Outbreak of Legionnaires' disease associated with cooling towers at a California state prison, 2015.

A large outbreak of Legionnaires' disease occurred at a California state prison in August 2015. We conducted environmental and epidemiological investigations to identify the most likely source of exposure and characterise morbidity. Sixty-four inmates had probable Legionnaires' disease; 14 had laboratory-confirmed legionellosis. Thirteen (17%) inmates were hospitalised; there were no deaths. Ill inmates were more likely to be ⩾65 years old (P < 0.01), have the chronic obstructive pulmonary disease (P < 0.01), diabetes mellitus (P = 0.02), hepatitis C infection (P < 0.01), or end-stage liver disease (P < 0.01). The case-patients were in ten housing units throughout the prison grounds. All either resided in or were near the central clinical building (for appointments or yard time) during their incubation periods. Legionella pneumophila serogroup 1 was cultured from three cooling towers on top of the central medical clinic (range, 880-1200 cfu/ml). An inadequate water management program, dense biofilm within the cooling towers, and high ambient temperatures preceding the outbreak created an ideal environment for Legionella sp. proliferation. All state prisons were directed to develop local operating procedures for maintaining their cooling towers and the state health department added a review of the maintenance plans to their environmental inspection protocol.

Outbreak epidemiologically linked with a composite product of beef, mechanically separated chicken and textured vegetable protein contaminated with multiple serotypes of Salmonella enterica including multidrug-resistant Infantis, California 2016.

A salmonellosis outbreak occurred at a California prison in April and May 2016. In a cohort study of 371 inmates, persons who consumed dishes from the prison kitchen made from ground meat had a higher attack rate (15%) than those who did not (4%) (risk ratio 3.4, 95% CI 1.1-10.6). The ground meat product was composed exclusively of beef, mechanically separated chicken (MSC) and textured vegetable protein; eight of eight lots of the product collected from the prison and processing facility were contaminated with Salmonella enterica of eight serotypes and 17 distinct PFGE patterns, including multidrug-resistant S. Infantis. Either the MSC or the beef could have been the source of the particular strains of S. enterica isolated from patients or the product. The microbiological evidence is most consistent with MSC as the source of the high levels of S. enterica in the epidemiologically linked meat product. Our findings contribute to the growing body of evidence about the hazard posed by the use of products containing raw mechanically separated poultry in kitchens in institutions.

Multistate outbreak of multidrug-resistant Salmonella newport infections associated with ground beef, October to December 2007.

In late October 2007, an outbreak of multidrug-resistant Salmonella Newport infections affected 42 case patients in California, Arizona, Idaho, and Nevada. A case-control study implicated ground beef from one chain store. Despite detailed ground beef purchase histories--including shopper card information for several case patients--traceback efforts by both the U.S. Department of Agriculture, Food Safety and Inspection Service and the California Department of Public Health were unable to identify the source of contamination. Case patients consumed multiple types of ground beef products purchased at numerous chain store A retail locations. These stores had received beef products for grinding from multiple beef slaughter-processing establishments. Detailed retail grinding logs and grinding policies that prevent cross-contamination between batches of ground beef products are crucial in the identification of contaminated beef products associated with foodborne illness.

Giardiasis outbreak at a camp after installation of a slow-sand filtration water-treatment system.

In July and August 2007, a giardiasis outbreak affected attendees of a private recreational camp in California. Twenty-six persons had laboratory-confirmed giardiasis; another 24 had giardiasis-like illness with no stool test. A retrospective cohort study determined that showering was associated with illness (adjusted odds ratio 3·1, 95% confidence interval 1·1-9·3). Two days before the outbreak began, the camp had installed a slow-sand water filtration system that included unsterilized sand. Review of historical water-quality data identified substantially elevated total coliform and turbidity levels in sand-filtered spring water used for showering during the suspected exposure period. Unfiltered spring water tested at the same time had acceptable coliform and turbidity levels, implicating the filtration system as the most likely contamination source. To prevent waterborne illness, slow-sand water filtration systems should use sterilized sand, and slow-sand-filtered water should not be used for any purpose where inadvertent ingestion could occur until testing confirms its potability.

