Michael C Samuel

Publications of Michael C Samuel

• Repeat Syphilis Among Men Who Have Sex With Men in California, 2002-2006: Implications for Syphilis Elimination Efforts.

  Authors: Stephanie E Cohen, Rilene A Chew Ng, Kenneth A Katz, Kyle T Bernstein, Michael C Samuel, Peter R Kerndt, Gail Bolan

  American journal of public health. 11/2011; 102(1):e1-e8.

  Objectives. We examined rates of and risk factors for repeat syphilis infection among men who have sex with men (MSM) in California. Methods. We analyzed 2002 to 2006 California syphilis surveillanceObjectives. We examined rates of and risk factors for repeat syphilis infection among men who have sex with men (MSM) in California. Methods. We analyzed 2002 to 2006 California syphilis surveillance system data. Results. During the study period, a mean of 5.9% (range: 4.9%-7.1% per year) of MSM had a repeat primary or secondary (PS) syphilis infection within 2 years of an initial infection. There was no significant increase in the annual proportion of MSM with a repeat syphilis infection (P = .42). In a multivariable model, factors associated with repeat syphilis infection were HIV infection (odds ratio [OR] = 1.65; 95% confidence interval [CI] = 1.14, 2.37), Black race (OR = 1.84; 95% CI = 1.12, 3.04), and 10 or more recent sex partners (OR = 1.99; 95% CI = 1.12, 3.50). Conclusions. Approximately 6% of MSM in California have a repeat PS syphilis infection within 2 years of an initial infection. HIV infection, Black race, and having multiple sex partners are associated with increased odds of repeat infection. Syphilis elimination efforts should include messages about the risk for repeat infection and the importance of follow-up testing. Public health attention to individuals repeatedly infected with syphilis may help reduce local disease burdens.

• A novel risk factor for a novel virus: obesity and 2009 pandemic influenza A (H1N1).

  Authors: Janice K Louie, Meileen Acosta, Michael C Samuel, Robert Schechter, Duc J Vugia, Kathleen Harriman, Bela T Matyas

  Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 02/2011; 52(3):301-12.

  many critically ill patients with 2009 pandemic influenza A (H1N1) (2009 H1N1) infection were noted to be obese, but whether obesity, rather than its associated co-morbidities, is an independent riskmany critically ill patients with 2009 pandemic influenza A (H1N1) (2009 H1N1) infection were noted to be obese, but whether obesity, rather than its associated co-morbidities, is an independent risk factor for severe infection is unknown. using public health surveillance data, we analyzed demographic and clinical characteristics of California residents hospitalized with 2009 H1N1 infection to assess whether obesity (body mass index [BMI] ≥ 30) and extreme obesity (BMI ≥ 40) were an independent risk factor for death among case patients ≥ 20 years old. during the period 20 April-11 August 2009, 534 adult case patients with 2009 H1N1 infection for whom BMI information was available were observed. Two hundred twenty-eight patients (43%) were ≥ 50 years of age, and 378 (72%) had influenza-related high-risk conditions recognized by the Advisory Committee on Immunization Practices as risk factors for severe influenza. Two hundred and seventy-four (51%) had BMI ≥ 30, which is 2.2 times the prevalence of obesity among California adults (23%) and 1.5 times the prevalence among the general population of the United States (33%). Of the 92 case patients who died (17%), 56 (61%) had BMI ≥ 30 and 28 (30%) had BMI ≥ 40. In multivariate analysis, BMI ≥ 40 (odds ratio [OR], 2.8; 95% confidence interval [CI], 1.4-5.9) and BMI ≥ 45 (OR, 4.2; 95% CI, 1.9-9.4), age ≥ 50 years (OR, 2.1; 95% CI, 1.2-3.7), miscellaneous immunosuppressive conditions (OR, 3.9; 95% CI, 1.6-9.5), and asthma (OR, 0.5; 95% CI, 0.3-0.9) were associated with death. half of Californians ≥ 20 years of age hospitalized with 2009 H1N1 infection were obese. Extreme obesity was associated with increased odds of death. Obese adults with 2009 H1N1 infection should be treated promptly and considered in prioritization of vaccine and antiviral medications during shortages.

• A review of adult mortality due to 2009 pandemic (H1N1) influenza A in California.

