Ian T Williams

Kenya Centers for Disease Control and Prevention, Kisumu, Nyanza Province, Kenya

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Publications (25)280.06 Total impact

  • Article: Salmonella typhimurium infections associated with peanut products.
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    ABSTRACT: Contaminated food ingredients can affect multiple products, each distributed through various channels and consumed in multiple settings. Beginning in November 2008, we investigated a nationwide outbreak of salmonella infections. A case was defined as laboratory-confirmed infection with the outbreak strain of Salmonella Typhimurium occurring between September 1, 2008, and April 20, 2009. We conducted two case-control studies, product "trace-back," and environmental investigations. Among 714 case patients identified in 46 states, 166 (23%) were hospitalized and 9 (1%) died. In study 1, illness was associated with eating any peanut butter (matched odds ratio, 2.5; 95% confidence interval [CI], 1.3 to 5.3), peanut butter-containing products (matched odds ratio, 2.2; 95% CI, 1.1 to 4.7), and frozen chicken products (matched odds ratio, 4.6; 95% CI, 1.7 to 14.7). Investigations of focal clusters and single cases associated with nine institutions identified a single institutional brand of peanut butter (here called brand X) distributed to all facilities. In study 2, illness was associated with eating peanut butter outside the home (matched odds ratio, 3.9; 95% CI, 1.6 to 10.0) and two brands of peanut butter crackers (brand A: matched odds ratio, 17.2; 95% CI, 6.9 to 51.5; brand B: matched odds ratio, 3.6; 95% CI, 1.3 to 9.8). Both cracker brands were made from brand X peanut paste. The outbreak strain was isolated from brand X peanut butter, brand A crackers, and 15 other products. A total of 3918 peanut butter-containing products were recalled between January 10 and April 29, 2009. Contaminated peanut butter and peanut products caused a nationwide salmonellosis outbreak. Ingredient-driven outbreaks are challenging to detect and may lead to widespread contamination of numerous food products.
    New England Journal of Medicine 08/2011; 365(7):601-10. · 53.30 Impact Factor
  • Article: 2008 outbreak of Salmonella Saintpaul infections associated with raw produce.
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    ABSTRACT: Raw produce is an increasingly recognized vehicle for salmonellosis. We investigated a nationwide outbreak that occurred in the United States in 2008. We defined a case as diarrhea in a person with laboratory-confirmed infection with the outbreak strain of Salmonella enterica serotype Saintpaul. Epidemiologic, traceback, and environmental studies were conducted. Among the 1500 case subjects, 21% were hospitalized, and 2 died. In three case-control studies of cases not linked to restaurant clusters, illness was significantly associated with eating raw tomatoes (matched odds ratio, 5.6; 95% confidence interval [CI], 1.6 to 30.3); eating at a Mexican-style restaurant (matched odds ratio, 4.6; 95% CI, 2.1 to ∞) and eating pico de gallo salsa (matched odds ratio, 4.0; 95% CI, 1.5 to 17.8), corn tortillas (matched odds ratio, 2.3; 95% CI, 1.2 to 5.0), or salsa (matched odds ratio, 2.1; 95% CI, 1.1 to 3.9); and having a raw jalapeño pepper in the household (matched odds ratio, 2.9; 95% CI, 1.2 to 7.6). In nine analyses of clusters associated with restaurants or events, jalapeño peppers were implicated in all three clusters with implicated ingredients, and jalapeño or serrano peppers were an ingredient in an implicated item in the other three clusters. Raw tomatoes were an ingredient in an implicated item in three clusters. The outbreak strain was identified in jalapeño peppers collected in Texas and in agricultural water and serrano peppers on a Mexican farm. Tomato tracebacks did not converge on a source. Although an epidemiologic association with raw tomatoes was identified early in this investigation, subsequent epidemiologic and microbiologic evidence implicated jalapeño and serrano peppers. This outbreak highlights the importance of preventing raw-produce contamination.
