Antimicrobial-resistant nontyphoidal Salmonella is associated with excess bloodstream infections and hospitalizations

BACKGROUND

Nontyphoidal Salmonella is a leading cause of foodborne illness. Few studies have explored the health consequences of antimicrobial-resistant Salmonella.

METHODS

The National Antimicrobial Resistance Monitoring System (NARMS) performs susceptibility testing on nontyphoidal Salmonella isolates. The Foodborne Diseases Active Surveillance Network (FoodNet) ascertains outcomes for patients with culture-confirmed Salmonella infection, in 9 states, each of which participates in NARMS. We analyzed the frequency of bloodstream infection and hospitalization among patients with resistant infections. Isolates defined as resistant to a clinically important agent were resistant to 1 or more of the following agents: ampicillin, ceftriaxone, ciprofloxacin, gentamicin, and/or trimethoprim-sulfamethoxazole.

RESULTS

During 1996-2001, NARMS received 7370 serotyped, nontyphoidal Salmonella isolates from blood or stool. Bloodstream infection occurred more frequently among patients infected with an isolate resistant to > or =1 clinically important agent (adjusted odds ratio [OR], 1.6; 95% confidence interval [CI], 1.2-2.1), compared with patients with pansusceptible infection. During 1996-2001, FoodNet staff ascertained outcomes for 1415 patients who had isolates tested in NARMS. Hospitalization with bloodstream infection occurred more frequently among patients infected with an isolate resistant to > or =1 clinically important agent (adjusted OR, 3.1; 95% CI, 1.4-6.6), compared with patients with pansusceptible infection.

CONCLUSIONS

Patients with antimicrobial-resistant nontyphoidal Salmonella infection were more likely to have bloodstream infection and to be hospitalized than were patients with pansusceptible infection. Mitigation of antimicrobial resistance in Salmonella will likely benefit human health.

Barriers to Creutzfeldt-Jakob disease autopsies, California

Creutzfeldt-Jakob disease (CJD) surveillance relies on autopsy and neuropathologic evaluation. The 1990–2000 CJD autopsy rate in California was 21%. Most neurologists were comfortable diagnosing CJD (83%), but few pathologists felt comfortable diagnosing CJD (35%) or performing autopsy (29%). Addressing obstacles to autopsy is necessary to improve CJD surveillance.

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.

SARS and common viral infections

In California, molecular testing was useful in decreasing suspicion for severe acute respiratory syndrome (SARS), by detecting common respiratory pathogens (influenza A/B, human metapneumovirus, picornavirus, Mycoplasma pneumoniae, Chlamydia spp., parainfluenza virus, respiratory syncytial virus, and adenovirus) in 23 (45%) of 51 patients with suspected SARS and 9 (47%) of 19 patients with probable SARS.

Multistate shigellosis outbreak and commercially prepared food, United States

In 2000, shigellosis traced to a commercially prepared dip developed in 406 persons nationwide. An ill employee may have inadvertently contaminated processing equipment. This outbreak demonstrates the vulnerability of the food supply and how infectious organisms can rapidly disseminate through point-source contamination of a widely distributed food item.

Antimicrobial resistance among Campylobacter strains, United States, 1997-2001

We summarize antimicrobial resistance surveillance data in human and chicken isolates of Campylobacter. Isolates were from a sentinel county study from 1989 through 1990 and from nine state health departments participating in National Antimicrobial Resistance Monitoring System for enteric bacteria (NARMS) from 1997 through 2001. None of the 297 C. jejuni or C. coli isolates tested from 1989 through 1990 was ciprofloxacin-resistant. From 1997 through 2001, a total of 1,553 human Campylobacter isolates were characterized: 1,471 (95%) were C. jejuni, 63 (4%) were C. coli, and 19 (1%) were other Campylobacter species. The prevalence of ciprofloxacin-resistant Campylobacter was 13% (28 of 217) in 1997 and 19% (75 of 384) in 2001; erythromycin resistance was 2% (4 of 217) in 1997 and 2% (8 of 384) in 2001. Ciprofloxacin-resistant Campylobacter was isolated from 10% of 180 chicken products purchased from grocery stores in three states in 1999. Ciprofloxacin resistance has emerged among Campylobacter since 1990 and has increased in prevalence since 1997.

