Climate change promotes deadly sleeping sickness

Climate change promotes tropical sleeping sickness

10.11.2011

Millions of people in southern Africa are affected by a devastating spread of lethal sleeping sickness. Benefiting from climate change and the associated increase in temperature, the main cause of the disease will find a new home in many new areas of South Africa. If the illness is not treated in time, it can lead to death. This alarming finding came from a science team at the US Center for Disease Control (CDC) using data from numerous climate researchers.

There are three different types of sleeping sickness, each of which differs significantly in the disease and symptoms. There are the African trypanosomiasis, the European sleeping sickness (brain inflammation) as well as the neurological narcolepsy. In all sleeping disorders, uncontrollable or seizure-type sleep attacks occur. The tropical form is mainly distributed in the southern part of the Sahara and is mainly transmitted by the tsetse fly. According to researchers from the US Centers for Disease Control (CDC) in Fort Collins, Colorado, as a result of ongoing climate change, by the year 2090, approximately 77 million people in Africa may be at risk of the infectious disease. The reason for this is a massive increase in temperature, which considerably extends the range of the tsetse flies. Scientists have come to this alarming result through a computer-generated climate simulation.

Tropical sleeping sickness in Africa
According to the Robert Koch Institute (RKI), tropical sleeping sickness occurs in the southern part of the Sahara desert and currently affects 36 African states. In recent decades, the spread of the disease has been successfully curbed by various measures. But civil wars, a lack of medical care, refugee migration and the lack of countermeasures have led to the fact that according to the World Health Organization WHO the occurrence of sleeping sickness has increased again. The WHO also estimates that the distribution will continue to increase.

The tsetse fly transmits the unicellular parasites Trypanosoma brucei gambiense (mainly in West and Central Africa) and Trypanosoma brucei rhodesiense (mostly in East Africa) by means of a painful sting. In this type of fly males and females can transmit the pathogen, because in this mosquito genus both sexes can sting. Not all tsetse flies are trypanosome carriers, so a stung man does not have to fall ill automatically. Depending on the region and the risk of infection, the average probability of developing is 1 in 100. According to the WHO, around 70,000 people are infected each year. About 60 million people live in so-called risky areas. All forms of the disease are life-threatening to humans and fatal without adequate end-stage treatment.

Überträger fly finds new habitats
The research team around Moore and colleagues fast in the trade magazine „interface“ In a study, the British Royal Society summarized the preferred areas of life and living conditions of the fly. In particular, the biting fly is known to favor tropical heat for breeding. Using this background knowledge, the researchers compared the data of various climate researchers, whose most pessimistic calculations predict global warming of 6.4 degrees Celsius to 2100. In the evaluations, the scientists also included the proportions of the human habitats south of the Sahara. They came to the conclusion that there would be no very large expansion of the potential habitats of the tsetse fly. If it comes to an increase in climate between 1.1 and 5.4 degrees Celsius due to an increase in climate-damaging carbon dioxide, the mosquito may become too warm in some parts of East Africa. Other regions of Africa, however, where the mosquito was previously too cold, could now become a new habitat. The best conditions for breeding are when the area has an annual warm, humid average temperature of 20.7 to 26.1 degrees. As a result, climate change could affect completely new and more densely populated areas. In addition, international researchers expect strong refugee flows due to climate change.

Sleeping sickness occurs in three stages
There are currently between 60 and 70 million people in the tsetse fly distribution area. After a bite and a transmission of the pathogen quickly result in high fever, chills, edema, itching, lymphadenopathy, rash and headache. Overall, the disease runs in three stages. In the second stage are complaints of the nervous system such as arrhythmia (heart stumbling), confusion and seizures added. Special features of the stadium are mainly massive sleep disorders and insomnia. In the third final disease state (4 to 6 months after infection), the patients fall into a veritable twilight state and the symptoms may resemble a Parkinson's disease. The clear evidence is ensured by laboratory tests and immunological methods. The treatment must be done in the hospital because the drugs used are highly toxic. Despite therapy, the mortality rate is 10 percent.

Sleeping sickness is not the only disease caused by climate change. According to international research, cholera, dengue fever and malaria will also find other areas of spread as temperature increases. In Europe, tropical diseases will increasingly occur in the near future. (Sb)

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