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PubMed2005

Automated methods for multiplexed pathogen detection.

Detection of pathogenic microorganisms in environmental samples is a difficult process. Concentration of the organisms of interest also co-concentrates inhibitors of many end-point detection methods, notably, nucleic acid methods. In addition, sensitive, highly multiplexed pathogen detection continues to be problematic. The primary function of the BEADS (Biodetection Enabling Analyte Delivery System) platform is the automated concentration and purification of target analytes from interfering substances, often present in these samples, via a renewable surface column. In one version of BEADS, automated immunomagnetic separation (IMS) is used to separate cells from their samples. Captured cells are transferred to a flow-through thermal cycler where PCR, using labeled primers, is performed. PCR products are then detected by hybridization to a DNA suspension array. In another version of BEADS, cell lysis is performed, and community RNA is purified and directly labeled. Multiplexed detection is accomplished by direct hybridization of the RNA to a planar microarray. The integrated IMS/PCR version of BEADS can successfully purify and amplify 10 E. coli O157:H7 cells from river water samples. Multiplexed PCR assays for the simultaneous detection of E. coli O157:H7, Salmonella, and Shigella on bead suspension arrays was demonstrated for the detection of as few as 100 cells for each organism. Results for the RNA version of BEADS are also showing promising results. Automation yields highly purified RNA, suitable for multiplexed detection on microarrays, with microarray detection specificity equivalent to PCR. Both versions of the BEADS platform show great promise for automated pathogen detection from environmental samples. Highly multiplexed pathogen detection using PCR continues to be problematic, but may be required for trace detection in large volume samples. The RNA approach solves the issues of highly multiplexed PCR and provides "live vs. dead" capabilities. However, sensitivity of the method will need to be improved for RNA analysis to replace PCR.

Automation↗

PubMed1999

Bacterial function and community structure in reactors treating biopolymers and surfactants at mesophilic and thermophilic temperatures.

Microbial communities capable of degrading biopolymers and surfactants typically found in graywater were selected in continuous-flow bioreactors operated at 30, 44, 53, or 62 degrees C. The effect of temperature upon microbial activity and community composition was determined. Microbial respiration of the organic components of the medium (including linear alkylbenzene sulfonate) was detected in samples from each reactor. The microbial community in each reactor was adapted to the operating temperature. Nucleic acid-based analyses of community composition showed that distinct consortia were present at each temperature. Community complexity was inversely related to temperature. The specific maintenance rate was twofold higher at 62 degrees C than at the lower temperatures. Under starvation conditions, microbes in the 62 degrees C system lost membrane integrity 30- to 100-fold faster than microbes at lower temperatures.

Journal Article↗

PubMed2006

Diversity of basidiomycetes in michigan agricultural soils.

We analyzed the communities of soil basidiomycetes in agroecosystems that differ in tillage history at the Kellogg Biological Station Long-Term Ecological Research site near Battle Creek, Michigan. The approach combined soil DNA extraction through a bead-beating method modified to increase recovery of fungal DNA, PCR amplification with basidiomycete-specific primers, cloning and restriction fragment length polymorphism screening of mixed PCR products, and sequencing of unique clones. Much greater diversity was detected than was anticipated in this habitat on the basis of culture-based methods or surveys of fruiting bodies. With "species" defined as organisms yielding PCR products with > or =99% identity in the 5' 650 bases of the nuclear large-subunit ribosomal DNA, 241 "species" were detected among 409 unique basidiomycete sequences recovered. Almost all major clades of basidiomycetes from basidiomycetous yeasts and other heterobasidiomycetes through polypores and euagarics (gilled mushrooms and relatives) were represented, with a majority from the latter clade. Only 24 of 241 "species" had 99% or greater sequence similarity to named reference sequences in GenBank, and several clades with multiple "species" could not be identified at the genus level by phylogenetic comparisons with named sequences. The total estimated "species" richness for this 11.2-ha site was 367 "species" of basidiomycetes. Since >99% of the study area has not been sampled, the accuracy of our diversity estimate is uncertain. Replication in time and space is required to detect additional diversity and the underlying community structure.