Prolonged diarrhea due to ciprofloxacin-resistant campylobacter infection

BACKGROUND

Campylobacter causes >1 million infections annually in the United States. Fluoroquinolones (e.g., ciprofloxacin) are used to treat Campylobacter infections in adults. Although human infections with ciprofloxacin-resistant Campylobacter have become increasingly common, the human health consequences of such infections are not well described.

METHODS

A case-control study of persons with sporadic Campylobacter infection was conducted within 7 FoodNet sites during 1998-1999. The E-test system (AB Biodisk) was used to test for antimicrobial susceptibility to ciprofloxacin; ciprofloxacin resistance was defined as a ciprofloxacin minimum inhibitory concentration of > or =4 microg/mL. We conducted a case-comparison study of interviewed persons who had an isolate tested.

RESULTS

Of 858 isolates tested, 94 (11%) were ciprofloxacin resistant. Among 290 persons with Campylobacter infection who did not take antidiarrheal medications, persons with ciprofloxacin-resistant infection had a longer mean duration of diarrhea than did persons with ciprofloxacin-susceptible infection (9 vs. 7 days [P=.04]). This difference was even more pronounced among the 63 persons who did not take antidiarrheal medications or antimicrobial agents (12 vs. 6 days [P=.04]). In a multivariable analysis-of-variance model, the persons with ciprofloxacin-resistant infection had a longer mean duration of diarrhea than did the persons with ciprofloxacin-susceptible infection (P=.01); this effect was independent of foreign travel. The association between ciprofloxacin resistance and prolonged diarrhea is consistent across a variety of analytical approaches.

CONCLUSIONS

Persons with ciprofloxacin-resistant Campylobacter infection have a longer duration of diarrhea than do persons with ciprofloxacin-susceptible Campylobacter infection. Additional efforts are needed to preserve the efficacy of fluoroquinolones.

Risk factors for sporadic cryptosporidiosis among immunocompetent persons in the United States from 1999 to 2001

Many studies have evaluated the role of Cryptosporidium spp. in outbreaks of enteric illness, but few studies have evaluated sporadic cryptosporidiosis in the United States. To assess the risk factors for sporadic cryptosporidiosis among immunocompetent persons, a matched case-control study was conducted in seven sites of the Foodborne Diseases Active Surveillance Network (FoodNet) involving 282 persons with laboratory-identified cryptosporidiosis and 490 age-matched and geographically matched controls. Risk factors included international travel (odds ratio [OR] = 7.7; 95% confidence interval [95% CI] = 2.7 to 22.0), contact with cattle (OR = 3.5; 95% CI = 1.8 to 6.8), contact with persons >2 to 11 years of age with diarrhea (OR = 3.0; 95% CI = 1.5 to 6.2), and freshwater swimming (OR = 1.9; 95% CI = 1.049 to 3.5). Eating raw vegetables was protective (OR = 0.5; 95% CI = 0.3 to 0.7). This study underscores the need for ongoing public health education to prevent cryptosporidiosis, particularly among travelers, animal handlers, child caregivers, and swimmers, and the need for further assessment of the role of raw vegetables in cryptosporidiosis.

Outbreak of Necrotizing Fasciitis Due to Clostridium sordellii among Black-Tar Heroin Users

In California, black tar heroin (BTH) use among injection drug users (IDUs) has resulted in an increased number of cases of wound botulism due to Clostridium botulinum, tetanus due to Clostridium tetani, and necrotizing soft-tissue infections due to a variety of clostridia. From December 1999 to April 2000, nine IDUs in Ventura County, California, developed necrotizing fasciitis; 4 died. Cultures of wound specimens from 6 case patients yielded Clostridium sordellii. Some of the patients appeared to have the toxic shock syndrome previously reported to be characteristic of toxin-mediated C. sordellii infection, which is characterized by hypotension, marked leukocytosis, and hemoconcentration. The suspected source of this outbreak was contaminated BTH that was injected subcutaneously or intramuscularly ("skin popped"). This outbreak of C. sordellii infection serves as another example of how BTH can potentially serve as a vehicle for transmitting severe and often deadly clostridial infections, and reinforces the need to educate IDUs and clinicians about the risks associated with skin popping of BTH.

