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Leishmania is a tropical disease that we most often catch when traveling to the regions of East Africa and South Asia. It is caused by Leishman protozoa, which are transmitted by flies. There is a specific animal reservoir for each Leishmania species. Also, the immune response depends not only on the immune state of the human body, but also on the protozoan species.
Leishmania – the definition of the disease
Leishmania (Leishmania) is the most common disease we catch when traveling to tropical countries (tropical disease). Therefore, its occurrence is most often located in tropical and subtropical areas, with the exception of Oceania and Australia. The cause of its formation are Leishmania protozoa, and it is transmitted by flies (mosquitoes). Every year, over a million cases of Leishmaniasis are diagnosed. This disease can occur in several forms:
- dermal and mucous (mainly found in Asia and Central America),
- skin,
- organ.
Each year, more than 85 people die from Leishmania around the world.
Leishmania – causes of the disease
As mentioned above, the disease is caused by Leishmania protozoa transmitted by flies. The disease usually affects the regions of East Africa and South Asia. Infection usually occurs from spring to fall, and the time it takes for full-blown Leishmania to develop may vary (usually several weeks).
How is Leishmania manifested?
The symptoms of Leishmania should be distinguished according to the different forms of the disease.
1. Cutaneous leishmania (otherwise known as “Allepo disease”). In this type of disease, skin lesions are of a different nature. They usually occur on the face and limbs. The first symptom of cutaneous leishmaniasis is the appearance of a red lump which gradually darkens over a period of several weeks and becomes an ulcer. The scabbed lesion begins to secrete serous fluid and the surrounding lymph nodes grow considerably. It is characteristic that with the development of the disease, secondary lesions begin to appear around the ulcers that have arisen. After several months of Leishmania, the skin lesions that have been formed begin to heal spontaneously and form discoloration and scars.
2. Cutaneous-mucosal leishmania. At first, the patient develops skin changes that resemble those present in the skin form. Interestingly, a few years after they heal, the patient begins to develop changes on the mucosa, which eventually lead to the destruction of the nasal septum or the lip. The resulting changes, bleeding and nasal obstruction appear due to the migration of protozoa from the skin to the mucous membranes.
3. Organ Leishmania. It is the most severe form of the disease because it damages the spleen, intestines, liver and bone marrow. Symptoms take a long time to develop, but the course of the disease can be very rapid. Another term for organ leishmania is black fever, which comes from the darker color of the skin during its duration. Patients with organ (visceral) leishmania develop a high temperature, diarrhea and enlargement of the lymph nodes, spleen and liver, while damage to internal organs leads to hemorrhagic diathesis and edema. In patients with this type of disease, tests show, among others: a decrease in albumin concentration, a decrease in the number of platelets, a decrease in erythrocytes and a low number of leukocytes.
How do we diagnose Leishmania?
Thanks to the microbiological examination of the specimen taken from the ulcer, it is possible to easily diagnose cutaneous or dermal-mucosal leishmania. Another method of testing is to perform the Motenegro test with killed protozoa, but it shows a positive result only ten weeks after the first skin symptoms appear. Rarely, parasite culture and serological tests are used, which are not useful.
However, in order to diagnose the visceral form of Leishmania, a biopsy of the spleen, bone marrow or liver should be performed. Contrary to the cutaneous and dermal-mucosal forms – here the cultivation of the parasite is used.
The following tests are also used in the diagnosis of the disease:
- method Western Blot,
- enzyme immunoassay (ELISA),
- metoda PCR.
Leishmania – treatment
Treatment of the disease can be somewhat complicated due to drug resistance and the large number of species causing the disease. In the form of cutaneous leishmania, no treatment is practically implemented, unless the lesions are very scattered and the lymph nodes are involved. On the other hand, mucosal leishmania is treated with intravenous preparations, and the therapy itself is quite long (it lasts about 60 days) and it may be necessary to repeat it several times. The treatment uses:
- pentamidine,
- ketoconazole,
- antimony compounds,
- paromycin,
- amphotericin B,
Note: Treatment of diseases that may coexist with leishmania, e.g. HIV infection, tuberculosis or liver failure, is also important in therapy.
Leishmania – can it be prevented?
Prevention is similar to that of malaria. Before traveling to a given region, make sure that there is Leishmania in a given place. In addition, it is necessary to protect yourself from mosquitoes and midges with clothes that tightly cover the skin or mosquito nets. It is also useful to use unwanted insect repellants that contain DEET. It should be emphasized that there is no drug prophylaxis in the case of Leishmania.
Source: A. Kaszuba, Z. Adamski: “Lexicon of dermatology”; XNUMXst edition, Czelej Publishing House