Epidemiological Studies of Vibrio vulnificus Sepsis

Park, Seok Don; Kim, Hyun Dai; Won, Tai Hyok; Seo, Phil Seung

Abstract

BACKGROUND: Vibrio vulnificus is an estuarine bacterium which is capable of causing rapidly fatal infections in humans following either ingestion of raw seafoods or entry from seawater into wounds. Although V. vulnificus sepsis (called as Vibrio sepsis) has been well known in Korea since 1982 and was designated as a legal communicable disease (group III) since August 2000, many patients occurr annually.
OBJECTIVE
We investigated the epidemiological features of Vibrio sepsis to offer basic data such as correlation among disease occurrence, seawater temperature, salinity and pH, amount of rainfall, incidence rate and consumed seafoods, in order to further prevent this disease.
METHODS
We reviewed the epidemiologic data on monthly disease occurrence, history of raw seafood consumption and kinds of consumed seafoods in 141 patients with Vibrio sepsis obtained from 105 admitted patients in hospitals and 36 case reports published in the Korean medical journals between 1982 and 2004. Environmental data on seawater temperature, salinity and pH were obtained from the National Fisheries Research & Development Institute. The monthly amount of rainfall was obtained from the Korea Meteorological Administration. The yearly occurrence of Vibrio vulnificus regional areas was obtained from the Korea Center for Disease Control & Prevention. Population data were obtained from the Korea National Statistical Office.
RESULTS
Patients began to develop in June when mean seawater temperature was over 18.9degrees C, and with a peak from July to September when seawater temperature was over 22degrees C. The majority of the patients were found in the southern and western coastal areas of Korea, especially, estuaries, where sea mud is abundant. Also disease occurrence was positively correlated with the amount of rainfall which can lower the salt concentration of seawater. Yearly occurrence of patients by regional area was the highest in the Jellanam-do during the 5 years since August 2000. The incidence rates per 100,000 population were highest in the Jellanam-do (0.69), lowest in the Jeju-do (0.01) and 0.10 in the whole areas. Seventy two percent of patients ingested 38 kinds of seafoods raw such as blue crab, goby, blood ark shell and many kinds of fishes and shellfishes. 9% of patients had not eaten seafood and 17% had either no records or unknown. 2% developed sepsis resulted from exposure of wounds to seawater.
CONCLUSION
Vibrio sepsis develops in summer months with much rain and mostly in the estuaries. These results suggest that Vibrio vulnificus multiply well in the warm and in relatively low salt seawater. We think that weather, environmental and geographic factors are important for the outbreak of Vibrio sepsis.