John A. Painter

Attribution of foodborne illnesses, hospitalizations, and deaths to food commodities by using outbreak data, United States, 1998-2008.

Each year, >9 million foodborne illnesses are estimated to be caused by major pathogens acquired in the United States. Preventing these illnesses is challenging because resources are limited and linking individual illnesses to a particular food is rarely possible except during an outbreak. We developed a method of attributing illnesses to food commodities that uses data from outbreaks associated with both simple and complex foods. Using data from outbreak-associated illnesses for 1998–2008, we estimated annual US foodborne illnesses, hospitalizations, and deaths attributable to each of 17 food commodities. We attributed 46% of illnesses to produce and found that more deaths were attributed to poultry than to any other commodity. To the extent that these estimates reflect the commodities causing all foodborne illness, they indicate that efforts are particularly needed to prevent contamination of produce and poultry. Methods to incorporate data from other sources are needed to improve attribution estimates for some commodities and agents.

Effect of handwashing on child health: a randomised controlled trial.

BACKGROUND More than 3.5 million children aged less than 5 years die from diarrhoea and acute lower respiratory-tract infection every year. We undertook a randomised controlled trial to assess the effect of handwashing promotion with soap on the incidence of acute respiratory infection, impetigo, and diarrhoea. METHODS In adjoining squatter settlements in Karachi, Pakistan, we randomly assigned 25 neighbourhoods to handwashing promotion; 11 neighbourhoods (306 households) were randomised as controls. In neighbourhoods with handwashing promotion, 300 households each were assigned to antibacterial soap containing 1.2% triclocarban and to plain soap. Fieldworkers visited households weekly for 1 year to encourage handwashing by residents in soap households and to record symptoms in all households. Primary study outcomes were diarrhoea, impetigo, and acute respiratory-tract infections (ie, the number of new episodes of illness per person-weeks at risk). Pneumonia was defined according to the WHO clinical case definition. Analysis was by intention to treat. FINDINGS Children younger than 5 years in households that received plain soap and handwashing promotion had a 50% lower incidence of pneumonia than controls (95% CI (-65% to -34%). Also compared with controls, children younger than 15 years in households with plain soap had a 53% lower incidence of diarrhoea (-65% to -41%) and a 34% lower incidence of impetigo (-52% to -16%). Incidence of disease did not differ significantly between households given plain soap compared with those given antibacterial soap. INTERPRETATION Handwashing with soap prevents the two clinical syndromes that cause the largest number of childhood deaths globally-namely, diarrhoea and acute lower respiratory infections. Handwashing with daily bathing also prevents impetigo.

Attributing illness to food.

Identification and prioritization of effective food safety interventions require an understanding of the relationship between food and pathogen from farm to consumption. Critical to this cause is food attribution, the capacity to attribute cases of foodborne disease to the food vehicle or other source responsible for illness. A wide variety of food attribution approaches and data are used around the world, including the analysis of outbreak data, case-control studies, microbial subtyping and source tracking methods, and expert judgment, among others. The Food Safety Research Consortium sponsored the Food Attribution Data Workshop in October 2003 to discuss the virtues and limitations of these approaches and to identify future options for collecting food attribution data in the United States. We summarize workshop discussions and identify challenges that affect progress in this critical component of a risk-based approach to improving food safety.

Combining drinking water treatment and hand washing for diarrhoea prevention, a cluster randomised controlled trial

Objectives  To evaluate the effectiveness of point of use water treatment with flocculent‐disinfectant on reducing diarrhoea and the additional benefit of promoting hand washing with soap.

Nonfoodborne Vibrio Infections: An Important Cause of Morbidity and Mortality in the United States, 1997–2006