  Authors: Janice K Louie, Cynthia Jean, Meileen Acosta, Michael C Samuel, Bela T Matyas, Robert Schechter

  PloS one. 01/2011; 6(4):e18221.

  While children and young adults had the highest attack rates due to 2009 pandemic (H1N1) influenza A (2009 H1N1), studies of hospitalized cases noted high fatality in older adults. We analyzedWhile children and young adults had the highest attack rates due to 2009 pandemic (H1N1) influenza A (2009 H1N1), studies of hospitalized cases noted high fatality in older adults. We analyzed California public health surveillance data to better characterize the populations at risk for dying due to 2009 H1N1. A case was an adult ≥20 years who died with influenza-like symptoms and laboratory results indicative of 2009 H1N1. Demographic and clinical data were abstracted from medical records using a standardized case report form. From April 3, 2009-August 10, 2010, 541 fatal cases ≥20 years with 2009 H1N1 were reported. Influenza fatality rates per 100,000 population were highest in persons 50-59 years (3.5; annualized rate = 2.6) and 60-69 years (2.3; annualized rate = 1.7) compared to younger and older age groups (0.4-1.9; annualized rates = 0.3-1.4). Of 486 cases hospitalized prior to death, 441 (91%) required intensive care unit (ICU) admission. ICU admission rates per 100,000 population were highest in adults 50-59 years (8.6). ICU case-fatality ratios among adults ranged from 24-42%, with the highest ratios in persons 70-79 years. A total of 425 (80%) cases had co-morbid conditions associated with severe seasonal influenza. The prevalence of most co-morbid conditions increased with increasing age, but obesity, pregnancy and obstructive sleep apnea decreased with age. Rapid testing was positive in 97 (35%) of 276 tested. Of 482 cases with available data, 384 (80%) received antiviral treatment, including 49 (15%) of 328 within 48 hours of symptom onset. Adults aged 50-59 years had the highest fatality due to 2009 H1N1; older adults may have been spared due to pre-existing immunity. However, once infected and hospitalized in intensive care, case-fatality ratios were high for all adults, especially in those over 60 years. Vaccination of adults older than 50 years should be encouraged.

• Children hospitalized with 2009 novel influenza A(H1N1) in California.

  Authors: Janice K Louie, Shilpa Gavali, Meileen Acosta, Michael C Samuel, Kathleen Winter, Cynthia Jean, Carol A Glaser, Bela T Matyas, Robert Schechter

  Archives of pediatrics & adolescent medicine. 11/2010; 164(11):1023-31.

  To describe clinical and epidemiologic features of 2009 novel influenza A(H1N1) in children. Analysis of data obtained from standardized report forms and medical records. Statewide public healthTo describe clinical and epidemiologic features of 2009 novel influenza A(H1N1) in children. Analysis of data obtained from standardized report forms and medical records. Statewide public health surveillance in California. Three hundred forty-five children who were hospitalized with or died of 2009 novel influenza A(H1N1). Laboratory-confirmed 2009 novel influenza A(H1N1). Hospitalization and death. From April 23 to August 11, 2009, 345 cases in children younger than 18 years were reported. The median age was 6 years. The hospitalization rate per 100 000 per 110 days was 3.5 (0.97 per 100 000 person-months), with rates highest in infants younger than 6 months (13.9 per 100 000 or 3.86 per 100 000 person-months). Two-thirds (230; 67%) had comorbidities. More than half (163 of 278; 59%) had pneumonia, 94 (27%) required intensive care, and 9 (3%) died; in 3 fatal cases (33%), children had secondary bacterial infections. More than two-thirds (221 of 319; 69%) received antiviral treatment, 44% (88 of 202) within 48 hours of symptom onset. In multivariate analysis, congenital heart disease (odds ratio [OR], 5.0; 95% confidence interval [CI], 1.9-13.5) and cerebral palsy/developmental delay (OR, 3.5; 95% CI, 1.7-7.4) were associated with increased likelihood of intensive care unit admission and/or death; likelihood was decreased in Hispanic (OR, 0.4; 95% CI, 0.2-0.8) and black (OR, 0.3; 95% CI, 0.1-1.0) children compared with white children. More than one-quarter of children hospitalized with 2009 novel influenza A(H1N1) reported to the California Department of Public Health required intensive care and/or died. Regardless of rapid test results, when 2009 novel influenza A(H1N1) is circulating, clinicians should maintain a high suspicion in children with febrile respiratory illness and promptly treat those with underlying risk factors, especially infants.

