Reduction of risk of watery diarrhea with point-of-use water filters during a massive outbreak of waterborne Cryptosporidium infection in Milwaukee, Wisconsin, 1993.

The occurrence of a massive waterborne outbreak of Cryptosporidium infection in Milwaukee, Wisconsin provided an opportunity to evaluate the effectiveness of point-of-use home water filters in preventing diarrheal illness associated with Cryptosporidium infection. Of 155 filter owners who responded to a televised request to contact the City of Milwaukee Health Department, 99 (64%) completed a self-administered questionnaire regarding their sources of drinking water, the characteristics of their home water filters, and diarrheal illness during the outbreak. Diarrhea among respondents was independently associated with residence in southern or central Milwaukee (the area served by the implicated South water treatment plant), having a home water filter with a pore diameter of greater than 1 micron, and drinking unfiltered tap water in a public building in southern Milwaukee. Among residents of southern and central Milwaukee, two (18%) of 11 persons who drank only submicron-filtered water at home and who did not drink unfiltered South plant water at work had watery diarrhea, compared with 50% (n = 2), 63% (n = 35), and 80% (n = 15) who reported drinking South plant water that was unfiltered or passed through a filter with a pore diameter > 1 micron at work only, home only, or both home and work, respectively (P = 0.02). The data indicate that use of submicron point-of-use water filters may reduce risk of waterborne cryptosporidiosis.

Regulation of proline and glucose transport in mouse intestine by dietary substrate levels.

Active uptake of D-glucose and L-proline at 50 mM was measured in everted intestinal sleeves of mice whose dietary carbohydrate and protein levels were being varied experimentally. Compared to a nearly carbohydrate-free meat diet, a 50% carbohydrate laboratory chow diet stimulated active glucose uptake in the proximal intestine without affecting proline uptake, passive glucose permeability, or several measures of mucosal mass. Switching from a low-protein high-carbohydrate to a high-protein no-carbohydrate diet reversibly stimulated proline uptake while inhibiting glucose uptake. For each solute and diet switch, the stimulation of transport was complete within 1 day, while the inhibition required several days. The results imply induction and repression of intestinal glucose and proline transport by dietary substrate levels. This mechanism, in conjunction with the normal gradient of nutrient concentrations along the intestine, is probably largely responsible for the gradient in nutrient transport along the intestine.