Vibrio vulnificus infection: epidemiology, clinical presentations, and prevention.

Vibrio vulnificus accounts for approximately 95% of all deaths associated with seafood consumption in the United States. The organism was first reported as a cause of human illness in 1979. (1) It is ubiquitous in marine bacterial flora along the Gulf of Mexico and the Atlantic and Pacific coasts. (2) Infections due to V. vulnificus are seasonal; over 85% occur between May and October. The organism is almost undetectable from December through March in samples collected from Apalachicola Bay, FL, where most of Florida's oyster production is based. Environmental factors, such as warm temperature (>68[degrees]F) and moderate salinity (<16 parts per thousand), favor the growth of V. vulnificus. (3)

Patients may present with a severe invasive infection, with three main clinical features: primary septicemia, wound infection, and gastroenteritis. Reports are also available for atypical presentations, including pneumonia after aspiration of seawater, septic arthritis, epiglottitis, spontaneous bacterial peritonitis, meningitis, endometritis, myositis, osteomyelitis, and corneal ulcer. (4), (5) More than 70% of infected individuals have distinctive bullous skin lesions that can strongly suggest the diagnosis in a patient with the appropriate history. The infective dose for gastrointestinal symptoms in healthy individuals is unknown, but for predisposed persons, septicemia can presumably occur with doses of fewer than 100 organisms. Although ingestion of raw or undercooked shellfish is the primary mode of transmission of the infection, V. vulnificus can also cause infection by directly contaminating open wounds during swimming, shellfish cleaning, and other marine activities.

The article authored by Ulusarac and Carter (6) in this issue of the Journal presents four interesting cases of V. vulnificus infection. Three of them had developed septicemia and one presented with corneal ulcers. The route of entry of the organism was undetermined for Case 1; however, the most likely route was gastrointestinal through ingestion of contaminated water. The other possibility is that he was infected through skin abrasion. Interestingly, this patient presented with necrotizing fasciitis. Another case in this series contracted the infection through the eyes while handling seafood. The authors emphasize the need for wearing gloves and eye shields in individuals at occupational risk for acquiring V. vulnificus infection.

Although the incidence of V. vulnificus infection is relatively low in the general population (0.6 per 1 million population), septicemia caused by the organism can be rapidly fatal (case fatality rate of 50% or more), particularly in individuals with preexisting liver disease, immunocompromised conditions, or other underlying illness. (1), (4) Individuals with preexisting liver disease are 80 times more likely to get sick and more than 200 times more likely to die as a result of eating raw oysters infected with V. vulnificus than a patient with no such disease. Conditions for the high-risk category include the following. (7) liver disease including cirrhosis from excessive alcohol intake, viral hepatitis, or other causes; hemochromatosis, an iron disorder; cancer (especially if taking anticancer drugs or receiving radiation treatment); lymphoma, leukemia, acquired immunodeficiency syndrome, or Hodgkin's disease; diabetes mellitus; chronic kidney disease; inflammatory bowel disease (or any patient receiving immunosuppressive drugs); long-term steroid use (for conditions such as chronic obstructive pulmonary disease and arthritis); achlorhydria; and medicines that reduce stomach acid.

One of the four cases reported by Ulusarac and Carter (6) had human immunodeficiency virus infection and hepatitis C infection with a history of asthma and alcohol abuse. Another patient had a history of alcohol-induced liver disease with elevated liver enzymes. Both of them survived.

Health care providers should consider V. vulnificus infection in the differential diagnosis of fever of unknown cause. In addition, providers should ask about a history of raw oyster ingestion or seawater contact when patients with preexisting liver disease or immunocompromised conditions present with fever, with or without bullae, cellulitis, or wound infection. Prompt administration of antibiotics (tetracycline or a third-generation cephalosporin) is crucial for saving lives when indicated.

Twenty states require reporting of Vibrio infections. Surveillance for culture-confirmed V. vulnificus infections has been conducted in the Gulf Coast states of Alabama, Florida, Louisiana, Mississippi, and Texas since 1988 and expanded to include FoodNet states in 1996 in collaboration with the Centers for Disease Control and Prevention. (8), (9) Timely reporting of V. vulnificus infections to the Centers for Disease Control and Prevention and regional Food and Drug Administration shellfish specialists enhances ongoing collaborative efforts to improve investigation and control of these infections. Public education should focus on the risks associated with consumption and handling of raw shellfish, especially in warm months. Some of the preventive measures, particularly for those at risk, are as follows: cook shellfish (oysters, clams, mussels) thoroughly; do not eat shellfish that do not open during cooking; do not eat raw shellfish; eat shellfish promptly after cooking and refrigerate leftovers; avoid cross-contamination of cooked seafood and other foods with raw seafood; avoid exposure of open wounds or broken skin to warm salt or brackish water, or to raw shellfish harvested from such waters; and wear protective clothing (eg, gloves and eye shields) when handling raw shellfish.

As in anything else, skill and confidence are learned through experience--haltingly and humiliatingly. Like the tennis player and the oboist and the guy who fixes hard drives, we need practice to get good at what we do. There is one difference in medicine, though: it is people we practice upon.

--Atul Gawande, Complications: A Surgeon's Notes on an Imperfect Science.

Contributed by Joshua D. Hartzell, MD

Accepted July 25, 2003.

Copyright [c] 2004 by The Southern Medical Association 0038-4348/04/9702-0118

References

(1.) Blake PA, Merson MH, Weaver RE, et al. Disease caused by a marine Vibrio: Clinical characteristics and epidemiology. N Engl J Med 1979; 300:1-5.

(2.) Oliver JD, Warner RA, Cleland DR. Distribution and ecology of Vibrio vulnificus and other lactose-fermenting marine vibrios in coastal waters of the southeastern United States. Appl Environ Microbiol 1982;44:1404-1414.

(3.) Kelly MT. Effect of temperature and salinity on Vibrio (Beneckea) vulnificus occurrence in a Gulf Coast environment. Appl Environ Microbiol 1982;44:820-824.

(4.) Tacket CO, Brenner F, Blake PA. Clinical features and an epidemiological study of Vibrio vulnificus infections. J Infect Dis 1984;149:558-561.

(5.) Johnson RW, Arnett FC. A fatal case of Vibrio vulnificus presenting as septic arthritis. Arch Intern Med 2001;161:2616-2618.

(6.) Ulusarac O, Carter E. South Med J 2003;96:168-173.

(7.) U.S. Food and Drug Administration, Center for Food Safety and Applied Nutrition Prime Connection. Vibrio vulnificus. Available at: http://vm.cfsan.fda.gov/|P5ear/FLVIBV.html. Accessed July 7, 2003.

(8.) Centers for Disease Control and Prevention, Division of Bacterial and Mycotic Diseases. Vibrio vulnificus. Available at: http://www.cdc.gov/ncidod/dbmd/diseaseinfo/vibriovulnificus_t.htm. Accessed July 7, 2003.

(9.) Centers for Disease Control and Prevention. Vibrio vulnificus infections associated with eating raw oysters: Los Angeles, 1996. Morb Mortal Wkly Rep 1996;45:621-624.

Amal K. Mitra, MD, MPH, DRPH

From the Department of Epidemiology & Biostatistics, Center for Community Health, University of Southern Mississippi, Hattiesburg, MS.

Reprint requests to Amal K. Mitra, MD, MPH, DrPH, Department of Epidemiology & Biostatistics, Center for Community Health, University of Southern Mississippi, Box 5122, Hattiesburg, MS 39406-5122. Email: [e-mail]