BACKGROUND Infections due to Vibrio species cause an estimated 8000 illnesses annually, often through consumption of undercooked seafood. Like foodborne Vibrio infections, nonfoodborne Vibrio infections (NFVI) also result in serious illness, but awareness of these infections is limited. METHODS We analyzed illnesses occuring during the period 1997-2006 that were reported to the Centers for Disease Control and Preventions Cholera and Other Vibrio Illness Surveillance system. The diagnosis of NFVI required isolation of Vibrio species from a patient with contact with seawater. RESULTS Of 4754 Vibrio infections reported, 1210 (25%) were NFVIs. Vibrio vulnificus infections were the most common (accounting for 35% of NFVIs), with 72% of V. vulnificus infections reported from residents of Gulf Coast states. Infections due to V. vulnificus resulted in fever (72% of cases), cellulitis (85%), amputation (10%), and death (17%). V. vulnificus caused 62 NFVI-associated deaths (78%). Recreational activities accounted for 70% of exposures for patients with NFVIs associated with all species. Patients with liver disease were significantly more likely to die as a result of infection (odds ratio, 7.8; 95% confidence interval, 2.8-21.9). Regardless of pre-existing conditions, patients were more likely to die when hospitalization occurred >2 days after symptom onset (odds ratio, 2.9; 95% confidence interval, 1.8-4.8). CONCLUSION NFVIs, especially those due to V. vulnificus, demonstrate high morbidity and mortality. Persons with liver disease should be advised of the risks associated with seawater exposure if a wound is already present or is likely to occur. Clinicians should consider Vibrio species as an etiologic agent in infections occurring in persons with recent seawater exposure, even if the individual was only exposed during recreational marine activities. Immediate antibiotic treatment with aggressive monitoring is advised in suspected cases.

Overseas Screening for Tuberculosis in U.S.-Bound Immigrants and Refugees

BACKGROUND In 2007, a total of 57.8% of the 13,293 new cases of tuberculosis in the United States were diagnosed in foreign-born persons, and the tuberculosis rate among foreign-born persons was 9.8 times as high as that among U.S.-born persons (20.6 vs. 2.1 cases per 100,000 population). Annual arrivals of approximately 400,000 immigrants and 50,000 to 70,000 refugees from overseas are likely to contribute substantially to the tuberculosis burden among foreign-born persons in the United States. METHODS The Centers for Disease Control and Prevention (CDC) collects information on overseas screening for tuberculosis among U.S.-bound immigrants and refugees, along with follow-up evaluation after their arrival in the United States. We analyzed screening and follow-up data from the CDC to study the epidemiology of tuberculosis in these populations. RESULTS From 1999 through 2005, a total of 26,075 smear-negative cases of tuberculosis (i.e., cases in which a chest radiograph was suggestive of active tuberculosis but sputum smears were negative for acid-fast bacilli on 3 consecutive days) and 22,716 cases of inactive tuberculosis (i.e., cases in which a chest radiograph was suggestive of tuberculosis that was no longer clinically active) were diagnosed by overseas medical screening of 2,714,223 U.S.-bound immigrants, representing prevalences of 961 cases per 100,000 persons (95% confidence interval [CI], 949 to 973) and 837 cases per 100,000 persons (95% CI, 826 to 848), respectively. Among 378,506 U.S.-bound refugees, smear-negative tuberculosis was diagnosed in 3923 and inactive tuberculosis in 10,743, representing prevalences of 1036 cases per 100,000 persons (95% CI, 1004 to 1068) and 2838 cases per 100,000 persons (95% CI, 2785 to 2891), respectively. Active pulmonary tuberculosis was diagnosed in the United States in 7.0% of immigrants and refugees with an overseas diagnosis of smear-negative tuberculosis and in 1.6% of those with an overseas diagnosis of inactive tuberculosis. CONCLUSIONS Overseas screening for tuberculosis with follow-up evaluation after arrival in the United States is a high-yield intervention for identifying tuberculosis in U.S.-bound immigrants and refugees and could reduce the number of tuberculosis cases among foreign-born persons in the United States.

The Increasing Burden of Imported Chronic Hepatitis B — United States, 1974–2008

Background Without intervention, up to 25% of individuals chronically infected with hepatitis B virus (HBV) die of late complications, including cirrhosis and liver cancer. The United States, which in 1991 implemented a strategy to eliminate HBV transmission through universal immunization, is a country of low prevalence. Approximately 3,000–5,000 U.S.-acquired cases of chronic hepatitis B have occurred annually since 2001. Many more chronically infected persons migrate to the United States yearly from countries of higher prevalence. Although early identification of chronic HBV infection can reduce the likelihood of transmission and late complications, immigrants are not routinely screened for HBV infection during or after immigration. Methods To estimate the number of imported cases of chronic hepatitis B, we multiplied country-specific prevalence estimates by the yearly number of immigrants from each country during 1974–2008. Results During 1974–2008, 27.9 million immigrants entered the U.S. Sixty-three percent were born in countries of intermediate or high chronic hepatitis B prevalence (range 2%–31%). On average, an estimated 53,800 chronic hepatitis B cases were imported to the U.S. yearly from 2004 through 2008. The Philippines, China, and Vietnam contributed the most imported cases (13.4%, 12.5%, and 11.0%, respectively). Imported cases increased from an estimated low of 105,750 during the period 1974–1977 to a high of 268,800 in 2004–2008. Conclusions Imported chronic hepatitis B cases account for approximately 95% of new U.S. cases. Earlier case identification and management of infected immigrants would strengthen the U.S. strategy to eliminate HBV transmission, and could delay disease progression and prevent some deaths among new Americans.