Agriculture↗

PubMedDate not supplied

Re-emergence of Chlamydia trachomatis infection after mass antibiotic treatment of a trachoma-endemic Gambian community: a longitudinal study.

BACKGROUND: Community-wide mass antibiotic treatment is a central component of trachoma control. The optimum frequency and duration of treatment are unknown. We measured the effect of mass treatment on the conjunctival burden of Chlamydia trachomatis in a Gambian community with low to medium trachoma prevalence and investigated the rate, route, and determinants of re-emergent infection. METHODS: 14 trachoma-endemic villages in rural Gambia were examined and conjunctival swabs obtained at baseline, 2, 6, 12, and 17 months. Mass antibiotic treatment with azithromycin was given to the community at baseline. C trachomatis was detected by qualitative PCR and individual infection load then estimated by real-time quantitative PCR. FINDINGS: C trachomatis was detected in 95 (7%) of 1319 individuals at baseline. Treatment coverage was 83% of the population (1328 of 1595 people). The effect of mass treatment was heterogeneous. In 12 villages all baseline infections (34 [3%] of 1062 individuals) resolved, and prevalence (three [0.3%]) and infection load remained low throughout the study. Two villages (baseline infection: 61 [24%] of 257 individuals) had increased infection 2 months after treatment (74 [30%]), after extensive contact with other untreated communities. Subsequently, this value reduced to less than half of that before treatment (25 [11%]). INTERPRETATION: Mass antibiotic treatment generally results in effective, longlasting control of C trachomatis in this environment. For low prevalence regions, one treatment episode might be sufficient. Infection can be reintroduced through contact with untreated populations. Communities need to be monitored for treatment failure and control measures implemented over wide geographical areas.

Administration, Oral↗

PubMedDate not supplied

Facilitators and barriers to continuing healthcare after jail: a community-integrated program.

A cooperative, community-oriented "public health model of correctional healthcare" was developed to address the needs of persons temporarily displaced into jail from the community, and to improve the health and safety of the community. It emphasizes 5 key elements: early detection, effective treatment, education, prevention, and continuity of care. In the program, physicians and case managers are "dually based"-they work both at the jail and at community healthcare centers. This, together with discharge planning, promotes continuity of care for inmates with serious and chronic medical conditions. This report characterizes the health status and healthcare in this group, and identifies facilitators and barriers to engagement in primary medical and mental health care after release from jail.

Ambulatory Care↗

PubMed2001

Autoantibodies to the 27 C-terminal amino acids of calpastatin are detected in a restricted set of connective tissue diseases and may be useful for diagnosis of rheumatoid arthritis in community cases of very early arthritis.

BACKGROUND: Calpastatin is the natural inhibitor of calpains, a protease that is overexpressed in rheumatoid synovial tissue and plays a key role in cartilage destruction. Autoantibodies to calpastatin (ACAST) were recently detected in rheumatoid arthritis (RA). Our aim was to determine their prevalence and their clinical significance. METHODS: ACAST were detected in a solid-phase enzyme-linked immunosorbent assay (ELISA) using a synthetic peptide corresponding to the 27 C-terminal amino acids of calpastatin (CAST-C27) as the antigen. All sera reacting with this peptide also bound to purified erythrocyte calpastatin in an ELISA and/or an immunoblot assay. The frequencies and clinical significance of ACAST-C27 were assessed in sera from a well-documented population of 102 community-recruited patients (76 females; mean age 50 yr) with RA that had been evolving for <5 yr (median 2 yr) (group 1), 109 healthy blood donors, 289 patients with non-RA rheumatic disease and 88 community cases of very early (median 4 months) arthritis, i.e. 58 RA and 30 non-RA patients (group 2). RESULTS: The sensitivity of ACAST-C27 for RA was 19.5% (20/102) in group 1 and 10.3% (6/58) in group 2. These antibodies were also found in patients with anti-double-stranded DNA-positive systemic lupus erythematosus (SLE) (15.5%) and patients with anti-Ro-positive Sjögren's syndrome (18.5%). However, they were not detected in cases of rheumatism resembling early RA, i.e. peripheral spondylarthropathies. ACAST-C27 were not detected in the 30 non-RA patients of group 2. They were predominantly of immunoglobulin isotype G3 and exclusively expressed lambda chains. Among ACAST-C27-positive sera, eight out of 20 (group 1) and four out of six (group 2) were negative for rheumatoid factor and anti-keratin antibodies/antiperinuclear factor. No relationship was found between ACAST-C27 and clinical, biological or radiological findings. CONCLUSION: ACAST-C27 are detected only in a restricted set of connective tissue diseases and therefore appear to be specific for RA when antibodies that are usually associated with SLE or primary Sjögren's syndrome are negative. Because of their presence in community cases of very early RA, particularly in some seronegative forms, ACAST-C27 may be useful in discriminating recent-onset RA from the more common non-RA rheumatic diseases, such as spondylarthropathies.