Point-source outbreak of coccidioidomycosis in construction workers.

Coccidioidomycosis results from inhaling spores of the fungus Coccidioides spp. in soil or airborne dust in endemic areas. We investigated an outbreak of coccidioidomycosis in a 12-person civilian construction crew that excavated soil during an underground pipe installation on Camp Roberts Military Base, California in October 2007. Ten (83.3%) workers developed symptoms of coccidioidomycosis; eight (66.7%) had serologically confirmed disease, seven had abnormal chest radiographs, and one developed disseminated infection; none used respiratory protection. A diagnosis of coccidioidomycosis in an eleventh worker followed his exposure to the outbreak site in 2008. Although episodic clusters of infections have occurred at Camp Roberts, the general area is not associated with the high disease rates found in California's San Joaquin Valley. Measures to minimize exposure to airborne spores during soil-disrupting activities should be taken before work begins in any coccidioides-endemic area, including regions with only historic evidence of disease activity.

Salmonella infections associated with mung bean sprouts: epidemiological and environmental investigations.

We investigated an outbreak of Salmonella Enteritidis (SE) infections linked to raw mung bean sprouts in 2000 with two case-control studies and reviewed six similar outbreaks that occurred in 2000-2002. All outbreaks were due to unusual phage types (PT) of SE and occurred in the United States (PT 33, 1, and 913), Canada (PT 11b and 913), and The Netherlands (PT 4b). PT 33 was in the spent irrigation water and a drain from one sprout grower. None of the growers disinfected seeds at recommended concentrations. Only two growers tested spent irrigation water; neither discarded the implicated seed lots after receiving a report of Salmonella contamination. We found no difference in the growth of SE and Salmonella Newport on mung beans. Mung bean sprout growers should disinfect seeds, test spent irrigation water, and discontinue the use of implicated seed lots when pathogens are found. Laboratories should report confirmed positive Salmonella results from sprout growers to public health authorities.

Risk factors for sporadic Shiga toxin-producing Escherichia coli O157 infections in FoodNet sites, 1999-2000.

To monitor risk factors for illness, we conducted a case-control study of sporadic Shiga toxin-producing Escherichia coli O157 (STEC O157) infections in 1999-2000. Laboratory-confirmed cases of STEC O157 infection were identified through active laboratory surveillance in all or part of seven states. Patients and age-matched controls were interviewed by telephone using a standard questionnaire. Information was collected on demographics, clinical illness, and exposures to food, water, and animals in the 7 days before the patient's illness onset. During the 12-month study, 283 patients and 534 controls were enrolled. STEC O157 infection was associated with eating pink hamburgers, drinking untreated surface water, and contact with cattle. Eating produce was inversely associated with infection. Direct or indirect contact with cattle waste continues to be a leading identified source of sporadic STEC O157 infections.

Yield of source-case and contact investigations in identifying previously undiagnosed childhood tuberculosis.

OBJECTIVE: To determine the extent to which source-case investigations, in which a child was the index tuberculosis (TB) case, and contact investigations of adult pulmonary cases, identified children and adults with previously undiagnosed TB or latent tuberculosis infection (LTBI). METHODS: We reviewed records of 111 source-case investigations and 38 contact investigations involving 164 TB cases among children <5 years of age from eight California health jurisdictions with a case rate greater than the state average for this age group (9.6/100000). RESULTS: In source-case investigations, 141 children <5 years and 113 children 5-14 years of age were evaluated for TB disease and LTBI. Fourteen previously undiagnosed TB cases were found, including seven children <5 years of age. Source-case investigations also identified persons who might benefit from treatment for LTBI (45% had a positive tuberculin reaction). In contact investigations of adult TB cases, 202 children <5 years and 122 children 5-14 years of age were evaluated. In addition to 46 children with TB <5 years of age, the basis on which these contact investigations were selected for study, four children 5-14 years of age and 10 adults were found to have TB disease. A high percentage (41%) of contacts with a positive tuberculin reaction was found, especially among household contacts. CONCLUSIONS: Source-case investigations and contact investigations are effective for finding previously undiagnosed cases of TB. They are also useful for identifying children and adults who would possibly benefit from treatment for LTBI. Earlier detection and treatment of adults with TB could interrupt transmission and be a step toward eliminating childhood TB.

