Leishmania mexicana causes localized (LCL) or diffuse cutaneous leishmaniasis (DCL). The cause of dissemination in DCL remains unknown, yet NK cells possibly play a role in activating leishmanicidal mechanisms during innate and adaptive immune responses. We had previously shown that Leishmania lipophosphoglycan (LPG) is a ligand for TLR2, activating human NK cells. We have now analyzed NK cells in LCL and DCL patients. NK numbers and effector mechanisms differed drastically between both groups of patients: DCL patients showed reduced NK cell numbers; diminished IFN-γ and TNF-α production; and lower TLR2, TLR1, and TLR6 expression as compared to LCL patients. The altered protein expression found in NK cells of DCL patients correlated with their down-regulation of IFN-γ gene expression in LPG-stimulated and non-stimulated cells as compared to LCL patients. NK cell response was further analyzed according to gender, age, and disease evolution in LCL patients showing that female patients produced higher IFN-γ levels throughout the disease progression, whereas TLR2 expression diminished in both genders with prolonged disease evolution and age. We furthermore show the activation pathway of LPG binding to TLR2 and demonstrated that TLR2 forms immunocomplexes with TLR1 and TLR6. In addition to the reduced NK cell numbers in peripheral blood, DCL patients also showed reduced NK cell numbers in the lesions. They were randomly scattered within the lesions, showing diminished cytokine production, which contrasts with those of LCL lesions, where NK cells produced IFN-γ and TNF-α and were found within organized granulomas. We conclude that in DCL patients the reduced NK-cell numbers and their diminished activity, evidenced by low TLR expression and low cytokine production, are possibly involved in the severity of the disease. Our results provide new information on the contribution of NK cells in Leishmania infections of the human host.

Thaumasioscolex didelphidis n. gen., n. sp. is described from the intestine of the black-eared opossum Didelphis marsupialis L. (Marsupialia: Didelphidae) from Los Tuxtlas, Veracruz, Mexico. The new genus differs from all proteocephalidean genera in the morphology of the scolex that is formed by 4 well separated lobes each containing 1 noncircular sucker opening laterally inside the exterolateral cavity, a large-sized body (length up to 1 m), a large number of testes, the shape of gravid proglottids that are inversely craspedote (the anterior border of a proglottid overlaps the posterior border of a preceding proglottid), eggs in groups mostly of 4-6 eggs each, and an embryophore bearing digitiform projections on its external surface. This is the first tapeworm of the Proteocephalidea, the members of which were previously reported exclusively from poikilotherm vertebrates (freshwater fishes, amphibians, and reptiles), found in a homoiotherm vertebrate.

Leishmania infantum is the causal agent of cutaneous and visceral canine leishmaniasis, a disease widely described in Europe and Latin America. This study describes a case of a canine Canary mastiff breed, born in Mexico that was referred to consult by an alopecic lesion and generalized lymph adenomegaly. Diagnosis of leishmaniasis was established by impression smears of the lesion that showed amastigotes within macrophages. Due to the poor body condition of the animal, euthanasia and necropsy were conducted and samples taken from skin, lymph nodes, liver, kidney, and spleen to perform histological and molecular analysis. In skin, spleen and kidney granulomatous lesions were observed showing amastigotes of Leishmania. The diagnosis of L. infantum was confirmed by using molecular tools. The report of this case suggests the potential risk of this disease in a non-endemic region from Mexico.