Adult↗

PubMed1997

Analysis of actinomycete communities by specific amplification of genes encoding 16S rRNA and gel-electrophoretic separation in denaturing gradients.

A group-specific primer, F243 (positions 226 to 243, Escherichia coli numbering), was developed by comparison of sequences of genes encoding 16S rRNA (16S rDNA) for the detection of actinomycetes in the environment with PCR and temperature or denaturing gradient gel electrophoresis (TGGE or DGGE, respectively). The specificity of the forward primer in combination with different reverse ones was tested with genomic DNA from a variety of bacterial strains. Most actinomycetes investigated could be separated by TGGE and DGGE, with both techniques giving similar results. Two strategies were employed to study natural microbial communities. First, we used the selective amplification of actinomycete sequences (E. coli positions 226 to 528) for direct analysis of the products in denaturing gradients. Second, a nested PCR providing actinomycete-specific fragments (E. coli positions 226 to 1401) was used which served as template for a PCR when conserved primers were used. The products (E. coli positions 968 to 1401) of this indirect approach were then separated by use of gradient gels. Both approaches allowed detection of actinomycete communities in soil. The second strategy allowed the estimation of the relative abundance of actinomycetes within the bacterial community. Mixtures of PCR-derived 16S rDNA fragments were used as model communities consisting of five actinomycetes and five other bacterial species. Actinomycete products were obtained over a 100-fold dilution range of the actinomycete DNA in the model community by specific PCR; detection of the diluted actinomycete DNA was not possible when conserved primers were used. The methods tested for detection were applied to monitor actinomycete community changes in potato rhizosphere and to investigate actinomycete diversity in different soils.

Actinomycetales↗

PubMed1998

Results of intermediate measures from a population-based, randomized trial of mammographic screening prevalence and detection of breast carcinoma among Asian women: the Singapore Breast Screening Project.

