Climate and behavioral change

In recent years, "malaria has been spreading into highland areas of East Africa, Indonesia, Afghanistan, and elsewhere" it was previously unknown. High elevations, low temperature, and temperate rainy seasons prevented malaria from entering these regions before. Now, the deadly disease is contracted locally in these previously malaria-safe environments. Malaria "is on the rise in some parts of the world" partly due to climate change. Other "factors such as migration and land-use changes are likely also at play."

"We assessed...conclusions from both sides and found that evidence for a role of climate in the dynamics is robust," write study authors Luis Fernando Chaves from Emory University and Constantianus Koenraadt of Wageningen University in the Netherlands. "However, we also argue that over-emphasizing a role for climate is misleading for setting a research agenda, even one which attempts to understand climate change impacts on emerging malaria patterns."

"Malaria, a parasitic disease spread to humans by mosquitoes, is common in warm climates of Africa, South America and South Asia." Development and survival of the mosquito and parasite depend on warm temperatures; therefore, "the disease has been spreading to the highlands, and many studies link the spread to global warming. But that conclusion is far from unanimous. Other studies have found no evidence of warming in highland regions, thus ruling out climate change as a driver for highland malaria."

Most studies, which conclude that climate change plays a significant role in highland malaria, tend to be statistically strong. Clearly, climate change does impact the range of malaria endemic regions; however, it may not be the only contributing factor. "What is needed, the researchers say, is a research approach that combines climate with other possible factors."

"Even if trends in temperature are very small, organisms can amplify such small changes and that could cause an increase parasite transmission," a researcher said. "More biological data will improve our overall understanding of malaria and will allow scientists to propose more general and accurate models on the impacts of climate change on malaria transmission."

Some factors contributing to the spread of malaria may be migration and agriculture. People "migrating from lowlands may be introducing the malaria parasite into highland regions. Changes in farming practices may also play a role. Irrigation associated with more intensive farming may be creating more places for mosquitoes to breed."

"The spread of malaria in highlands is of great concern to those who work to contain the disease. But understanding the many factors that influence the spread of highland malaria could help with efforts to control the disease worldwide."

Source:
University of Chicago Press Journals (2010, March 4). Climate change one factor in malaria spread. ScienceDaily. Retrieved March 4, 2010, from http://www.sciencedaily.com­ /releases/2010/03/100303162906.htm

Malaria & Climate Change

Update on climate change as it relates to malaria (4 March 2010)

Every year approximately one million people die from malaria, and most of those are children. 350-500 million people are infected annually. This blood parasite is spread through the bite of infested mosquitoes and most frequently occurs within tropical regions. However, "malaria is an extremely climate-sensitive" disease that cannot be contained to the tropics (Patz). Medical researchers warn about the global threat of malaria in the future due primarily to climate change.

Climate change threatens to expand the mosquito's habitats, thereby spreading the disease. A joint study by the State University of New York and the Kenya Medical Research Institute showed that changes "in temperature can affect the development and survival of malaria parasites and the mosquitoes that carry them...Rainfall also influences the availability of mosquito habitats and the size of mosquito populations, the research found" (Barclay). A study conducted by Brown University researchers revealed that "an epidemic in Ethiopia was attributed to higher temperatures, rainfall and relative humidity than in previous years" (Brown).

A research team at University of Michigan (lead by M Pascual) has "documented a warming trend in the East African highlands from 1950 to 2002, concomitant with increases in malaria incidence. Moreover, their findings confirm the importance of the well recognized nonlinear and threshold responses of malaria (a biological system) to the effect of regional temperature change...For example, showing that the biological response of mosquito populations to warming can be more than an order of magnitude larger than the measured change in temperature represents a stunning finding, critical in advancing risk assessment of climate change impacts" (Patz).

[UNEP projected malaria distribution]

Outside of Africa, malaria is moving to higher altitudes and colder regions within endemic areas. "Malaria cases have been reported on the Bolivian high plateau," (Pabon). These individuals contracted the disease locally, meaning that malaria-carrying mosquitoes are now present in a region where they were previously unknown.

The US and UK are also under threat by malaria. Outbreaks of malaria within the US are not unknown, and may continue to increase as climates change. Florida and Louisiana are particularly susceptible to the disease. Across the pond, the UK reported 1370 cases of malaria in 2008. Six deaths were officially blamed on malaria (HPA). "A high likelihood of a major heat wave" may lead "to as many as 10,000 deaths, hitting the UK by 2012" warns the government (Prince). In coming years "the UK is to be hit by regular malaria outbreaks, fatal heat waves and contaminated drinking water within five years because of global warming, the Government has warned the NHS [National Health Service]" (Prince).

"The best climate conditions for malaria are a long rainy season that is warm and wet, followed by a dry season that is not too hot, followed by a hot and wet short rainy season," (Barclay). Pure global warming is not the primary culprit, instead a general shift in climate across regions is feared. Malaria is a devastating disease that infiltrates all areas of life. Epidemics destroy the health, economy, and cultural fabric of regions where malaria is prevalent.

We can make adjustments in our lives to prevent climate change; however, we also need to attack malaria to prevent its spread. Help Infectious Bite stop malaria in its tracks by supporting our cause or by donating to one of the many reputable agencies that provide mosquito nets and medicine to people threatened by malaria. Together we can Bite Malaria Back.

Sources:
Barclay, Eliza. " Climate Change Fueling Malaria in Kenya, Experts Say..." National Geographic. 9 January 2008.

Brown University. "Climate Change and Malaria". http://www.brown.edu/Research/EnvStudies_Theses/full9900/creid/climate_change_and_malaria.htm

Pabon, Cristina. Malaria spreading on Bolivian High Plains. SciDevNet.

Patz, Jonathan A. Sarah H Olson. "Malaria risk and temperature…" PNAS.

Prince, Rosa. "Malaria Warning as UK becomes warmer." Telegraph.co.uk. 12 Feb 2008.

UNEP: Map (http://maps.grida.no/go/graphic/climate_change_and_malaria_scenario_for_2050)