Andrew C. Voetsch

FoodNet Estimate of the Burden of Illness Caused by Nontyphoidal Salmonella Infections in the United States

To determine the burden of Salmonella infections in the United States, Foodborne Diseases Active Surveillance Network (FoodNet) investigators conducted population-based active surveillance for culture-confirmed Salmonella infections during 1996-1999 at FoodNet laboratories. In addition, all clinical microbiology FoodNet laboratories were surveyed to determine their practices for isolating Salmonella. Telephone interviews were also conducted among residents of the FoodNet sites to determine the proportion of persons with diarrheal illness who sought medical care and the proportion who submitted stool specimens for bacterial culture. Using our model, we estimated that there were 1.4 million nontyphoidal Salmonella infections in the United States, resulting in 168,000 physician office visits per year during 1996-1999. Including both culture-confirmed infections and those not confirmed by culture, we estimated that Salmonella infections resulted in 15,000 hospitalizations and 400 deaths annually. These estimates indicate that salmonellosis presents a major ongoing burden to public health.

Highly resistant Salmonella Newport-MDRAmpC transmitted through the domestic US food supply: a FoodNet case-control study of sporadic Salmonella Newport infections, 2002-2003.

BACKGROUND A new multidrug-resistant (MDR) strain of Salmonella serotype Newport, Newport-MDRAmpC, has recently emerged. We sought to identify the medical, behavioral, and dietary risk factors for laboratory-confirmed Salmonella Newport infection, including that with Newport-MDRAmpC. METHODS A 12-month population-based case-control study was conducted during 2002-2003 in 8 sites of the Foodborne Diseases Active Surveillance Network (FoodNet), with 215 case patients with Salmonella Newport infection and 1154 healthy community control subjects. RESULTS Case patients with Newport-MDRAmpC infection were more likely than control subjects to have taken an antimicrobial agent to which Newport-MDRAmpC is resistant during the 28 days before the onset of diarrheal illness (odds ratio [OR], 5.0 [95% confidence interval {CI}, 1.6-16]). Case patients with Newport-MDRAmpC infection were also more likely to have eaten uncooked ground beef (OR, 7.8 [95% CI, 1.4-44]) or runny scrambled eggs or omelets prepared in the home (OR, 4.9 [95% CI, 1.3-19]) during the 5 days before the onset of illness. International travel was not a risk factor for Newport-MDRAmpC infection but was a strong risk factor for pansusceptible Salmonella Newport infection (OR, 7.1 [95% CI, 2.0-24]). Case patients with pansusceptible infection were also more likely to have a frog or lizard in their household (OR, 2.9 [95% CI, 1.1-7.7]). CONCLUSIONS Newport-MDRAmpC infection is acquired through the US food supply, most likely from bovine and, perhaps, poultry sources, particularly among persons already taking antimicrobial agents.

Re-assessment of risk factors for sporadic Salmonella serotype Enteritidis infections: a case-control study in five FoodNet Sites, 2002-2003.

Active surveillance for laboratory-confirmed Salmonella serotype Enteritidis (SE) infection revealed a decline in incidence in the 1990s, followed by an increase starting in 2000. We sought to determine if the fluctuation in SE incidence could be explained by changes in foodborne sources of infection. We conducted a population-based case-control study of sporadic SE infection in five of the Foodborne Diseases Active Surveillance Network (FoodNet) sites during a 12-month period in 2002-2003. A total of 218 cases and 742 controls were enrolled. Sixty-seven (31%) of the 218 case-patients and six (1%) of the 742 controls reported travel outside the United States during the 5 days before the cases illness onset (OR 53, 95% CI 23-125). Eighty-one percent of cases with SE phage type 4 travelled internationally. Among persons who did not travel internationally, eating chicken prepared outside the home and undercooked eggs inside the home were associated with SE infections. Contact with birds and reptiles was also associated with SE infections. This study supports the findings of previous case-control studies and identifies risk factors associated with specific phage types and molecular subtypes.

