Leishmaniasis is a disease transmitted by sand flies or butterfly mosquitoes. These mosquitoes bite both animals, such as dogs, and humans. The causative agent of the tropical infectious disease – the leishmania – are unicellular parasites. The symptoms can vary depending on the form of the disease and the disease can even take a fatal course. You can learn interesting facts about leishmaniasis here.
Distribution of leishmaniasis
Infection with leishmania can cause leishmaniasis. The name of the disease and the group of pathogens goes back to the Scottish tropical physician and pathologist William Leishman, who at the beginning of the last century discovered and described the disease later named after him. Another name is Oriental bump. The disease is most common in tropical countries and southern Europe. According to estimates, around twelve million people are infected with the causative agent of leishmaniasis, and it is assumed that two million new infections occur each year. About 60,000 people die from the rarer form, visceral leishmaniasis (visceral: affecting the internal organs). The far more common form is cutaneous leishmaniasis (skin leishmaniasis).
Dry cutaneous leishmaniasis.
In dry cutaneous leishmaniasis, a slight redness develops at the injection site, which later develops into a swelling that grows over the course of several weeks. This dry “bump” is painless and usually heals after several months, but leaves a scar. Because the infection takes place over a long period of time, the body’s immune response also increases during the infection period, so that once an infection has passed, it leaves a lifelong immunity.
Wet skin leishmaniasis – weeping ulcer.
In addition to the dry cutaneous form, there is also wet cutaneous leishmaniasis, which involves a weeping ulcer. The course of disease and healing is similar to that of dry leishmaniasis.
Mucocutaneous leishmaniasis: symptoms only later.
Mucocutaneous leishmaniasis is more complicated. In this clinical picture, there is also a puncture in the skin with the development of the typical bump, but after the initial infection – and sometimes up to 30 years later – the parasites infect the mucous membranes of the nose, throat, lips and larynx via the lymphatic and blood vessels. The first signs are nosebleeds or obstructed nasal breathing after the initial infection. The pathogens can also attack and destroy the nasal septum: The affected patient then develops a so-called “tapir nose,” in which the nose has collapsed in on itself. The disintegration of the tissue often results in further infections and mutilations. This form of leishmaniasis must be treated with medication in any case.
Kala-azar – the black disease
The most severe form of the disease is visceral leishmaniasis, in which the internal organs are affected. It is also known as kala-azar. It occurs in more than 88 countries-most notably Brazil, the Indian subcontinent, and Sudan. The World Health Organization (WHO) estimates that about 500,00 people contract new cases of kala-azar each year.
Symptoms of kala-azar
The disease, which can now be treated with antibiotics, is always fatal without treatment. The term kala-azar comes from Persian and means “black disease”: in this form of leishmaniasis, the skin turns blackish. After an incubation period of three to six months – but sometimes only after years – flu-like symptoms appear in the affected person:
- High fever
- Chills
- Increasing feeling of illness
- Nausea
- Vomiting
- Diarrhea
- Lymph node swelling
- Bronchitis
- Upper abdominal pain due to enlargement of the liver and spleen.
Hair loss, bleeding from the skin and mucous membranes, and anemia may also occur. The diseased lose considerable weight, the organ infestation by the parasites inflates the abdomen.
How is the disease transmitted?
All forms of leishmaniasis are caused by single-celled parasites transmitted by sandflies or butterflies. The parasites usually live in rodents, dogs, and foxes. From there, they enter the insect’s intestine through a first mosquito bite, where they multiply and develop. In a second mosquito bite, the parasites are then transmitted to humans.There is no vaccination against leishmaniasis. The only protection is provided by clothing with long arms and legs, and consistent mosquito repellent throughout.
