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.

Outbreak of cryptosporidiosis at a California waterpark: employee and patron roles and the long road towards prevention.

In August-September 2004, a cryptosporidiosis outbreak affected >250 persons who visited a California waterpark. Employees and patrons of the waterpark were affected, and three employees and 16 patrons admitted to going into recreational water while ill with diarrhoea. The median illness onset date for waterpark employees was 8 days earlier than that for patrons. A case-control study determined that getting water in one's mouth on the waterpark's waterslides was associated with illness (adjusted odds ratio 7.4, 95% confidence interval 1.7-32.2). Laboratory studies identified Cryptosporidium oocysts in sand and backwash from the waterslides' filter, and environmental investigations uncovered inadequate water-quality record keeping and a design flaw in one of the filtration systems. Occurring more than a decade after the first reported outbreaks of cryptosporidiosis in swimming pools, this outbreak demonstrates that messages about healthy swimming practices have not been adopted by pool operators and the public.

A large outbreak of scombroid fish poisoning associated with eating escolar fish (Lepidocybium flavobrunneum).

In August 2003, an outbreak of scombroid fish poisoning occurred at a retreat centre in California, USA. In a retrospective cohort study, 42 (75%) of the 56 dinner attendees who ate escolar fish (Lepidocybium flavobrunneum) met the case definition. Individuals who ate at least 2 oz of fish were 1.5 times more likely to develop symptoms than those who ate less (relative risk 1.5, 95% confidence interval 0.9-2.6), and to develop more symptoms (median 7 vs. 3 symptoms, P = 0.03). Patients who took medicine had a longer duration of symptoms than those who did not (median 4 vs. 1.5 h, P = 0.05), and experienced a greater number of symptoms (median 8 vs. 3 symptoms, P = 0.0002). Samples of fish contained markedly elevated histamine levels (from 2000 to 3800 ppm). This is one of the largest reported outbreaks of scombroid fish poisoning in the United States and was associated with a rare vehicle for scombroid fish poisoning, escolar.

Use of stool collection kits delivered to patients can improve confirmation of etiology in foodborne disease outbreaks.

BACKGROUND: In 68% of foodborne disease outbreaks, no etiologic pathogen is identified. In two-thirds of outbreaks with no identified etiology, no stool specimens are submitted for testing. METHODS: From April 2001 to March 2003, we pilot-tested use of prepackaged, self-contained stool specimen collection kits in 3 states, delivered to and from patients by courier or mail, to improve rates of specimen collection in the outbreak setting. Specimens were tested for bacterial and viral pathogens at health department laboratories, and results were correlated with epidemiological investigation data. RESULTS: Specimens were returned by > or =1 person in 52 (96%) of 54 outbreaks in which kits were deployed; in total, 263 (76%) of 347 persons who received kits returned specimens. Resolution of symptoms was the most commonly cited reason for nonsubmission of kits. An etiology was confirmed in 37 (71%) of 52 outbreaks with specimens returned; 28 (76%) were attributable to norovirus, and 9 (24%) were attributed to bacterial pathogens. Stool kits were well received and cost an average of approximately 43 dollars per specimen returned. CONCLUSIONS: In two-thirds of foodborne disease outbreaks in which delivered stool collection kits were successfully deployed, an etiologic organism was identified. Delivery of kits to and from patients to improve rates of stool collection in outbreaks in which specimens might otherwise not be submitted could substantially reduce the number of outbreaks with an unknown etiology.

Epidemiology of salmonellosis in California, 1990-1999: morbidity, mortality, and hospitalization costs.

Salmonella is a common cause of bacterial foodborne illness in the United States. The epidemiology and costs of nontyphoidal salmonellosis in California from 1990 through 1999 are described using surveillance, hospitalization, and death data. Trends in Salmonella rates and factors associated with prolonged hospitalization were evaluated using Poisson and linear regression models, respectively. There were 56,660 reported cases, 11,102 hospitalizations, and 74 deaths attributed to Samonella. Reported case and hospital discharge rates have decreased since 1996. Among reported cases, infants had the highest rate (121 cases per 10(5) person-years), followed by children 1-4 years of age (40 cases per 10(5) person-years). The highest hospitalization rates were among the elderly and young children. Most deaths occurred among persons aged 65 or more years (59%). Among hospitalizations, gastroenteritis (61%) and septicemia (23%) were the most common Salmonella diagnoses. Salmonella pneumonia patients were the oldest (median age, 55 years) and Salmonella meningitis patients the youngest (median age, 0.3 years). These two diagnoses were the costliest, approaching 30,000 dollars (median) per hospitalization. Having an acquired immunodeficiency syndrome diagnosis or multiple Salmonella diagnoses was independently associated with prolonged hospitalization. The estimated 10-year hospitalization costs for Salmonella were $200 million. Salmonellosis is a costly disease that disproportionately affects the young and elderly.