    New England Journal of Medicine 02/2011; 364(10):918-27. · 53.30 Impact Factor
  • Article: Incidence and transmission patterns of acute hepatitis C in the United States, 1982-2006.
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    ABSTRACT: Monitoring disease incidence and transmission patterns is important to characterize groups at risk for hepatitis C virus (HCV) infection. Clinical cases generally represent about 20% to 30% of all newly acquired infections. We used sentinel surveillance to determine incidence and transmission patterns for acute hepatitis C in the United States using data from 25 years of population-based surveillance in the general community. Acute cases of hepatitis C were identified from 1982 through 2006 by a stimulated passive surveillance system in 4 to 6 US counties. Cases were defined by a discrete onset of symptoms, alanine aminotransferase (ALT) levels greater than 2.5 times the upper limit of normal (×ULN), negative findings for serologic markers for acute hepatitis A and B, and positive findings for antibody to HCV or HCV RNA. Incidence and frequency of reported risk factors were the main outcome measures. Of 2075 patients identified, the median age was 31 years, 91.5% had ALT values greater than 7×ULN, 77.3% were jaundiced, 22.5% were hospitalized, and 1.2% died. Incidence averaged 7.4 per 100,000 individuals (95% confidence interval [CI], 6.4-8.5 per 100,000) during 1982 to 1989 then declined averaging 0.7 per 100,000 (95% CI, 0.5-1.0 per 100,000) during 1994 to 2006. Among 1748 patients interviewed (84.2%), injection drug use (IDU) was the most commonly reported risk factor. The average number of IDU-related cases declined paralleling the decline in incidence, but the proportion of IDU-related cases rose from 31.8% (402 of 1266) during 1982 to 1989 to 45.6% (103 of 226) during 1994 to 2006. Among IDU-related cases reported during 1994 to 2006, 56 of 61 individuals (91.8%) had been in a drug treatment program and/or incarcerated. The incidence of acute HCV declined substantially over the 25 years of population-based surveillance. Despite declines, IDU is the most common risk factor for new HCV infection.
    Archives of internal medicine 02/2011; 171(3):242-8. · 11.46 Impact Factor
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    Article: National outbreak of Salmonella serotype saintpaul infections: importance of Texas restaurant investigations in implicating jalapeño peppers.
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    ABSTRACT: In May 2008, PulseNet detected a multistate outbreak of Salmonella enterica serotype Saintpaul infections. Initial investigations identified an epidemiologic association between illness and consumption of raw tomatoes, yet cases continued. In mid-June, we investigated two clusters of outbreak strain infections in Texas among patrons of Restaurant A and two establishments of Restaurant Chain B to determine the outbreak's source. We conducted independent case-control studies of Restaurant A and B patrons. Patients were matched to well controls by meal date. We conducted restaurant environmental investigations and traced the origin of implicated products. Forty-seven case-patients and 40 controls were enrolled in the Restaurant A study. Thirty case-patients and 31 controls were enrolled in the Restaurant Chain B study. In both studies, illness was independently associated with only one menu item, fresh salsa (Restaurant A: matched odds ratio [mOR], 37; 95% confidence interval [CI], 7.2-386; Restaurant B: mOR, 13; 95% CI 1.3-infinity). The only ingredient in common between the two salsas was raw jalapeño peppers. Cultures of jalapeño peppers collected from an importer that supplied Restaurant Chain B and serrano peppers and irrigation water from a Mexican farm that supplied that importer with jalapeño and serrano peppers grew the outbreak strain. Jalapeño peppers, contaminated before arrival at the restaurants and served in uncooked fresh salsas, were the source of these infections. Our investigations, critical in understanding the broader multistate outbreak, exemplify an effective approach to investigating large foodborne outbreaks. Additional measures are needed to reduce produce contamination.
    PLoS ONE 01/2011; 6(2):e16579. · 4.09 Impact Factor
  • Article: Human Salmonella infections linked to contaminated dry dog and cat food, 2006-2008.
