Prediction of gastrointestinal disease with over-the-counter diarrheal remedy sales records in the San Francisco Bay Area.

BACKGROUND: Water utilities continue to be interested in implementing syndromic surveillance for the enhanced detection of waterborne disease outbreaks. The authors evaluated the ability of sales of over-the-counter diarrheal remedies available from the National Retail Data Monitor to predict endemic and epidemic gastrointestinal disease in the San Francisco Bay Area. METHODS: Time series models were fit to weekly diarrheal remedy sales and diarrheal illness case counts. Cross-correlations between the pre-whitened residual series were calculated. Diarrheal remedy sales model residuals were regressed on the number of weekly outbreaks and outbreak-associated cases. Diarrheal remedy sales models were used to auto-forecast one week-ahead sales. The sensitivity and specificity of signals, generated by observed diarrheal remedy sales exceeding the upper 95% forecast confidence interval, in predicting weekly outbreaks were calculated. RESULTS: No significant correlations were identified between weekly diarrheal remedy sales and diarrhea illness case counts, outbreak counts, or the number of outbreak-associated cases. Signals generated by forecasting with the diarrheal remedy sales model did not coincide with outbreak weeks more reliably than signals chosen randomly. CONCLUSIONS: This work does not support the implementation of syndromic surveillance for gastrointestinal disease with data available though the National Retail Data Monitor.

Heterogeneous dermatitis complaints after change in drinking water treatment: a case report.

BACKGROUND: The disinfectant monochloramine minimizes the formation of potentially hazardous and regulated byproducts, and many drinking water utilities are shifting to its use. CASE PRESENTATION: After a drinking water utility serving 2.4 million people switched to monochloramine for residual disinfection, a small number of residents complained of dermatitis reactions. We interviewed 17 people about their symptoms. Skin appearance, symptoms, and exposures were heterogeneous. Five respondents had history of hives or rash that preceded the switch to monochloramine. CONCLUSION: The complaints described were heterogeneous, and many of the respondents had underlying or preexisting conditions that would offer plausible alternative explanations for their symptoms. We did not recommend further study of these complaints.

Review of syndromic surveillance: implications for waterborne disease detection.

Syndromic surveillance is the gathering of data for public health purposes before laboratory or clinically confirmed information is available. Interest in syndromic surveillance has increased because of concerns about bioterrorism. In addition to bioterrorism detection, syndromic surveillance may be suited to detecting waterborne disease outbreaks. Theoretical benefits of syndromic surveillance include potential timeliness, increased response capacity, ability to establish baseline disease burdens, and ability to delineate the geographical reach of an outbreak. This review summarises the evidence gathered from retrospective, prospective, and simulation studies to assess the efficacy of syndromic surveillance for waterborne disease detection. There is little evidence that syndromic surveillance mitigates the effects of disease outbreaks through earlier detection and response. Syndromic surveillance should not be implemented at the expense of traditional disease surveillance, and should not be relied upon as a principal outbreak detection tool. The utility of syndromic surveillance is dependent on alarm thresholds that can be evaluated in practice. Syndromic data sources such as over the counter drug sales for detection of waterborne outbreaks should be further evaluated.

Reducing Legionella colonization in water systems with monochloramine.

Monochloramine disinfection of municipal water supplies is associated with decreased risk for Legionnaires' disease. We conducted a 2-year, prospective, environmental study to evaluate whether converting from chlorine to monochloramine for water disinfection would decrease Legionella colonization of hot water systems. Water and biofilm samples from 53 buildings were collected for Legionella culture during 6 intervals. Prevalence ratios (PRs) comparing Legionella colonization before and after monochloramine disinfection were adjusted for water system characteristics. Legionella colonized 60% of the hot water systems before monochloramine versus 4% after conversion (PR 0.07, 95% confidence interval 0.03-0.16). The median number of colonized sites per building decreased with monochloramine disinfection. Increased prevalence of Legionella colonization was associated with water heater temperatures <50 degrees C, buildings taller than 10 stories, and interruptions in water service. Increasing use of monochloramine in water supplies throughout the United States may reduce Legionella transmission and incidence of Legionnaires' disease.

Improving cryptosporidium testing methods: a public health perspective.

Cryptosporidium is a protozoan parasite found in surface waters throughout the United States. Waterborne cryptosporidiosis outbreaks may be associated with contaminated drinking water supplies. The approved method, USEPA (United States Environmental Protection Agency) Method 1623, for testing for the presence of Cryptosporidium in United States surface waters has several limitations. Firstly, recovery efficiency varies widely. Secondly, Method 1623 does not specify a mechanism for assessing the viability and infectivity of oocysts detected, or the Cryptosporidium species of the oocysts. Lastly, there are logistical limitations which are relevant to Method 1623 in particular, and to the state of the science of Cryptosporidium testing in general. Methods that give specific results more quickly, with higher recoveries and better consistency must be developed and made accessible for utilities to use. Improved Cryptosporidium testing methods can minimize uncertainty; this, in turn, will simplify the risk communication task, and the level of trust which the public has in the water utility can be maintained and improved. This paper reviews the current and ongoing research on analytical, monitoring, and sampling methods for Cryptosporidium, and identifies the needs that should be considered in future research.

Association of DDT and DDE with birth weight and length of gestation in the Child Health and Development Studies, 1959-1967.

