White mice were used to study the infectivity of the eggs of Lagochilascaris minor Leiper, 1909 after incubation in liquid media, with or without preservative substances. Potassium bichromate (K2Cr2O7) at 1% restrict hatching, while 1% formalin gave a greater larval yield. Incubation of eggs in distilled water, in Roux or Falcon flasks gave a good yield, whether the eggs were obtained from human feces or from experimentally infected cats. Treatment of eggs with Sodium hypochlorite (NaOCl) at 5.25% for 2 min prior to inoculation, produced a notable increment of the larval yield in the infections.

Fue realizado un estudio para determinar las variaciones en la infectividad de huevos de Lagochilascaris minor Leiper, 1909, cuando son incubados en medios líquidos con o sin substancias preservadoras, usándose como modelo experimental al ratón blanco. El agregado de Bicromato de Potasio (K2Cr2O7) al 1% en el medio de incubación, restringe la eclosión de los huevos del parásito, mientras que el uso de Formalina al 1% produce un mayor rendimiento. La incubación de huevo del parásito en agua destilada usando recipientes tipo Roux o modelo Falcón, se mostró con un buen rendimiento, aún cuando estas experiencias se realizaron c|n heces humanas, o de gatos experimentalmente infectados. El uso de Hipoclorito de Sodio (NaOCl) al 5,25% por 2 minutos, antes de la inoculación en los ratones albinos, produjo un notable incremento del rendimiento en las infecciones.

Reports of natural infections of sylvatic carnivores by adult worms of species similar to Lagochilascaris minor in the Neotropical region led to attempts to estabilish experimental cycles in laboratory mice and in cats. Also, larval development was seen in the skeletal muscle of an agouti (Dasyprocta leporina) infected per os with incubated eggs of the parasite obtained from a human case. In cats, adult worms develop and fertile eggs are expelled in the feces: in mice, larval stages of the parasite develop, and are encapsulate in the skeletal muscle, and in the adipose and subcutaneous connective tissue. From our observations, we conclude that the larva infective for the mouse is the early 3rd stage, while for the final host the infective form is the later 3rd stage. A single moult was seen in the mouse, giving rise to a small population of 4th stage larvae, long after the initial infection.

Physical exam and skin biopsy were performed and peripheral blood samples drawn from 10% of the inhabitants of 26 jungle villages of the State of Bolívar, Venezuela. One hundred and fifty three Indians and an inhabitant of mixed blood from 13 different communities were found to be infected with mansonelliasis representing a global index of 36.40% in the endemic area. The parasitosis was found to be concentrated in three areas. The largest, located in the southwest of the country and forming part of an extent infected area embarking neighboring parts of Venezuela and Brazil, contains villages with a parasite index of 80.76% and 94.44%. A second focus is located in the southeast, its carriers, as those of the first, are infected with Mansonella ozzardi. In a third, central eastern focus infections with Mansonella pertans were found. The patients infected with M. ozzardi were apparently asintomatic and their physical exam was normal, even though individual parasite densities up to 30,000 microfilariae/ml blood and 22,000/gr skin were found.

En 26 asentamientos selváticos del Estado Bolívar, Venezuela, fueron muestreados el 10% o más de sus residentes mediante examen físico, biopsias de piel y toma de sangre periférica. En 13 de las comunidades se detectaron 153 indígenas y un mestizo infectados con Mansonelosis, representando un índice global de 36,40% para el área endémica. La parasitosis se concentró en tres focos: El mayor situado en la región Suroccidental y formando parte de una extensa superficie infectada, que abarca territorios vecinos de Venezuela y Brasil; con aldeas de índices parasitarios colectivos de 80,76% y 94,44%. Un segundo foco está situado en la región Suroriental y los portadores, al igual que en el anterior, están infectados con Mansonela ozzardi. El tercer foco Centro-oriental presentó infecciones por M. pertans. No fue posible concretar un cuadro nosológico en los infectados por M.ozzardi, a pesar de haberse detectado densidades parasitarias individuales de 30.000 microfilarias por ml de sangre y de 22.000 por gr de piel.