Biomedical subjects
Publications and source records attributed to D L Swerdlow.
Food borne diseases cause a significant burden of illness in the United States. The Food Borne Diseases Active Surveillance Network (FoodNet), established in 1995, continues to monitor the burden and causes of food borne diseases and provide much of the data to address this public health problem.
The epidemiology of foodborne diseases is rapidly changing. In the past 15 years, new foodborne pathogens, such as Campylobacter jejuni and Escherichia coli O157:H7, have emerged as important public health problems. Well-recognized pathogens, such as Salmonella serotype Enteritidis, have increased in prevalence or become associated with new vehicles, and pathogens such as C. jejuni and S. Typhimurium are becoming increasingly resistant to antimicrobial agents. Evolving trends in foodborne diseases are being driven by the same factors that have led to the emergence of other infectious diseases: changes in demographic characteristics of the population, human behavior, industry, and technology and the shift toward a global economy, microbial adaptation, and breakdown in the public health infrastructure. Addressing emerging foodborne disease will require more sensitive and timely surveillance, enhanced methods of laboratory identification and subtyping, and identification of effective prevention and control strategies.
Campylobacter jejuni is the most common food borne bacterial pathogen and leading cause of food borne disease in humans in the United States and other industrialized nations. Approximately four million cases of human campylobacteriosis occur each year in the United States. Although the majority of cases consist of limited diarrheal illness, severe sequelae can affect a small portion of patients with campylobacteriosis that may include reactive arthritis and Guillain-Barré syndrome. Animal reservoirs primarily include poultry (C. jejuni) and swine (C. coli). Pathogen reduction during poultry processing and safe handling of raw poultry in the kitchen are needed to prevent illness.
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Between 23 August and 15 December 1990 an epidemic of cholera affected Mozambican refugees in Malawi causing 1931 cases (attack rate = 2.4%); 86% of patients had arrived in Malawi < 3 months before illness onset. There were 68 deaths (case-fatality rate = 3.5%); most deaths (63%) occurred within 24 h of hospital admission which may have indicated delayed presentation to health facilities and inadequate early rehydration. Mortality was higher in children < 4 years old and febrile deaths may have been associated with prolonged i.v. use. Significant risk factors for illness (P < 0.05) in two case-control studies included drinking river water (odds ratio [OR] = 3.0); placing hands into stored household drinking water (OR = 6.0); and among those without adequate firewood to reheat food, eating leftover cooked peas (OR = 8.0). Toxigenic V. cholerae O1, serotype Inaba, was isolated from patients and stored household water. The rapidity with which newly arrived refugees became infected precluded effective use of a cholera vaccine to prevent cases unless vaccination had occurred immediately upon camp arrival. Improved access to treatment and care of paediatric patients, and increased use of oral rehydration therapy, could decrease mortality. Preventing future cholera outbreaks in Africa will depend on interrupting both waterborne and foodborne transmission of this pathogen.
OBJECTIVES: A 1993 large water-borne outbreak of Salmonella typhimurium infections in Gideon, Mo, a city of 1100 with an unchlorinated community water supply, was investigated to determine the source of contamination and the effectiveness of an order to boil water. METHODS: A survey of household members in Gideon and the surrounding township produced information on diarrheal illness, water consumption, and compliance with the boil water order. RESULTS: More than 650 persons were ill; 15 were hospitalized, and 7 died. Persons consuming city water were more likely to be ill (relative risk [RR] = 9.1, 95% confidence interval [CI] = 2.9, 28.4), and the attack rate increased with increased water consumption. S. typhimurium was recovered from samples taken from a city fire hydrant and a water storage tower. Persons in 31% (30/ 98) of city households had drunk unboiled water after being informed about the boil water order, including 14 individuals who subsequently became ill. Reasons for noncompliance included "not remembering" (44%) and "disbelieving" (25%) the order. CONCLUSIONS: Communities with deteriorating water systems risk widespread illness unless water supplies are properly operated and maintained. Effective education to improve compliance during boil water orders is needed.
In recent years infection caused by Salmonella serotype Enteritidis (SE) phage type 4 has spread through Europe but has been uncommon in the USA. The first recognized outbreak of this strain in the USA occurred in a Chinese restaurant in EI Paso, Texas, in April 1993; no source was identified. In September 1993, a second outbreak caused by SE phage type 4 was associated with the same restaurant. To determine the cause of the second outbreak, we compared food exposures of the 19 patients with that of two control groups. Egg rolls were the only item significantly associated with illness in both analyses (first control group: odds ratio [OR] 8.2, 95% confidence interval [CI] 2.3-31.6; second control group: OR 13.1, 95% CI 2.1-97.0). Retrospective analysis of the April outbreak also implicated egg rolls (OR 32.4, 95% CI 9.1-126.6). Egg roll batter was made from pooled shell eggs and was left at room temperature throughout the day. These two outbreaks of SE phage type 4 likely could have been prevented by using pasteurized eggs and safe food preparation practices.
The epidemiology of foodborne diseases in the United States have changed in recent decades as new pathogens have emerged, the food supply has changed, and the number of people with heightened susceptibility to foodborne diseases has increased. Emerging pathogens are those that have recently increased or are likely to increase within 2 decades. Emergency is often the consequence of changes in some aspect of the social environment. The global economy, for example, has facilitated the rapid transport of perishable foods, increasing the potential for exposure to foodborne pathogens from other parts of the world. Other factors altering foodborne disease patterns are the types of food that people eat, the sources of those foods, and the possible decline in public awareness of safe food preparation practices. Aging, extension of life expectancy for the chronically ill through medical technology, and the AIDS epidemic have increased the public health impact of foodborne diseases because they increase the proportion of the population susceptible to severe illness after infection with a foodborne pathogen. The evolving epidemiology of foodborne diseases must be monitored and understood to implement appropriate prevention technologies.
