Climate change promotes tropical sleeping sickness
Millions of people in southern Africa are affected by the devastating spread of life-threatening sleeping sickness. Favored by climate change and the associated rise in temperature, the main carrier of the disease will find a new home in numerous new areas of South Africa. If the disease is not treated in time, it can lead to death. A scientific team from the US Center for Disease Control (CDC) came to this alarming conclusion using data from numerous climate researchers.
There are three different types of sleeping sickness, each of which clearly differs in the disease and symptoms. There is African trypanosomiasis, European sleeping sickness (inflammation of the brain) and neurological narcolepsy. Uncontrollable or seizure-like sleep attacks occur in all sleeping diseases. The tropical form is mainly found in the southern part of the Sahara and is mainly transmitted by the tsetse fly. According to researchers at the United States' Center for Disease Control (CDC) in Fort Collins, Colorado, as a result of progressive climate change, around 77 million people in Africa could be at additional risk of the infectious disease by 2090. The reason for this is a massive rise in temperature, which significantly expands the distribution area of the tsetse flies. The scientists came to this worrying 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 countries. In the past decades, the spread of the disease has been successfully curbed by various measures. However, civil wars, a lack of medical care, migrations to refugees and a lack of countermeasures have led to an increase in the incidence of sleeping sickness again, according to the World Health Organization (WHO). According to its own calculations, the WHO also assumes that the spread will continue to increase.
The tsetse fly transmits the unicellular parasites Trypanosoma brucei gambiense (predominantly in West and Central Africa) and Trypanosoma brucei rhodesiense (mostly in East Africa) using a painful sting. With this type of fly, males and females can transmit the pathogen because both sexes can bite in this genus of mosquitoes. Not all tsetse flies are trypanosome carriers, so that a stung person does not automatically fall ill. Depending on the region and the risk of infection, the average probability of becoming ill is 1 in 100. According to the WHO, around 70,000 people become infected each year. Around 60 million people live in so-called high-risk areas. All forms of the disease are life-threatening and deadly without adequate treatment.
Carrier fly finds new habitats
The research team led by Moore and colleagues fasted together in the study "Interface" of the English Royal Society in a study the preferred areas of life and living conditions of the fly together. In particular, the mosquito is known to prefer tropical warmth for breeding. With this background knowledge, the researchers compared the data from various climate researchers, whose most pessimistic calculations predict global warming from 6.4 degrees Celsius to 2100. The scientists also included the proportions of human habitats south of the Sahara in the evaluations. They came to the conclusion that there would be no very large expansion of the potential habitats of the tsetse fly. If, due to an increase in climate-damaging carbon dioxide, the temperature rises between 1.1 and 5.4 degrees Celsius, the mosquito in some parts of East Africa could become too warm. Other regions of Africa, however, where the mosquito was previously too cold, could now become a new habitat. The best conditions for a brood are when the area has an average annual temperature of 20.7 to 26.1 degrees. Accordingly, completely new and densely populated areas could be affected in the course of climatic change. International researchers also expect strong flows of refugees due to climate change.
Sleeping sickness occurs in three stages
Between 60 and 70 million people currently live in the distribution area of the tsetse fly. After a sting and transmission of the pathogen, high fever, chills, edema, itching, swelling of the lymph nodes, skin rash and headache quickly occur. Overall, the disease runs in three stages. In the second stage there are complaints of the nervous system such as cardiac arrhythmia (stumbling), confusion and seizures. A special feature of the stage are massive sleep disorders and insomnia. In the third final state of illness (4 to 6 months after infection), the patients fall into a regular twilight state and the symptoms can resemble Parkinson's disease. The clear evidence is guaranteed by laboratory tests and immunological methods. Treatment must take place in the hospital because the medication used is highly toxic. Despite therapy, the death rate is 10 percent.
Sleeping sickness is not the only disease that is being promoted by climate change. According to international research, cholera, dengue and malaria will also find further areas of expansion as the temperature rises. In the near future, there will actually be more and more tropical diseases in Europe. (sb)
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