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.

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.

Invasive group A streptococcal infections in children with varicella in Southern California.

OBJECTIVE: To describe demographic and clinical features of invasive group A streptococcal (GAS) infections in children with varicella in Southern California in early 1994. METHODS: From hospitals of Los Angeles and Orange Counties, children with invasive GAS infections after varicella between January 1 and April 8, 1994, were identified by hospital infection control nurses. Medical records of patients were reviewed, and any available GAS isolate was further tested. RESULTS: Twenty-four cases were identified; 54% were male, 50% were Hispanic and the median age was 3 years (range, 0.5 to 8). Four cases died before hospitalization. The other 20 were hospitalized for a median of 10 days (range, 4 to 50): 14 presented with cellulitis (1 with concomitant epiglottitis), 2 with myositis/necrotizing fasciitis, 2 with pneumonia and 2 with bacteremia without apparent source. Five had evidence of multiorgan involvement including two patients fulfilling criteria of streptococcal toxic shock-like syndrome. Of 19 patients with blood cultures, 10 (53%) had GAS bacteremia. Onset of GAS infection was suggested, as a median, on Day 4 of varicella, with fever, vomiting and localized swelling being commonly reported. The mean maximum temperature on the day of admission was 39.4 degrees C (102.9 degrees F). Four GAS isolates were M1T1 and one was M3T3. Five isolates produced streptococcal pyrogenic exotoxins A and B. CONCLUSIONS: Invasive GAS disease, including streptococcal toxic shock-like syndrome, is a serious complication of varicella. Physicians should be alert for the complication of GAS when fever and localized swelling or signs of cellulitis develop 3 days or more after the onset of varicella. Widespread use of varicella vaccine may decrease invasive GAS infections in this setting.

Risk factors for invasive group A streptococcal infections in children with varicella: a case-control study.

OBJECTIVE: To identify characteristic clinical manifestations and potential risk factors for invasive group A streptococcal (GAS) disease in children with varicella. DESIGN AND PARTICIPANTS: A case-control study was conducted in Los Angeles and Orange Counties, CA. Cases were children with varicella who developed invasive GAS disease between January 1 and May 3, 1994 (n = 25). Controls were acquaintance, neighborhood or schoolmate children with uncomplicated varicella during the study period (n = 62). Cases were compared with controls with regard to underlying illness, child care practices, parental home health practices, health care-seeking behaviors, sociodemographic characteristics and clinical characteristics. RESULTS: Controlling for age we found that cases were more likely than controls: (1) to be cared for in the home vs. out-of-home child care (odds ratio (OR), 4.4 (95% confidence interval (95% CI), 1.1 to 17)); (2) to report having asthma (OR, 6.2 (95% CI, 1.2 to 41.0)) and to be taking albuterol (OR, 11.6 ((95% CI, 1.0 to 581)); (3) to be secondary varicella cases within a household (OR, 7.3 (95% CI, 2.2 to 25)); (4) to report fever after Day 2 of varicella; and (5) to have contacted their health care provider later than controls (Day 3.8 rather than Day 1.7, P < 0.001). CONCLUSIONS: To our knowledge this is the first case-control study exploring potential risk factors for invasive GAS disease in children with varicella. Both previously healthy children with varicella and those with underlying medical problems, including asthma, may be at increased risk for GAS complications. Interventions should be targeted to parents and health care providers to increase awareness of early signs and symptoms of invasive GAS disease in children with varicella. Additional studies are needed to confirm the associations suggested by this study between GAS complications of varicella and asthma, in-home child care, secondary vs. primary varicella household cases and delayed contact with medical care providers.

Prevalence of human T cell lymphotropic virus types 1 and 2 (HTLV-1/2) in selected Tijuana subpopulations.

To assess the prevalence of human T cell lymphotropic virus type 1 and 2 (HTLV-1/2) infections among potentially high-risk populations in the city of Tijuana, Mexico, the prevalence of specific antibodies was determined and information on risk behaviors was obtained between June and October 1988. The study involved 631 presumably healthy individuals, randomly selected from a study population recruited sequentially from prisoners, prostitutes, and injecting drug users (IDUs), and randomly from homosexual and bisexual men. The presence of HTLV-1/2 antibodies was determined by enzyme immunoassay and an immunofluorescence method, and positive reactions were confirmed by a radioimmunoprecipitation assay and Western blot. The prevalence of HTLV-1/2 was 2% (2 of 105) among prostitutes, 7% (29 of 410) among prisoners, 1% (1 of 105) among homosexual/bisexual men, and 21% (22 of 106) among IDUs. To properly identify the specific HTLV type, a subsequent sample of 41 imprisoned IDUs were voluntarily and anonymously recruited in June 1990 and asked to donate 20 ml of whole blood. Twenty-two percent (9 of 41) were serologically positive for HTLV-1/2, and polymerase chain reaction analysis performed on peripheral blood mononuclear cells identified HTLV-2 as the specific virus prevalent in this group. Two individuals were positive for human immunodeficiency virus type 1 (HIV-1). One of these individuals was coinfected with HTLV-2.(ABSTRACT TRUNCATED AT 250 WORDS)

Epidemic cholera in Trujillo, Peru 1992: utility of a clinical case definition and shift in Vibrio cholerae O1 serotype.

