Leishmaniasis
Leishmaniasis infantum Wikipedia
https://en.wikipedia.org/wiki/Leishmania_infantum
Leishmaniasis is caused by parasitic protozoa in the genus Leishmania and is transmitted primarily through the bites of infected female sandflies. There are three main forms of the disease: cutaneous, mucocutaneous, and visceral. The form that develops depends partly on the parasite species and the infected person’s immune response. Not everyone who becomes infected develops symptoms. WHO, 2023
The Amazon supports a diversity of Leishmania species, including Leishmania braziliensis, an important cause of cutaneous and mucocutaneous disease. The relative importance of different species varies geographically, making it difficult to describe any one species as dominant throughout the region. Soares et al., 2024
Cutaneous leishmaniasis is the most common form worldwide. It produces skin lesions, often on exposed areas where sandflies bite. These may begin as small bumps before developing into ulcers with raised edges. The sores are usually painless, although secondary bacterial infections can make them painful. Lesions can persist for months or years and often leave lasting scars, even after they heal. CDC, 2025
Some species within the Leishmania (Viannia) subgenus, including L. braziliensis, can also cause mucosal or mucocutaneous leishmaniasis. In this form, parasites spread to the mucous membranes of the nose, mouth, or throat. Symptoms may appear years after the original skin lesions have healed. Untreated disease can destroy tissue and cause severe disfigurement. However, this complication develops in only a minority of infections. CDC, 2025
Visceral leishmaniasis is the most dangerous form. In the Americas, it is caused by Leishmania infantum. It affects internal organs, including the spleen, liver, and bone marrow, and can cause prolonged fever, weight loss, anemia, and enlargement of the liver and spleen. According to the World Health Organization, untreated visceral leishmaniasis is fatal in more than 95% of cases. This figure refers to people who develop the disease, rather than everyone infected with the parasite. Soares et al., 2024; WHO, 2023
Human activity can alter the conditions that allow leishmaniasis to spread. Deforestation, settlement, and movement into forested areas can change people’s exposure to infected sandflies. Poor housing and inadequate waste management can also provide sandflies with breeding or resting sites near homes. The effects depend on local conditions, including the sandfly species and animal hosts involved, so forest clearance does not produce the same outcome everywhere. WHO, 2023
Several treatments are available, but the choice depends on the disease form, parasite species, location where infection occurred, and the patient’s health. Miltefosine is an oral option for certain infections, including some caused by L. braziliensis, although its effectiveness varies geographically. Other treatments include pentavalent antimonial drugs and liposomal amphotericin B, which is an important treatment for visceral leishmaniasis. Prompt treatment of mucosal and visceral disease helps prevent severe complications and death. CDC, 2024
References:
Bezmer, Jacob M. Freire-Paspuel Byron P. Schallig, Henk D F H. De Vries, Henry J C. Calvopina, Manuel. (June 12, 2023) Leishmania species and clinical characteristics of Pacific and Amazon cutaneous leishmaniasis in Ecuador and determinants of health-seeking delay: a cross-sectional study PubMed
Valdivia, Hugo O. Zorrilla, Victor O. Espada, Liz J. Perez, Jocelyn G. Razuri, Hugo R. Vera, Hugo. Fernandez, Roberto, Tong, Carlos. Ghersi, Bruno M. Vasquez, Gissella M. Burrus, Roxanne G. Lescano, Andres G. Montgomery, Joel M. (February 10, 2021) Diversity, distribution and natural Leishmania infection of sand flies from communities along the Interoceanic Highway in the Southeastern Peruvian Amazon PLOS Neglected Tropical Diseases
https://pmc.ncbi.nlm.nih.gov/articles/PMC7875382/
Gramiccia, Marina. Gradoni, Luigi. (October 2005) The current status of zoonotic leishmaniases and approaches to disease control International Journal for Parasitology Volume 35 Issues 11-12 Pages 1169-1180
https://www.sciencedirect.com/science/article/abs/pii/S0020751905002420
Magill, Alan J. Hill, David R. Ryan, Edward T. (2012) Hunter’s Tropical Medicine and Emerging Infectious Disease Ninth Edition Elsevier
(January 12, 2023) Leishmaniasis World Health Organization
(April 23, 2025) Leishmaniasis Center for Disease Control and Prevention
https://www.cdc.gov/yellow-book/hcp/travel-associated-infections-diseases/leishmaniasis.html
Soares, Rodrigo Pedro. Fontes, Igor Campos. Dutra-Rego, Felipe. Rugani, Jeronimo Nunes. Moreira, Paulo Otavio L. Da Matta, Vania Lucia Ribeiro. Flores, Gabriela Venicia Araujo. Pacheco, Maria Sandoval. De Andrade, Andrey Jose. Da Costa-Ribeiro, Magda Clara Vieira. Shaw, Jeffrey Jon. Laurenti, Marcia Dalastra (August 9, 2024) Unveiling the Enigmatic nature of six neglected Amazonian Leishmania (Viannia) species using the hamster model: Virulence, Histopathology and prospection of LRV1 PLOS Neglected Tropical Diseases
https://pmc.ncbi.nlm.nih.gov/articles/PMC11315283/
Dos Santos, Cleber Vinicius Brito. Seva, Anaia de Paixao. Werneck, Guilherme Loureiro. Struchiner, Claudio Jose (August 25, 2021) Does deforestation drive visceral leishmaniasis transmission? A causal analysis Proceedings of the Royal Society Biological Sciences
https://royalsocietypublishing.org/doi/full/10.1098/rspb.2021.1537
(March 13, 2024) Clinical Care of Leishmaniasis Center for Disease Control and Prevention
https://www.cdc.gov/leishmaniasis/hcp/clinical-care/index.html