BACKGROUND: Although increasing rates of breast carcinoma incidence have been observed in Asian countries, appropriate strategies for detecting early stage breast carcinoma in such communities have been difficult to formulate, particularly because no large population screening trial specifically involving Asian women has been reported. The objective of this study was to evaluate the effectiveness and quality of mammography as a screening technique for Singaporean women, who are predominantly Chinese. METHODS: In this prospective study, 166,600 women in Singapore ages 50-64 years were randomized to either 2-view mammography without physical examination (67,656) or observation (97,294, controls) over 2 years. RESULTS: Of these women, 28,231 (41.7%) responded and were screened; they were more likely to be married, have more formal education, be working, be Chinese, and be in a higher socioeconomic group (P < 0.001 for all variables). To assess for response bias that could affect outcome, results were also evaluated for nonrespondents (n = 39,425). The incidence rate of cancers among nonrespondents (1 per 1000 woman-years) was less than the 1.3 in women not invited to have screening (P = 0.03, relative risk [RR], 1.3; 95% confidence interval [CI], 1.0-1.7). However, cancers arising from nonrespondents did not differ significantly in stage distribution when compared with cancers within the control group. For every 1000 women screened, 4.8 cancers were detected. The prevalence ratio (the number of cancers detected per 1000 women at first screening divided by the corresponding incidence rate in controls per year) was 3.6 for screened women and 2.4 for women invited to have screening. The majority of cancers detected through screening were early stage, with 64% as either ductal carcinoma in situ (26%) or Stage I disease (38%) and was significantly more than the corresponding 26% in women not invited to have screening (P < 0.001). When only invasive cancers were considered, screened women still had more early cancers, with 65% having no lymph node involvement, compared with 47% in the group not invited to have screening (P = 0.001; RR, 1.4; 95% CI, 1.2-1.7). Women who were screened had half the risk of having Stage II or later cancers (P < 0.0001; RR, 0.5; 95% CI, 0.4-0.7) when compared with women not invited to have screening. This higher detection rate of early cancers through screening was accomplished with acceptable recall rates of 8% for further mammographic films or physical examination and a biopsy rate of 1.0% (10 per 1000 women screened). The interval cancer rate was 2.1 per 10,000 women screened in the first year of follow-up. CONCLUSIONS: These positive results of intermediate measures suggest that, in Asian communities, screening mammography could be an important modality for detecting early stage breast carcinoma. However, the low compliance rates suggest that health education efforts must focus on issues related to acceptability if such programs are to succeed.

Aged↗

PubMed2003

Demonstration of declining community prevalence of Chlamydia trachomatis infection using sentinel surveillance.

BACKGROUND: Chlamydia trachomatis infection rates in Alabama increased dramatically from 1996 to 1998, due in part to expanded screening. Detection of prevalent infection through increased testing could mask timely detection of the impact of screening programs on community prevalence. GOAL: The goal of the study was to evaluate the temporal trend in prevalence among women aged 15 to 34 years attending reproductive healthcare clinics in Birmingham, Alabama. STUDY DESIGN: Between 1995 and 1998, systematic screening of the first 60 women presenting each month to each of six participating clinics was performed with urine-based testing for chlamydia. RESULTS: In contrast to the 218% increase in chlamydia prevalence detected through passive surveillance, during the study period surveillance in sentinel sites revealed that first-visit chlamydia prevalence declined from 12.8% to 8.6%. CONCLUSIONS: Sentinel site surveillance served as a valuable adjunct to passive surveillance for determining the true trend of chlamydia prevalence during the hyperendemic phase of a local epidemic.

Adolescent↗

PubMed1997

Detection of BK polyomavirus genotypes in healthy and HIV-positive children.

Urine samples from 211 community children (3-7 years age), from 33 HIV type-1 infected children and from 56 HIV-negative children were collected and analyzed for the presence of BK virus (BKV) DNA by PCR. PCR amplifications were carried out using primers specific for the BKV structural region VP1. We also investigated the distribution of BKV subtypes by a restriction fragment polymorphism assay (RFLP). We demonstrated BKV DNA in 3.8% of 211 community children with a higher prevalence of subtype I. In HIV-1 positive children we detected BKV DNA in 2 urine samples (6%) out of 33, both belonging to subtype I. The HIV-negative cluster did not show any positivity to BKV DNA. The results confirm a more frequent primary BKV infection in children of 3-5 years of age and a higher prevalence in hospitalized children affected by HIV-1. The most relevant finding was that among both the community and HIV-1 positive children the subtype I was the most frequently detected.

BK Virus↗

PubMed2002

Development and evaluation of a 16S ribosomal DNA array-based approach for describing complex microbial communities in ready-to-eat vegetable salads packed in a modified atmosphere.

