Viability of preserved Cryptosporidium baileyi oocysts

The present study was undertaken to determine the viability and infectivity of oocysts of Cryptosporidium baileyi that had been stored from 1 to 40 months at 4 degrees C preserved in 2.5% potassium dichromate solution. Oocysts of C. baileyi were purified from the feces of experimentally infected chickens using discontinuous sucrose gradients. Subsequently, the purified oocysts were suspended in 2.5% potassium dichromate solution at a concentration of 1 x 10 (7) organism/ml, and their viabilities were assessed by nucleic acid staining, histologic examination, and infectivity to 2-day-old chickens. All chickens inoculated with oocysts that had been stored for 1-18 months developed patent infections, while chickens infected with older oocysts remained uninfected. Between 5.8% and 82.2% of the oocysts, stored at 4 degrees C in 2.5% potassium dichromate solution, were found to be viable, as determined by nucleic acid staining. Parasite colonization in the bursa of Fabricius was detected in the microvillus border of bursal epithelium. The finding that C. baileyi oocysts remain infective to chickens for at least 18 months offers important time-saving advantages to investigators who frequently require large numbers of oocysts.

Avaliaçäo da influência do formol e do hipoclorito de sódio na pesquisa de oocistos de Cryptosporidium nas fezes, através do método de heine / The evaluation of the effect of formol and sodium hypochlorite on the demonstration of Cryptosporidium oocysts in feces by Heine's method

Cryptosporidium oocysts were searched by Heine's method in stools of nine calves with cryptosporidiosis after stool treatment with two disinfectants, 10 per cent paraformaldehyde solution and 14.5 per cent sodium hypochlorite solution. After 30 minutes exposition to sodium hypochlorite solution oocysts became non refractile and acquired a reddish tinge, making their identification difficult. No morphological alterations occurred in oocysts after paraformaldehyde treatment. We recommend paraformaldehyde at 10 per cent concentration as means of human immunodeficiency virus (HIV) inactivation for routine use in stool examinations and therefore making safer those type of procedures for laboratory personnel, when using Heine's method

Efecto de los corticosteroides sobre una infección experimental con Cryptosporidium / Corticosteroids effect on Crystosporidium experimental infection

Ratones blancos de la cepa NGP (20-30 g de peso) fueron inoculados vía oral con 10 elevado a 1, 10 elevado a 3 y 10 elevado a 5, ooquistes de Cryptosporidium sp. aislado de un caso humano. Algunos de ellos fueron tratados semanalmente con 5 ó 10 mg de acetato de cortisona, durante 1 mes. Infecciones muy altas con el parásito fueron obtenidas en los animales tratados con el inmunosupresor, los cuales también mostraron una patología clara, no sólo a través de la apariencia general sino por los parámetros de supervivencia y curva de peso corporal. Se establece un modelo de estudio de la criptosporidiosis usando ratones NGP adultos, acetato de cortisona como inmunosupresor y un inóculo tan bajo como 10 elevado a 3, ooquistes lo que facilita cualquier investigación. Se discuten estos hallazgos, a la luz del uso de los corticosteroides en el tratamiento de las enfermedades infecciosas del hombre