We present a case of severe chronic diarrhea requiring parenteral nutritional support to both cover the nutritional needs and allow for intestinal rest for later adaptation to enteral nutrition, altogether allowing for the etiologic diagnosis and disease healing.

INTRODUCTION: Faecal contamination in wastewater and drinking water is linked to the dissemination of water related diseases. The bacteria, virus and parasites present in drinking water are responsible for substantial morbidity and mortality, especially among infants. Giardia spp. and Cryptosporidium spp. were the organisms selected as parasite contamination indicators. Their presence serves as a useful tool for evaluating water quality and determining sanitary risk. At present, in Colombia, concentration and occurrence of these parasites is unknown and an immediate assessment was considered necessary. OBJECTIVE: Protozoan presence was determined in five sampling stations in the Bogotá river upper basin and in two drinking water plants near the same area. MATERIALS AND METHODS: The techniques applied for counting encysted forms consisted of inorganic flocculation for wastewater or filtration for drinking water. Fluorogenic vital dyes tested for viability. RESULTS: The presence of Cryptosporidium spp. was confirmed in two of the sampled stations and at two of the drinking water plants. Giardia spp. was found at two of the drinking water plants but not at the sampled stations. Viable cysts were found for Cryptosporidium spp. in one of the samples from the Bogotá river, but only inviable exemplars were obtained from the drinking water plants. CONCLUSIONS: The results revealed protozoan presence in drinking and residual water implying the presence of a potential sanitary hazard.

In the past few years many waterborne outbreaks related to Cryptosporidium have been described. Current methods for detection of Cryptosporidium in water for the most part rely on viability assays which are not informative concerning the infectivity of oocysts. However, for estimation of the risk of infection with Cryptosporidium this information is required. For environmental samples the oocyst counts are often low, and the oocysts have been exposed to unfavorable conditions. Therefore, determination of the infectivity of environmental oocysts requires an assay with a high level of sensitivity. We evaluated the applicability of in vitro cell culture immunofluorescence assays with HCT-8 and Caco-2 cells for determination of oocyst infectivity in naturally contaminated water samples. Cell culture assays were compared with other viability and infectivity assays. Experiments with Cryptosporidium oocysts from different sources revealed that there was considerable variability in infectivity, which was illustrated by variable 50% infective doses, which ranged from 40 to 614 oocysts, and the results indicated that not only relatively large numbers of fresh oocysts but also aged oocysts produced infection in cell cultures. Fifteen Dutch surface water samples were tested, and the cell culture immunofluorescence assays were not capable of determining the infectivity for the low numbers of naturally occurring Cryptosporidium oocysts present in the samples. A comparison with other viability assays, such as the vital dye exclusion assay, demonstrated that surrogate methods overestimate the number of infectious oocysts and therefore the risk of infection with Cryptosporidium. For accurate risk assessment, further improvement of the method for detection of Cryptosporidium in water is needed.

In a retrospective analysis, we assessed the usefulness of two serologic enzyme-linked immunosorbent assays as epidemiologic tools for the detection of cryptosporidiosis episodes in children from a Peruvian community. The incidence rate determined by the serologic assay was higher than the rate determined by stool microscopy (0.77 versus 0.41 infection/child-year of surveillance).

The occurrence of Cryptosporidium oocysts in feces from a population of wild eastern grey kangaroos inhabiting a protected watershed in Sydney, Australia, was investigated. Over a 2-year period, Cryptosporidium oocysts were detected in 239 of the 3,557 (6.7%) eastern grey kangaroo fecal samples tested by using a combined immunomagnetic separation and flow cytometric technique. The prevalence of Cryptosporidium in this host population was estimated to range from 0.32% to 28.5%, with peaks occurring during the autumn months. Oocyst shedding intensity ranged from below 20 oocysts/g feces to 2.0 x 10(6) oocysts/g feces, and shedding did not appear to be associated with diarrhea. Although morphologically similar to the human-infective Cryptosporidium hominis and the Cryptosporidium parvum "bovine" genotype oocysts, the oocysts isolated from kangaroo feces were identified as the Cryptosporidium "marsupial" genotype I or "marsupial" genotype II. Kangaroos are the predominant large mammal inhabiting Australian watersheds and are potentially a significant source of Cryptosporidium contamination of drinking water reservoirs. However, this host population was predominantly shedding the marsupial-derived genotypes, which to date have been identified only in marsupial host species.

The CP15 and CP23 surface proteins on the sporozoite of Cryptosporidium parvum are major protective antigens. The recombinant plasmid pET28-15-23 was constructed based on the plasmids pMD18-T-15 and pMD18-T-23 with two pairs of specific primers using DNA recombinant technique. In the primers, a synthetic linker sequence encoding a peptide (G-G-S) was designed. After identification, the recombinant plasmids were transformed to component cells of Escherichia coli BL21 (DE3). The positive strain containing the recombinant plasmid could express a specific fusion protein (CP15-23, MW approximately 25 kDa) induced by IPTG. The fusion protein could be recognized by the positive serum of mice infected with Cryptosporidium parvum oocysts specifically. The BALB/c mice were immunized with 80 microg of CP15-23 protein 4 times at 2 week intervals. The mice produced specific antibodies that responded to the lysate of Cryptosporidium parvum oocysts and could prevent Cryptosporidium parvum infection. The results indicated that the recombinant fusion protein CP15-23 would be used as a candidate antigen to prevent cryptosporidiosis.

The present study investigated the prevalence rate of Cryptosporidium parvum as a cause of diarrhea. We examined 942 stools of unidentified reasons occurring in patients in whom no immunosuppression had been detected. We examined the stools for Cryptosporidium parvum via modified acid-fast staining. The clinical records of all of the positive patients were then analyzed. Nine (1%) of the stools among the 942 diarrheal patients were positive for C. parvum. The positive rate in the males was 1.1%(6/522) and the positive rate of the females was 0.7%(3/420). Age distribution revealed that the highest positive rates were in patients in their sixties, with a positive rate of 2.5%(4/158). In the clinical tests, levels of c-reactive protein, erythrocyte sedimentation rates, and neutrophil proportions were normally increased in the peripheral blood, whereas the lymphocyte proportion exhibited a tendency towards decrease. The pathological findings were compatible with an inflammatory reaction in the host.