Epidemic cholera continues in Peru. Since 1991, cholera surveillance in Peru has been based mainly on clinical recognition. To determine the proportion of reported cholera patients who actually have cholera and to evaluate the clinical case definition used in surveillance, we cultured rectal swabs from patients presenting with acute diarrhea in March 1992 in Trujillo, Peru. Of 197 patients meeting the clinical case definition, 174 (88%) had confirmed Vibrio cholerae O1 infection. In this epidemic setting, watery diarrhea of sudden onset in a person of any age presenting for treatment is highly predictive of cholera. Of note, 90% of the current V. cholerae O1 El Tor isolates were of serotype Ogawa, while a year earlier, all were of serotype Inaba.

Detection of the agents of human ehrlichioses in ixodid ticks from California.

A study was conducted in northern California to estimate the prevalence and distribution in ixodid ticks of the rickettsial agents of human monocytic (HME) and human granulocytic (HGE) ehrlichioses. More than 650 ixodid ticks were collected from 17 sites in six California counties over a 15-month period. Ehrlichia chaffeensis, the causative agent of HME, was detected by a nested polymerase chain reaction (PCR) in Ixodes pacificus (minimum infection rate [MIR] = 13.3%) and Dermacentor variabilis (infection rate=20.0%) from a municipal park in Santa Cruz County. The HGE agent was detected by nested PCR in I. pacificus adults from a heavily used recreational area in Alameda County (MIR = 4.7%) and a semirural community in Sonoma County (MIR = 6.7%). Evidence of infection with Ehrlichia spp. was not detected in D. occidentalis adults or I. pacificus nymphs. This study represents the first detection of E. chaffeensis in California ticks and the first report of infection in Ixodes spp. The competency of I. pacificus to be coinfected with and to transmit multiple disease agents, including those of human ehrlichioses and Lyme disease, has yet to be determined.

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.

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.

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.

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.

Surveillance for epidemic cholera in the Americas: an assessment.

In January 1991, epidemic cholera appeared in Peru and quickly spread to many other Latin American countries. Because reporting of cholera cases was often delayed in some areas, the scope of the epidemic was unclear. An assessment of the conduct of surveillance for cholera in several countries identified some recurrent problems involving surveillance case definitions, laboratory surveillance, surveillance methods, national coordination, and data management. A key conclusion is that a simple, well-communicated cholera surveillance system in place during an epidemic will facilitate prevention and treatment efforts. We recommend the following measures: a) simplify case definitions for cholera; b) focus on laboratory surveillance of patients with diarrhea primarily in the initial stage of the epidemic; c) use predominantly the "suspect" case definition when the number of "confirmed" cases rises; d) transmit weekly the numbers of cases, hospitalized patients, and deaths to regional and central levels; e) analyze data frequently and distribute a weekly or biweekly summary; and f) report the number of cholera cases promptly to the World Health Organization.

Tinea capitis in California children: a population-based study of a growing epidemic.

OBJECTIVE: To describe trends in tinea capitis incidence among California children and to determine subpopulations at increased risk. DESIGN: Retrospective population-based study. SETTING: California, 1984 through 1993. POPULATION: Children < 10 years of age enrolled in Medi-Cal. OUTCOME MEASURES: California Medi-Cal provider data for first-time prescriptions of oral griseofulvin suspension were used to estimate annual incidence of tinea capitis and calculate risk ratios. RESULTS: From 1984 through 1993, the incident rate for prescriptions of oral griseofulvin suspension increased by 84.2% for all children, 140.4% for white children, and 209.7% for African-American children. In 1993, incidence rates (per 10,000 enrolled) were 252.1 claimants for African-American children, 23.1 for white, 17.5 for Hispanic, and 14.3 for Asian/Pacific Islander. The highest rate by location was San Francisco County (172.2). In age groups < 5 years and 5 to 9 years, African-American children were 13.1 and 17.6 times more likely to be prescribed griseofulvin than Hispanic children. Since 1987, incidence rates for children 5 to 9 years of age were higher compared with children ages < 5 years. CONCLUSIONS: Tinea capitis is epidemic among California children with higher rates in the northern counties studied. African-American children are the most affected by this epidemic; however, white children have also experienced increased rates.

Wound botulism in California, 1951-1998: recent epidemic in heroin injectors.

California has reported most of the world's wound botulism (WB) cases and nearly three-fourths of the cases reported in the United States. We reviewed the clinical, epidemiologic, and laboratory features of WB. From the first case in 1951, through 1998, a total of 127 cases were identified-93 in the last 5 years. The dramatic increase has been due to an epidemic (of WB) in people who inject black tar heroin. Whereas early cases of WB occurred after gross trauma, all but 1 of the last 102 cases occurred in drug users, primarily those who inject drugs subcutaneously ("skin poppers"). Cases are occurring disproportionately in Hispanics and women. Misdiagnosis and diagnostic delays of up to 64 days have occurred. This unprecedented, ongoing epidemic is now being reported in other states. We discuss the clinical and laboratory features that distinguish botulism from conditions that can mimic it, the relative yield of various diagnostic laboratory tests for botulism, and its treatment.