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    ABSTRACT: Human Salmonella infections associated with dry pet food have not been previously reported. We investigated such an outbreak of Salmonella Schwarzengrund and primarily affecting young children. Two multistate case-control studies were conducted to determine the source and mode of infections among case-patients with the outbreak strain. Study 1 evaluated household exposures to animals and pet foods, and study 2 examined risk factors for transmission among infant case-patients. Environmental investigations were conducted. Seventy-nine case-patients in 21 states were identified; 48% were children aged 2 years or younger. Case-households were significantly more likely than control households to report dog contact (matched odds ratio [mOR]: 3.6) and to have recently purchased manufacturer X brands of dry pet food (mOR: 6.9). Illness among infant case-patients was significantly associated with feeding pets in the kitchen (OR: 4.4). The outbreak strain was isolated from opened bags of dry dog food produced at plant X, fecal specimens from dogs that ate manufacturer X dry dog food, and an environmental sample and unopened bags of dog and cat foods from plant X. More than 23 000 tons of pet foods were recalled. After additional outbreak-linked illnesses were identified during 2008, the company recalled 105 brands of dry pet food and permanently closed plant X. Dry dog and cat foods manufactured at plant X were linked to human illness for a 3-year period. This outbreak highlights the importance of proper handling and storage of pet foods in the home to prevent human illness, especially among young children.
    PEDIATRICS 09/2010; 126(3):477-83. · 4.47 Impact Factor
  • Article: Attribution of hepatitis C virus seroconversion risk in young injection drug users in 5 US cities.
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    ABSTRACT: BACKGROUND. In studies of hepatitis C virus (HCV) seroconversion in injection drug users (IDUs), some have questioned whether underreporting of syringe sharing, a stigmatized behavior, has led to misattribution of HCV risk to other injection-related behaviors. METHODS. IDUs aged 15-30 years who were seronegative for human immunodeficiency virus and HCV antibodies were recruited into a prospective study in 5 US cities. Behavioral data were collected via computer-assisted self-interviewing to reduce socially desirable reporting. Hazard ratios (HRs) were estimated to assess associations between behavior and HCV seroconversion. Because the shared use of cookers, cottons, and rinse water was highly correlated, a summary variable was created to represent drug preparation equipment sharing. RESULTS. Among 483 IDUs who injected during the period covered by the follow-up assessments, the incidence of HCV infection was 17.2 cases per 100 person years; no HIV seroconversions occurred. Adjusting for confounders, the shared use of drug preparation equipment was significantly associated with HCV seroconversion (adjusted HR, 2.66; 95% confidence interval, 1.03-23.92), but syringe sharing was not (adjusted HR, 0.91). We estimated that 37% of HCV seroconversions in IDUs were due to the sharing of drug preparation equipment. CONCLUSIONS. Associations between sharing drug preparation equipment and HCV seroconversion are not attributable to underascertainment of syringe sharing. Avoiding HCV infection will require substantial reductions in exposure to all sources of contaminated blood.
    The Journal of Infectious Diseases 02/2010; 201(3):378-85. · 6.41 Impact Factor
  • Article: Hepatitis C virus transmission in hemodialysis units: importance of infection control practices and aseptic technique.
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    ABSTRACT: We investigated 4 hepatitis C virus (HCV) infection outbreaks at hemodialysis units to identify practices associated with transmission. Apparent failures to follow recommended infection control precautions resulted in patient-to-patient HCV transmission, through cross-contamination of the environment or intravenous medication vials. Fastidious attention to aseptic technique and infection control precautions are essential to prevent HCV transmission.
    Infection Control and Hospital Epidemiology 10/2009; 30(9):900-3. · 3.67 Impact Factor
  • Article: Prevalence of hepatitis C virus infection among injection drug users in the United States, 1994-2004.