There is a clear need for new approaches in the field of microbial community analyses, since the methods used can be severely biased. We have developed a DNA array-based method that targets 16S ribosomal DNA (rDNA), enabling the direct detection and quantification of microorganisms from complex communities without cultivation. The approach is based on the construction of specific probes from the 16S rDNA sequence data retrieved directly from the communities. The specificity of the assay is obtained through a combination of DNA array hybridization and enzymatic labeling of the constructed probes. Cultivation-dependent assays (enrichment and plating) and cultivation-independent assays (direct fluorescence microscopy and scanning electron microscopy) were used as reference methods in the development and evaluation of the method. The description of microbial communities in ready-to-eat vegetable salads in a modified atmosphere was used as the experimental model. Comparisons were made with respect to the effect of storage at different temperatures for up to 12 days and with respect to the geographic origin of the crisphead lettuce (Spanish or Norwegian), the main salad component. The conclusion drawn from the method comparison was that the DNA array-based method gave an accurate description of the microbial communities. Pseudomonas spp. dominated both of the salad batches, containing either Norwegian or Spanish lettuce, before storage and after storage at 4 degrees C. The Pseudomonas population also dominated the batch containing Norwegian lettuce after storage at 10 degrees C. On the contrary, Enterobacteriaceae and lactic acid bacteria dominated the microbial community of the batch containing Spanish lettuce after storage at 10 degrees C. In that batch, the Enterobacteriaceae also were abundant after storage at 4 degrees C as well as before storage. The practical implications of these results are that microbial communities in ready-to-eat vegetable salads can be diverse and that microbial composition is dependent both on the origin of the raw material and on the storage conditions.

Bacteria↗

PubMed2002

Prevalence of hyperesthesia detected by current perception threshold test in subjects with glucose metabolic impairments in a community.

OBJECTIVE: Recent studies reported that hyperesthesia may be an indicator of early diabetic polyneuropathy. Using the current perception threshold (CPT) test, which stimulates peripheral sensory nerve fibers by three different frequencies (2,000, 250, and 5 Hz), we investigated the relationship between hyperesthesia and glucose metabolic impairment in a community. METHODS: The number of subjects, aged 40 to 79 years, was 2,074. The CPT values at each frequency were classified into three categories (hyperesthesia, normal, and hypoesthesia). Subjects were also subgrouped into three groups (normal, insulin resistance, and diabetes) according to glucose metabolic status, and those with hypoesthesia at each frequency were excluded in the analyses. RESULTS: The prevalence of hyperesthesia at 2,000, 250, and 5 Hz in male diabetic subjects were 14.1, 15.6, and 7.7%, respectively, and 22.2, 24.5, and 16.4% respectively in female diabetic subjects. In logistic regression analysis adjusted for age, females with diabetes showed a significantly high odds ratio (OR) for hyperesthesia at 2,000 Hz (OR, 2.42; 95% confidence interval (95%CI), 1.18 to 4.97) and 250 Hz (OR, 2.65; 95%CI, 1.31 to 5.37). In male diabetic subjects, a significantly high odds ratio for hyperesthesia was seen at 250 Hz (OR, 2.09; 95%CI, 1.07 to 4.05). CONCLUSION: Our results suggested that hyperesthesia may emerge coupled with developing diabetes, supporting the precedent hypothesis.

Adult↗

PubMed1995

The Wisconsin Diabetes Control Program: a health systems and community-based approach.

The Wisconsin Diabetes Control Program will address the health needs of people with diabetes by working closely with the Wisconsin Affiliate of the American Diabetes Association and other diabetes health professionals in the state. The 5-year program will use both health systems and community-based approaches to coordinate prevention, detection, and control activities required to reduce the burden of this chronic condition. This program represents a major shift in focus from previous diabetes control programs supported by the CDC, and is designed to establish the program as a key component of an evolving health care environment.

Community Health Services↗

PubMed2006

Detection of new methicillin-resistant Staphylococcus aureus clones containing the toxic shock syndrome toxin 1 gene responsible for hospital- and community-acquired infections in France.