Alfalfa sprouts and Salmonella Kottbus infection: a multistate outbreak following inadequate seed disinfection with heat and chlorine.

Raw sprouts have been implicated in a number of foodborne disease outbreaks. Because contaminated seeds are usually responsible, many sprout producers attempt to disinfect seeds before germination and detect sprout contamination during production. In March 2001, we detected an increased number of Salmonella serotype Kottbus isolates in California. Overall, we identified 31 cases from three western states. To identify the cause, we conducted a case-control study with the first 10 identified case-patients matched to 20 controls by age, sex, and residential area. Our case-control study found illness to be statistically associated with alfalfa sprout consumption. The traceback investigation implicated a single sprouter, where environmental studies yielded Salmonella Kottbus from ungerminated seeds and floor drains within the production facility. Pulsed-field gel electrophoresis patterns of all patient, seed, and floor drain Salmonella Kottbus isolates were indistinguishable. Most implicated sprouts were from seeds that underwent heat treatment and soaking with a 2,000-ppm sodium hypochlorite solution rather than the Food and Drug Administration (FDA)-recommended 20,000-ppm calcium hypochlorite soak. Other implicated seeds had been soaked in a calcium hypochlorite solution that, when tested, measured only 11,000 ppm. The outbreak might have been averted when screening tests of sprout irrigation water detected Salmonella in January; however, confirmatory testing of these samples was negative (but testing improperly utilized refrigerated irrigation water). Producers should use the enrichment broth of positive screening samples, not refrigerated irrigation water, for confirmatory testing. Until other effective disinfection technologies are developed, producers should adhere to FDA recommendations for sprout seed disinfection.

A multistate outbreak of Salmonella enterica serotype Baildon associated with domestic raw tomatoes.

Salmonella enterica serotype Baildon, a rare serotype, was recovered from 86 persons in eight states; 87% of illnesses began during a 3-week period ending January 9, 1999. Raw restaurant-prepared tomatoes were implicated in multiple case-control studies. Contamination likely occurred on the farm or during packing; more effective disinfection and prevention strategies are needed.

Escherichia coli O157 and Salmonella infections associated with sprouts in California, 1996-1998.

BACKGROUND: In California, from 1996 through 1998, more than 50% of multicounty outbreaks with confirmed food vehicles were related to alfalfa or clover sprouts. OBJECTIVE: To summarize investigations of sprout-associated outbreaks. DESIGN: Matched case-control studies. SETTING: California. PATIENTS: Outbreak-associated patients and matched population controls. MEASUREMENTS: Matched odds ratios and 95% CIs; traceback and environmental investigations of sprout and seed growers; and pulsed-field gel electrophoresis of isolates from patients, sprouts, and seeds. RESULTS: Five sprout-associated outbreaks of salmonellosis and one outbreak of infection with nonmotile Shiga toxin-producing Escherichia coli O157 occurred. Six hundred patients had culture-confirmed disease, and two died. It is estimated that these outbreaks caused 22 800 cases of gastrointestinal illness or urinary tract infection. In the case-control studies, odds ratios for the association between illness and alfalfa sprout consumption ranged from 5.0 to infinity (all were statistically significant). Three sprout growers were implicated, and each was associated with two outbreaks. Outbreak strains of Salmonella were isolated from sprouts supplied by two sprout growers and from seeds used by the third sprout grower. CONCLUSIONS: As currently produced, sprouts can be a hazardous food. Seeds can be contaminated before sprouting, and no method can eliminate all pathogens from seeds. Seed and sprout growers should implement measures to decrease contamination. The general public should recognize the risks of eating sprouts, and populations at high risk for complications from salmonellosis or E. coli O157 infection should avoid sprout consumption.

An outbreak of Salmonella serotype Thompson associated with fresh cilantro.

