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

Eco-epidemiology

Small bands of males chased game through the savannahs. Females dug along the forest edges for roots, and searched the bushes for edible berries. Humans lived in isolated groups, which constantly moved in search of better subsistence. Then around ten thousand years ago, human settlements sprouted in the plains. Flocks grazed in pastures and humans tended their fields. This social transition "from hunting to agriculture brought permanent settlements, domestication of animals, and changes in diet. It also brought new infectious diseases, in what scientists call an 'epidemiologic transition'" (University).

"Another of these" epidemiologic "transitions came with the Industrial Revolution. Infectious diseases decreased in many places while cancer, allergies and birth defects shot up" (University). Changes to the environment, including shifts in the variety and type of species in a location, cause the emergence of new diseases or the resurgence of old diseases that were once rare.

"Now, it seems, another epidemiologic transition is upon us. A host of new infectious diseases -- like West Nile Virus -- have appeared. And infectious diseases thought to be in decline -- like malaria -- have reasserted themselves and spread" (University). Humans across the globe are falling victim to malaria, an ancient infectious disease, which was once considered to be limited to isolated tropical regions.

According to Pongsiri, a scientist conducting research on the resurgence of infectious disease, the studies "show that emergence or reemergence of many diseases is related to loss of biodiversity." She asserts that this disturbing trend is "not just case-study specific". "Something is happening at a global scale" (University). For example, it is now known that malaria rises and spreads from deforestation. The clearing of forests results in changes to the watershed, including the creation of reservoirs where malaria-carrying mosquitoes can breed. Elevation in regional temperature due to pollution or deforestation can increase the potential habitat of the mosquitoes, causing the disease to spread.

"It is new to think about biodiversity -- and therefore, species and land conservation -- as integral to public health. Until recently, almost no epidemiologists, nor medical schools, were framing questions of human infectious disease prevention in terms of, say, habitat structure, promoting genetic diversity in non-human species, or protecting animal predators as ecosystem regulators. Human diseases, goes the conventional thinking, are best understood and treated by looking at humans."

"Now there is the beginning of a movement to bring epidemiology and ecology together," says Pongsiri.

More info: http://www.sciencedaily.com/releases/2009/12/091203132157.htm

Source:
University of Vermont. "Biodiversity Loss Can Increase Infectious Diseases in Humans." ScienceDaily 3 December 2009. 5 December 2009 .

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)

Malaria in Russia

Many people believe that it is impossible to contract malaria in countries that are far away from the tropics. Unfortunately, this is not the case. Even Russia is not immune to the threat of malaria.

"Dozens of people acquire malaria infections in Moscow annually". Most of these cases are "due to people who arrive in the city from southern countries", but surprisingly some people become "infected from home-grown strains of the disease" (Dmitriyev). In 2007, "128 incidents of malaria were registered in Russia. Two of the cases proved fatal. The average annual rate is 100 cases, with the bulk of them occurring in Moscow, Moscow Region and St. Petersburg" (Dmitriyev).

Because malaria is not as prevalent in Russia as it is in tropical regions of the world, "doctors in Russia often lack qualification to diagnose patients" with malaria "and provide the appropriate medical treatment in a timely fashion. Even more often, they fail to determine the exact form of the disease. This may lead to multiple after-effects resulting in the patient's death" (Dmitriyev).

Global climate change threatens to unleash new waves of malaria in Russia. From history, we can see how rises in malaria cases directly corresponds with warm years. For example, "extensive flooding in 1922 resulted in the creation of standing pools of water over wide areas of the upper Volga River basin, which resulted in an explosion of the population of ...mosquitoes" (Packard 7).

"Less than half of all malaria cases in Russia...are caused by guests from tropical countries" (Dmitriyev). Reservoirs, water-logged ditches, and stagnant ponds at parks and recreation areas provide breeding grounds for mosquitoes in Russia. In June of 2008, "the human welfare service successfully eradicated the bulk of the mosquitoes' larvae at several Moscow administrative districts" through regular spraying of these breeding areas (Dmitriyev).

Russia is also contributing to the movement to eradicate malaria worldwide. In 2007, Russia "committed $US 20 MLN to the task" of fighting malaria in Africa. In response, Dr. Brian Chituwa (Zambian Minister of Health) said, "We are confident that this significant contribution will reduce malaria deaths and bring us closer to achieving our millennium development goals" (Russia).



Sources:
Dmitriyev, Sergey. "Malaria Threat." The Moscow News. 24 Jul 2008.

Packard, Randall M. The making of a tropical disease.

"Russia Joins the Fight Against African Malaria." Russia Today. 20 Oct 2007.