Comparing serologic response against enteric pathogens with reported diarrhea to assess the impact of improved household drinking water quality.

We evaluated enteric infection serology as an alternative outcome measure to diarrhea prevalence in a randomized controlled trial of household-based drinking water treatment; 492 households were randomly assigned to 5 household-based water treatment interventions or control. Individuals were followed weekly over 52 weeks to measure diarrhea prevalence. Study subjects of age

Rapid diagnosis of typhoid fever by enzyme-linked immunosorbent assay detection of Salmonella serotype typhi antigens in urine.

We developed and evaluated an enzyme-linked immunosorbent assay (ELISA) using monoclonal antibodies to capture somatic antigen 9 (O9), flagellar antigen d (Hd), and the Vi capsular polysaccharide antigen (Vi) from the urine of persons with and without typhoid fever. Sequential urine samples were collected from 44 patients with blood culture-confirmed typhoid fever and from two control groups. The first control group included patients with brucellosis (n = 12) and those with clinically diagnosed, non-typhoid, acute, febrile illness (n = 27). The second control group was a sample of healthy volunteer laboratory workers (n = 11). When assessed relative to date of fever onset, sensitivity was highest during the first week for all three antigens: Vi was detected in the urine of nine (100%) patients, O9 in 4 (44%) patients, and Hd in 4 (44%) patients. Sequential testing of two urine samples from the same patient improved test sensitivity. Combined testing for Vi with O9 and Hd produced a trend towards increased sensitivity without compromising specificity. The specificity for Vi exceeded 90% when assessed among both febrile and healthy control subjects, but was only 25% when assessed among patients with brucellosis. Detection of urinary Vi antigen with this ELISA shows promise for the diagnosis of typhoid fever, particularly when used within the first week after fever onset. However, positive reactions for Vi antigen in patients with brucellosis must be understood before urinary Vi antigen detection can be developed further as a useful rapid diagnostic test.

Diarrhea incidence and farm-related risk factors for Escherichia coli O157:H7 and Campylobacter jejuni antibodies among rural children.

Serum samples were obtained from 215 farm-resident children and 396 non-farm-resident children living in a defined rural Wisconsin population. Antibodies to Campylobacter jejuni and Escherichia coli O157:H7 lipopolysaccharide (O157 LPS) immunoglobulin G were measured, and the incidence of clinic visits for diarrheal illness was determined. Risk factors were assessed in a telephone interview. There were 363 children (59%) with C. jejuni antibodies (seropositive for >or=2 immunoglobulin classes) and 86 (14%) with O157 LPS antibodies. Increasing age and farm residence were independently associated with C. jejuni seropositivity by multivariate analysis. O157 LPS antibodies were independently associated with increasing age, female sex, manure contact, and sheep contact. The incidence of clinically recognized diarrhea was similar among children with and without antibodies to C. jejuni and O157 LPS, but the clinic visit rate for diarrhea was 46% lower among farm-resident children. These results are consistent with reduced occurrence of clinical illness from repeated antigenic stimulation in a farm environment.

Listeriolysin O-Based Latex Agglutination Test for the Rapid Detection of Listeria monocytogenes in Foods.

A latex agglutination-based test for the rapid detection of Listeria monocytogenes in foods was developed. An antilisteriolysin O (LLO) monoclonal antibody (HID5E12D7; IgG2b) covalently bound to polystyrene amidine-modified latex beads was used in a slide agglutination assay. The latex reagent detected 0.1 ng/ml of LLO in phosphate-buffered saline plus bovine serum albumin. It reacted with culture supernatants of L. monocytogenes but not with other Listeria species or Streptococcus groups A through G. The listeriolysin O latex agglutination assay (LLOLAT) was applied to 24-h and 48-h USDA primary enrichment cultures of 208 food samples obtained from refrigerators of listeriosis patients enrolled in a study to determine the role of foods in sporadic listeriosis. Of 19 samples positive by cultural techniques, 17 were positive by the LLOLAT. Cultures with low (<0.3 CFU/g) levels of L. monocytogenes were positive in the LLOLAT. No cross-reactivity occurred when using a heterogeneous monoclonal antibody. The LLOLAT is a sensitive, specific and rapid test and may be useful for screening foods for L. monocytogenes .