is projected that, by 2020, the continent will have close to a quarter of its population experiencing water stress, low agricultural yields, and natural disasters like droughts and famines, as well as increased negative health impacts.

Diseases and other negative health impacts are significant results of the environmental impacts of climate change., pointing to the closer link between climate change and occurrences of diseases across the world.

Environmental degradation and diseases

As discussed above, environmental degradation resulting from climate change has created ideal conditions for infectious diseases to emerge, re surge and quickly spread through populations across the globe. Communicable diseases account for over seventeen million deaths annually across the earth. This increase in global climatic changes has also altered the functional balance between diseases and pathogens, by affecting the relation between prey and predators, which plays a crucial role in controlling the growth and spread of pathogenic microorganisms. In fact, warmer or wetter conditions have enabled the spread of a great rage of infectious diseases from their endemic regions to newer ones. Experts warn that climate change will have wide ranging and far damaging implications on human health just as uncontrolled disease waves had severe impacts on populations during the era of the industrial revolution across the globe.

IPCCC (2001) indicates that countries with low socioeconomic development indicators lack many key elements of adaptive capacity to respond to climate change and subsequent environmental crises. There is increased environmental pressure due to factors like population growth and industrialization, depletion of already scarce natural resources, and high levels of abject poverty. Sub-Saharan Africa struggles to improve the living conditions of its people as it simultaneously seeks to increase socioeconomic growth, which unfortunately leads to high levels of consumption and production; factors that leads to climate change.

The impacts of climate change, climate variability and extreme events, land degradation and loss of biodiversity, are experience in multiple ways: loss of human live, threats to the economic livelihoods of many communities, increase in the prevalence and severity of diseases, among others (United Nations Framework Convection on Climate Change, 2011). Least developed countries are highly vulnerable to these impacts and their consequences and there is very little capacity to cope, owing to the limits of the institutional and community capacities (ibid).

At the moment, a warming climate, combined with widespread rapid ecological changes, is thought to have a stimulating change in disease patterns, which will affect humans in three major ways. These are: creation of ideal conditions for infectious disease outbreaks, increased potential for spread of vector borne diseases, which will expose millions of people to new health risks and diseases, and lastly, the hindrance of future efforts to control the spread of diseases across regions.

Scientists postulate that these changes will result in extreme weather conditions in some regions, which will bring about a drastic shift in the numbers of pests and disease vectors, leading to increased rates of transmission. This is because the rates of reproduction, spread and bites in many pests depends on weather patterns, and are usually high in warmer and wetter conditions (which are the most prevalent.) Warming also increases the numbers of pests and micro-organisms, due to the creation of optimal circumstances for both metabolism and reproduction at the interface of temperate conditions. This is directly correlated to the transmission and spread of diseases.

​​Climate change and pests

Experts have further provided several examples of the strong link between climate change and the increase of pests. For instance, heavy rains have the effect of producing insect-breeding sites, driving rodents from burrows, and contaminating clean water systems. More specific examples of this relation include the case of southern Africa, where rodent populations exploded in 1994, following heavy rainfall in 1993 that had been preceded by a prolonged drought. As a result, the maize crop in Zimbabwe was crippled and plague broke out in Zimbabwe, Malawi and Mozambique.

Another case in point is the dramatic increase in the incidence of respiratory illness, cardiovascular disease and eye irritations in Asia, across Mediterranean nations, in the Amazon, in Mexico's tropical rain forest, in Central America and Florida in the US due to occurrences of extreme droughts and wild fires. Droughts, on the other hand, led to increased cholera in many tropical regions. Heat waves killed thousands in India, and hundreds in the US and Central Europe. The Horn of Africa saw the death of humans and livestock alike due to upsurges in outbreaks of cholera, malaria, and Rift Valley Fever, caused by prolonged drought conditions. Latin America has not been spared either, as flooding along the Pacific coast and in southern Brazil resulted in increases in cholera and vector-borne diseases. Rodent out breaks spread wildly in Latin America and the US in early 1998, due to the creation of climatic conditions, which favored their growth and reproduction rates while keeping their mortality at bay.

United Nations Human Settlement Program (2008) has noted that sub-Saharan Africa is the least urbanized region in the whole world. Only 39% of the total population lives in cities. Extreme climatic vagaries of El Nino and La Nina affected lives and ecosystems in a massive way with the cold phase of 1995 to 1997, which brought heavy rains and flooding to many areas, while the period that followed brought some of the worst droughts in recent years. Those rains have contributed to the outbreak of disease such as Murray valley encephalitis and Ross River virus in Australia and the widespread outbreak of malaria in Pakistan, South Africa and Argentina. Droughts in sub Saharan Africa resulted in an increase of such diseases as meningitis (weakening of the mucus membrane on the human body, a condition that makes penetration by colonizing organisms easy.). Thousands died in the outbreak.