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    ABSTRACT: To examine hepatitis C virus (HCV) seroprevalence among injection drug users in 4 US cities from 1994 through 2004. Demographic characteristics, behaviors, and prevalence of HCV antibody among 5088 injection drug users aged 18-40 years from Baltimore, Maryland; Chicago, Illinois; Los Angeles, California; and New York, New York, enrolled in 3 related studies--Collaborative Injection Drug User Study (CIDUS) I (1994-1996), CIDUS II (1997-1999), and CIDUS III/Drug User Intervention Trial (2002-2004)--were compared using the chi(2) and Mantel-Haenszel tests of significance. Trends over time were assessed by logistic regression. Prevalence of HCV infection was 65%, 35%, and 35% in CIDUS I, CIDUS II, and CIDUS III, respectively. The adjusted prevalence odds ratio (OR) of being HCV antibody positive increased with the number of years of injection drug use (OR, 1.93 [95% confidence interval {CI}, 1.68-2.21] for each year of injecting within the first 2 years; OR, 1.09 [95% CI, 1.07-1.11] for each year of injecting beyond the first 2 years). Significant decreases were observed in the prevalence of HCV antibody between CIDUS I and CIDUS III in Baltimore (OR, 0.30; 95% CI, 0.20-0.43) and Los Angeles (OR, 0.17; 95% CI, 0.09-0.31) and among people of races other than black in Chicago (OR, 0.12; 95% CI, 0.08-0.17). No decrease in prevalence was seen in New York (OR, 1.04; 95% CI, 0.69-1.58) or among blacks in Chicago (OR, 0.55; 95% CI, 0.16-1.90). Although regional differences exist, our data suggest that the incidence of HCV infection among injection drug users in the United States decreased from 1994 through 2004.
    Clinical Infectious Diseases 07/2008; 46(12):1852-8. · 9.15 Impact Factor
  • Article: Methods to recruit and retain a cohort of young-adult injection drug users for the Third Collaborative Injection Drug Users Study/Drug Users Intervention Trial (CIDUS III/DUIT).
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    ABSTRACT: New injection drug users (IDUs) are at high risk for blood-borne viral infections. Given U.S. policy to only fund proven-effective HIV prevention interventions, insights into conducting intervention trials among young IDUs are provided here by describing methods and participants' characteristics in the CIDUS III/DUIT study. In 2002-2004, 15-30-year-old IDUs in Baltimore, Chicago, Los Angeles, New York, and Seattle were recruited through community outreach, advertising and coupon-based participant referrals. Baseline interviews assessed sociodemographics, injection, and sexual behaviors. Antibody tests for HIV and hepatitis A, B, and C viruses (HAV, HBV, and HCV) were conducted. IDUs who were HIV and HCV antibody negative at baseline were eligible to participate in a randomized controlled HIV/HCV prevention trial. Follow-up assessments were conducted 3 and 6 months post-intervention. Data were analyzed to identify participant differences at baseline by city, trial enrollment, and trial retention. Baseline assessments were completed by 3285 IDUs. Participants were mean age 23.8 years, 69% male, 64% White, 17% Hispanic, and 8% Black. Seroprevalence of HIV, HCV, HBV, and HAV antibodies were 2.9, 34.4, 22.4, and 19.3%, respectively. Of the 2062 (62.7%) baseline participants who were HIV and HCV antibody negative, 859 (41.7%) were randomized. At least one follow-up assessment was completed by 712 (83%) randomized participants. Contextual factors, primarily homelessness, were associated with lower enrollment and retention. Recruitment and retention of young-adult IDUs for complex intervention trials is complicated, yet feasible. Risk behaviors among participants enrolling in and completing the trial reflected those eligible to enroll.
    Drug and Alcohol Dependence 12/2007; 91 Suppl 1:S4-17. · 3.38 Impact Factor
  • Article: Population-based surveillance for acute liver failure.
