Introduction
Malaria is an infectious disease caused by the parasites: The different pathogens lead to different forms of malaria, which can be distinguished from each other by their symptoms, among other things. They reach humans almost exclusively via the bite of an Anopheles mosquito. Malaria leads to flu-like symptoms with usually high fever.
As a result of complications, such as acute kidney failure and lung failure, the disease can lead to death. Especially in tropical areas, malaria is one of the most frequent causes of death. Malaria belongs to the tropical diseases. Many other diseases belong to this group, such as dengue fever or Ebola, which did not lead to a serious epidemic until 2015.
- Plasmodium vivax
- Plasmodium oval
- Plasmodium malariaeand
- Plasmodium falciparum.
Synonyms
malaria, marsh fever, marsh fever
EpidemiologyFrequencyOccurrence
Approximately 250 million malaria cases occur annually. About 90% of them come from Africa. This makes it the second most common infectious disease in the world after tuberculosis.
Over 2 million people die of malaria every year. Every fifth death of a child in Africa is caused by a malaria disease. Especially the population of tropical and subtropical areas is exposed to the risk of infection, which means that about 40-50% of the world’s population is constantly at risk. In Germany, however, there are about 500-1000 cases of malaria per year.
History
Malaria epidemics have been documented over thousands of years. One knows of cases with the old Egyptians about 3500 years ago, who saw the curse of the gods coming over them. Even for the fall of the Roman Empire epidemics are said to have played a decisive role.
British conquerors are said to have regularly drunk tonic water, which contains the effective antidote quinine to protect against malaria. In order to bear the bitter taste, gin was often added. In 1907 the Frenchman Alphonse Laveran was awarded the Nobel Prize for his discovery of the malaria pathogen.
The causative agents of malaria are the protozoa (unicellular endoparasites) Plasmodium ovale, Plasmodium vivax (leading to Malaria tertiana), Plasmodium malariae (Malaria quartana) and Plasmodium falciparum (Malaria tropica). The carrier of malaria is the female anopheles mosquito. Very rarely, malaria cases can also occur during birth by the sick mother or during blood transmission.
Through the mosquito’s bite, the so-called sporozoites (infectious form of the parasite) enter the human bloodstream. Thus they pass through the liver within a few minutes and settle there in the liver cells. Through asexual reproduction, a so-called schizont is formed, which in turn contains thousands of merozoites (exoerythrocytic phase).
Within a week the schizont bursts together with the liver cell and the merozoites enter the blood. They nest in the red blood cells (erythrocytes), whereupon they develop into schizopods by multiplication. On average, these contain about 12 merozoites (erythrocyte phase).
When the affected red blood cells burst, the body reacts with a feverish attack on the released merozoites and their toxins. The merozoites floating in the blood then attack other red blood cells again. This cycle of bursting, infestation, multiplication and bursting again lasts 48 hours for P. vivax and oval, and 72 hours for P. malariae.
This explains why the fever attacks occur cyclically every 3 (P. vivax and oval) and 4 days (P. malariae). The P. falciparum is not subject to such a rhythm, therefore irregular fever attacks occur here. A detailed overview of all tropical diseases can be found under the article: Overview of tropical diseases