A population-based estimate of the burden of diarrhoeal illness in the United States: FoodNet, 1996-7.

This study was performed to better understand and more precisely quantify the amount and burden of illness caused by acute diarrhoea in the United States today. A telephone-based population survey was conducted between 1 July, 1996, and 31 June, 1997, in sites of the Foodborne Diseases Active Surveillance Network (FoodNet). The overall prevalence of acute diarrhoea in the 4 weeks before interview was 11%, giving a rate of 1.4 episodes of diarrhoea per person per year. The rate of diarrhoeal illness defined as a diarrhoeal episode lasting longer than 1 day or which resulted in significant impairment of daily activities was 0.7 per person per year. It can be concluded that acute diarrhoea is common and represents a significant burden of illness in the United States. Our data on self-reported diarrhoea, when generalized to the entire nation, suggests 375 million episodes of acute diarrhoea each year in the United States. Many of these episodes are mild. However, our data also indicate that there are approximately 200 million episodes of diarrhoeal illness each year in the United States.

Invasive group A streptococcal infections in the San Francisco Bay area, 1989-99.

To describe the epidemiology of invasive group A streptococcal (iGAS) infections in the San Francisco Bay Area, population-based active surveillance for laboratory-confirmed iGAS was conducted by the California Emerging Infections Program in three California counties. From January 1989 to December 1999, 1415 cases of iGAS were identified. Mean iGAS incidence was 4.06/100,000 person-years and case fatality ratio was 13%, with no linear trends over time. Incidence was lowest in adolescents, was higher in men than women (4.4 vs. 3.2/100,000 person-years), and was higher in African-Americans (6.7) than in non-Hispanic (4.1) or Hispanic (3.4) Whites, Asians (2.2) or Native Americans (17/100,000 person-years). Injecting drug use was the riskiest underlying condition and was associated with the highest attributable risk. Cases were associated with several underlying conditions, but 23% occurred in previously healthy persons. From 1989-1999, iGAS infections in the San Francisco Bay Area became neither more common nor more deadly.

Macrolide resistance among invasive Streptococcus pneumoniae isolates.

CONTEXT: Macrolide antibiotics, including erythromycin, clarithromycin, and azithromycin, are the mainstays of empirical pneumonia therapy. Macrolide resistance among Streptococcus pneumoniae, the most common cause of community-acquired pneumonia, is increasing in the United States. Whether resistance is a significant problem or whether macrolides remain useful for treatment of most resistant strains is unknown. OBJECTIVE: To examine the epidemiology of macrolide-resistant pneumococci in the United States. DESIGN AND SETTING: Analysis of 15 481 invasive isolates from 1995 to 1999 collected by the Centers for Disease Control and Prevention's Active Bacterial Core surveillance system in 8 states. MAIN OUTCOME MEASURES: Trends in macrolide use (1993-1999) and resistance and factors associated with resistance, including examination of 2 subtypes, the M phenotype, associated with moderate minimum inhibitory concentrations (MICs), and the MLS(B) phenotype, associated with high MICs and clindamycin resistance. RESULTS: From 1993 to 1999, macrolide use increased 13%; macrolide use increased 320% among children younger than 5 years. Macrolide resistance increased from 10.6% in 1995 to 20.4% in 1999. M phenotype isolates increased from 7.4% to 16.5% (P<.001), while the proportion with the MLS(B) phenotype was stable (3%-4%). The median erythromycin MIC (MIC(50)) of M phenotype isolates increased from 4 microg/mL to 8 microg/mL. In 1999, M phenotype strains were more often from children than persons 5 years or older (25.2% vs 12.6%; P<.001) and from whites than blacks (19.3% vs 11.2%; P<.001). CONCLUSIONS: In the setting of increasing macrolide use, pneumococcal resistance has become common. Most resistant strains have MICs in the range in which treatment failures have been reported. Further study and surveillance are critical to understanding the clinical implications of our findings.