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    ABSTRACT: Most U.S. studies of acute liver failure (ALF) patients have been conducted at tertiary care liver transplantation centers. The aim of this study was to conduct population-based surveillance for ALF. We conducted population-based surveillance for ALF within the 8 counties comprising Metropolitan Atlanta between November 2000 and October 2004. ALF cases were defined as the presence of coagulopathy, any grade of hepatic encephalopathy within 26 wk of illness onset, and no history of underlying liver disease. A questionnaire was administered and medical records were reviewed to determine clinical features, etiologies, and outcomes. A total of 65 cases were enrolled, yielding an annualized incidence for all causes of ALF of 5.5 (95% CI 4.3-7.0) per million. Acetaminophen (APAP)-related ALF was the most common (41%) etiology in adults while ALF of undetermined etiology was most common (38%) in children, followed by APAP-related ALF (25%). Unintentional APAP overdose was the most common type (61%) of APAP-related cause. Blacks were more likely than other races to have ALF of undetermined etiology (32%vs 11%). Overall mortality was 40%, with 27 (42%) surviving with supportive care alone and 8 (12%) requiring orthotopic liver transplantation. Our population-based study suggests approximately 1,600 ALF cases occur in the United States each year. Consistent with findings from studies conducted exclusively at liver transplantation centers, APAP-related ALF was the most common etiology. Increased awareness of APAP-related ALF in the medical community may limit future cases. More research is warranted into ALF of undetermined etiology, especially in children.
    The American Journal of Gastroenterology 12/2007; 102(11):2459-63. · 7.28 Impact Factor
  • Article: Changes in hepatitis C virus (HCV) viral load and interferon-alpha levels in HIV/HCV-coinfected patients treated with highly active antiretroviral therapy.
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    ABSTRACT: Reports are mixed as to whether highly active antiretroviral therapy (HAART) increases liver transaminase levels or hepatitis C virus (HCV) titers in HIV/HCV-coinfected individuals. It is hypothesized that increases in HCV RNA titers may result from changes in endogenous interferon-alpha (IFN-alpha) production. HIV/HCV-coinfected patients receiving HAART were tested at baseline, 1, 2, 3, 6, and 9 months for liver transaminase levels, HIV and HCV viral loads, and IFN-alpha. Linear regression analysis was used to determine the effect of HAART on liver transaminase levels, HCV viral load, and IFN-alpha. Initiating HAART did not increase liver transaminase levels in majority of cases. In patients (n = 30) with baseline HIV titer >10,000 copies/mL, HCV titers increased 0.69 log10 and IFN-alpha decreased -0.96 log10 during HAART, in association with a > or =0.5 log10 decrease in HIV titer. As HIV titers reached their nadir approximately 4 months after initiation of HAART, HCV titers remained 0.54 log10 and IFN-alpha -0.71 log10 above and below baseline levels, respectively. HCV titers and IFN-alpha levels did not change from baseline in patients with baseline HIV titer < or =10,000 copies/mL. Coinfected patients did not have evidence of hepatoxicity HAART. In patients with baseline HIV titer >10,000 copies/mL, suppression of HIV replication by HAART was associated with an increase in HCV titer and a decrease in endogenous IFN-alpha levels.
    JAIDS Journal of Acquired Immune Deficiency Syndromes 08/2006; 42(3):293-7. · 4.43 Impact Factor
  • Article: Locally acquired hepatitis E virus infection, El Paso, Texas.
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    ABSTRACT: Hepatitis E virus (HEV) is an enterically transmitted RNA virus that causes both epidemic and sporadic cases of acute hepatitis. Despite sero-surveys showing antibody to HEV in up to 36% of the US population, acute hepatitis E has been reported among individuals with no history of international travel only three times in the United States. We report a case of apparently locally-acquired hepatitis E that occurred in El Paso, Texas that was 98% similar to a previously isolated HEV found in swine in the United States. Like the three previous cases, a thorough investigation found no conclusive sources of infection. Active case surveillance found no additional cases.
    Journal of Medical Virology 07/2006; 78(6):741-6. · 2.82 Impact Factor
  • Article: An outbreak of hepatitis B virus infection among methamphetamine injectors: the role of sharing injection drug equipment.
