PHARS was queried to identify records from June 2005 to June 2024 for individuals with recent travel and suspected or confirmed cholera. Variables extracted and analyzed included traveler characteristics, travel information (departure and arrival locations, conveyance type), clinical information (reported symptoms, laboratory results), whether a conveyance contact investigation was conducted, and any secondary cases identified during follow-up. To determine the final destination, we used the destination or US address listed in the report or the reporting state, depending on the availability of data. To identify reports in PHARS, cholera cases were defined as symptoms compatible with cholera and a documented positive laboratory test, while suspected cholera cases were defined as compatible symptoms, but no documented positive laboratory test. De-identified data were analyzed descriptively using Excel, with 2 duplicate reports excluded. In addition, cruise-related cases are not regularly reported in PHARS; therefore, cruise-related reports were excluded from the analysis.

Cases identified in PHARS were cross-referenced with CDC cholera laboratory data to confirm positive results for toxigenic Vibrio cholerae. To report these results, we defined “confirmed cholera” as those for which a laboratory result confirmed the presence of toxigenic Vibrio cholerae, and we defined “non-cholera” as any cases that did not have a confirmed toxigenic laboratory result.

This activity, a secondary data analysis of data collected during routine operational work, was reviewed by the CDC (STARS ID: 0900f3eb821d861c) and deemed non-research; therefore, it did not require submission to the CDC Institutional Review Board. The operational work conducted was consistent with applicable federal law and CDC policy.^†

Thirty-seven non-duplicate reports for travelers with a suspicion of cholera were identified in PHARS during the analysis period. The majority (29/37, 78%) of reports were received before 2012, and of those, almost all (26/29, 90%) were reported during 2010–2011 (Supplementary Digital Content Figure 1, available at http://links.lww.com/JPHMP/B561).

Of the 37 reports, 35 (95%) involved air travel, 1 (3%) involved land travel, and 1 (3%) had an unknown mode of travel. For the 32 reports that included age, the median age reported was 34 years (interquartile range: 21–59 years). CDC PHSs were notified by HDs (26/37, 70%), US Customs and Border Protection (3/37, 8%), other CDC programs (2/37, 5%), fire rescue (1/37, 3%), an airline (1/37, 3%), and a hospital (1/37, 3%). Among the 30 reports that included country of travel origin, 22 (73%) indicated Haiti as the origin (Table 1). Nineteen of the 37 reports (51%) listed Florida as the traveler’s final destination and 22 (59%) were reported to the Miami PHS (Table 1). Additional information on travel origins, US destinations, demographics, and reported symptoms is summarized in Table 1.

Twenty-three of the 37 (62%) reports included laboratory results, and 17 (46%) cases were confirmed as positive for toxigenic Vibrio cholerae by CDC laboratory records. The remaining 6 reports listed the following laboratory results: 3 (50%) had negative test results, 2 (33%) had positive results for non-toxigenic Vibrio cholerae, and 1 (17%) had positive results but could not be confirmed in CDC laboratory records. All 17 confirmed cases were identified as Vibrio cholerae serogroup O1, serotype Ogawa. Sixteen (94%) of the travelers with confirmed cholera were hospitalized. Of the 14 hospitalized individuals for whom age was available, 2 (14%) were pediatric (range: 2–9 years), 9 (64%) were aged 18–61 years, and 3 (21%) were older adults (range: 70–73 years).

None of the reports indicated that a contact investigation was warranted on any conveyance according to CDC protocol. Cholera infection did not result in any deaths in this cohort.

Over the past 19 years, CDC PHSs have received 37 reports of suspected cholera among travelers (after exclusion of a cruise-related case), with nearly half of those cases confirmed as toxigenic Vibrio cholerae through laboratory testing. The majority of cases occurred before 2012 and were linked to the 2010 Haiti outbreak.

There are a number of limitations to this analysis. Data reported to PHSs were manually entered into PHARS by PHS staff, and some entries were incomplete or contained errors. Many reports lacked laboratory confirmation, meaning some illnesses may have been caused by pathogens other than toxigenic Vibrio cholerae, and some cholera cases may have been missed. Even among cases with reported positive lab results, some lacked sufficient documentation to confirm whether the case definition was met.⁷ This was partly due to the broad case definition and the frequent lack of clinical specificity in report entries, which often listed only general symptoms such as “diarrhea.” Cases may have gone unreported or were incompletely reported to HDs due to variations in clinical presentation and other factors, limiting the effectiveness of surveillance efforts. Cruise-related cases were excluded from this analysis, as they are reported to the CDC’s VSP. Furthermore, a 2011 change in CDC reporting guidance limited the requirement to notify PHSs of cholera cases in travelers to specific circumstances, resulting in a decrease in the number of reports to PHSs. However, since cholera cases are typically reported to CDC via the Cholera and Other Vibrio Illness Surveillance (COVIS) system—the primary reporting system for US Vibrio infections—this reduction in PHS reports likely did not result in missed cases that posed a true transmission risk during travel. No contact investigations were conducted on conveyances, in accordance with CDC protocols, and no secondary cases were identified. This limits the ability to assess potential transmission dynamics or undetected secondary spread in travel-related settings. Relevant contextual information, such as migration status or whether individuals were visiting friends and relatives (VFR) in cholera-endemic areas, was often missing or not systematically collected, potentially obscuring important risk factors. Occupation data, including whether individuals were engaged in humanitarian response or other high-risk settings, were also inconsistently reported and should be interpreted with caution. Ongoing training for port and airline staff to recognize and report potential infectious illnesses in travelers, especially during outbreaks, remains critical for supporting timely detection and public health response.

The risk of cholera transmission during air travel is likely low, and cholera does not pose a substantial risk in countries with improved water and sanitation systems, such as the United States.⁸ Current PHS reporting recommendations appear sufficient to capture travelers infected with cholera who truly pose a transmission risk. Public health action for travelers with suspected cholera may be necessary on occasion based on individual assessments. When airlines or other port partners notify PHSs about travelers with watery diarrhea, CDC staff can conduct a public health risk assessment, including determination of recent travel to cholera-endemic or outbreak areas. If cholera is suspected, travelers may be referred for medical evaluation and testing in coordination with HDs to ensure cases are not missed and appropriate follow-up care is provided.⁹ Clinicians evaluating patients with severe watery diarrhea should obtain a complete travel history and consider cholera testing if the patient reports travel to outbreak or endemic areas.