June 2, 2025 Author : Saraiva da Cunha (infectious diseases) Leishmaniasis is a disease of mammals, including humans, with a higher incidence in tropical and subtropical regions. It remains endemic in Asia, Middle East, North Africa and Central and South America. It also exists in Europe, particularly in Mediterranean countries, including Portugal. In recent years, travel has contributed to the increase in imported cases to more developed countries. Around 1.5 to 3 million new cases and approximately 70 thousand deaths due to the leishmaniasis are recorded each year worldwide. It is a zoonosis, that is, it is an infectious disease transmitted between animals and humans. It is also a very old disease . Its existence in ancient Egypt, in the years 3500-2800 BC, and its origin in Sudan are documented. Since then, several species belonging to the genus Leishmania have been identified. In reality, leishmaniasis is a group of diseases : The causes are several species of protozoan parasites of the genus Leishmania. There are several species of Leishmania, of which around two dozen can infect humans. The parasites are transmitted to humans through a vector: sand flies , which are very small insects: an adult is less than 3.5 mm long. There are several species of sandflies. Phlebotomine sandflies are one of the most important and are particularly active at night. Females feed on the blood of mammals, which they need to complete their life cycle. it is at this time, with their painful bites, that, if infected, they transmit Leishmania. In addition to the role of sandflies as a vector for transmitting the disease, transmission is also possible from mother to child (congenital transmission) and through blood transfusion or sharing of needles and syringes (drugs dependency). Dogs are the main domestic species that is a reservoir of Leishmania and therefore an important source of infection. Mainland Portugal is considered an endemic area for canine leishmaniasis , with the most affected regions being Castelo Branco and Portalegre. Bragança, Guarda, Coimbra, Santarém, Setúbal and Faro also have high seroprevalence. Other species of reservoir mammals are, for example, some rodents and monkeys. In Europe, there are two most relevant species of Leishmania: Leishmania tropica , in Greece and neighboring countries, which causes cutaneous leishmaniasis. Leishmania infantum and Leishmania donovani throughout the Mediterranean region, which can cause cutaneous and visceral leishmaniasis. Symptoms, diagnosis and treatment There are two main forms of leishmaniasis: Cutaneous; Visceral, also called kala-azar. The mucocutaneous form is rarer, commonly found in Central and South America. After infection, the incubation period can vary from 10 days to several months. Symptoms of cutaneous leishmaniasis are skin lesions , which are generally self-limiting (resolving on their own) within a few months, but can leave disfiguring scars. When the infection spreads, it can reach several organs. In this case, visceral leishmaniasis will occur, with symptoms like fever, malaise, weight loss, increased liver and spleen volume, for example, of varying severity, with a greater probability of being fatal if not treated in time. Most of severe and fatal cases of leishmaniasis occur in Bangladesh, Brazil, India, Nepal and Sudan. This disseminated form of leishmaniasis is particularly important in immunosuppressed patients, such as those infected with HIV. Diagnosis of the disease is based on the epidemiological context, reported history of the disease, symptoms and laboratory identification of the parasite. Treatment of leishmaniasis is primarily aimed at eliminating the parasite, often using combinations of drugs , studied to reduce the possibility of developing resistance. Prevention of leishmaniasis There are no medications or vaccines to prevent leishmaniasis in men. Therefore, the main preventive measure is protection against sandfly bites, both in the regions where one lives and if their presence is known , and especially when traveling to regions where the prevalence is still high. Reinforcing nighttime mosquito prevention measures and avoiding exposure to animals in regions where the disease is endemic and where sandflies are active is very important. In Portugal, measures to prevent leishmaniasis in dogs (for example, with specific collars or through vaccination) are recommended by veterinarians, not only because of the risk to public health but also because of the serious effects that the disease has on animals. Sources European Centre for Disease Prevention and Control. Leishmaniasis . Maxfield L, Crane JS. Leishmaniasis . Meet the infectious diseases clinical team from Hospital da Luz network. The content published in the Health Guide is intended for the general public and is provided for informational and educational purposes only. It does not replace individual medical assessment, diagnosis, or personalized clinical advice from a qualified healthcare professional. The content is produced or reviewed by physicians and other healthcare professionals at Hospital da Luz and is based on the knowledge available at the time of publication or the most recent update, as indicated at the beginning of each item.
