Anna E. Newton

Increasing Rates of Vibriosis in the United States, 1996–2010: Review of Surveillance Data From 2 Systems

BACKGROUND The Centers for Disease Control and Prevention monitors vibriosis through 2 surveillance systems: the nationwide Cholera and Other Vibrio Illness Surveillance (COVIS) system and the 10-state Foodborne Diseases Active Surveillance Network (FoodNet). COVIS conducts passive surveillance and FoodNet conducts active surveillance for laboratory-confirmed Vibrio infections. METHODS We summarized Vibrio infections (excluding toxigenic V. cholerae O1 and O139) reported to COVIS and FoodNet from 1996 through 2010. For each system, we calculated incidence rates using US Census Bureau population estimates for the surveillance area. RESULTS From 1996 to 2010, 7700 cases of vibriosis were reported to COVIS and 1519 to FoodNet. Annual incidence of reported vibriosis per 100,000 population increased from 1996 to 2010 in both systems, from 0.09 to 0.28 in COVIS and from 0.15 to 0.42 in FoodNet. The 3 commonly reported Vibrio species were V. parahaemolyticus, V. vulnificus, and V. alginolyticus; both surveillance systems showed that the incidence of each increased. In both systems, most hospitalizations and deaths were caused by V. vulnificus infection, and most patients were white men. The number of cases peaked in the summer months. CONCLUSIONS Surveillance data from both COVIS and FoodNet indicate that the incidence of vibriosis increased from 1996 to 2010 overall and for each of the 3 most commonly reported species. Epidemiologic patterns were similar in both systems. Current prevention efforts have failed to prevent increasing rates of vibriosis; more effective efforts will be needed to decrease rates.

Cholera in the United States, 2001–2011: a reflection of patterns of global epidemiology and travel

US cholera surveillance offers insight into global and domestic trends. Between 2001 and 2011, 111 cases were reported to the Centers for Disease Control and Prevention. Cholera was associated with international travel in 90 (81%) patients and was domestically acquired in 20 (18%) patients; for one patient, information was not available. From January 2001 to October 2010, the 42 (47%) travel-associated cases were associated with travel to Asia. In October 2010, a cholera epidemic started in Haiti, soon spreading to the Dominican Republic (Hispaniola). From then to December 2011, 40 (83%) of the 48 travel-associated cases were associated with travel to Hispaniola. Of 20 patients who acquired cholera domestically, 17 (85%) reported seafood consumption; 10 (59%) ate seafood from the US Gulf Coast. In summary, an increase in travel-associated US cholera cases was associated with epidemic cholera in Hispaniola in 2010-2011. Travel to Asia and consumption of Gulf Coast seafood remained important sources of US cholera cases.

Impact of 2003 State Regulation on Raw Oyster–associated Vibrio vulnificus Illnesses and Deaths, California, USA

TOC summary: After regulation was implemented, the number of cases and deaths dropped significantly; a similar national regulation would likely decrease US infections.

Typhoid Fever Outbreak Associated With Frozen Mamey Pulp Imported From Guatemala to the Western United States, 2010

BACKGROUND Fifty-four outbreaks of domestically acquired typhoid fever were reported between 1960 and 1999. In 2010, the Southern Nevada Health District detected an outbreak of typhoid fever among persons who had not recently travelled abroad. METHODS We conducted a case-control study to examine the relationship between illness and exposures. A case was defined as illness with the outbreak strain of Salmonella serotype Typhi, as determined by pulsed-field gel electrophoresis (PFGE), with onset during 2010. Controls were matched by neighborhood, age, and sex. Bivariate and multivariate statistical analyses were completed using logistic regression. Traceback investigation was completed. RESULTS We identified 12 cases in 3 states with onset from 15 April 2010 to 4 September 2010. The median age of case patients was 18 years (range, 4-48 years), 8 (67%) were female, and 11 (92%) were Hispanic. Nine (82%) were hospitalized; none died. Consumption of frozen mamey pulp in a fruit shake was reported by 6 of 8 case patients (75%) and none of the 33 controls (matched odds ratio, 33.9; 95% confidence interval, 4.9). Traceback investigations implicated 2 brands of frozen mamey pulp from a single manufacturer in Guatemala, which was also implicated in a 1998-1999 outbreak of typhoid fever in Florida. CONCLUSIONS Reporting of individual cases of typhoid fever and subtyping of isolates by PFGE resulted in rapid detection of an outbreak associated with a ready-to-eat frozen food imported from a typhoid-endemic region. Improvements in food manufacturing practices and monitoring will prevent additional outbreaks.

Effectiveness of typhoid vaccination in US travelers.

Typhoid vaccination is recommended in the United States before travel to countries where typhoid fever is endemic, though little information is available on its effectiveness in travelers. We estimated typhoid vaccination effectiveness (VE) by comparing vaccination status in cases of typhoid fever and paratyphoid fever (Salmonella Paratyphi A infection, against which typhoid vaccine offers no protection) reported in the United States. We included travelers to Southern Asia and excluded persons <2 years old and cases in which vaccination status was not reported. From 2008 through 2011, 744 eligible cases (602 typhoid, 142 paratyphoid A) were reported to CDC. Typhoid vaccination was reported for 5% (29/602) of typhoid patients and for 20% (29/142) of paratyphoid A patients. Estimated VE was 80% (95% confidence interval, 66-89%). Because of missing data, we could not estimate VE for specific vaccines. We demonstrated moderate effectiveness of typhoid vaccination in US travelers, supporting vaccination recommendations.

