Assessment of the spatial occurrence of childhood leukaemia mortality using standardized rate ratios with a simple linear Poisson model.

Reports of a suspected cluster of childhood leukaemia cases in West Central Phoenix have led to a number of epidemiological studies in the geographical area. We report here on a death certificate-based mortality study, which indicated an elevated rate ratio of 1.95 during 1966-1986, using the remainder of the Phoenix standard metropolitan statistical area (SMSA) as a comparison region. In the process of analysing the data from this study, a methodology for dealing with denominator variability in a standardized mortality ratio was developed using a simple linear Poisson model. This new approach is seen as being of general use in the analysis of standardized rate ratios (SRR), as well as being particularly appropriate for cluster investigations.

Organic mercury exposure from fungicide-contaminated eggs.

During a period of 50 to 55 days from early January to March 2, 1979, 14 members of an extended family in Yakima, Washington, ate eggs contaminated with organic mercury. Seed grain which had been treated with a mercurial fungicide and fed to chickens in a home flock was the source of exposure. Blood mercury levels in family members ranged from 0.9 to 20.2 ppb and correlated positively with average daily egg consumption (r = 0.92). There were no symptoms or physical signs of organic mercury intoxication. Prompt confiscation of the contaminated grain, eggs, and chicken flock terminated the exposure and may have prevented the development of serious illness.

Anonymous HIV testing: the impact of availability on demand in Arizona.

The purpose of this study was to evaluate the impact of anonymous testing availability on human immunodeficiency virus (HIV) test demand in Arizona. Testing patterns before and after the introduction of anonymous testing were compared. Client knowledge of new test policy and delay in testing until an anonymous option was available were assessed. Test numbers among men who have sex with men showed a statistically significant increase after introduction of an anonymous testing option. Arizona continues to maintain anonymous testing availability. Public health agencies should consider how test policy may influence people's HIV test decisions.

1% permethrin cream rinse vs 1% lindane shampoo in treating pediculosis capitis.

The therapeutic efficacy and tolerance of a single application of 1% permethrin cream rinse, applied for ten minutes, and a single application of 1% lindane shampoo applied, as recommended by the manufacturer, for four minutes, against the head louse Pediculus humanus var capitis were compared in a single-blinded, randomized, controlled clinical trial. Of 573 patients enrolled at eight centers, 559 were assessable for tolerance and 508 for efficacy. Of the 257 patients treated with 1% permethrin cream rinse, 99% were lice free at 14 days; of the 251 patients treated with 1% lindane shampoo, 85% were lice free at 14 days. The difference is statistically significant. For both treatments, adverse experiences were infrequent, mild, and usually difficult to distinguish from the symptoms of head lice infestation. A single ten-minute application of 1% permethrin cream rinse was well tolerated, highly effective, and therapeutically superior to a single four-minute application of 1% lindane shampoo.

Controlled trial of Giardia lamblia: control strategies in day care centers.

BACKGROUND: Strategies for control of Giardia lamblia in day care differ in numbers of children treated and in costs to parents and day care operators. The effectiveness of these strategies has not been systematically evaluated. METHODS: We conducted a prospective randomized controlled trial comparing three strategies for control of Giardia in infant-toddler day care centers: Group 1, exclusion and treatment of symptomatic and asymptomatic infected children; Group 2, exclusion and treatment of symptomatic infection only; Group 3, exclusion and treatment of symptomatic infection, treatment of asymptomatic infection in the center. The study included 31 day care centers with 4180 child-months of observation. Giardia prevalence was determined before intervention and 1, 2, 4, and 6 months later; new infants and toddlers were tested on admission. RESULTS: Initial Giardia prevalences were 18% to 22% in the three groups. Giardia was identified in 10.5% of 676 new infants and toddlers entering study day care centers during the 6-month follow-up. Giardia prevalences by intervention group were 8%, 12%, and 7% at 1 month, and 7%, 8%, and 8% at 6 months. CONCLUSIONS: The stricter intervention resulted in greater cost in terms of child day care and parents' work days lost, but did not result in significantly better control of Giardia infections in this day care environment.

Eradication of head lice with a single treatment.

