In July 1995, 40 Montana residents were identified with laboratory-confirmed Escherichia coli O157:H7 infection; 52 residents had bloody diarrhea without laboratory confirmation. The median age of those with laboratory-confirmed cases was 42 years (range, 4- 86); 58% were female. Thirteen patients were hospitalized, and 1 developed hemolytic-uremic syndrome. A case-control study showed that 19 (70%) of 27 patients but only 8 (17%) of 46 controls reported eating purchased (not home-grown) leaf lettuce before illness (matched odds ratio, 25.3; 95% confidence interval, 3.9-1065.6). Pulsed-field gel electrophoresis identified a common strain among 22 of 23 isolates tested. Implicated lettuce was traced to two sources: a local Montana farm and six farms in Washington State that shipped under the same label. This outbreak highlights the increasing importance of fresh produce as a vehicle in foodborne illness. Sanitary growing and handling procedures are necessary to prevent these infections.

This large outbreak of cyclosporiasis in North America in 1996 was associated with the consumption of Guatemalan raspberries. The outbreak illustrates the need to consider that a local cluster of foodborne illness may be part of a widespread outbreak and to pursue investigations to the source of the implicated vehicle.

Our data suggest that ciprofloxacin and ceftriaxone are appropriate empirical therapy for suspected typhoid fever; however, resistance may be anticipated. Continued monitoring of antimicrobial resistance among Salmonella Typhi strains will help determine vaccination and treatment policies. JAMA. 2000;283:2668-2673.

To clarify indications for typhoid vaccination, we reviewed laboratory-confirmed cases of typhoid fever reported to the United States Centers for Disease Control and Prevention between 1994 and 1999. To estimate the risk of adverse events associated with typhoid vaccination, we reviewed reports to the Vaccine Adverse Event Reporting System for the same period. Acute Salmonella enterica serotype Typhi infection was reported for 1393 patients. Of these patients, recent travel was reported by 1027 (74%), only 36 (4%) of whom reported having received a vaccination. Six countries accounted for 76% of travel-associated cases (India [30%], Pakistan [13%], Mexico [12%], Bangladesh [8%], The Philippines [8%], and Haiti [5%]). For 626 travelers who traveled to a single country, the length of stay was

Bacterial diarrheal diseases cause substantial morbidity and mortality in sub-Saharan Africa, but data on the epidemiology and antimicrobial susceptibility patterns of enteric bacterial pathogens are limited. Between May 1997 and April 1998, a clinic-based surveillance for diarrheal disease was conducted in Asembo, a rural area in western Kenya. In total, 729 diarrheal specimens were collected, and 244 (33%) yielded >or=1 bacterial pathogen, as determined by standard culture techniques; 107 (44%) Shigella isolates, 73 (30%) Campylobacter isolates, 45 (18%) Vibrio cholerae O1 isolates, and 33 (14%) Salmonella isolates were identified. Shigella dysenteriae type 1 accounted for 22 (21%) of the Shigella isolates. Among 112 patients empirically treated with an antimicrobial agent and whose stool specimens yielded isolates on which resistance testing was done, 57 (51%) had isolates that were not susceptible to their antimicrobial treatment. Empiric treatment strategies for diarrheal disease in western Kenya need to be reevaluated, to improve clinical care.

Typhoid fever is a significant cause of morbidity and mortality worldwide, causing an estimated 16 million cases and 600,000 deaths annually. Although overall rates of the disease have dramatically decreased in the United States, the number of travel-related infections has increased in recent decades. Drug resistance among Salmonella enterica serotype Typhi strains has emerged worldwide, making antimicrobial susceptibility testing an important function in public health laboratories. Pulsed-field gel electrophoresis (PFGE) subtyping of food-borne and waterborne pathogens has proven to be a valuable tool for the detection of outbreaks and laboratory-based surveillance. This retrospective study examined the distribution of PFGE patterns of S. enterica serotype Typhi isolates from patients with a history of international travel. Isolates were collected as part of a passive laboratory-based antimicrobial susceptibility surveillance study. Isolates were PFGE subtyped by using the restriction enzyme XbaI to restrict the total genomic DNA. Isolates indistinguishable with XbaI were further characterized using the restriction enzyme BlnI. A total of 139 isolates were typed, representing travel to 31 countries. Restriction fragment patterns consisted of 14 to 18 fragments ranging in size from 580 to 40 kbp. Seventy-nine unique PFGE patterns were generated using XbaI. Isolates from the same geographic region did not necessarily have similar PFGE patterns. Of the 139 isolates, 46 (33%) were resistant to more than one antimicrobial agent (multidrug resistant [MDR]). Twenty-seven (59%) of 46 MDR isolates had indistinguishable PFGE patterns with both XbaI and BlnI. It appears that MDR S. enterica serotype Typhi has emerged as a predominant clone in Southeast Asia and the Indian subcontinent.

ObjectiveTo provide HIV seroincidence data among men who have sex with men (MSM) in the United States and to identify predictive factors for seroconversion.MethodsFrom 1998–2002, 4684 high-risk MSM, age 18–60 years, participated in a randomized, placebo-controlled HIV vaccine efficacy trial at 56 U.S. clinical trial sites. Demographics, behavioral data, and HIV status were assessed at baseline and 6 month intervals. Since no overall vaccine efficacy was detected, data were combined from both trial arms to calculate HIV incidence based on person-years (py) of follow-up. Predictors of seroconversion, adjusted hazards ratio (aHR), were evaluated using a Cox proportional hazard model with time-varying covariates.ResultsOverall, HIV incidence was 2.7/100 py and was relatively uniform across study sites and study years. HIV incidence was highest among young men and men reporting unprotected sex, recreational drug use, and a history of a sexually transmitted infection. Independent predictors of HIV seroconversion included: age 18–30 years (aHR = 2.4; 95% CI 1.4,4.0), having >10 partners (aHR = 2.4; 95% CI 1.7,3.3), having a known HIV-positive male sex partner (aHR = 1.6; 95% CI 1.2, 2.0), unprotected anal intercourse with HIV positive/unknown male partners (aHR = 1.7; 95% CI 1.3, 2.3), and amphetamine (aHR = 1.6; 95% CI 1.1, 2.1) and popper (aHR = 1.7; 95% CI 1.3, 2.2) use.ConclusionsHIV seroincidence was high among MSM despite repeated HIV counseling and reported declines in sexual risk behaviors. Continuing development of new HIV prevention strategies and intensification of existing efforts will be necessary to reduce the rate of new HIV infections, especially among young men.

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