Methicillin-resistant Staphylococcus aureus (MRSA) clones harboring the toxic shock syndrome toxin 1 (tst) gene have been detected in France and in Switzerland since 2002. During a passive survey conducted between 2002 and 2003, we collected 103 tst-positive S. aureus isolates from 42 towns in France, of which 27 were resistant to methicillin. The tst-positive MRSA belonged to two clones: a major clone comprising 25 isolates of sequence type (ST) 5 and agr group 2 and a minor clone comprising two isolates of ST30 and agr3. The tst-positive MRSA clones were associated with both hospital-acquired (12 cases) and community-acquired (8 cases) infections. The MRSA clones were mainly isolated from children (overall median age, 3 years). They caused a variety of clinical syndromes, including toxic shock syndrome and suppurative infections. Both clones were found to harbor a type IV staphylococcal chromosomal cassette mec (SCCmec) and to have similar antibiotic resistance profiles (usually resistant to oxacillin, kanamycin, and tobramycin and with intermediate resistance to fusidic acid). The origin of these clones is unclear. The tst-positive agr2 MRSA clone has the same sequence type (ST5) of two pandemic nosocomial MRSA clones, namely, the Pediatric clone and the New York/Japan clone. These findings suggest that all these clones are phylogenetically related. The pulsotype of the tst-positive MRSA clones differed from that of methicillin-sensitive S. aureus (MSSA) clones by a single band involving the SCCmec element. These findings suggest that the tst-positive MRSA clones may have emerged from their respective MSSA counterparts.

Adolescent↗

PubMed2002

Extended-spectrum beta-lactamase-producing Enterobacteriaceae strains in community-acquired bacteremia in Southern Israel.

BACKGROUND: In recent years, extended-spectrum beta-lactamase (ESBL)-producing Enterobacteriaceae have emerged in many hospitals worldwide. The increasing dissemination and long-term carriage of these organisms within the community carry tremendous implications on the empirical therapy of community-acquired infection. MATERIAL/METHODS: To evaluate the prevalence and clinical features of community-acquired bacteremia involving ESBL-producing Enterobacteriaceae in southern Israel (ESBL-P) we retrospectively studied all Enterobacteriaceae bacteremias during an 8-month period in the Negev region using medical and laboratory records. Antibiotic susceptibility was determined using the disk-diffusion method. ESBL production was determined using an E-test ESBL strip. Cases involving ESBL-P were compared to those involving non-producing strains (ESBL-NP) using the chi-square test. RESULTS: In all, 187 Enterobacteriaceae bacteremias were detected, of which 119 were community-acquired (63.6%). ESBL-P were found in six cases (5%) which are described herein in greater detail. Patients with ESBL-P bacteremia were older, and were more likely to stay in the intensive-care unit. Urinary catheterization and bed-ridden conditions were significant risk factors for ESBL-P. ESBL-P strains were significantly resistant to nearly all antibiotic agents except for imipienem and piperacillin-tazobactam as opposing to ESBL-NP. Patients with ESBL-P bacteremia were more likely to suffer from complications and had a higher mortality. CONCLUSIONS: This paper is the first to describe community-acquired Enterobacteriaceae bacteremia involving ESBL-P strains in Israel. Although the exact prevalence of these organisms in Israel is currently unknown, our findings suggest that ESBL-producers have already begun to disseminate in our community.

Adult↗

PubMed2003

Evaluating a campaign to detect early stage breast tumors in the United States.

Growing concern over failure to detect early stage breast cancer has led communities across the United States to participate in the Breast Cancer Awareness Month program. This program mobilizes local public and private institutions, particularly the media, to reach a large audience each October with information on salutary behaviors, including screening, and on resources that can assist newly motivated audiences to adopt the behaviors. Although the scholarly literature includes no assessments of the effect of the program on the actual detection of early stage breast tumors, similar programs targeting other illnesses (e.g., AIDS) are quickly emerging. We attempt such an assessment by applying time-series designs to 92 quarters (beginning January, 1975) of data obtained from cancer registries in the Atlanta and Detroit metropolitan areas as well as in the San Francisco Bay Area. We find that the detection of in situ and local breast tumors increased in all three communities during the quarters that included Breast Cancer Awareness Month. We conclude that community mobilization may have its intended benefit but suggest that community organizers not ignore unintended costs including the emotional and physical sequelae of false positives.