Complaints of foodborne illness in San Francisco, California, 1998.

Foodborne diseases are an important public problem affecting millions of Americans each year and resulting in substantial morbidity and mortality. Many foodborne infections occur in outbreak settings. Outbreaks are often detected by complaints from the public to health authorities. This report reviews complaints received by the San Francisco Department of Public Health involving suspected foodborne illness in 1998. Although such foodborne complaints are commonly received by health officials, we provide the first review of population-based data describing such complaints. We use a broad definition of a foodborne disease outbreak. We judged a complaint to be a "likely foodborne disease outbreak" if it involved more than one person and more than one family; no other common meals were shared recently by ill persons; diarrhea, vomiting, or both was reported; and the incubation period was more than one hour. In 1998, 326 complaints of foodborne illness, involving a total of 599 ill people, were received by the Communicable Disease Control Unit in San Francisco. The complaints involved from 1 to 36 ill persons, with 61% involving one ill person and 25% involving two ill persons. Of the 126 reports involving illness in more than one person, 77 (61%) were judged to be likely foodborne disease outbreaks. Three of these 77 outbreaks had been investigated prior to our review. This project confirms that more foodborne disease outbreaks occur than are reported to state and national outbreak surveillance systems. Our review of the San Francisco system highlights opportunities for gleaning valuable information from the foodborne disease complaint systems in place in most jurisdictions.

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.

Predominant kidney involvement in a fatal case of hantavirus pulmonary syndrome caused by Sin Nombre virus.

A 27-year-old woman presented to a hospital with symptoms resembling pyelonephritis; respiratory distress did not develop until nearly a day after admission and she subsequently died. The Unexplained Deaths and Critical Illnesses Project of the Centers for Disease Control and Prevention confirmed Sin Nombre virus infection by the results of serological testing and sequencing of the viral genome; staining of Sin Nombre virus antigen in the pulmonary capillaries was relatively weak.

Risk of infection from needle reuse at a phlebotomy center.

OBJECTIVES: This study determined infection risk for HIV, hepatitis B virus (HBV), and hepatitis C virus (HCV) from needle reuse at a phlebotomy center that possibly exposed 3810 patients to infection. METHODS: We used a model for the risk of infection per blood draw, supplemented by subsequent testing results from 1699 patients. RESULTS: The highest risk of transmission was for HBV infection: 1.1 x 10(-6) in the best case and 1.2 x 10(-3) in the (unlikely) worst case. Subsequent testing yielded prevalence rates of 0.12%, 0.41%, and 0.88% for HIV, HBV, and HCV, respectively, lower than National Health and Nutrition Examination Survey III prevalence estimates. CONCLUSIONS: The infection risk was very low; few, if any, transmissions are likely to have occurred.

Risk factors for severe pulmonary and disseminated coccidioidomycosis: Kern County, California, 1995-1996.

Surveillance for coccidioidomycosis (CM) and a case-control study for risk factors among adults were conducted in Kern County, California. From January 1995 through December 1996, 905 cases of CM were identified, for an annual incidence of 86 cases per 100,000 population. A total of 380 adults were enrolled in the case-control study: 77 had severe pulmonary disease, 33 had disseminated disease, and 270 control patients had mild disease. Independent risk factors for severe pulmonary disease included diabetes, recent history of cigarette smoking, income of < $15,000 per year, and older age. Oral antifungal therapy before hospitalization was associated with a reduced risk of CM pneumonia. Risk factors for disseminated disease were black race, income of < $15,000 per year, and pregnancy. Early treatment of CM with oral antifungal agents may prevent severe pulmonary disease in groups considered to be at high risk, such as elderly individuals, persons with diabetes, and smokers. Persons at risk for severe CM may benefit from vaccination once an effective CM vaccine is available.

Disease reporting from an automated laboratory-based reporting system to a state health department via local county health departments.

