Dermal species of Leishmania have a relatively broad temperature range for optimal growth in vitro, with temperature differences accompanied by a form change. This suggests that when the host is living in moderate temperatures (22°C), infection may proceed at temperatures lower than those that occur in tropical regions (32°C), and a different clinical expression of the disease due to a different parasitic form may result. The aim of this study was to investigate the effect of environmental temperature on the clinical expression of the disease. BALB/C mice infected with Leishmania mexicana were housed at 32°±2°C or 22°±1°C, and assessed for the development of inflammation and the presence of parasites in organs using PCR and immunohistology. The clinical expression of leishmaniasis at 32°C included inflammation at the site of inoculation with swelling of the nose and tail, whereas at 22°C, up to 50% of the infected mice developed dry exfoliative dermatitis with alopecia on the dorsum. In both cases, parasite colonization was confirmed in the skin, with parasites at more external locations at 22°C. Parasite visceralization was confirmed in all internal organs and glands in both cases based on PCR and immunohistology. In conclusion, the clinical expression of diffuse leishmaniasis by Leishmania mexicana in laboratory mice is modified by temperature, from nodular inflammation at 32°C, to dry exfoliative dermatitis and alopecia at 22°C, with parasite visceralization in both cases.

Leishmania mexicana is a protozoan parasite that causes a disease in humans with frequent relapses after treatment. It is also highly resistant to the currently available drugs. For this reason, there is an urgent need for more effective antileishmanial drugs. Hydroxyurea, an anticancer drug, is toxic to replicating eukaryotic cells and has been proven to be effective in arresting the Leishmania major cell cycle. In this study, hydroxyurea was tested in an in vitro model of intracellular Leishmania infection in macrophages. The parasite density in infected macrophages was measured by microscopy after incubation for various times and treatment with hydroxyurea at different concentrations. Viable parasites that could be transformed into promastigotes by shifting the temperature to 26°C were counted every other day after the replacement of hydroxyurea with fresh medium. Meglumine antimoniate, the standard drug treatment for Leishmania mexicana, was used as a reference drug under the same experimental conditions. Hydroxyurea completely eliminated Leishmania parasites when it was used at a dosage of 10 or 100 g/ml. Differences in the length of treatment needed to achieve elimination were as follows: the 10-g/ml doses required 9 days, while 3 days was sufficient when 100 g/ml was used. Hydroxyurea had a 50% effective dose of 0.015 g/ml in vitro, which was observed on day 6 after exposure. Hydroxyurea is highly effective in killing intracellular amastigotes in vitro.

Objetivo. Evaluar la calidad higiénico-sanitaria, fisicoquímica y microbiológica de leche cruda bovina destinada a la venta, producida en un establo familiar y en tres mercados públicos del estado de Tabasco. Materiales y métodos. La calidad higiénico-sanitaria se determinó de acuerdo con la información general del predio, instalaciones, proceso de ordeño, limpieza y desinfección. La calidad fisicoquímica se determinó evaluando proteínas totales, caseína, grasa butírica, lactosa, sólidos no grasos y densidad. La calidad microbiológica fue determinada mediante la acidez titulable, prueba de alcohol, contenido de células somáticas, potencial de óxido-reducción, materia extraña, inhibidores bacterianos y bacterias mesofílicas aerobias. Resultados. La leche producida en el establo familiar, fue evaluada con la máxima calidad fisicoquímica y microbiológica en referencia a los estándares que evalúa la normatividad oficial mexicana establecidas en México por el Consejo para el fomento de la calidad de la leche y sus derivados, A. C. En cambio, la leche en los tres mercados públicos se consideró de rechazo, indicando posible contaminación durante los procesos de ordeña, así como en el manejo y transporte hacia los mercados públicos. Conclusiones. Las muestras de leche provenientes de los mercados públicos se consideraron no aptas para consumo humano ni para elaboración de subproductos.