2023 Highlights
- The number of confirmed vibriosis cases remained similar to past years.
- Only 20% of cases positive by multiplex PCR were confirmed by culture, indicating a high number of false-positives on these platforms.
There were 89 Vibrio spp. cases reported in 2023. Of those, 23 were culture-confirmed and 66 tested positive by a culture-independent diagnostic test (CIDT) and were not subsequently culture-confirmed. The 23 culture-confirmed cases of Vibrio spp. infection reported in 2023 represent a 15% increase from the 20 cases reported in 2022 but is similar to the median annual number of cases reported from 2012 to 2022 (median, 22 cases; range, 15 to 40). V. parahaemolyticus accounted for 13 (57%) cases, V. cholerae for 6 (26%), and V. alginolyticus, V. fluvialis, and Grimontia hollisae (in the Vibrionaceae family and prior to 2003 classified in the Vibrio genus) for one case (4%) each. One isolate was not received at the MDH Public Health Laboratory for confirmation and species identification. Serotyping was performed on all V. cholerae specimens, and all were non-O1/non-O139.
Vibrio was isolated from stool in 19 (83%) of the 23 culture-confirmed cases. The specimen source for the remaining four cases was ear effusion (3 cases) and wound (1 case). Four (17%) cases were hospitalized for a median of 2.5 days (range, 1 to 6 days), and no cases died. Travel history was available for 18 cases. Ten (56%) of these cases traveled outside of Minnesota in the week before their symptom onset, including six (33%) who traveled internationally. Four cases traveled to Mexico and two traveled to Costa Rica. Of the 12 cases with Vibrio isolated from stool who were able to be interviewed about exposure to seafood in the week before illness onset, 11 (92%) had raw or undercooked seafood exposure, including 9 (75%) who reported consuming raw oysters.
In 2023, 84 patients tested positive for Vibrio spp. by CIDT conducted at a clinical laboratory. Of these, 66 (79%) were not culture-confirmed. Six (9%) specimens were not received at the MDH Public Health Laboratory for culture confirmation, and 60 (91%) were received at MDH and tested negative by culture. Ten (13%) CIDT-only cases were hospitalized for a median of 3 days (range, 1 to 50 days) and none died. Fourteen (30%) of the 47 CIDT-only cases who were interviewed traveled outside of Minnesota, and 7 (15%) traveled internationally (3 to the Dominican Republic and 1 each to China, El Salvador, Mexico, and Pakistan). Among the 37 CIDT-only cases interviewed about food exposures, 9 (24%) reported eating raw or undercooked seafood including four (11%) who had raw oysters. CIDT-only cases differed markedly from culture-confirmed cases regarding exposures, suggesting that a high proportion of CIDT-positive tests represented false positives.
One culture-confirmed case was part of an outbreak in Rhode Island associated with consuming raw oysters from the Dutch Island Harbor area. This case ate oysters while traveling to Rhode Island.