Persistent diarrhea, arthritis, and other complications of enteric infections: a pilot survey based on California FoodNet surveillance, 1998-1999

Numerous complications of enteric infections have been described, including persistent diarrhea, reactive arthritis, and Guillain-Barre syndrome. We determined the frequency of self-reported complications of enteric infections in a pilot study in the California site of the Foodborne Diseases Active Surveillance Network. From 1 April 1998 through 31 March 1999, active surveillance identified 1454 infections in Alameda and San Francisco counties, of which 52% were Campylobacter infections, 22% were Salmonella infections, 15% were Shigella infections, 6% were Cryptosporidium infections, 2% were Escherichia coli O157:H7 infections, 2% were Yersinia infections, and 1% were Vibrio infections. We mailed surveys to 1331 eligible participants, and 571 (43%) were returned. A new health problem following infection was reported by 153 (27%) of the respondents: 12 (8%) reported new onset of joint pain and 53 (35%) reported new gastrointestinal symptoms, of whom 38 reported persistent diarrhea, including 2 who reported irritable bowel syndrome. Three respondents reported hair loss. The frequency, nature, and etiology of these complications merit further investigation.

Invasive Salmonella infections in the United States, FoodNet, 1996-1999: incidence, serotype distribution, and outcome

Invasive Salmonella infections are severe and can be life threatening. We analyzed population-based data collected during 1996-1999 by the Foodborne Diseases Active Surveillance Network (FoodNet), to determine the incidences, infecting serotypes, and outcomes of invasive Salmonella infection. We found that the mean annual incidence of invasive salmonellosis was 0.9 cases/100,000 population and was highest among infants (7.8 cases/100,000). The incidence was higher among men than women (1.2 vs. 0.7 cases/100,000; P<.001) and higher among blacks, Asians, and Hispanics than among whites (2.5, 2.0, and 1.3 cases/100,000 population, respectively, vs. 0.4 cases/100,000; all P<.001). Seventy-four percent of cases were caused by 8 Salmonella serotypes: Typhimurium, Typhi, Enteritidis, Heidelberg, Dublin, Paratyphi A, Choleraesuis, and Schwarzengrund. Of 540 persons with invasive infection, 386 (71%) were hospitalized and 29 (5%) died; 13 (45%) of the deaths were among persons aged > or =60 years. Invasive Salmonella infections are a substantial health problem in the United States and contribute to hospitalizations and deaths.

Prior antimicrobial agent use increases the risk of sporadic infections with multidrug-resistant Salmonella enterica serotype Typhimurium: a FoodNet case-control study, 1996-1997

Several strains of multidrug-resistant (MDR) Salmonella serotype Typhimurium, including MDR S. Typhimurium definitive type 104, cause almost 10% of Salmonella infections among humans in the United States. To determine the risk factors for acquiring sporadic MDR S. Typhimurium infection, we conducted a population-based, case-control study using data from the Foodborne Diseases Active Surveillance Network (FoodNet) during 1996-1997. S. Typhimurium isolates from 5 FoodNet surveillance areas (California, Connecticut, Georgia, Minnesota, and Oregon) were tested for antimicrobial resistance and phage typing. Telephone interviews were conducted with ill persons and matched control subjects. Compared with both control subjects and patients infected with pansensitive strains of S. Typhimurium, patients with MDR S. Typhimurium infection were significantly more likely to have received an antimicrobial agent, particularly an agent to which the Salmonella isolate was resistant, during the 4 weeks preceding illness onset. Prudent antimicrobial agent use among humans and among veterinarians and food-animal producers is necessary to reduce the burden of drug-resistant salmonellosis in humans.