Awareness↗

PubMed1981

Usefulness of the PERI demoralization scale screen for psychiatric disorder in a community sample.

The authors gave the PERI Demoralization Scale (PERI-D), a measure of nonspecific psychological distress, to 528 subjects drawn from a larger longitudinal community survey. Respondents also were interviewed using the Schedule for Affective Disorders and Schizophrenia (SADS), a structured clinical interview. Based on the SADS, subjects were given diagnoses based on Research Diagnostic Criteria (RDC). The results corroborate earlier findings of a modest relationship between self-reported symptoms of distress and the diagnosis of clinical psychiatric disorder. There was somewhat better fit between RDC diagnoses of depression, particularly major depression, and PERI-D symptom scores, suggesting the PERI-D items may be slightly more useful for detecting cases of depression in the community than for the broader range of psychiatric disorders. In general, the authors concur with earlier writers who suggest that brief psychiatric symptom scales may be useful as screening tests in community surveys, but such instruments do not in themselves provide good-estimates of the prevalence of clinical psychiatric disorders in the community.

Affective Symptoms↗

PubMed1999

Epidemic and endemic seroprevalence of antibodies to Cryptosporidium and Giardia in residents of three communities with different drinking water supplies.

This study was carried out to compare cryptosporidiosis and giardiasis seroprevalence rates in residents of three communities. Community (Com 1) uses drinking water from deep wells, community 2 (Com 2) uses surface water from a protected watershed, and community 3 (Com 3) uses surface water frequently containing Cryptosporidium oocysts and Giardia cysts. Unfiltered drinking water from each community was collected at the tap and tested for Cryptosporidium oocysts and Giardia cysts during the 12 months in which sera were collected for testing. No oocysts or cysts were detected in the water from the Com 1 deep wells; oocysts and cysts were detected intermittently in the drinking water from the other two communities. A waterborne outbreak of cryptosporidiosis occurred in a municipality adjacent to Com 3 six months into this 12-month study. Sera from residents of each of the communities were collected proportionately by month and by population size. Coded sera were tested for IgG to Cryptosporidium using a previously developed Western blotting method. The presence or absence of bands at 15-17 kD and/or 27 kD was recorded for the 1,944 sera tested. Definite bands at 15-17 kD and/or 27 kD were detected in 981 (50.5%) of the sera. A total of 33.2% of sera from Com 1 (community using deep wells) were positive using the same criteria compared with 53.5% (Com 2) and 52.5% (Com 3) of sera from the two communities using surface drinking water. Both bands (15-17 kD plus 27 kD) were detected in 582 sera (29.9%) from the three communities: 14.1% of sera from Com 1 compared with 32.7% from Com 2 and 31.5% from Com 3. These findings are consistent with a lower risk of exposure to Cryptosporidium from drinking water obtained from deep well sources. However, analysis of results by calendar quarter showed a significant (P < 0.001) increase in the number of Com 3 positive sera (compared with Com 1) following the waterborne outbreak. Without this outbreak-related observation, a significant overall difference in seropositivity would not have been seen. We also observed that in sera from the community affected by the outbreak, the presence on immunoblots of both Cryptosporidium bands appeared to be the best indicator of recent infection. Seroprevalence rates using an ELISA to detect IgG to Giardia were estimated using the same sera. Overall 30.3% (590 of 1,944) of sera were positive by the ELISA. A total of 19.1% of sera from Com 1, 34.7% from Com 2 and 16.0% from Com 3 were seropositive. Rates for both Com 3 and Com 1 did not change significantly over time. In Com 2, rates decreased significantly (P < 0.001) during the last half of the study period (third and fourth calendar quarters). The reasons for the decrease in seroprevalence in Com 2 sera are presently not known. These studies show intriguing associations between seroprevalence, outbreak-related laboratory serologic data, and patterns of parasite contamination of drinking water. Further studies are required to validate the serologic approach to risk assessment of waterborne parasitic infections at a community level.

Animals↗