Further, researchers list other diseases whose increase in recent decades has been associated with climate changes, either in localized settings or over great regions. These include; Guinea worm, leishmaniasis, lymphatic filiasis, onchocerciasis, and Chagas’ disease, which altogether are feared to affect more than 147 million globally already.

The World Health Organization (1996) observed that changes in climate combined with the alarming rates of environmental degradation have resulted in creation of new disease strains that are alien and unknown to medicine. The same WHO report observes that this phenomenon has enabled widespread resurgence and spread of disease in many areas across the globe.

Scientists observe that there is a changing transition pattern in the transmission of diseases. The underlying argument is that warmer (and sometimes wetter) conditions across the earth are extending the range of infectious diseases from their endemic regions (where the inhabitants have developed some levels of immunity and resistance against them over the years.) Global warming and its impact of creating warmer winters has significantly increased the transmission of vector borne diseases in many high elevation areas, where due to cold conditions they were previously non-existent. Dengue fever and malaria are on the increase in high altitude areas, including the mountain ranges of east and central Africa, as well as parts of Asia. Similar impacts have been observed in Zimbabwe and South Africa, and are projected to keep on increasing as the concentration of carbon dioxide and its global warming effects continuously rise.

Cholera

The outbreak of a cholera epidemic in Rwanda in 1994 is another example that researchers used to explain the relation between climate change and the proliferation of disease. The epidemic is thought to have cost over forty thousand lives in a span of weeks, due to changes in weather patterns that favored its hasty spread across the African nation. Although the civil war and political turmoil besieging the country at the time may have contributed to low response, the influence of climatic and ecological instability cannot be underestimated in the evaluation of the epidemic. Prior to that, in 1991, there was a pandemic of a new strain of cholera transmitting microbe known as vibrio cholerae, which is common in water algae and phytoplankton, in the Americas. Later, in 1992, it was also reported in India. Scientists argue that the interplay of environmental changes, the microbe itself, and its human hosts occasioned the spread of this strain and increased its active impacts in humans.

There is also a worrying trend of increasing predator numbers, a factor attributed to climate change and environmental variability. This is expected to have a significant impact on the increased transmission of diseases in the years to come, as the predator/prey balance in natural ecosystems is significantly altered. This leads to increase in infectious diseases, as their carriers increase past the numbers of predators that help keep them in check. For instance, the increase in reproduction of mosquitoes larvae in water leads to a direct proportion of those that survive attacks by fresh water fish which is in some cases dwindling, and therefore leads to greater populations of mosquitoes which are vectors for some of the most serious diseases across the world.

Conclusion

The increasing rate of global warming- courtesy of carbon dioxide and other green house gas emissions from human activities- has led to climatic changes and environmental degradation, which in turn have resulted to great challenges in relation to diseases and human health. Many diseases which were previously unknown in certain climatic zones are now finding their way to such areas, due to changes in the weather conditions. Further, many diseases that had been thought extinct are reemerging in areas with altered climatic conditions that favor their comeback. It is therefore important that stakeholders and decision makers at industrial, government and international policy levels come up with stringent and workable means of cutting down on green house gases emission to combat the spread of global warming effects, and the resultant climate change, which has produced devastating impacts especially among poorer nations. Further, there should be increased funding of adaptation and coping programs and projects in affected areas, to minimize the impacts on human health and curtail the spread of diseases.

References

1. Ayanlade, N, Adeoye NO & Babatimehin O (2010) Climate Change and Security: Climate Change/variability and malaria transmission in Sub-Saharan Africa, An international conference on the occasion of the 250th anniversary of the Royal Norwegian Society of Sciences and Letters, Trondheim, Norway, 21-24 June 2010.
2. WHO, (2001), Malaria Early Warning Systems, Concepts, Indicators and Partners. A Framework for Field Research in Africa. Geneva: WHO.
3. IPCC (2001) Climate Change 2001: Synthesis Report. Contribution of Working Groups I, II, and III to the Third Assessment Report of the Intergovernmental Panel on Climate Change. Watson, Robert T., ed. New York: Cambridge University Press.

CLIMATE EMERGENCY INSTITUTE

​ The health and human rights approach to climate change