The pesticide p,p'-dichlorodiphenyltrichloroethane (DDT) and its persistent metabolite p,p'-dichlorodiphenyldichloroethylene (DDE) are associated with negative reproductive outcomes in animals. In humans, however, the findings are inconsistent. Using data from the Child Health and Development Studies, a longitudinal study of 20,754 pregnancies among San Francisco Bay Area women from 1959 to 1967, the authors examined the effects of maternal serum DDT and DDE concentrations on preterm birth, small-for-gestational-age birth, birth weight, and gestational age in 420 male subjects. Data were analyzed using multivariate logistic regression for preterm and small-for-gestational-age birth and linear regression for birth weight and gestational age. Median serum concentrations of DDE were 43 mug/liter (interquartile range: 32-57; range: 7-153) and of DDT were 11 mug/liter (interquartile range: 8-16; range: 3-72), several times higher than current US concentrations. The adjusted odds ratio for preterm birth was 1.28 (95% confidence interval (CI): 0.73, 2.23) for DDE and 0.94 (95% CI: 0.50, 1.78) for DDT. For small-for-gestational-age birth, the adjusted odds ratio was 0.75 (95% CI: 0.44, 1.26) for DDE and 0.69 (95% CI: 0.73, 1.27) for DDT; none of the study results achieved statistical significance. Given the persistence of DDT in the environment and its continuing role in malaria control, studies using more robust data should continue to assess this relation.

Organochlorine pesticides and male genital anomalies in the child health and development studies.

Increasing rates of cryptorchidism and hypospadias in human populations may be caused by exogenous environmental agents. We conducted a case-control study of serum levels of p,p'-dichlorodiphenyltrichloroethane (DDT) and its major metabolite, p,p'-dichlorodiphenyldichloroethylene (DDE), and cryptorchidism and hypospadias in the Child Health and Development Study, a longitudinal cohort of pregnancies that occurred between 1959 and 1967, a period when DDT was produced and used in the United States. Serum was available from the mothers of 75 male children born with cryptorchidism, 66 with hypospadias, and 4 with both conditions. We randomly selected 283 controls from the cohort of women whose male babies were born without either of these conditions. Overall, we observed no statistically significant relationships or trends between outcomes and serum measures. After adjusting for maternal race, triglyceride level, and cholesterol level, compared with boys whose mothers had serum DDE levels < 27.0 ng/mL, boys whose mothers had serum DDE levels > or = 61.0 ng/mL had odds ratios of 1.34 [95% confidence interval (CI), 0.51-3.48] for cryptorchidism and 1.18 (95% CI, 0.46-3.02) for hypospadias. For DDT, compared with boys whose mothers had serum DDT levels < 10.0 ng/mL, boys whose mothers had serum DDT levels > or = 20.0 ng/mL had adjusted odds ratios of 1.01 (95% CI, 0.44-2.28) for cryptorchidism and 0.79 (95% CI, 0.33-1.89) for hypospadias. This study does not support an association of DDT or DDE and hypospadias or cryptorchidism.

Postmenopausal hormone use and lens opacities.

PURPOSE: Women are at higher risk for age-related cataract than men, and it has been hypothesized that this difference is due in part to gender-related hormonal differences. METHODS: We investigated the association between postmenopausal hormone use and lens opacities in a population of 480 postmenopausal women from the Nurses' Health Study for whom we had prospectively collected exposure data. Participants received standardized eye exams; the Lens Opacity Classification System III (LOCS III) was used to measure the degree of opacification. RESULTS: A total of 342 women had some opacity in one or both eyes. Overall, we did not observe a significant association between current hormone use and presence of any type of opacity (compared to never users, multivariate relative risk: 0.85; 95% confidence interval (CI): 0.54-1.34). In ordinal logistic regression compared to never users, current hormone users had multivariate relative risks of cortical opacities of 0.80 (95% CI: 0.54-1.19) and for past users the relative risk was 0.76 (95% CI: 0.48-1.22). For nuclear opacities, the comparable relative risk for current use of hormones was 0.77 (95% CI: 0.52-1.13), and for past use the relative risk was 1.48 (95% CI: 0.92-2.34). Current use of estrogen-only preparations was associated with a 49% decreased risk of nuclear opacities compared to never use (multivariate relative risk 0.51, 95% CI: 0.29-0.89). CONCLUSIONS: While the overall findings are null, they do not exclude the possibility of a protective effect, particularly among current estrogen users.

Smoking cessation and risk of cataract extraction among US women and men.

Although the observational evidence linking cigarette smoking with risk of senile cataract is well-established, it is unclear whether any benefit is obtained from quitting smoking. Therefore, in this study, the authors examined the association between time since quitting smoking and incidence of cataract extraction in women and men enrolled in the Nurses' Health Study and the Health Professionals Follow-up Study, respectively. There were 4,281 incident physician-confirmed cases of cataract and 1,038,493 accumulated person-years of follow-up. Compared with current smokers, former smokers who had quit smoking 25 or more years previously had a 20% lower risk of cataract extraction after adjustment for age, average number of cigarettes smoked per day, and other potential risk factors (relative risk (RR) = 0.80, 95% confidence interval (CI): 0.71, 0.91). However, risk among past smokers did not decrease to the level seen among never smokers (for never smokers, RR = 0.64, 95% CI: 0.52, 0.79). The observed relation was similar when data were examined by cataract subtype (>25 years since quitting vs. current smoking: primarily nuclear cataract, RR = 0.82, 95% CI: 0.68, 0.97; primarily posterior subcapsular cataract, RR = 0.90, 95% CI: 0.71, 1.13). These findings suggest that any healing from damage due to cigarette smoking occurs at a very modest pace, and they emphasize the importance of never starting to smoke or quitting early in life.