Reduction in the Incidence of Invasive Listeriosis in Foodborne Diseases Active Surveillance Network Sites, 1996-2003

BACKGROUND Listeriosis is a leading cause of death among patients with foodborne diseases in the United States. Monitoring disease incidence is an important element of listeriosis surveillance and control. METHOD We conducted population-based surveillance for Listeria monocytogenes isolates obtained from normally sterile sites at all clinical diagnostic laboratories in the Foodborne Diseases Active Surveillance Network from 1996 through 2003. RESULTS The incidence of laboratory-confirmed invasive listeriosis decreased by 24% from 1996 through 2003; pregnancy-associated disease decreased by 37%, compared with a decrease of 23% for patients > or =50 years old. The highest incidence was reported among Hispanic persons from 1997 through 2001. Differences in incidence by age group and ethnicity may be explained by dietary preferences. CONCLUSION The marked decrease in the incidence of listeriosis may be related to the decrease in the prevalence of L. monocytogenes contamination of ready-to-eat foods since 1996. The crude incidence in 2003 of 3.1 cases per 1 million population approaches the governments Healthy People objective of 2.5 cases per 1 million population by 2005. Further decreases in listeriosis incidence will require continued efforts of industry and government to reduce contamination of food and continued efforts to educate consumers and clinicians.

Laboratory Practices for Stool-Specimen Culture for Bacterial Pathogens, Including Escherichia coli O157:H7, in the FoodNet Sites, 1995–2000

In 2000, we surveyed microbiologists in 388 clinical laboratories, which tested an estimated 339,000 stool specimens in 1999, about laboratory methods and policies for the routine testing of stool specimens for Salmonella, Shigella, Campylobacter, and Vibrio species, Yersinia entercolitica, and Escherichia coli O157:H7. The results were compared with those of similar surveys conducted in 1995 and 1997. Although these laboratories reported routinely testing for Salmonella, Shigella, and Campylobacter species, only 57% routinely tested for E. coli O157:H7, 50% for Y. entercolitica, and 50% for Vibrio species. The mean proportions of stool specimens that yielded these pathogens were as follows: Campylobacter, 1.3% of specimens; Salmonella, 0.9%; Shigella, 0.4%; and E. coli O157:H7, 0.3%. The proportion of laboratories that routinely tested for E. coli O157:H7 increased from 59% in 1995 to 68% in 2000; however, the proportion of stool specimens tested decreased from 53% to 46%. E. coli O157:H7 should be routinely sought in stool specimens submitted for microbiologic culture.

Risk factors for sporadic Shiga toxin-producing Escherichia coli O157 infections in FoodNet sites, 1999-2000.

To monitor risk factors for illness, we conducted a case-control study of sporadic Shiga toxin-producing Escherichia coli O157 (STEC O157) infections in 1999-2000. Laboratory-confirmed cases of STEC O157 infection were identified through active laboratory surveillance in all or part of seven states. Patients and age-matched controls were interviewed by telephone using a standard questionnaire. Information was collected on demographics, clinical illness, and exposures to food, water, and animals in the 7 days before the patients illness onset. During the 12-month study, 283 patients and 534 controls were enrolled. STEC O157 infection was associated with eating pink hamburgers, drinking untreated surface water, and contact with cattle. Eating produce was inversely associated with infection. Direct or indirect contact with cattle waste continues to be a leading identified source of sporadic STEC O157 infections.