Farm visits and undercooked hamburgers as major risk factors for sporadic Escherichia coli O157:H7 infection: data from a case-control study in 5 FoodNet sites

In 1996, active surveillance in 5 Foodborne Diseases Active Surveillance Network (FoodNet) sites revealed up to a 9-fold difference in Escherichia coli O157:H7 (O157) infection incidence between sites. A matched case-control study of sporadic O157 cases was conducted in these sites from March 1996 through April 1997. Case subjects were patients with non-outbreak-related diarrheal illness who had O157 isolated from their stool samples. Control subjects were healthy persons matched by age and telephone number exchange. Overall, 196 case patients and 372 controls were enrolled. O157 infections were associated with farm exposure, cattle exposure, eating a pink hamburger (both at home and away from home), eating at a table-service restaurant, using immunosuppressive medication, and obtaining beef through a private slaughter arrangement. Variations in cattle exposures may explain a part of the regional variability of O157 infection incidence. O157 control measures should focus on reducing risks associated with eating undercooked hamburger, dining at table-service restaurants, and farm exposures.

Epidemiology of sporadic Campylobacter infection in the United States and declining trend in incidence, FoodNet 1996-1999

Campylobacter species are a leading cause of foodborne illness in the United States, but few population-based data describing patterns and trends of disease are available. We summarize data on culture-confirmed cases of Campylobacter infection reported during 1996-1999 to the Foodborne Diseases Active Surveillance Network (FoodNet) system. The average annual culture-confirmed incidence was 21.9 cases/100,000 population, with substantial site variation (from 43.8 cases/100,000 population in California to 12.2 cases/100,000 population in Georgia). The incidence among male subjects was consistently higher than that among female subjects in all age groups. The incidence trended downward over the 4 years, with incidences of 23.6, 25.2, 21.4, and 17.5 cases/100,000 population for 1996-1999, respectively--a 26% overall decrease. This trend was sharpest and most consistent in California. Overall, we estimate that ~2 million people were infected with Campylobacter in the United States each year during this time period. Although the number of Campylobacter infections appears to have decreased in the United States during 1996-1999, the disease burden remains significant, which underscores the need to better understand how the disease is transmitted.

Fluoroquinolone‐ResistantCampylobacterInfections: Eating Poultry Outside of the Home and Foreign Travel Are Risk Factors

A 12-month, population-based, case-control study of Campylobacter infections was conducted at Foodborne Disease Active Surveillance Network surveillance areas during 1998-1999. Of 858 Campylobacter isolates tested for antimicrobial susceptibility to the fluoroquinolone ciprofloxacin, 94 (11%) were resistant. Travel outside of the United States was reported by 27 (42%) of 64 patients with fluoroquinolone-resistant Campylobacter infection and by 51 (9%) of 582 patients with fluoroquinolone-susceptible Campylobacter infection (odds ratio [OR], 7.6; 95% confidence interval [CI], 4.3-13.4). When patients with domestically acquired fluoroquinolone-resistant Campylobacter infection were compared with matched healthy control subjects in a multivariate analysis, those infected were 10 times more likely to have eaten chicken or turkey cooked at a commercial establishment (18 [55%] of 33 case patients vs. 7 [21%] of 33 controls; matched OR, 10.0; 95% CI, 1.3-78). Although travel outside of the United States was associated with fluoroquinolone-resistant Campylobacter infection, most infections among study participants were domestically acquired. This study provides additional evidence that poultry is an important source of domestically acquired fluoroquinolone-resistant Campylobacter infection. Control measures should include efforts to improve food handling in commercial establishments.

Hospitalizations and Deaths Due toSalmonellaInfections, FoodNet, 1996–1999

Nontyphoidal Salmonella causes a higher proportion of food-related deaths annually than any other bacterial pathogen in the United States. We reviewed 4 years (1996-1999) of population-based active surveillance data on laboratory-confirmed Salmonella infections from the Emerging Infections Program's Foodborne Diseases Active Surveillance Network (FoodNet), to determine the rates of hospitalization and death associated with Salmonella infection. Overall, 22% of infected persons were hospitalized, with the highest rate (47%) among persons aged >60 years. Fifty-eight deaths occurred, for an estimated annual incidence of 0.08 deaths/100,000 population. These deaths accounted for 38% of all deaths reported through FoodNet from 1996 through 1999, and they occurred primarily among adults with serious underlying disease. Although Salmonella infection was seldom listed as a cause of death on hospital charts and death certificates, our chart review suggests that Salmonella infection contributed to these deaths.

