Malaria is one of the most important infectious diseases worldwide, affecting up to 500 million new cases every year and killing up to 3 million people. Through travel to Asian and African countries, malaria also plays a role in Germany, although the malaria pathogens are not native here.
Malaria is an infectious disease with typical fever attacks, which is triggered by malaria pathogens, the plasmodia. These plasmodia are transmitted to humans by a specific species of mosquito, the Anopheles mosquito.
Distribution of malaria
Malaria is typical of tropical and subtropical areas.
The majority of infections occur in Africa, specifically in the area south of the Sahara to the north of South Africa – according to WHO estimates, between 300 and 500 million people are infected with this disease there every year, and more than one million children die.
In Asia, the border region between Thailand and Myanmar, Laos, Cambodia, the Indonesian islands east of Bali, Papua New Guinea and the Solomon Islands are particularly affected.
In South America, parts of Brazil are at risk. However, tourism also affects people who do not actually live in the risk areas. In recent years, several hundred Germans have been infected each year during vacation trips.
Most of these infections occurred in West African countries and in Kenya. Extremely rarely, one can also become infected if an infected mosquito gets into an airplane. Then a transmission, the airport malaria, can still occur in the airplane or at the airport. Most often, malaria is transmitted through the bite of a female Anopheles mosquito infected with plasmodia.
Very rarely, malaria can also be transmitted from person to person during a blood transfusion or from mother to unborn child during pregnancy. Also, “healthy” mosquitoes can become infected by sucking human blood infected with malaria pathogens and thus become vector mosquitoes – this has also occurred.
Origin of malaria
Malaria is caused by four different species of plasmodia – namely Plasmodium falciparum, ovale, vivax, and malariae. These four species cause three different types of malaria, which differ from each other in terms of fever progression and disease severity.
The plasmodia spend part of their life cycle in the mosquito and the other part in humans. Their development in humans is closely related to the fever episodes that occur during malaria illness. Through the bite of the mosquito infected with plasmodia, the pathogens enter the human bloodstream. They migrate to the liver, where they remain and develop for between 5 and 18 days, depending on the species.
At the end of this stage, the infected liver cells burst and the malaria pathogens re-enter the bloodstream. There they attach to red blood cells (erythrocytes), invade them, and continue to multiply. Thus, when the erythrocytes break down, many pathogens are released, which in turn infect new red blood cells. This mechanism causes the recurrent episodes of fever.