• Socioeconomic gradients in sexually transmitted diseases: a geographic information system-based analysis of poverty, race/ethnicity, and gonorrhea rates in California, 2004-2006.

  Authors: Yuri P Springer, Michael C Samuel, Gail Bolan

  American journal of public health. 06/2010; 100(6):1060-7.

  We quantified the relationship between gonorrheal infection rates in California and a measure of poverty status and investigated how this relationship and the spatial dispersion of cases varied amongWe quantified the relationship between gonorrheal infection rates in California and a measure of poverty status and investigated how this relationship and the spatial dispersion of cases varied among the 4 dominant racial/ethnic groups in the state. We geocoded gonorrhea cases reported in California between 2004 and 2006, and estimated the poverty status of each case by using the percentage of residents living below poverty in the census tract of residence. We calculated infection rates for African American, Asian, Hispanic, and White cases in each of 4 poverty strata. We mapped cases to visualize the patterns of spatial dispersion associated with each race/ethnicity-poverty combination. There was a strong positive relationship between poverty and infection, but racial/ethnic disparities in infection, driven by a disproportionate level of gonorrhea among African Americans, eclipsed this differential. The degree of spatial aggregation varied substantially among groups and was especially pronounced for African Americans with gonorrhea in the highest poverty category. Prevention efforts should target low-income neighborhood "hot spots" to reach the largest numbers of cases, particularly among African Americans.

• A closer look at age: deconstructing aggregate gonorrhea and chlamydia rates, California, 1998-2007.

  Authors: Heather S Jacobs, Michael C Samuel, Joan M Chow, Gail Bolan

  Sexually transmitted diseases. 02/2010; 37(5):328-34.

  Risk of gonorrheal (GC) and chlamydial (CT) infection is highly associated with age. Case rates typically are reported in 5-year categories. Highest rates are seen consistently in the 15- to 19-yearRisk of gonorrheal (GC) and chlamydial (CT) infection is highly associated with age. Case rates typically are reported in 5-year categories. Highest rates are seen consistently in the 15- to 19-year and 20- to 24-year age groups for both genders. It is not clear how aggregate, age-specific rates mask finer differences in risk by single age across and within racial/ethnic groups. California case-based surveillance data for 1998 through 2007 were used to calculate GC and CT rates by single age at diagnosis. The distribution of single gender and age-specific rates was compared with 5-year age-specific rates. Descriptive statistics for age by race/ethnicity were calculated, and trends over time were assessed. Female, single-age-specific GC and CT rates for 2007 increased strikingly during adolescence and then declined quickly. Male, single-age-specific GC rates declined more gradually than did CT rates. The rate for the aggregate 15- to 19-year-old age group fit the single-age rates poorly, particularly for females, who in 2007 had a peak rate at age 19 for GC (497 per 100,000) and for CT (3640 per 100,000), though the highest aggregate rate was for ages 20 to 24. Blacks had the youngest mean age for both GC and CT. Mean ages increased significantly from 1998 through 2007 for female GC and CT cases, as well as for male CT cases. Age and race/ethnicity data should be examined in finer detail than the 5-year aggregate data, in order to target sexually transmitted disease prevention and control interventions more effectively.

• Factors associated with death or hospitalization due to pandemic 2009 influenza A(H1N1) infection in California.

  Authors: Janice K Louie, Meileen Acosta, Kathleen Winter, Cynthia Jean, Shilpa Gavali, Robert Schechter, Duc Vugia, Kathleen Harriman, Bela Matyas, Carol A Glaser, Michael C Samuel, Jon Rosenberg, John Talarico, Douglas Hatch

  JAMA : the journal of the American Medical Association. 11/2009; 302(17):1896-902.