HIV Risk Behaviors and Testing History in Historically Black College and University Settings

Objectives. From 2001 through 2005, African Americans accounted for the largest percentage of new cases of human immunodeficiency virus (HIV)/ acquired immunodeficiency syndrome (AIDS) in all age categories, especially among people aged 13 to 24 years. Although students attending historically black colleges and universities (HBCUs) report many of the behaviors that promote HIV transmission, their risk behaviors and HIV testing practices have not been well-characterized. We compared the demographic and behavioral characteristics of people who have been previously tested for HIV with those of people tested for the first time in this demonstration project to increase HIV testing at HBCUs. Methods. The Centers for Disease Control and Prevention and collaborating partners conducted rapid HIV testing and behavioral surveys at HBCUs in Arkansas, Georgia, Mississippi, and Washington, D.C., from January 2005 to April 2007. We recruited a convenience sample of students and community members at different campus venues including student health centers, dormitories, and student activity centers. Results. Our analysis included 5,291 people, 42% of whom reported they had never been tested for HIV. People who had been tested in the past were more likely to be older, believe they were at high risk for infection, have visited a health-care facility, and report behaviors that increased their risk of HIV infection. Conclusion. Respondents who believed they were at increased risk for HIV infection or reported behaviors that increased their risk for infection were more likely to have been tested for HIV. Future research should compare actual vs. perceived risk for HIV infection and contrast how each impacts HIV testing.

Determining the Burden of Human Illness From Food Borne Diseases: CDC’s Emerging Infectious Disease Program Food Borne Diseases Active Surveillance Network (FoodNet)

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.

HIV Screening in an Urban Emergency Department: Comparison of Screening Using an Opt-In Versus an Opt-Out Approach

OBJECTIVE We compare outcomes of opt-in and opt-out HIV screening approaches in an urban emergency department. METHODS This was a 1-year prospective observational study comparing 2 6-month screening approaches. Eligibility for opt-in and opt-out screening was identical: aged 15 years or older, medically stable, and able to complete general consent. During the opt-in phase, triage nurses referred patients to HIV testers stationed at triage, who obtained separate opt-in written consent and performed rapid oral fluid tests. During the opt-out phase, registration staff conducted integrated opt-out consent and then referred patients to HIV testers. We assessed the proportion of potentially eligible patients who were offered screening (screening offer rate), the proportion offered screening who accepted (screening acceptance rate), the proportion who accepted screening and subsequently completed testing (test completion rate), and the proportion of potentially eligible patients who completed testing (overall screening rate) during each phase. RESULTS For the opt-in versus the opt-out phases, respectively, there were 23,236 potentially eligible patients versus 26,757, screening offer rate was 27.9% versus 75.8% (P<.001), screening acceptance rate was 62.7% versus 30.9% (P<.001), test completion rate was 99.8% versus 74.6% (P<.001), and overall screening rate was 17.4% versus 17.5% (P = .90). CONCLUSION A significantly higher proportion of patients were offered HIV screening with an opt-out approach at registration. However, this was offset by much higher screening acceptance and test completion rates with the opt-in approach at triage. Overall screening rates with the 2 approaches were nearly identical.

Willingness of men who have sex with men (MSM) in the United States to be circumcised as adults to reduce the risk of HIV infection.

Background Circumcision reduces HIV acquisition among heterosexual men in Africa, but it is unclear if circumcision may reduce HIV acquisition among men who have sex with men (MSM) in the United States, or whether MSM would be willing to be circumcised if recommended. Methods We interviewed presumed-HIV negative MSM at gay pride events in 2006. We asked uncircumcised respondents about willingness to be circumcised if it were proven to reduce risk of HIV among MSM and perceived barriers to circumcision. Multivariate logistic regression was used to identify covariates associated with willingness to be circumcised. Results Of 780 MSM, 133 (17%) were uncircumcised. Of these, 71 (53%) were willing to be circumcised. Willingness was associated with black race (exact odds ratio [OR]: 3.4, 95% confidence interval [CI]: 1.3–9.8), non-injection drug use (OR: 6.1, 95% CI: 1.8–23.7) and perceived reduced risk of penile cancer (OR: 4.7, 95% CI: 2.0–11.9). The most commonly endorsed concerns about circumcision were post-surgical pain and wound infection. Conclusions Over half of uncircumcised MSM, especially black MSM, expressed willingness to be circumcised. Perceived risks and benefits of circumcision should be a part of educational materials if circumcision is recommended for MSM in the United States.