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    ABSTRACT: To identify risk factors for acute hepatitis B virus (HBV) infection among Wyoming methamphetamine injectors. A case-control study conducted in the setting of an outbreak. A county in central Wyoming, United States. Cases were identified through surveillance and contact tracing and were defined as Natrona County, Wyoming, residents who were either symptomatic or confirmed serologically to be acutely infected with HBV during January-August, 2003. Controls were susceptible to HBV infection. All participants identified themselves as methamphetamine injectors. Participants were administered a survey that inquired about risk factors for HBV infection, including drug use practices and sexual behaviors. Controls were also tested serologically for acute HBV infection. Among the 18 case-patients and 49 controls who participated in the study, sharing water used to prepare injections and/or rinse syringes was associated with HBV infection (94% of case-participants versus 44% of controls; OR = 21.9, 95% CI: 2.7, 177.8), as was sharing cotton filters (89% of case-participants versus 52% of controls; OR = 7.4, 95% CI: 1.5, 35.6); sharing syringes was not statistically associated. In logistic regression models adjusted for age, sex, and interview site, sharing rinse water and sharing cotton remained statistically associated. Methamphetamine use has become increasingly prevalent in the United States. Our findings highlight the need for awareness of risks associated with injection drug use and sharing behaviors. Enhanced hepatitis B vaccination programs and educational campaigns that target methamphetamine injectors specifically, including those living in rural areas, should be developed and implemented.
    Addiction 06/2006; 101(5):726-30. · 4.31 Impact Factor
  • Article: Hepatitis C virus infection in Samoa and American Samoa.
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    ABSTRACT: Little is known about the prevalence of hepatitis C virus (HCV) in Pacific islands. In this study, serum specimens collected in 1985 and 2002 among the general populations of Samoa and American Samoa were tested for antibody to HCV by a third-generation enzyme immunoassay and a recombinant immunoblot assay. Of the 3,466 specimens tested, 8 (0.2%; 95% confidence interval = 0.07-0.4%) were positive for antibody to HCV. Prevalence did not vary by location or demographic characteristic. Thus, HCV is present in the Samoas but at a low prevalence.
    The American journal of tropical medicine and hygiene 03/2006; 74(2):261-2. · 2.59 Impact Factor
  • Article: Transmission of hepatitis C virus to several organ and tissue recipients from an antibody-negative donor.
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    ABSTRACT: Although hepatitis C virus (HCV) transmission through tissue transplantation has been rarely reported, a donor with undetected viremia may infect several recipients. A patient developed acute hepatitis C shortly after tissue transplantation. Ninety-one tissues or organs had been recovered from the donor. To determine whether the donor was the source of infection and the extent of transmission to other organ and tissue recipients. Descriptive epidemiologic study; serum testing for HCV infection. Recipients were located in 16 states and 2 other countries. Donor and graft recipients. Hepatitis C virus infection was defined as the presence of anti-HCV or HCV RNA. The authors determined the genetic relatedness of viral isolates from the donor and recipients by genotype comparison and quasi-species analysis. The donor was anti-HCV-negative but was HCV RNA-positive (genotype 1a). Forty persons received transplants during 22 months. Five persons were HCV-infected before transplantation or had a genotype other than 1a, and 5 persons had no post-transplantation serum specimens available. Of the remaining 30 recipients, HCV infection occurred in 8 recipients: 3 of 3 organ recipients, 1 of 2 saphenous vein recipients, 1 of 3 tendon recipients, and 3 of 3 tendon with bone recipients. These 8 recipients had viral isolates genetically related to those of the donor. No cases occurred in recipients of skin (n = 2), cornea (n = 1), or irradiated bone (n = 16). Post-transplantation serum specimens were unavailable for 5 recipients. An anti-HCV-negative donor was the source of HCV infection for 8 recipients of organs or tissues. Although HCV transmission from anti-HCV-negative donors is probably uncommon, changes in donor screening to include routine testing for HCV RNA merit further consideration to improve the safety of transplantation.
    Annals of internal medicine 12/2005; 143(9):648-54. · 16.73 Impact Factor
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    Article: An outbreak of hepatitis A associated with green onions.