  CONTEXT: Pandemic influenza A(H1N1) emerged rapidly in California in April 2009. Preliminary comparisons with seasonal influenza suggest that pandemic 2009 influenza A(H1N1) disproportionatelyCONTEXT: Pandemic influenza A(H1N1) emerged rapidly in California in April 2009. Preliminary comparisons with seasonal influenza suggest that pandemic 2009 influenza A(H1N1) disproportionately affects younger ages and causes generally mild disease. OBJECTIVE: To describe the clinical and epidemiologic features of pandemic 2009 influenza A(H1N1) cases that led to hospitalization or death. DESIGN, SETTING, AND PARTICIPANTS: Statewide enhanced public health surveillance of California residents who were hospitalized or died with laboratory evidence of pandemic 2009 influenza A(H1N1) infection reported to the California Department of Public Health between April 23 and August 11, 2009. MAIN OUTCOME MEASURE: Characteristics of hospitalized and fatal cases. RESULTS: During the study period there were 1088 cases of hospitalization or death due to pandemic 2009 influenza A(H1N1) infection reported in California. The median age was 27 years (range, <1-92 years) and 68% (741/1088) had risk factors for seasonal influenza complications. Sixty-six percent (547/833) of those with chest radiographs performed had infiltrates and 31% (340/1088) required intensive care. Rapid antigen tests were falsely negative in 34% (208/618) of cases evaluated. Secondary bacterial infection was identified in 4% (46/1088). Twenty-one percent (183/884) received no antiviral treatment. Overall fatality was 11% (118/1088) and was highest (18%-20%) in persons aged 50 years or older. The most common causes of death were viral pneumonia and acute respiratory distress syndrome. CONCLUSIONS: In the first 16 weeks of the current pandemic, the median age of hospitalized infected cases was younger than is common with seasonal influenza. Infants had the highest hospitalization rates and persons aged 50 years or older had the highest mortality rates once hospitalized. Most cases had established risk factors for complications of seasonal influenza.

• Methamphetamine and cocaine use among Mexican migrants in California: the California-Mexico Epidemiological Surveillance Pilot.

  Authors: María Teresa Hernández, Melissa A Sanchez, Lorena Ayala, Carlos Magis-Rodríguez, Juan D Ruiz, Michael C Samuel, Bart K Aoki, Alvaro H Garza, George F Lemp

  AIDS education and prevention : official publication of the International Society for AIDS Education. 10/2009; 21(5 Suppl):34-44.

  Methamphetamine and cocaine use have been associated with a vulnerability to HIV infection among men who have sex with men and among men who have sex with women but not specifically among MexicanMethamphetamine and cocaine use have been associated with a vulnerability to HIV infection among men who have sex with men and among men who have sex with women but not specifically among Mexican migrants in the United States. The California-Mexico Epidemiological Surveillance Pilot was a venue-based targeted survey of male and female Mexican migrants living in rural and urban areas in California. Among men (n = 985), the percentage of methamphetamine/cocaine use in the past year was 21% overall, 20% in male work venues, 19% in community venues, and 25% in high-risk behavior venues. Among women, 17% reported methamphetamine/cocaine use in high-risk behavior venues. Among men, methamphetamine/cocaine use was significantly associated with age less than 35 years, having multiple sex partners, depressive symptoms, alcohol use, sexually transmitted infections (including HIV), and higher acculturation. Prevention interventions in this population should be targeted to specific migrant sites and should address alcohol, methamphetamine, and cocaine use in the context of underlying psychosocial and environmental factors.

• Neonatal herpes morbidity and mortality in California, 1995-2003.

  Authors: Sheldon R Morris, Heidi M Bauer, Michael C Samuel, Deborah Gallagher, Gail Bolan

  Sexually transmitted diseases. 02/2008; 35(1):14-8.

  BACKGROUND: Neonatal herpes infections can have serious consequences. Methods for monitoring the incidence of neonatal herpes have not been standardized. OBJECTIVES: To use existing data to examineBACKGROUND: Neonatal herpes infections can have serious consequences. Methods for monitoring the incidence of neonatal herpes have not been standardized. OBJECTIVES: To use existing data to examine neonatal herpes-related morbidity in California. METHODS: California hospital discharge and mortality data were used to identify neonatal herpes cases, defined as a herpes-related discharge diagnosis with an admitting age of 42 days or less, and neonatal herpes-related deaths. California birth data were used to identify pregnancies complicated by herpes and to determine cesarean section rates. RESULTS: The overall incidence of neonatal herpes was 12.1 per 100,000 live births per year, with no observable change from 1995 to 2003. Neonatal herpes-related mortality, which was estimated to be 0.8 deaths per 100,000 live births, also did not show significant change over time. Between 1995 and 2002, herpes complication in labor declined steadily from 0.23% to 0.09% of all labors (P <0.0001). Among pregnancies with herpes as a complication of labor, cesarean section rates increased from 72.2% to 78.3% (P = 0.01), whereas overall cesarean rates increased from 20.0% to 26.0% (P <0.0001). CONCLUSIONS: Existing data can be used to monitor the morbidity and mortality of neonatal herpes. Because the rate of neonatal herpes cases and deaths was stable from 1995 to 2003 despite a decrease in herpes complications in labor and an increase in cesarean rates, new interventions are needed to prevent neonatal herpes.