Illnesses Caused by Marine Toxins

Marine toxins are produced by algae or bacteria and are concentrated in contaminated seafood. Substantial increases in seafood consumption in recent years, together with globalization of the seafood trade, have increased potential exposure to these agents. Marine toxins produce neurological, gastrointestinal, and cardiovascular syndromes, some of which result in high mortality and long-term morbidity. Routine clinical diagnostic tests are not available for these toxins; diagnosis is based on clinical presentation and a history of eating seafood in the preceding 24 h. There is no antidote for any of the marine toxins, and supportive care is the mainstay of treatment. In particular, paralytic shellfish poisoning and puffer fish poisoning can cause death within hours after consuming the toxins and may require immediate intensive care. Rapid notification of public health authorities is essential, because timely investigation may identify the source of contaminated seafood and prevent additional illnesses. Extensive environmental monitoring and sometimes seasonal quarantine of a harvest are employed to reduce the risk of exposure.

Recipes for foodborne outbreaks: a scheme for categorizing and grouping implicated foods.

BACKGROUND To better understand the sources of foodborne illness, we propose a scheme for categorizing foods implicated in investigations of outbreaks of foodborne diseases. Because nearly 2000 foods have been reported as causing outbreaks in the United States, foods must be grouped for meaningful analyses. METHODS We defined a hierarchy of 17 mutually exclusive food commodities. We defined the following three commodity groups from which nearly all food is derived: aquatic animals, land animals, and plants. We defined three commodities in aquatic animals, six in land animals, and eight in plants. We considered each food as a set of ingredients composed of one or more commodities. We defined a simple food as one made of ingredients that are all in one commodity and a complex food as one containing ingredients in more than one commodity. We determined likely ingredients using a panel of epidemiologists and a web-based search process. RESULTS We assigned 1709 (95%) of the 1794 foods implicated in outbreaks of foodborne diseases reported to Centers for Disease Control and Prevention from 1973 to 2006. Of those, 987 (57%) were simple foods and 722 (43%) were complex foods. DISCUSSION This categorization may serve as an input for modeling the attribution of human illness to specific food commodities and could be used by policy makers, health officials, regulatory agencies, and consumer groups to evaluate the contribution of various food commodities to illness.

Persistent Latent Tuberculosis Reactivation Risk in United States Immigrants

RATIONALE Current guidelines limit latent tuberculosis infection (LTBI) evaluation to persons in the United States less than or equal to 5 years based on the assumption that high TB rates among recent entrants are attributable to high LTBI reactivation risk, which declines over time. We hypothesized that high postarrival TB rates may instead be caused by imported active TB. OBJECTIVES Estimate reactivation and imported TB in an immigrant cohort. METHODS We linked preimmigration records from a cohort of California-bound Filipino immigrants during 2001-2010 with subsequent TB reports. TB was likely LTBI reactivation if the immigrant had no evidence of active TB at preimmigration examination, likely imported if preimmigration radiograph was abnormal and TB was reported less than or equal to 6 months after arrival, and likely reactivation of inactive TB if radiograph was abnormal but TB was reported more than 6 months after arrival. MEASUREMENTS AND MAIN RESULTS Among 123,114 immigrants, 793 TB cases were reported. Within 1 year of preimmigration examination, 85% of TB was imported; 6 and 9% were reactivation of LTBI and inactive TB, respectively. Conversely, during Years 2-9 after U.S. entry, 76 and 24% were reactivation of LTBI and inactive TB, respectively. The rate of LTBI reactivation (32 per 100,000) did not decline during Years 1-9. CONCLUSIONS High postarrival TB rates were caused by detection of imported TB through active postarrival surveillance. Among immigrants without active TB at baseline, reported TB did not decline over 9 years, indicating sustained high risk of LTBI reactivation. Revised guidelines should support LTBI screening and treatment more than 5 years after U.S. arrival.