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    ABSTRACT: In November 2003, a large hepatitis A outbreak was identified among patrons of a single Pennsylvania restaurant. We investigated the cause of the outbreak and factors that contributed to its unprecedented size. Demographic and clinical outcome data were collected from patients with laboratory confirmation of hepatitis A, and restaurant workers were tested for hepatitis A. A case-control study was conducted among patrons who dined at the restaurant between October 3 and October 6, 2003. Sequence analysis was performed on a 315-nucleotide region of viral RNA extracted from serum specimens. Of 601 patients identified, 3 died; at least 124 were hospitalized. Of 425 patients who recalled a single dining date at the restaurant, 356 (84 percent) had dined there between October 3 and October 6. Among 240 patients in the case-control study, 218 had eaten mild salsa (91 percent), as compared with 45 of 130 controls (35 percent) (odds ratio, 19.6; 95 percent confidence interval, 11.0 to 34.9) for whom data were available. A total of 98 percent of patients and 58 percent of controls reported having eaten a menu item containing green onions (odds ratio, 33.3; 95 percent confidence interval, 12.8 to 86.2). All restaurant workers were tested, but none were identified who could have been the source of the outbreak. Sequences of hepatitis A virus from all 170 patients who were tested were identical. Mild salsa, which contained green onions grown in Mexico, was prepared in large batches at the restaurant and provided to all patrons. Green onions that were apparently contaminated before arrival at the restaurant caused this unusually large foodborne outbreak of hepatitis A. The inclusion of contaminated green onions in large batches that were served to all customers contributed to the size of the outbreak.
    New England Journal of Medicine 10/2005; 353(9):890-7. · 53.30 Impact Factor
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    Article: Molecular epidemiology of foodborne hepatitis a outbreaks in the United States, 2003.
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    ABSTRACT: Molecular epidemiologic investigations can link geographically separate foodborne hepatitis A outbreaks but have not been used while field investigations are in progress. In 2003, outbreaks of foodborne hepatitis A were reported in multiple states. Case-control studies were conducted in 3 states. Hepatitis A virus was sequenced from serologic specimens from individuals associated with outbreaks and from individuals concurrently ill with hepatitis A in non-outbreak settings in the United States and Mexico. Case-control studies in Tennessee (TN), North Carolina (NC), and Georgia (GA) found green onions to be associated with illness among restaurant patrons (TN: odds ratio [OR], 65.5 [95% confidence interval {CI}, 8.9-482.5; NC: OR, 2.4 [95% CI, 0.3-21.9]; GA: OR, 20.9 [95% CI, 3.9-110.3]). Viral sequences from TN case patients differed by 2 nt, compared with those from case patients in NC and GA. A third sequence, differing from the TN and GA/NC sequences by 1 nt, was identified among case patients in a subsequent outbreak in Pennsylvania. Each outbreak sequence was identical to > or =1 sequence isolated from northern Mexican resident(s) with hepatitis A. The sources of green onions served in restaurants in TN and GA were 3 farms in northern Mexico. Ongoing viral strain surveillance facilitated the rapid implementation of control measures. Incorporation of molecular epidemiologic methods into routine hepatitis A surveillance would improve the detection of hepatitis A outbreaks and increase our understanding of hepatitis A epidemiology in the United States.
    The Journal of Infectious Diseases 10/2005; 192(8):1323-30. · 6.41 Impact Factor
  • Article: Risk factors for hepatitis B in an outbreak of hepatitis B and D among injection drug users.