• Sexually transmitted diseases and risk behaviors among California farmworkers: results from a population-based survey.

  Authors: Monique Brammeier, Joan M Chow, Michael C Samuel, Kurt C Organista, Jamie Miller, Gail Bolan

  The Journal of rural health : official journal of the American Rural Health Association and the National Rural Health Care Association. 01/2008; 24(3):279-84.

  The prevalence of sexually transmitted diseases and associated risk behaviors among California farmworkers is not well described. To estimate the prevalence of sexually transmitted diseases (STDs)The prevalence of sexually transmitted diseases and associated risk behaviors among California farmworkers is not well described. To estimate the prevalence of sexually transmitted diseases (STDs) and associated risk behaviors among California farmworkers. Cross-sectional analysis of population-based survey data from 6 California agricultural regions was performed for participants tested for Chlamydia trachomatis (CT), Neisseria gonorrhea (GC), and syphilis, and who completed an interviewer-administered behavioral risk factor survey. Among the 403 males and 234 females examined and interviewed, males (29.3%) were more likely than females (9.6%) to have had 2 or more sex partners in the past 5 years. Forty-two percent of males ever had sex with a commercial sex worker; unmarried males were more likely than married males to report sex with a commercial sex worker in the past 2 years. Twelve percent of males and 5% of females reported ever having had an STD. Most participants did not report any methods to protect against STDs. Of 192 males and 178 females tested for CT, 3 males and no females were positive. No cases of GC were found. Of 387 males and 194 females tested for syphilis, 4 males and 1 female had positive rapid plasma reagin (RPR) and Treponema pallidum particle agglutination (TPPA) results. In this population-based survey among agricultural workers, there was low STD prevalence but high prevalence of sexual risk behaviors, particularly among males.

• An evaluation of the relative sensitivities of the venereal disease research laboratory test and the Treponema pallidum particle agglutination test among patients diagnosed with primary syphilis.

  Authors: Linda Creegan, Heidi M Bauer, Michael C Samuel, Jeffrey Klausner, Sally Liska, Gail Bolan

  Sexually transmitted diseases. 01/2008; 34(12):1016-1018.

  BACKGROUND: Because definitive methods for diagnosing primary syphilis are limited, it is important to optimize the sensitivity of serodiagnosis. OBJECTIVE: To determine the most sensitive testingBACKGROUND: Because definitive methods for diagnosing primary syphilis are limited, it is important to optimize the sensitivity of serodiagnosis. OBJECTIVE: To determine the most sensitive testing approach to the diagnosis of primary syphilis, using the commonly available serologic tests: the Venereal Disease Research Laboratory (VDRL) test and the Treponema pallidum particle agglutination (TP-PA) test. METHODS: Sensitivities of 2 serologic testing strategies for primary syphilis were compared among 106 darkfield-confirmed cases treated in San Francisco from January 2002 through December 2004. RESULTS: The sensitivity of the diagnostic strategy using VDRL confirmed by TP-PA was 71% (95% CI, 61%-79%). Substituting Rapid Plasma Reagin test for VDRL in a subset of 51 patients produced the same sensitivity (71%; 95% CI, 56%-83%). The sensitivity of TP-PA as the first-line diagnostic test was 86% (95% CI, 78%-92%). The sensitivity of the former approach was significantly lower among HIV-positive patients, compared with HIV-negative patients (55% vs. 77%, P = 0.05). CONCLUSIONS: The TP-PA test as the first-line diagnostic test yielded higher sensitivity for primary syphilis than did the use of the currently recommended strategy.

• Trends in the use of sexually transmitted disease diagnostic technologies in California, 1996-2003.

  Authors: Katherine Ahrens, K. Jayne Bradbury, Heidi M Bauer, Michael C Samuel, Gail Gould, Giannina Donatoni, Chandra Higgins, Peter Kerndt, Gail Bolan

  Sexually transmitted diseases. 08/2007; 34(7):513-8.