The clinical management and outcome of nail salon-acquired Mycobacterium fortuitum skin infection

Nontuberculous mycobacterial infections are becoming more common. Recently, Mycobacterium fortuitum and other rapidly growing mycobacteria have been found to cause severe skin and soft-tissue infections in association with nail salon whirlpool footbaths. We recently investigated a large outbreak of M. fortuitum furunculosis among women who received pedicures at a single nail salon. To better define the clinical course of such infections, we collected clinical details from physicians who were treating outbreak patients. We constructed multivariable linear models to evaluate the effect of antibiotic treatment on disease duration. Sixty-one patients were included in the investigation. The mean disease duration was 170 days (range, 41-336 days). Forty-eight persons received antibiotic therapy for a median period of 4 months (range, 1-6 months), and 13 persons were untreated. Isolates were most susceptible to ciprofloxacin and minocycline. Early administration of therapy was associated with shorter duration of disease only in persons with multiple boils (P<.01). One untreated, healthy patient had lymphatic disease dissemination.

Consumer attitudes and use of antibiotics

Recent antibiotic use is a risk factor for infection or colonization with resistant bacterial pathogens. Demand for antibiotics can be affected by consumers' knowledge, attitudes, and practices. In 1998-1999, the Foodborne Diseases Active Surveillance Network (FoodNet( conducted a population-based, random-digit dialing telephone survey, including questions regarding respondents' knowledge, attitudes, and practices of antibiotic use. Twelve percent had recently taken antibiotics; 27% believed that taking antibiotics when they had a cold made them better more quickly, 32% believed that taking antibiotics when they had a cold prevented more serious illness, and 48% expected a prescription for antibiotics when they were ill enough from a cold to seek medical attention. These misguided beliefs and expectations were associated with a lack of awareness of the dangers of antibiotic use; 58% of patients were not aware of the possible health dangers. National educational efforts are needed to address these issues if patient demand for antibiotics is to be reduced.

Is drinking water a risk factor for endemic cryptosporidiosis? A case-control study in the immunocompetent general population of the San Francisco Bay Area

BACKGROUND

Cryptosporidiosis, caused by Cryptosporidium, is an enteric illness that has received much attention as an infection of immunocompromised persons as well as in community outbreaks (frequently waterborne). There are, however, no studies of the risk factors for sporadic community-acquired cryptosporidiosis in the immunocompetent US population. We undertook a case-control study in the San Francisco Bay Area as part of a national study sponsored by the Centers for Disease Control and Prevention to ascertain the major routes of transmission for endemic cryptosporidiosis, with an emphasis on evaluating risk from drinking water.

METHODS

Cases were recruited from a population-based, active surveillance system and age-matched controls were recruited using sequential random-digit dialing. Cases (n = 26) and controls (n = 62) were interviewed by telephone using a standardized questionnaire that included information about the following exposures: drinking water, recreational water, food items, travel, animal contact, and person-to-person fecal contact, and (for adults) sexual practices.

RESULTS

In multivariate conditional logistic regression analyses no significant association with drinking water was detected. The major risk factor for cryptosporidiosis in the San Francisco Bay Area was travel to another country (matched odds ratio [95% confidence interval]: 24.1 [2.6, 220]).

CONCLUSION

The results of this study do not support the hypothesis that drinking water is an independent risk factor for cryptosporidiosis among the immunocompetent population. These findings should be used to design larger studies of endemic cryptosporidiosis to elucidate the precise mechanisms of transmission, whether waterborne or other.

Epidemic and sporadic cases of nontuberculous mycobacterial keratitis associated with laser in situ keratomileusis

PURPOSE

To report national case-finding results for nontuberculous mycobacterial keratitis and describe its association with laser in situ keratomileusis (LASIK).

DESIGN

Enhanced passive disease reporting.

METHODS

In April 2001, we investigated a California cluster of Mycobacterium chelonae keratitis associated with hyperopic LASIK using a contact lens mask. To identify other possibly related cases, the American Academy of Ophthalmology e-mailed its members asking them to report recent cases of nontuberculous mycobacterial keratitis to the Centers for Disease Control and Prevention.

RESULTS

Forty-three additional cases of keratitis were reported (onsets between August 2000 and June 2001). Of these, 31 occurred as part of two unrelated LASIK-associated outbreaks. The 12 other reported cases occurred in sporadic fashion. Of the latter cases, 4 were associated with LASIK surgery. None of the reported cases were related to the M. chelonae cluster in California.