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    ABSTRACT: During January-April, 2000, 12 cases of acute hepatitis B were reported in Pierce County, Washington, compared with seven in all of 1999. Seven (58.3%) case patients were injection drug users (IDUs), three of whom were coinfected with hepatitis D virus (HDV) and died of fulminant hepatitis. Vaccination clinics were implemented at the local health department and needle exchange program to control the outbreak. We investigated this outbreak to determine risk factors for hepatitis B virus (HBV) transmission among IDUs. Hepatitis B cases were ascertained through routine surveillance and prevaccination testing at vaccination clinics. We conducted a case-control study comparing IDU case patients with HBV-susceptible IDUs identified at the vaccination clinics. Fifty-eight case patients were identified during January-December, 2000, 20 (34.5%) of whom were coinfected with HDV. Thirty-eight case patients (65.5%) reported current IDU. In the case-control study, the 17 case patients were more likely than the 141 controls to report having more than one sex partner [odds ratio (OR) =4.8, 95% confidence interval (CI) =1.5-15.0], injecting more than four times a day (OR = 4.5, 95% CI =1.2-15.6) and sharing drug cookers with more than two people (58.8% vs. 14.0%, OR =14.0, 95% CI =2.4-81.5). Results were similar after controlling for syringe sharing in multivariable analysis. IDUs should be vaccinated against hepatitis B and should be advised against sharing drug injection equipment.
    Journal of Urban Health 10/2005; 82(3):468-78. · 2.13 Impact Factor
  • Article: A large outbreak of hepatitis B virus infections associated with frequent injections at a physician's office.
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    ABSTRACT: To determine whether hepatitis B virus (HBV) transmission occurred among patients visiting a physician's office and to evaluate potential transmission mechanisms. Serologic survey, retrospective cohort study, and observation of infection control practices. Private medical office. Those visiting the office between March 1 and December 26, 2001. We identified 38 patients with acute HBV infection occurring between February 2000 and February 2002. The cohort study, limited to the 10 months before outbreak detection, included 91 patients with serologic test results and available charts representing 18 case-patients and 73 susceptible patients. Overall, 67 patients (74%) received at least one injection during the observation period. Case-patients received a median of 14 injections (range, 2-25) versus 2 injections (range, 0-17) for susceptible patients (P < .001). Acute infections occurred among 18 (27%) of 67 who received at least one injection versus none of 24 who received no injections (RR, 13.6; CI95, 2.4-undefined). Risk of infection increased 5.2-fold (CI95, 0.6-47.3) for those with 3 to 6 injections and 20.0-fold (CI95, 2.8-143.5) for those with more than 6 injections. Typically, injections consisted of doses of atropine, dexamethasone, vitamin B12, or a combination of these mixed in one syringe. HBV DNA genetic sequences of 24 patients with acute infection and 4 patients with chronic infection were identical in the 1,500-bp region examined. Medical staff were seronegative for HBV infection markers. The same surface was used for storing multidose vials, preparing injections, and dismantling used injection equipment. Administration of unnecessary injections combined with failure to separate clean from contaminated areas and follow safe injection practices likely resulted in patient-to-patient HBV transmission in a private physician's office.
    Infection Control and Hospital Epidemiology 09/2005; 26(9):745-50. · 3.67 Impact Factor
  • Article: Prevalence and correlates of crack-cocaine injection among young injection drug users in the United States, 1997-1999.
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    ABSTRACT: We estimated prevalence and identified correlates of crack-cocaine injection among young injection drug users in the United States. We analyzed data from the second Collaborative Injection Drug Users Study (CIDUS II), a 1997-1999 cohort study of 18-30-year-old, street-recruited injection drug users from six US cities. Crack-cocaine injection was reported by 329 (15%) of 2198 participants. Prevalence varied considerably by site (range, 1.5-28.0%). No participants injected only crack-cocaine. At four sites where crack-cocaine injection prevalence was greater than 10%, recent (past 6 months) crack-cocaine injection was correlated with recent daily injection and sharing of syringes, equipment, and drug solution. Lifetime crack-cocaine injection was correlated with using shooting galleries, initiating others into drug injection, and having serologic evidence of hepatitis B virus and hepatitis C virus infection. Crack-cocaine injection may be a marker for high-risk behaviors that can be used to direct efforts to prevent HIV and other blood-borne viral infections.
    Drug and Alcohol Dependence 04/2005; 77(3):227-33. · 3.38 Impact Factor