Could Global Warming Mean More Malaria?

by Enya O'Riordan on March 27, 2014

Global_Malaria_ReportedCases_2010

                    The increase in the rise of the average global temperature, otherwise, otherwise known as global warming, has many visible and predictable harmful effects on the environment, animal populations, and human health. Since malaria is transmitted through mosquitoes and mosquitoes are generally found in warm climates, it has been widely assumed that the incidence of malaria will rise and its geographical scope will expand as we enter a warmer future.  But do we really have reason to be concerned?  Some experts are concerned that that as global warming continues, malaria will spread to locations where it was previously limited due to a cooler climate.  On the other hand, other experts claim that there are many confounding factors that may be a better explanation for the increasing incidence of malaria in the world, including drug resistance, failing mosquito control programs, ill-equipped public health facilities and sub-par living standards.

                    The increase in the rise of the average global temperature, otherwise, otherwise known as global warming, has many visible and predictable harmful effects on the environment, animal populations, and human health. Since malaria is transmitted through mosquitoes and mosquitoes are generally found in warm climates, it has been widely assumed that the incidence of malaria will rise and its geographical scope will expand as we enter a warmer future.  But do we really have reason to be concerned?  Some experts are concerned that that as global warming continues, malaria will spread to locations where it was previously limited due to a cooler climate.  On the other hand, other experts claim that there are many confounding factors that may be a better explanation for the increasing incidence of malaria in the world, including drug resistance, failing mosquito control programs, ill-equipped public health facilities and sub-par living standards.

                     When comparing incidence of malaria throughout the world, tropical regions do provide the perfect climate and temperature for the development and survival of mosquitoes.  For the optimal development of the Anopheles mosquito, temperatures must be between 20 and 30 degrees Celsius, while other necessary climactic factors include high humidity, small stagnant pools of water, and availability of food.  However, when the temperature rises above 30 degrees, the life span of the mosquito actually begins to fall.  Mosquitoes also tend to flourish in areas with ample rainfall.  The above effects of temperature and climate on malaria provide reasonable evidence that global warming will causing a rising incidence in malaria, including in areas where malaria was never an issue.  The recent increase in Malaria in the east African highlands and other Asian and South American countries has supported this theory.

                     But are there other possible explanations for the recent surge of cases of malaria throughout the world?  As it turns out,  there are many.  One of the main countering arguments to the “global warming case” is the argument for drug resistance.  Resistance to chloroquine, the main drug used to treat malaria, is one of the major reasons for the resurgence of malaria in tropical African countries.  Drug resistance is often a consequence prescription regimens which aren’t completed, therefore that person passes on a new drug-resistant strain of malaria to the next mosquito that bites them.   Poor vector control is yet another possible explanation for the rising incidence of malaria: the spraying of DDT was halted when malaria counts reached a low in 1975, but malaria has been recurring ever since.  Poor provision of health services, especially in rural areas, presents another challenge to treating malaria.

                     But two larger global phenomenons are the most likely culprits of increasing malaria: population growth and migration/travel.  The world’s population is rapidly growing, and if population growth is not matched by subsequent improvements in healthcare, then it follows that there will be more cases of malaria.  Finally, increased world travel allows the virus to reach parts of the globe where it is has been eradicated: if an individual infected with malaria travels to another region of unstable transmission, they can transmit the disease to a local population that has a low immunity to the disease.

                    Global warming alone is not likely to cause a drastic increase in global incidence of malaria – but the malaria epidemic is changing depending on which region of the world you live in.  Developed nations of the Western world, which have wide access to healthcare, have very little to be concerned about.  However, in many developing regions of the world malaria incidence is increasing – due to deteriorating health facilities, antimalarial drug resistance, decreased vector control efforts and population growth.  The international and local endemic communities are nonetheless coming together in order to find innovative ways to tackle this virus, be sure to check out this TED Talk on how one group of scientists are re-engineering mosquitoes in order to fight disease!

Re-Engineering Mosquitoes to Fight Disease

Sources:

http://www.theguardian.com/environment/2014/mar/07/climate-change-malaria-africa-study

http://www.who.int/globalchange/climate/summary/en/index5.html

http://www.libyanjournalofmedicine.net/index.php/ljm/article/view/4799


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