After the sting, the amastigotes replicate within the Langerhans cells of the skin. Depending on the immune response, the infection is either overcome or results in chronic illness or fatal outcome.Ĭutaneous leishmaniasis: Typical clinical manifestations include the oriental sore or aleppo button in the Near East and the cutaneous verruciform leishmaniasis in South America. The pathogens propagate from the stinging site causing lymphad-enopathy and progressive swelling of the spleen and liver. A papule remains visible at the stinging site which swells up due to the entering leucocytes. Visceral leishmaniasis, synonym: kala-azar: After a sand fly sting, the promastigotes are ingested by macrophages and replicate in an intracellular manner. Different Leishmania types can cause clinically overlapping clinical symptoms. The classification of Leishmania has not yet been completed. Viannia's replication cycle slightly differs in the vector. The genus Leishmania is subdivided into the subgenera Leishmania (world-wide geographical distribution) and Viannia (only occurs in America). Around 90% of the cases of cutaneous leishmaniasis occur in the countries of the Middle East, in Afghanistan up to Central Asia, and in Latin America up to Peru, and around 90% of the cases of mucocutaneous leishmaniasis in Brazil, Bolivia and Peru. Around 90% of all cases of visceral leishmaniasis occur in eastern India and Bangladesh, in Sudan and in Brazil. Leishmania belongs to the family of trypanosomatides in the order of kinetoplastides, and their evolution probably dates back 1 billion years.Īpproximately 350 million people are threatened by Leishmania, and around 12 million have chronic pathological symptoms. The Leishmania pathogen was described for the first time by the Russian military doctor Borovsky in a skin wound in 1898. Leishmaniasis of the Old World was described around 1500 AD in the region of present-day Afghanistan in the Middle East. ![]() In 1911, Gaspar Vianna found the difference in the replication cycles between Leishmania of the Old World and that of the New World. Indications pointing to mutilating infections of the face can be found on ceramic containers excavated in Central America that date as far back as 1,000 years, and on pictures of the Spanish conquerors in the 16th century. ![]() Leishmania is wide-spread in tropical and subtropical regions world-wide. These protozoae were characterised by Leishman and Donovan in 1903. In this context, transmission of a protozoa infection by domestic animals, with the exception of malaria, as explained above, should also be considered. Attempts at developing a protective vaccine against these protozoae have so far not been successful and will prove to be difficult in future, too, due to the great variability of the surface antigens of the protozoae. The transmission risk can normally be reduced by keeping apart and combating the vector or vehicle. They are by definition typical pathogenic agents of zoonoses and can therefore not be eradicated. The protozoae listed in table table1 1 are also wide-spread in animals. Therefore – unlike the pathogens discussed here – they are not zoonoses. Plasmodia have adapted to humans in such a way that they cannot be transmitted from humans to different species (the chimpanzee is a rare exception) and vice versa. The three typical clinical patterns of malaria and the transmission of the four types of plasmodia (Plasmodium falciparum, Plasmodium ovale, Plasmodium vivax and Plasmodium malariae) by blood have already been described by the subgroup of the Advisory Committee Blood (Arbeitskreis Blut) and are therefore not discussed in more detail in this paper. However, such a transmission cannot be ruled out entirely as reports of transmissions by organs and stem cells show. Since acutely infected donors are excluded from donating blood for 4 weeks following an episode of diarrhoea, the probability of an infection is negligibly low. Therefore, they will not be discussed in detail. ![]() ![]() Up to now, transmissions by these protozoae have not been reported in Germany. After the gastrointestinal symptoms have subsided, these agents are normally no longer present in the blood. They cause infections of the gastrointestinal tract and occasionally lead to penetration of tissue layers so that they are also present in the blood following phagocytosis by macrophages/monocytes within a short period, e.g. Infectious agents such as Giardia lamblia, Dientamoeba sp., Entamoeba sp., Cryptosporidium parvum and Isospora belli are also protozoae which can infect humans, depending on region, food and water hygiene, and which can be transmitted via blood in exceptional cases.
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