  OBJECTIVE: To describe trends in STD diagnostic test volume and test technology in California from 1996 to 2003. STUDY: A self-administered survey was mailed annually to licensed clinicalOBJECTIVE: To describe trends in STD diagnostic test volume and test technology in California from 1996 to 2003. STUDY: A self-administered survey was mailed annually to licensed clinical laboratories in California that performed STD testing. Data were collected on volume and diagnostic test type for chlamydia, gonorrhea, syphilis, chancroid, HIV, hepatitis B, herpes simplex virus (HSV), and human papilloma virus (HPV). Data were analyzed for trends over time. RESULTS: Response rates ranged from 77% to 99% per survey year. The total number of chlamydia, gonorrhea, and syphilis tests increased from 8.1 to 9.3 million annually. The proportion of chlamydia and gonorrhea tests performed using nucleic acid amplification testing increased from 5% to 66% and from 1% to 59%, respectively. Gonorrhea culture testing decreased from 42% to 10% of all gonorrhea tests. HIV test volume increased from 2.4 to 3.1 million tests. Newer technology tests for HSV and HPV were less common but increased in use. Non-public health laboratories conducted over 90% of all STD testing. CONCLUSIONS: Analyzing trends in diagnostic technologies enhances our understanding of the epidemiology of STDs and monitoring laboratory capacity and practices facilitates implementation of STD control activities.

• Listeria monocytogenes infection from foods prepared in a commercial establishment: a case-control study of potential sources of sporadic illness in the United States.

  Authors: Jay K Varma, Michael C Samuel, Ruthanne Marcus, Robert M Hoekstra, Carlota Medus, Suzanne Segler, Bridget J Anderson, Timothy F Jones, Beletshachew Shiferaw, Nicole Haubert, Melanie Megginson, Patrick V McCarthy, Lewis Graves, Thomas Van Gilder, Frederick J Angulo

  Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 03/2007; 44(4):521-8.

  BACKGROUND: Listeria monocytogenes has been estimated to cause >2500 illnesses and 500 deaths annually in the United States. Efforts to reduce foodborne listeriosis have focused on foods frequentlyBACKGROUND: Listeria monocytogenes has been estimated to cause >2500 illnesses and 500 deaths annually in the United States. Efforts to reduce foodborne listeriosis have focused on foods frequently implicated in outbreaks. Potential sources for L. monocytogenes infection not associated with outbreaks remain poorly understood. METHODS: The Foodborne Diseases Active Surveillance Network conducts surveillance for culture-confirmed listeriosis at clinical laboratories in 9 states. After excluding outbreak-associated cases, we attempted to enroll eligible case patients with L. monocytogenes infection in a case-control study from 2000 through 2003. Control subjects were recruited through health care providers and were matched to case patients by state, age, and immunosuppression status. Data were collected about exposures occurring in the 4 weeks before specimen collection from the case patients. RESULTS: Of the 249 case patients with L. monocytogenes infection, only 12 (5%) had cases that were associated with outbreaks; 6 other patients were ineligible for other reasons. Of 231 eligible case patients, 169 (73%) were enrolled in the study. We classified 28 case patients as having pregnancy-associated cases. We enrolled 376 control subjects. In multivariable analysis, L. monocytogenes infection was associated with eating melons at a commercial establishment (odds ratio, 2.6; 95% confidence interval, 1.4-5.0) and eating hummus prepared in a commercial establishment (odds ratio, 5.7; 95% confidence interval, 1.7-19.1). CONCLUSIONS: Most cases of L. monocytogenes infection were not associated with outbreaks. Reducing the burden of foodborne listeriosis may require interventions directed at retail environments and at foods, such as melons and hummus, that are not commonly recognized as high risk. Because of the severity of listeriosis, pregnant women and other persons at risk may wish to avoid eating these newly implicated foods.

• Case-control study of shigellosis in San Francisco: the role of sexual transmission and HIV infection.

  Authors: Tomás J Aragón, Duc J Vugia, Sue Shallow, Michael C Samuel, Arthur Reingold, Frederick J Angulo, Williamson Z Bradford

  Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 03/2007; 44(3):327-34.