OBJECTIVE: The authors assessed the completeness of disease reporting from a managed care organization's automated laboratory-based reporting system to the California Department of Health Services (CDHS) via local public health departments. METHODS: The authors identified all positive laboratory tests for 1997 from the computerized database of Kaiser Permanente Northern California for seven infections for which there are statutory reporting requirements: Campylobacter jejuni, Chlamydia trachomatis, Cryptosporidium parvum, hepatitis A, Neisseria meningitidis, Neisseria gonorrhoeae, and Salmonella (N = 7,331 reports). Cases were then matched by computer query to records of cases reported to CDHS. To determine why cases were not found in CDHS records, a sample of un-matched cases was searched at two county health departments. RESULTS: Overall, 84.5% (95% CI 83.4, 85.6) of the laboratory reports submitted with accompanying demographic information were successfully matched with cases in the CDHS disease surveillance database. Frequency of matching for specific diseases ranged from 79.4% (95% CI 75.6, 83.3) for N. gonorrhoeae to 88.4% (95% CI 85.3, 91.6) for C. jejuni. Reports were more likely to be matched when the county of residence was the same as the county of the health care facility. At the county level, reasons for failure of cases to be forwarded to CDHS included: errors due to manual data entry, failure to forward information from the county of diagnosis to the county of residence, and incorrect disease coding. CONCLUSION: Automated laboratory-based reporting is highly effective, but some data are lost with off-line transfer of information. To optimize surveillance accuracy and completeness, reporting at all levels should be done via direct electronic data transfer.

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.

Prevalence of high-risk food consumption and food-handling practices among adults: a multistate survey, 1996 to 1997. The Foodnet Working Group.

Risk factors for foodborne diseases include consumption of high-risk foods and unsanitary food-handling practices; however, little is known about the prevalence of these risk factors in the general population. A survey was done in five FoodNet sites (California, Connecticut, Georgia, Minnesota, Oregon) to determine the prevalence of these risk factors in the population. A total of 7,493 adults were interviewed by telephone between 1 July 1996 and 30 June 1997. Results showed that 1.5% drank raw milk, 1.9% ate raw shellfish, 18% ate runny egg, 30% preferred pink hamburger, 93% said they almost always washed their cutting board after cutting raw chicken, and 93% said they almost always washed their hands after handling raw meat or poultry, during 5 days before interview. The results differed by state and demographic group. Consumption of raw shellfish (3.2%) and undercooked hamburger (43%) were more common in Connecticut than other states. Raw milk consumption was more common among people who lived on a farm (8.6%) compared with people who lived in a city or urban area (1.1%). Preference for undercooked hamburger was more common among men (35%), young adults (18 to 25 years, 33%), people with college education (38%), and among people with household income of more than $100,000/year (49%). African-Americans were less likely to prefer undercooked hamburger compared to other racial groups (10% versus 30%). Young adults compared to older adults were less likely to wash their hands after handling raw chicken (88% versus 95%), and men washed their hands less often than women (89% versus 97%). Although there were statistical differences between demographic groups, they are insufficient to warrant targeted educational programs.

Active, multisite, laboratory-based surveillance for Cryptosporidium parvum.

Cryptosporidium parvum leaped to the attention of the United States following the 1993 outbreak in Milwaukee, Wisconsin, which sickened 400,000 people. Other outbreaks in the United States have been associated with drinking and recreational water, consumption of contaminated foods, contact with animals, and childcare attendance. Despite its public health importance, the number of people who become infected each year is not known. In 1997, active surveillance for C. parvum was added to the Foodborne Diseases Active Surveillance Network (FoodNet), a collaborative effort among the Centers for Disease Control and Prevention, selected state health departments, the U.S. Departments of Agriculture and Food and Drug Administration. During the first 2 years of surveillance, 1,023 laboratory-confirmed cases of cryptosporidiosis were detected in FoodNet (Connecticut, Minnesota, Oregon, and selected counties in California, Georgia, Maryland, and New York). The annual rate per 100,000 persons was 2.3. Sixteen percent of case-patients were hospitalized. A seasonal increase in case detection was noted in late summer among persons less than 15 years of age. These data represent the first active multistate ascertainment of laboratory-confirmed cryptosporidiosis cases and provide useful information on the burden of disease in the United States.