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We review the epidemiology and prevention of and future research priorities for bacterial enteric infections in persons infected with the human immunodeficiency virus (HIV). HIV-infected persons are more frequently infected with Salmonella, Campylobacter, Listeria, and (possibly) Shigella species than are individuals not infected with HIV. In addition, Salmonella and (possibly) Campylobacter infections are more likely to be severe, recurrent, or persistent and associated with extraintestinal disease when they occur in HIV-infected persons. Infections caused by Shigella and Vibrio species can also result in more serious disease in HIV-infected persons than in those not infected with HIV. Risk of these infections can be reduced with proper precautions, particularly those pertaining to food hygiene, animal contact, and travel. Individuals infected with HIV should be informed of their increased risk of acquiring these diseases and should be counseled on the recommended precautions.
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A household survey in 1991, at the onset of the Latin American cholera epidemic, investigated high attack rates in Trujillo, Peru, and determined the association between blood group O and severe cholera. Of 463 persons in 69 households, 173 (37%) reported diarrhea, 21% required rehydration therapy, and 4% were hospitalized; these treatment requirements greatly exceeded estimates based on other populations. Elevated vibriocidal or antitoxic antibody titers were present in 52% of 321 from whom serum was obtained; 73% were blood group O. Blood group O was strongly associated with severe cholera: Infected persons had more diarrheal stools per day than persons of other blood groups, were more likely to report vomiting and muscle cramps, and were almost eight times more likely to require hospital treatment. Since prevalence of blood group O in Latin America may be the world's highest, estimates of treatment requirements should be increased to prevent unnecessary deaths.
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OBJECTIVE: To describe and determine the source of a large outbreak of Escherichia coli O157:H7 (ECO157) infections in Missouri. DESIGN: A case-control study and a household survey. SETTING: A small city in a rural Missouri township that had an unchlorinated water supply. PATIENTS: Case patients were residents of or visitors to Burdine Township with bloody diarrhea or diarrhea and abdominal cramps occurring between 15 December 1989 and 20 January 1990. MEASUREMENTS: Escherichia coli O157 was isolated from 21 stool specimens. All isolates were resistant to sulfisoxazole, tetracycline, and streptomycin; produced Shiga-like toxins I and II; and had one 60-megadalton plasmid. RESULTS: Among the 243 case patients, 86 had bloody stools, 32 were hospitalized, 4 died, and 2 had the hemolytic uremic syndrome. In the case-control study, no food was associated with illness, but ill persons had drunk more municipal water than had controls (P = 0.04). The survey showed that, during the peak of the outbreak, bloody diarrhea was 18.2 times more likely to occur in persons living inside the city and using municipal water than in persons living outside the city and using private well water (P = 0.001). Shortly before the peak of the outbreak, 45 water meters were replaced, and two water mains ruptured. The number of new cases declined rapidly after residents were ordered to boil water and after chlorination of the water supply. CONCLUSIONS: This was the largest outbreak of ECO157 infections, the first due to a multiply resistant organism, and the first shown to be transmitted by water. System-wide chlorination as well as hyperchlorination during repairs might have prevented this outbreak. Both bloody and nonbloody diarrhea may be common manifestations of this infection, which is probably underdiagnosed because of the failure of routine stool cultures to identify the organism. Cities with deteriorating water systems using untreated water risk widespread illness from contaminated drinking water.
The epidemic of cholera that began in Peru in January, 1991, marked the first such epidemic in South America this century. Subsequently, over 533,000 cases and 4700 deaths have been reported from nineteen countries in that hemisphere. We investigated the epidemic in Trujillo, the second largest city in Peru. Trujillo's water supply was unchlorinated and water contamination was common. Suspect cholera cases were defined as persons presenting to a health facility with acute diarrhoea between Feb 1, and March 31, 1991. We studied a cohort of 150 patients who had been admitted to hospital and conducted a matched case-control study with 46 cases and 65 symptom-free and serologically uninfected controls; we also carried out a water quality study. By March 31, 1991, 16,400 cases of suspected cholera (attack rate 2.6%), 6673 hospital admissions, and 71 deaths (case-fatality rate 0.4%) had been reported in the province of Trujillo. 79% of stool cultures of patients with diarrhoea presenting to a single hospital yielded Vibrio cholerae O1. In the case-control study, drinking unboiled water (odds ratio [OR] 3.1, 95% confidence interval [CI] 1.3-7.3), drinking water from a household water storage container in which hands had been introduced into the water (4.2, 1.2-14.9), and going to a fiesta (social event) (3.6, 1.1-11.1) were associated with illness. The water quality study showed progressive contamination during distribution and storage in the home: faecal coliform counts were highest in water from household storage containers and lowest in city well water. V cholerae O1, biotype El Tor, serotype Inaba, was isolated from three city water samples. Cholera control measures in Trujillo should focus on treatment of water and prevention of contamination during distribution and in the home. Trujillo's water and sanitation problems are common in South America; similar control measures are needed throughout the continent to prevent spread of epidemic cholera.
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