An outbreak of Salmonella serotype Thompson in California was identified through laboratory-based surveillance and investigated with case-control, traceback, and laboratory studies. There were 35 "sporadic" cases and a restaurant-associated outbreak of 41 cases with onset between 6 March and 31 March 1999. Three case patients were hospitalized. A case-control study found a significant association between illness and eating cilantro at a restaurant (63% of case patients vs. 34% of control subjects; odds ratio, 3.5; 95% confidence interval, 1.1-11.4). Although common distributors of cilantro were identified, inadequate records prohibited the identification of a single farm supplying cilantro. At room temperature, Salmonella Thompson grew more rapidly and to a higher concentration on chopped cilantro, compared with whole-leaf cilantro. Freshly made salsa (pH 3.4) supported growth of Salmonella Thompson. Cilantro should be served promptly after chopping. Accurate records of the distribution of produce should be available, and bacterial contamination of produce should be prevented in retail and wholesale establishments, in packing sheds, and on farms.

High incidence of extra-intestinal infections in a Salmonella Havana outbreak associated with alfalfa sprouts.

OBJECTIVE: To determine a vehicle and point source for an outbreak of Salmonella Havana. METHODS: The authors conducted a case-control study and traceback investigation of 14 residents of California and four from Arizona with onsets of illness from Apr 15, 1998, to June 15, 1998, and Salmonella Havana infections with identical PFGE patterns. RESULTS: Seventeen of 18 patients were women. Seventeen were adults 20-89 years of age. Nine (50%) had diarrheal illness, 6 (33%) had urinary tract infections, 2 (11%) had sepsis, and one had an infected surgical wound after appendectomy. Four patients were hospitalized, and one died. Eating alfalfa sprouts was associated with S. Havana infection (OR = 10.0; 95% confidence interval 1.2, 83.1; P = 0.01). CONCLUSIONS: This outbreak resulted in a high incidence of extra-intestinal infections, especially urinary tract infections, and high morbidity. Raw alfalfa sprouts, often considered a safe "heath food," can be a source of serious foodborne disease outbreaks.

The impact of health communication and enhanced laboratory-based surveillance on detection of cyclosporiasis outbreaks in California.

We investigated the timing of diagnosis, influence of media information on testing for Cyclospora, and the method used to identify cases during eight cyclosporiasis outbreaks in California in spring of 1997. We found that Internet information, media reports, and enhanced laboratory surveillance improved detection of these outbreaks.

Missed opportunities for preventing tuberculosis among children younger than five years of age.

OBJECTIVES: Childhood tuberculosis (TB) is an important indicator of public health success in interrupting and preventing TB transmission. To determine the frequency and types of missed opportunities for preventing TB among children <5 years of age. METHODS: We collected data from the public health records of child TB cases and their adult source cases. These children were from health jurisdictions where TB case rates in children were higher than the California average for this age group. RESULTS: We reviewed the records for 165 children reported with TB (20% confirmed by culture). These children were evaluated for TB because of signs or symptoms of illness (32%), a contact investigation (26%), screening (22%), a source case investigation (4%), and unknown reasons (16%). Excluding 4 children infected by Mycobacterium bovis, only 59 of 161 children (37%) had a source case found. Children found in a contact investigation, born in the United States, <1 year of age, or who were black were more likely to have a source case found than children who did not have one of these characteristics. Of 43 children found in a contact investigation, improvements in contact investigations may have prevented TB in 17 of these children (40%). Among the 43 adult source cases, factors that may have facilitated transmission include delayed reporting in 23%, a delayed contact investigation in 21%, and delayed or nondocumented bacteriologic sputum conversion in 42% of culture-positive cases. CONCLUSIONS: Important missed opportunities to prevent TB in children include the failure to find and appropriately manage adult source cases and failure to completely evaluate and properly treat children exposed to TB. Improvements in case detection, case management, and contact investigations are necessary to eliminate TB in children.

An outbreak of Salmonella serogroup Saphra due to cantaloupes from Mexico.

An outbreak of Salmonella serogroup Saphra (S. saphra) infections was studied by laboratory-based surveillance, case-control and trace-back studies, and a survey of cantaloupe preparation practices. Twenty-four patients with S. saphra infections had illness onsets between 23 February and 15 May 1997; 75% were

Viral meningitis in child care center staff and parents: an outbreak of echovirus 30 infections.