CONCLUSIONS

Laser in situ keratomileusis-associated keratitis with nontuberculous mycobacteria may be more common than previously known.

Endemic cryptosporidiosis and exposure to municipal tap water in persons with acquired immunodeficiency syndrome (AIDS): a case-control study

BACKGROUND

In persons with acquired immunodeficiency syndrome (AIDS), Cryptosporidium parvum causes a prolonged, severe diarrheal illness to which there is no effective treatment, and the risk of developing cryptosporidiosis from drinking tap water in non-outbreak settings remains uncertain. To test the hypothesis that drinking tap water was associated with developing cryptosporidiosis, we conducted a matched case-control study among persons with AIDS in San Francisco.

METHODS

Among patients reported to the San Francisco AIDS Registry from May 1996 through September 1998, we compared patients who developed cryptosporidiosis to those who did not. Cases were individually matched to controls based on age, sex, race/ethnicity, CD4+ T lymphocyte count, date of CD4+ count, and date of case diagnosis. Population attributable fractions (PAFs) were calculated.

RESULTS

The study consisted of 49 cases and 99 matched controls. In the multivariable analysis with adjustments for confounders, tap water consumption inside and outside the home at the highest exposure categories was associated with the occurrence of cryptosporidiosis (inside the home: odds ratio (OR), 6.76; 95% CI 1.37-33.5, and outside the home: OR 3.16; 95% CI 1.23-8.13). The PAF was 85%; that is, the proportion of cases of cryptosporidiosis in San Francisco AIDS patients attributable to tap water consumption could have been as high as 85%.

CONCLUSIONS

Although the results from this observational study cannot be considered definitive, until there is more data, we recommend persons with AIDS, especially those with compromised immune systems, consider avoiding tap water.

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.

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.

Exposure to rodents and rodent-borne viruses among persons with elevated occupational risk

Persons who have frequent contact with rodents as part of their occupation may be at increased risk of exposure to rodent-borne viruses such as Sin Nombre virus (SNV), the agent of hantavirus pulmonary syndrome, and Whitewater Arroyo virus (WWA), a New World arenavirus. Eighty-one persons with possible occupational exposure to rodents completed questionnaires and provided specimens for serologic testing. Seventy-two participants reported handling rodents as part of their job. The mean total number of rodents handled during participants' careers was approximately 2200. IgG antibody to lymphocytic choriomeningitis virus was detected in serum from one (1.2%) participant. IgG antibody to SNV, WWA, and Amapari viruses was not detected in any of the serum specimens. Despite considerable exposure to rodents, participants did not have significant serological evidence of exposure to rodent-borne viruses.

Population-based trends in pediatric hemolytic uremic syndrome in California, 1994-1999: substantial underreporting and public health implications

This paper describes the epidemiology of childhood hemolytic uremic syndrome (HUS) in California, for which hospitalization data were used, and the proportion of cases reported to public health authorities. HUS discharge data for children < or =17 years of age were extracted from the population-based California Patient Discharge Data Set for 1994-1999 and were linked electronically with HUS reports to public health authorities. Incidence rates per 100,000 children were calculated. The authors identified 585 HUS hospitalizations; 369 were incident cases. The average HUS incidence rate was 0.67 (95% confidence interval: 0.61, 0.74); rates rose modestly from 1994 (0.59, 95% confidence interval: 0.44, 0.78) to 1997 (0.80, 95% confidence interval: 0.63, 10.0) and decreased modestly thereafter (0.59, 95% confidence interval: 0.45, 0.77). Rates were highest for northern California children < or =5 years of age (1.85, 95% confidence interval: 1.55, 2.19). The hospital case-fatality rate was 2.7% (95% confidence interval: 1.1, 4.4); the median charge was $39,500 per child. Only 43.9% of HUS cases in the California Patient Discharge Data Set were reported to public health authorities. Despite heightened efforts to control Shiga toxin-producing Escherichia coli exposures (the predominant cause of childhood HUS in the United States), HUS incidence rates remained relatively stable in California. Reporting HUS cases to public health authorities is important for disease control.