Changing Patterns in Enteric Fever Incidence and Increasing Antibiotic Resistance of Enteric Fever Isolates in the United States, 2008–2012

BACKGROUND Enteric fever in the United States has been primarily associated with travel and with worrisome changes in global patterns of antimicrobial resistance. We present the first comprehensive report of National Typhoid and Paratyphoid Fever Surveillance System (NTPFS) data for a 5-year period (2008-2012). METHODS We reviewed data on laboratory-confirmed cases reported to NTPFS, and related antimicrobial susceptibility results of Salmonella Typhi and Paratyphi A isolates sent for testing by participating public health laboratories to the Centers for Disease Control and Preventions National Antimicrobial Resistance Monitoring System laboratory. RESULTS During 2008-2012, 2341 enteric fever cases were reported, 80% typhoid and 20% paratyphoid A. The proportion caused by paratyphoid A increased from 16% (2008) to 22% (2012). Foreign travel within 30 days preceding illness onset was reported by 1961 (86%) patients (86% typhoid and 92% paratyphoid A). Travel to southern Asia was common (82% for typhoid, 97% for paratyphoid A). Among 1091 (58%) typhoid and 262 (56%) paratyphoid A isolates tested for antimicrobial susceptibility, the proportion resistant to nalidixic acid (NAL-R) increased from 2008 to 2012 (Typhi, 60% to 68%; Paratyphi A, 91% to 94%). Almost all NAL-R isolates were resistant or showed decreased susceptibility to ciprofloxacin. Resistance to at least ampicillin, chloramphenicol, and trimethoprim-sulfamethoxazole (multidrug resistant [MDR]) was limited to Typhi isolates, primarily acquired in southern Asia (13%). Most MDR isolates were also NAL-R. CONCLUSIONS Enteric fever in the United States is primarily associated with travel to southern Asia, and increasing resistance is adding to treatment challenges. A bivalent typhoid and paratyphoid vaccine is needed.

From the CDC: New Country‐Specific Recommendations for Pre‐Travel Typhoid Vaccination

Typhoid fever continues to be an important concern for travelers visiting many parts of the world. This communication provides updated guidance for pre-travel typhoid vaccination from the US Centers for Disease Control and Prevention (CDC) and describes the methodology for assigning country-specific recommendations.

Vibriosis, not cholera: toxigenic Vibrio cholerae non-O1, non-O139 infections in the United States, 1984-2014.

Toxigenic strains of Vibrio cholerae serogroups O1 and O139 have caused cholera epidemics, but other serogroups - such as O75 or O141 - can also produce cholera toxin and cause severe watery diarrhoea similar to cholera. We describe 31 years of surveillance for toxigenic non-O1, non-O139 infections in the United States and map these infections to the state where the exposure probably originated. While serogroups O75 and O141 are closely related pathogens, they differ in how and where they infect people. Oysters were the main vehicle for O75 infection. The vehicles for O141 infection include oysters, clams, and freshwater in lakes and rivers. The patients infected with serogroup O75 who had food traceback information available ate raw oysters from Florida. Patients infected with O141 ate oysters from Florida and clams from New Jersey, and those who only reported being exposed to freshwater were exposed in Arizona, Michigan, Missouri, and Texas. Improving the safety of oysters, specifically, should help prevent future illnesses from these toxigenic strains and similar pathogenic Vibrio species. Post-harvest processing of raw oysters, such as individual quick freezing, heat-cool pasteurization, and high hydrostatic pressurization, should be considered.

Vibrio mimicus infection associated with crayfish consumption, Spokane, Washington, 2010.

We report a cluster of severe diarrheal disease caused by Vibrio mimicus infection among four persons who had consumed leftover crayfish the day after a private crayfish boil. Gastrointestinal illness caused by Vibrio mimicus has not been reported previously in Washington State. Three cases were laboratory confirmed by stool culture; using PCR, isolates were found to have ctx genes that encode cholera toxin (CT). Two of the cases were hospitalized under intensive care with a cholera-like illness. The illnesses were most likely caused by cross-contamination of cooked crayfish with uncooked crayfish; however, V. mimicus was not isolated nor were CT genes detected by PCR in leftover samples of frozen crayfish. Clinicians should be aware that V. mimicus can produce CT and that V. mimicus infection can cause severe illness.

Typhoid fever acquired in the United States, 1999–2010: epidemiology, microbiology, and use of a space–time scan statistic for outbreak detection

Although rare, typhoid fever cases acquired in the United States continue to be reported. Detection and investigation of outbreaks in these domestically acquired cases offer opportunities to identify chronic carriers. We searched surveillance and laboratory databases for domestically acquired typhoid fever cases, used a space-time scan statistic to identify clusters, and classified clusters as outbreaks or non-outbreaks. From 1999 to 2010, domestically acquired cases accounted for 18% of 3373 reported typhoid fever cases; their isolates were less often multidrug-resistant (2% vs. 15%) compared to isolates from travel-associated cases. We identified 28 outbreaks and two possible outbreaks within 45 space-time clusters of ⩾2 domestically acquired cases, including three outbreaks involving ⩾2 molecular subtypes. The approach detected seven of the ten outbreaks published in the literature or reported to CDC. Although this approach did not definitively identify any previously unrecognized outbreaks, it showed the potential to detect outbreaks of typhoid fever that may escape detection by routine analysis of surveillance data. Sixteen outbreaks had been linked to a carrier. Every case of typhoid fever acquired in a non-endemic country warrants thorough investigation. Space-time scan statistics, together with shoe-leather epidemiology and molecular subtyping, may improve outbreak detection.