OBJECTIVE: A report of five cases of viral meningitis among adults with children enrolled in a child care center prompted an investigation of risk factors for viral transmission from children to adult household members. METHODS: To determine recent echovirus 30 (E30) infections, the authors conducted a serologic survey. To determine risk factors for infection among adult household members, they conducted a retrospective cohort study using written questionnaires. RESULTS: Recent E30 infections were found in 84% of children tested, 57% of adult household members tested, and 47% of staff members tested. Infected adults were more likely than infected children to have clinical meningitis. Among adult household members, changing diapers was a risk factor for recent infection. Women who changed > or = 90 diapers per month had a higher infection rate than women who changed fewer diapers; in contrast, men who changed > or = 90 diapers per month had a lower infection rate than men who changed fewer diapers. Handwashing was protective: there was a negative correlation between handwashing after diaper changes and E30 infection among adults with infected children in diapers. CONCLUSIONS: Because child care centers can be a source of enteroviral infections among adult household members, adults with viral meningitis should be questioned about their children's day care or preschool attendance. The importance of handwashing should be stressed to adults with children in day care.

B notifications and the detection of tuberculosis among foreign-born recent arrivals in California.

OBJECTIVE: To evaluate the effectiveness and limitations of the B notification program for detecting tuberculosis among recent foreign-born arrivals in California. DESIGN: Retrospective cohort study. All foreign-born visa holders with a B notification who arrived in California from January 1992 through September 1995 (n = 27 412) were matched with a listing of foreign-born persons who arrived in the US during the same time period and who were reported to have active tuberculosis in California within one year of their arrival from January 1992 through September 1996 (n = 2547). RESULTS: Overall, 3.5% (95% confidence interval 3.3%, 3.8%) of all persons with a B notification were reported to have active tuberculosis within a year of arrival. Recent arrivals with a B notification and tuberculosis accounted for 38% of all foreign-born cases of tuberculosis reported within one year of arrival. Compared to recent arrivals without a B notification, those with a B notification were more likely to have pulmonary tuberculosis, less likely to have smear-positive pulmonary disease and reported with tuberculosis sooner after their arrival in the US. The B notification program was not able to identify 87% of the smear-positive pulmonary tuberculosis cases in adults, and did not identify 99% of these highly infectious cases among Latin Americans. CONCLUSIONS: Although the evaluation of persons who enter the US with B notifications has a high yield for identifying active tuberculosis cases, it was not able to identify the majority of recent arrivals with the most infectious form of tuberculosis.

Tuberculosis prevention in methadone maintenance clinics. Effectiveness and cost-effectiveness.

To determine the effectiveness and cost-effectiveness of a program to provide screening for tuberculosis infection and directly observed preventive therapy (DOPT) in methadone maintenance clinics, we determined completion rates of screening for tuberculosis infection, medical evaluation, and preventive therapy, as well as the number of active tuberculosis cases and tuberculosis-related deaths prevented, in five clinics in San Francisco, California. Between 1990 and 1995, a total of 2,689 clients (of whom 18% were HIV-seropositive) were screened at least once. Of eligible clients, 99% received tuberculin skin tests, 96% received a medical examination, 91% began isoniazid preventive therapy, and 82% completed preventive therapy. Program effectiveness was enhanced by close collaboration between public health and methadone maintenance programs and the use of incentives and enablers. Over a 3-yr follow-up period, only one verified case of tuberculosis was reported among clients with a positive tuberculin skin test, thereby preventing as much as 95% of expected tuberculosis cases. Over 10 yr, we estimate the program would prevent 30.0 (52%) of 57.7 expected cases of tuberculosis, and 7.6 (57%) of 13.4 expected tuberculosis-related deaths. The program cost $771,569, but averted an estimated $876,229, for a net savings of $104,660 (average of $3, 724 per case prevented). Our study demonstrates that when effectively implemented, screening for tuberculosis infection and DOPT in methadone maintenance clinics is a highly cost-effective approach to prevent tuberculosis.