Cutaneous leishmaniasis in Argentina
Between 2019 and 2024, 990 confirmed cases of cutaneous leishmaniasis were reported in Argentina. 59.3% of the cases occurred in the Northwest Argentine region (NOA), where Salta and Jujuy reported 385 and 165 cases, respectively. The Northeast Argentine region (NEA) is the region with the next highest number of reports (35.5% of the total), mainly in Misiones (135 cases) and Chaco (131 cases).
The temporal trend is downward, driven by the epidemiological situation in the NOA region, while it is stable in the NEA region, where there has been an increase in Chaco and Formosa in recent years. These regions likely present different seasonality's, with peaks in July in the NOA region and in November-January in the NEA region, possibly related to peak transmission in the fall and spring seasons, respectively. There were 12 reported cases with a history of travel to another Latin American country, and five cases reported residence in another country. In 2025, up to epidemiological week 14, 13 confirmed cases have been reported, 53.7% of them in Salta, all cases in individuals over 18 years of age.
In the cutaneous cases that were collected, the average time from diagnosis to diagnosis was 77.65 days, being shorter in the Northwest (50.89 days) and longer in the Central region (180.78 days).
Parasitology: Blood & Tissue Flagellates
The majority of cases affected males (80.8%) and those between 20 and 49 years of age (58.5% of the total). Forty-nine cases were identified that presented possible relapses, 37 with cutaneous involvement and 12 with mucosal involvement. In 54 cases, associated professions were identified, such as farmers, foresters, park rangers, and military personnel, the latter linked to an outbreak in Misiones.
Leishmaniasis is a group of anthropozoonotic diseases caused by different parasites of the genus Leishmania.
They are transmitted to susceptible mammals—including humans—by the bite of the female sandfly of different species (subfamily Phlebotominae), giving rise to distinct vector-parasite-reservoir/host complexes.
In Argentina, autochthonous transmission cycles of the following clinical variants have been recorded: visceral leishmaniasis, which represents the most severe form, and tegumentary leishmaniasis, which includes, among others, cutaneous and mucosal forms.
Cutaneous leishmaniasis is an infectious disease that affects the skin. Its clinical spectrum is highly varied and depends on the interaction of several factors: age, nutritional status, immunological response, host genetic susceptibility, infecting species, vector, dose, and inoculation site. The cutaneous presentation is the most common of all leishmaniasis and causes high morbidity, but is rarely life-threatening. In the Americas, at least 15 species of the subgenera Leishmania (L.) and Viannia (V.) have been described as being linked to this presentation. In Argentina, Leishmania (V.) braziliensis is the etiologic agent, although there are reports of isolations of L. (L.) amazonensis and L. (V.) guyanensis in patients in the Chaco region of Salta.
Transmission occurs when an infected female sandfly feeds on a vertebrate. In Argentina, the main species involved in the transmission of Leishmania braziliensis is Nyssomyia neivai; Migonemyia migonei and the Evandromyia cortelezzii complex have also been implicated.
Multiple reservoirs (vertebrate animals that maintain the parasite in nature and perpetuate the transmission cycle) have been implicated in the parasite's life cycle; some of those identified include marsupials (Didelphis species), sloths (Choloepus and Bradypus species), the lesser anteater (Tamandua tetradactyla), the fox (Cerdocyon thous), and rodents (Rattus, Proechimys, Nectomys, and Oryzomys species, among others). There are different main reservoirs in each transmission focus, and the interaction between the reservoirs and the parasites is complex, multifactorial, circumstantial, and dynamic.
Localized cutaneous leishmaniasis is the most common presentation, and the lesions can be single or multiple (up to 10 lesions) located in areas exposed to bites, mainly on the extremities. The lesion begins as a papule that evolves into a rounded, painless nodule, which progressively enlarges to form an ulcer.
Characteristically, it has raised, defined edges and a granular base that may or may not have exudate and is painless. Secondary lesions, nodular and/or ulcerated, may appear, and occasionally become superinfected, and may present purulent exudate and cause pain. There are other rare presentations of cutaneous leishmaniasis, such as disseminated cutaneous leishmaniasis, diffuse anergic cutaneous leishmaniasis, atypical cutaneous leishmaniasis, and chronic recurrent cutaneous leishmaniasis.