Single application of Nix (permethrin 1% creme rinse) and Rid were compared as treatments for Pediculosis capitis in 435 patients, the majority of whom were children. Seven days after the treatment, 98 per cent of the permethrin-treated and 85 per cent of the Rid-treated patients were free of lice. At 14 days, prior to nit removal, 96 per cent of the permethrin-treated and 62 per cent of the Rid-treated patients were still lice free. Seventeen (7 per cent) permethrin-treated and 32 (16 per cent) Rid-treated patients were reported to have adverse experiences.

The changing epidemiology of invasive group A streptococcal infections and the emergence of streptococcal toxic shock-like syndrome. A retrospective population-based study.

OBJECTIVE: To determine disease incidence and changes in the epidemiology of invasive group A streptococcal infections in a community in Arizona. DESIGN AND SETTING: We retrospectively surveyed microbiology records from all 10 hospitals in Pima County, Arizona, to identify patients who had Streptococcus pyogenes isolated from blood, sterile body fluid, or tissue biopsy specimens between April 1985 and March 1990. Demographic and clinical information was abstracted from the medical records of these patients. PATIENTS: A total of 128 patients with a median age of 53.5 years (range, 6 months to 96 years). OUTCOME MEASURES: Racial/ethnic differences in disease incidence; mortality and changes in the clinical spectrum of disease over the study period. RESULTS: The annual age-adjusted incidence was 4.3 per 100,000 but was 46.0 per 100,000 among Native Americans. Advanced age, age less than 5 years, hypotension, and multi-organ system involvement were significantly associated with increased mortality. From 1985 to 1990, the proportion of infections with hypotension, rash, desquamation, renal impairment, and gastrointestinal involvement increased significantly (chi 2 for trend P < or = .02 for each feature). A toxic shock-like syndrome occurred in 8% of infections since 1988, compared with none of the infections between 1985 and 1987 (P = .04). Patients with the syndrome were younger than patients with other invasive infections (median age 15 vs 54 years, P = .02), and were less likely to have underlying medical conditions (P = .008). CONCLUSIONS: Significant changes occurred in the spectrum of invasive group A streptococcal infections in Pima County, Arizona, between 1985 and 1990. Native Americans were at increased risk of acquiring these infections. Patients with the streptococcal toxic shock-like syndrome had epidemiologic features that distinguished them from patients with other invasive infections, including younger age and less underlying illness.

Diarrheal illness among infants and toddlers in day care centers: effects of active surveillance and staff training without subsequent monitoring.

From October 1981 to September 1984, the authors conducted a three-year longitudinal study of diarrhea among infants and toddlers attending day care centers in Maricopa County, Arizona. In the third year of study, they evaluated the effects on diarrhea rates of staff training without external monitoring and of active surveillance conducted throughout the study. From 21 study day care centers, they randomly selected 10 ("intervention day care centers") to receive staff training in procedures to reduce transmission of infectious diarrhea. Continuing active surveillance in the 10 intervention and 11 control day care centers found no difference between diarrhea rates in intervention day care centers in the pre- and posttraining years and no difference between diarrhea rates in the two groups of centers either before or after the training intervention. Biweekly family-based surveys during the two months after training also demonstrated no difference between infant-toddler diarrhea rates in intervention and control day care centers. These surveys found the 21 study day care centers to have significantly higher diarrhea rates than did day care homes or households not using day care, but significantly lower rates than day care centers not included in the active surveillance. Continuous surveillance without training was associated with a significant decrease in diarrheal illness during the course of longitudinal study. One-time staff training without subsequent monitoring did not result in additional decreases and did not lower day care center diarrhea rates to the levels observed in day care homes and households not using day care.

Prevention of secondary transmission of pertussis in households with early use of erythromycin.

To examine the effectiveness of erythromycin therapy and prophylaxis for pertussis, 17 households with one secondary case or more were compared with 20 households without secondary cases following a community-wide pertussis outbreak in Maricopa County, Arizona, in 1988. There were no significant differences between the two household groups in age distribution of members, size, crowding, race, proportion of children aged 7 months to 18 years with three or more diphtheria and tetanus toxoids and pertussis vaccine doses, or in the age distribution, vaccination status, or medical care of patients with primary cases. However, median intervals from onset of illness in primary cases to initiation of erythromycin therapy (for cases) and prophylaxis (for contacts) were 11 and 16 days, respectively, in households without secondary spread, vs 21 and 22 days, respectively, in households with secondary spread. These results provide additional evidence that erythromycin is effective in the medical management of pertussis and should be initiated promptly to minimize secondary spread.