  BACKGROUND: Shigella species infect approximately 450,000 persons annually in the United States. Person-to-person transmission of Shigella species, which have a low infectious dose, occursBACKGROUND: Shigella species infect approximately 450,000 persons annually in the United States. Person-to-person transmission of Shigella species, which have a low infectious dose, occurs frequently, particularly in areas with poor sanitation and hygiene. Sexual transmission of Shigella species among men who have sex with men (MSM) has been inferred from outbreaks of shigellosis among that population, and limited studies have suggested the importance of human immunodeficiency virus (HIV) infection as a risk factor for shigellosis. No population-based study of sporadic shigellosis has evaluated the role of sexual practices (especially among MSM) and HIV infection along with other established risk factors for shigellosis. METHODS: We conducted a population-based case-control study of shigellosis in adults in San Francisco, California, during the period 1998-1999. Cases of Shigella infection were identified through laboratory-based active surveillance conducted by the California Emerging Infections Program. Seventy-six case patients were matched by sex with 146 control subjects. Exposure data were collected on established risk factors, sexual practices, and HIV infection status. Bivariable and multivariable analyses were conducted. Population-attributable fractions were calculated. RESULTS: From the multivariable analysis, for men, shigellosis was associated with MSM (odds ratio [OR], 8.24; 95% confidence interval [CI], 2.70-25.2), HIV infection (OR, 8.17; 95% CI, 2.71-24.6), direct oral-anal contact (OR, 7.50; 95% CI, 1.74-32.3), and foreign travel (OR, 20.0; 95% CI, 5.26-76.3), with population-attributable fractions of 0.72, 0.42, 0.31, and 0.18, respectively. For women, shigellosis was associated only with foreign travel (OR, 21.0; 95% CI, 2.52-899), with a population-attributable fraction of 0.37. CONCLUSIONS: Among MSM, shigellosis is predominantly a sexually transmitted disease, with direct oral-anal contact conferring the highest risk and HIV infection likely contributing to increased host susceptibility.

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

  Authors: Michael C Samuel, Duc J Vugia, Sue Shallow, Ruthanne Marcus, Suzanne Segler, Teresa McGivern, Heidi Kassenborg, Kevin Reilly, Malinda Kennedy, Frederick Angulo, Robert V Tauxe

  Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 05/2004; 38 Suppl 3:S165-74.

  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 onCampylobacter 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.

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

  Authors: Kevin L Winthrop, Kim Albridge, David South, Peggy Albrecht, Marcy Abrams, Michael C Samuel, Wendy Leonard, Joanna Wagner, Duc J Vugia

  Clinical infectious diseases : an official publication of the Infectious Diseases Society of America. 02/2004; 38(1):38-44.

  Nontuberculous mycobacterial infections are becoming more common. Recently, Mycobacterium fortuitum and other rapidly growing mycobacteria have been found to cause severe skin and soft-tissueNontuberculous 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.

• Antibiotic resistance patterns of bacterial isolates from blood in San Francisco County, California, 1996-1999.

  Authors: Susan S Huang, Brian J Labus, Michael C Samuel, Dairian T Wan, Arthur L Reingold

  Emerging infectious diseases. 03/2002; 8(2):195-201.

  Countywide antibiotic resistance patterns may provide additional information from that obtained from national sampling or individual hospitals. We reviewed susceptibility patterns of selectedCountywide antibiotic resistance patterns may provide additional information from that obtained from national sampling or individual hospitals. We reviewed susceptibility patterns of selected bacterial strains isolated from blood in San Francisco County from January 1996 to March 1999. We found substantial hospital-to-hospital variability in proportional resistance to antibiotics in multiple organisms. This variability was not correlated with hospital indices such as number of intensive care unit or total beds, annual admissions, or average length of stay. We also found a significant increase in methicillin-resistant Staphylococcus aureus, vancomycin-resistant Enterococcus, and proportional resistance to multiple antipseudomonal antibiotics. We describe the utility, difficulties, and limitations of countywide surveillance.

• Assessment of the Association of Chlamydia trachomatis Infection and Adverse Perinatal Outcomes with the Use of Population-Based Chlamydia Case Report Registries and Birth Records

  Authors: Joan M Chow, Mi-Suk Kang, Michael C Samuel, Gail Bolan

• California Gonorrhea Surveillance System: Methodologic Aspects and Key Results of a Sample-Based System

  Authors: Michael C Samuel, A. Rain Mocello, Denise Gilson, K. Jayne Bradbury, Gail Bolan