Cutaneous leishmaniasis in a returning traveller

Non-Endemic Leishmaniases Reported Globally in Humans between 2000 and 2021—A Comprehensive Review

Leishmaniases are human and animal parasitic diseases transmitted by phlebotomine sand flies. Globalization is an important driver of the burden and in the current dynamics of these diseases. A systematic review of articles published between 2000 and 2021 was conducted using the PubMed search engine to identify the epidemiology and clinical management of imported human leishmaniases as a fundamental step to better manage individual cases and traveler and migrant health from a global perspective. A total of 275 articles were selected, representing 10,341 human imported cases. Identified drivers of changing patterns in epidemiology include conflict and war, as well as host factors, such as immunosuppression, natural and iatrogenic. Leishmania species diversity associated with different clinical presentations implies diagnostic and treatment strategies often complex to select and apply, especially in non-endemic settings. Thus, diagnostic and management algorithms for medical clinical decision support are proposed. Increased surveillance of non-endemic cases, whether in vulnerable populations such as refugees/migrants and immunocompromised individuals or travelers, could improve individual health and mitigate the public health risk of introducing Leishmania species into new areas.

"Chiclero's Ulcer" Due to Leishmania mexicana in Travelers Returning from Central America: A Case Report and Review of the Literature

Cutaneous leishmaniasis (CL) due to a New World species of Leishmania is increasingly seen among returning international travelers, and most cases arise from travel to Mexico, Central and South America. We described a case of CL in a women presenting a nonhealing ulceration under her right ear with slight increase of size of the left parotid gland under the skin lesion, evolving for 4 months. In her history of travel, she reported a ten-day stay in Mexico during the Christmas vacation in the Yucatan region with only half a day walking in the tropical forest. Diagnosis of CL due to Leishmania mexicana was done via PCR detection and sequencing from swab sampling of the lesion. The patient recovered without antiparasitic treatment. Clinicians should consider diagnosing Chiclero’s ulcer in patients returning from endemic areas such as Central America and Texas who present with chronic ulceration. A noninvasive sampling is sufficient for the PCR-based diagnosis of this disease.

Molecular diagnosis and therapy for cutaneous leishmaniasis of a returned traveler from Mexico

Leishmaniasis is prevalent in Southern Europe, the Middle East, India, Africa, and Central and South America. Cutaneous leishmaniasis may spontaneously heal over time without treatment; however, risk of visceral dissemination and the impact of cosmetic defect are important concerns. We report a Case of cutaneous leishmaniasis in a patient who ever traveled to Mexico before the onset of a deteriorating wound around the swollen left eyebrow. A diagnosis of infection with Leishmania mexicana was made based on histopathological examination and molecular identification. Systemic treatment with liposomal amphotericin B and ketoconazole were administered with gradual healing of the lesion. Also, this traveler case implicates that the spread of endemic parasitic diseases may be a concealed risk on the public health for Taiwan underlying globalization.

Structural explanation for the tunable substrate specificity of an E. coli nucleoside hydrolase: insights from molecular dynamics simulations

Parasitic protozoa rely on nucleoside hydrolases that play key roles in the purine salvage pathway by catalyzing the hydrolytic cleavage of the N-glycosidic bond that connects nucleobases to ribose sugars. Cytidine-uridine nucleoside hydrolase (CU-NH) is generally specific toward pyrimidine nucleosides; however, previous work has shown that replacing two active site residues with Tyr, specifically the Thr223Tyr and Gln227Tyr mutations, allows CU-NH to process inosine. The current study uses molecular dynamics (MD) simulations to gain atomic-level insight into the activity of wild-type and mutant E. coli CU-NH toward inosine. By examining systems that differ in the identity and protonation states of active site catalytic residues, key enzyme-substrate interactions that dictate the substrate specificity of CU-NH are identified. Regardless of the wild-type or mutant CU-NH considered, our calculations suggest that inosine binding is facilitated by interactions of the ribose moiety with active site residues and Ca²⁺, and π-interactions between two His residues (His82 and His239) and the nucleobase. However, the lack of observed activity toward inosine for wild-type CU-NH is explained by no residue being correctly aligned to stabilize the departing nucleobase. In contrast, a hydrogen-bonding network between hypoxanthine and a newly identified general acid (Asp15) is present when the two Tyr mutations are engineered into the active site. Investigation of the single CU-NH mutants reveals that this hydrogen-bonding network is only maintained when both Tyr mutations are present due to a π-interaction between the residues. These results rationalize previous experiments that show the single Tyr mutants are unable to efficiently hydrolyze inosine and explain how the Tyr residues work synergistically in the double mutant to stabilize the nucleobase leaving group during hydrolysis. Overall, our simulations provide a structural explanation for the substrate specificity of nucleoside hydrolases, which may be used to rationally develop new treatments for kinetoplastid diseases.

Cutaneous and mucocutaneous leishmaniasis: Clinical perspectives

Leishmaniasis is endemic in 98 countries and territories, with 1.2 million new cases per year, making it a worldwide concern. The deadly visceral form is a leading cause of death from tropical parasitic infections, second only to malaria. Leishmaniasis appears to be increasing in many countries because of extended urbanization. The disease reservoir includes small mammals; parasite transmission occurs via bite of the female phlebotomine sandfly. Disease manifestations vary and largely depend upon the Leishmania species acquired. It may be first evident with a range of findings-from a localized cutaneous ulcer to diffuse painless dermal nodules-or, in the mucocutaneous form, ulceration of the oropharynx. In the potentially deadly visceral form, the internal organs and bone marrow are affected.

Leishmaniasis in travelers: a literature review

Leishmaniasis is a vector-borne protozoan infection whose clinical spectrum ranges from asymptomatic infection to fatal visceral leishmaniasis. Over the last decades, an increase in imported leishmaniasis cases in developed, non-endemic countries, have been pointed-out from a review of the international literature. Among the possible causes are increasing international tourism, influx of immigrants from endemic regions and military operations. The main area for the acquisition of cutaneous leishmaniasis, especially for adventure travelers on long-term trips in highly-endemic forested areas, is represented from South America, whereas popular Mediterranean destinations are emerging as the main areas to acquire visceral variant. Leishmaniasis should be considered in the diagnostic assessment of patients presenting with a compatible clinical syndrome and a history of travel to an endemic area, even if this occurred several months or years before. Adventure travelers, researchers, military personnel, and other groups of travelers likely to be exposed to sand flies in endemic areas, should receive counseling regarding leishmaniasis and appropriate protective measures.