Prevention of Vibrio vulnificus infections. Assessment of regulatory educational strategies.

CONTEXT: Vibrio vulnificus-related disease caused by eating contaminated raw oysters prompted California to implement regulatory educational initiatives in 1991. OBJECTIVE: To assess California guidelines and education efforts with regard to the prevention of V. vulnificus infections in Los Angeles County and to evaluate compliance with state regulations mandating posting of warning signs concerning risks of eating raw oysters. DESIGN: Review of epidemiologic investigations of V. vulnificus infections in Los Angeles County between 1993 and 1995; telephone interviews of patients or surrogates; and a survey of restaurants serving raw oysters in Los Angeles County. SETTING: General community. MAIN OUTCOME MEASURES: Prior warning of patients and posting of warning signs in restaurants. RESULTS: Recent cases of V. vulnificus infections in Los Angeles County suggest that a unique, vulnerable group (uninsured Hispanic men with viral or alcoholic liver disease) has not been reached through education efforts. Of a total of 11 cases, information regarding being warned about the hazard of eating raw shellfish was available for 8; of these, only 1 case was reported as having been warned, but he had misunderstood the preventive message. Warning signs were not posted adequately in more than 50% of restaurants surveyed and one third of these establishments had signs in English only. Warnings were never located on dining tables and rarely included in menus. CONCLUSION: A more effective strategy is required to prevent V.vulnificus infections in Los Angeles County.

Transmission of hepatitis B virus to multiple patients from a surgeon without evidence of inadequate infection control.

BACKGROUND: Although about 1 percent of surgeons are infected with hepatitis B virus (HBV), transmission from surgeons to patients is thought to be uncommon. In July 1992, a 47-year-old woman became ill with acute hepatitis B after undergoing a thymectomy in which a thoracic-surgery resident who had had acute hepatitis B six months earlier assisted. METHODS: To determine whether the surgeon transmitted HBV to this patient and others, we conducted chart reviews, interviews, and serologic testing of thoracic-surgery patients at the two hospitals where the surgeon worked from July 1991 to July 1992. Hepatitis B surface antigen (HBsAg) subtypes and DNA sequences from the surgeon and from infected patients were determined. RESULTS: Of 144 susceptible patients in whose surgery the infected surgeon participated, 19 had evidence of recent HBV infection (13 percent). One of the hospitals was selected for additional study, and none of the 124 susceptible patients of the other thoracic surgeons at this hospital had evidence of recent HBV infection (relative risk, infinity; 95 percent confidence interval, 4.7 to infinity). No evidence was found for any common source of HBV other than the infected surgeon. The HBsAg subtype and the partial HBV DNA sequences from the surgeon were identical to those in the infected patients. Transmission of the infection was associated with cardiac transplantation (relative risk, 4.9; 95 percent confidence interval, 1.5 to 15.5) but not with other surgical procedures. The surgeon was positive for hepatitis B e antigen and had a high serum HBV DNA concentration (15 ng per milliliter). Our investigations identified no deficiencies in the surgeon's infection-control practices. CONCLUSIONS: In this outbreak there was surgeon-to-patient HBV transmission despite apparent compliance with recommended infection-control practices. We could not identify any specific events that led to transmission.

An outbreak of cholera from food served on an international aircraft.

In February 1992, an outbreak of cholera occurred among persons who had flown on a commercial airline flight from South America to Los Angeles. This study was conducted to determine the magnitude and the cause of the outbreak. Passengers were interviewed and laboratory specimens were collected to determine the magnitude of the outbreak. A case-control study was performed to determine the vehicle of infection. Seventy-five of the 336 passengers in the United States had cholera; 10 were hospitalized and one died. Cold seafood salad, served between Lima, Peru and Los Angeles, California was the vehicle of infection (odds ratio, 11.6; 95% confidence interval, 3.3-44.5). This was the largest airline-associated outbreak of cholera ever reported and demonstrates the potential for airline-associated spread of cholera from epidemic areas to other parts of the world. Physicians should obtain a travel history and consider cholera in patients with diarrhoea who have travelled from cholera-affected countries. This outbreak also highlights the risks associated with eating cold foods prepared in cholera-affected countries.

Swimming-associated cryptosporidiosis.

In July and August 1988, an outbreak of gastroenteritis affected 44 of 60 (73%) persons from 5 separate swimming groups who had used the same swimming pool in Los Angeles. Cryptosporidium was identified in 5 of 8 (63%) stool specimens, and the clinical picture was consistent with Cryptosporidium infection. Resistance of Cryptosporidium to chlorine, an inadequately maintained pool filtration system, repeated exposure to pool water, and possible continuing pool contamination may have contributed to ongoing transmission. Cryptosporidium should be considered a potential etiologic agent of gastroenteritis associated with recreational water use.

An outbreak of bacteremic Campylobacter jejuni infection.

During September 1980, an outbreak of bacteremic Campylobacter jejuni infection occurred in metropolitan Los Angeles. The outbreak was recognized when blood cultures obtained from 11 previously healthy persons with acute febrile illnesses (characterized in over 80% by fever, diarrhea, and headaches) were positive for C. jejuni. All recovered after an illness that lasted a mean of 8 days. A surveillance system failed to reveal a concomitant outbreak of gastroenteritis. Isolates had identical biochemical characteristics, susceptibility patterns to antimicrobial agents, and serotypes. Isolates from 2 patients were found to be susceptible to bactericidal activity of normal human serum. When bacteremic case-patients were matched with healthy controls, a significant association (p less than 0.05, odds ratio 10) between illness and consumption of processed turkey was established. Although turkey was not available for culture, and processing of turkey theoretically destroys Campylobacter, turkey carcasses are known to be heavily contaminated with the pathogen.

Salmonellosis outbreak on transatlantic flights; foodborne illness on aircraft: 1947-1984.

In March 1984, 186 cases of gastroenteritis due to Salmonella enteritidis were reported after 29 flights to the United States on an international airline. An estimated 2,747 passengers on flights to the United States were affected. Illness was associated with flying supersonic or first class (odds ratio = 15, p less than 0.001). Eating food from the first-class menu was associated with illness (p = 0.09), and eating a tourist-class entree was protective (p less than 0.01). In 23 reported outbreaks of foodborne illness on aircraft, Salmonella has been the most common pathogen (seven outbreaks), followed by Staphylococcus (five outbreaks), and Vibrio species (five outbreaks). Outbreaks are most often the result of an improper temperature for preparation or for holding food in the flight kitchens. Serving the flight crew meals from one kitchen carries the risk that the entire crew will become ill.