For this study, we isolated Helicobacter pylori from wastewater by a series of steps beginning with immunomagnetic separation and cell culture. After Gram staining and three standard microbial tests, the 16S rRNA sequences of a total of 23 out of 37 putative H. pylori isolates were verified by PCR. Eleven H. pylori isolates were genotyped and fell into four vacA classes: those with the vacA allelic variants s1a and m1, s1b and m1, s2 and m2, or s2 and m1. Most H. pylori isolates were of the vacA s1a/m1 type, which has been shown to be associated with advanced diseases based on genotyping of H. pylori from gastric cancer patients. These results demonstrated that H. pylori survives in water and may be a potential source of H. pylori transmission, especially where water is not adequately treated.

The dry-composting toilet, which uses neither water nor sewage infrastructure, is a practical solution in areas with inadequate sewage disposal and where water is limited. These systems are becoming increasingly popular and are promoted to sanitize human excreta and to recycle them into fertilizer for nonedible plants, yet there are few data on the safety of this technology. This study analyzed fecal coliform reduction in approximately 90 prefabricated, dry-composting toilets (Sistema Integral de Reciclamiento de Desechos Orgánicos [SIRDOs]) that were installed on the U.S.-Mexico border in Ciudad Juárez, Chihuahua, Mexico. The purpose of this study was to determine fecal coliform reduction over time and the most probable method of this reduction. Biosolid waste samples were collected and analyzed at approximately 3 and 6 months and were classified based on U.S. Environmental Protection Agency standards. Results showed that class A compost (high grade) was present in only 35.8% of SIRDOs after 6 months. The primary mechanism for fecal coliform reduction was found to be desiccation rather than biodegradation. There was a significant correlation (P ‫؍‬ 0.008) between classification rating and percent moisture categories of the biosolid samples: drier samples had a greater proportion of class A samples. Solar exposure was critical for maximal class A biosolid end products (P ‫؍‬ 0.001). This study only addressed fecal coliforms as an indicator organism, and further research is necessary to determine the safety of composting toilets with respect to other pathogenic microorganisms, some of which are more resistant to desiccation.

Abstract. This study identified differences in the epidemiology of Giardia and Cryptosporidium infection for lowincome populations residing on the United States-Mexico border. Participation included 77 households in three communities lacking adequate municipal water and sewage services. The household was the unit of analysis and sampling was from household biosolid waste from newly installed composting toilets. The proportion of households positive for Giardia and Cryptosporidium was high, 82% and 70%, respectively, and this was in contrast to the few households (14%) reporting at least one individual with diarrhea symptoms. This finding indicated that most of the participant families were chronically infected but asymptomatic. In the multivariate analysis, there was a statistically significant protective effect for Cryptosporidium in those households that purified drinking water but not for Giardia. Those households with children less than five years of age were 1.3 times at risk for Giardia infection. Our findings highlighted differences in the transmission mode of these two pathogens and underscore the need for interventions addressing hygiene, water supply, and sanitation.