Waterborne outbreak of Norwalk virus gastroenteritis at a southwest US resort: role of geological formations in contamination of well water.

From April 17 to May 1, 1989, gastroenteritis developed in about 900 people during a visit to a new resort in Arizona, USA. Of 240 guests surveyed, 110 had a gastrointestinal illness that was significantly associated with the drinking of tap water from the resort's well (relative risk = 16.1, 95% confidence interval 14.5 to 17.8) and this risk increased significantly with the number of glasses of water consumed (p less than 0.005). Three of seven paired sera tested for antibodies to the Norwalk agent had a four-fold or greater rise in titre. Water contaminated with faecal coliforms was traced back to the deep water well, which remained contaminated even after prolonged pumping. Effluent from the resort's sewage treatment facility seeped through fractures in the subsurface rock (with little filtration) directly into the resort's deep well. Although the latest technology was used to design the resort's water and sewage treatment plants, the region's unique geological conditions posed unexpected problems that may trouble developers faced with similar subsurface geological formations and arid climatic conditions in many parts of the world. In these areas, novel solutions are needed to provide adequate facilities for the treatment of sewage and supply of pure drinking water.

Foodborne hepatitis A infection: a report of two urban restaurant-associated outbreaks.

The cities of Portland, Oregon, and Buffalo, New York, each experienced a restaurant-associated foodborne outbreak of viral hepatitis type A during 1975. Although there were several food handlers ill with viral hepatitis A in each of the restaurants involved, each outbreak was the apparent result of food contamination by a single food handler. In the Buffalo outbreak, food contamination was documented to have occurred for a brief period of time six days prior to onset of any symptoms in the index case. These outbreaks point out the uncommon occurrence of food contamination by individuals ill with type A viral hepatitis, the usefulness of two types of food questionnaires in identifying the vehicle(s) of transmission, and the apparent lack of benefit of widespread immune serum globulin administration as a control measure in this setting.

An outbreak of non-A, non-B hepatitis associated with the infusion of a commercial factor IX complex during cardiovascular surgery.

An outbreak of non-A, non-B hepatitis was recognized among cardiovascular surgical patients from one hospital in June 1985. Illness was found to be significantly associated with a commercial brand of factor IX complex given to patients because of intraoperative bleeding. A change in the commercial brand of factor IX stocked by the hospital pharmacy had occurred in October 1984 and coincided with the onset of the outbreak. A retrospective study of cardiovascular surgery patients identified 23 cases and 7 probable cases of non-A, non-B hepatitis among patients who had received infusions of brands A and B factor IX complex. Three cases were in brand A recipients and 27 were in brand B recipients. Respective brand-specific attack rates were 5 and 42% (relative risk = 7.7; p less than 2 x 10(-5); chi 2 test). Nineteen of 30 case patients (63%) were jaundiced, including 2 brand A recipients and 17 brand B recipients. Median peak serum aminotransferase was 690.5 IU (range 27-2,824). The incubation period for cases in brand B recipients was a median of 7 weeks (range 2-17 weeks). Prevention of non-A, non-B hepatitis in this population requires adhering to strict indications for the use of clotting factor preparations and avoiding these products when at all possible. Heat treatment of clotting factor products may reduce the risk of viral disease transmission, but certain methods may not inactivate the causative agents of non-A, non-B hepatitis.

Group A meningococcal disease in skid rows: epidemiology and implications for control.

Interviews conducted during outbreaks of group A meningococcal disease in skid row communities suggested that heavy alcohol use was associated with increased risk of disease. Frequent moving within skid row and from one skid row to another was characteristic of a subpopulation with increased risk of disease and may have facilitated spread within and between skid rows. The observations discussed herein have important implications for control of communicable diseases in and near skid rows.