Hurricane Katrina: Infectious Disease Issues

Abstract and Commentary

By Lin H. Chen MD

Assistant Clinical Professor, Harvard Medical School, Director, Travel Resource Center, Mount Auburn Hospital

Dr. Chen reports no consultant, stockholder, speaker’s bureau, research, or other financial relationship with any company having ties to this field of study.

Synopsis: Wound infections from Vibrio vulnificus and Vibrio parahaemolyticus were diagnosed in evacuees from areas devastated by Hurricane Katrina. The increased occurrence of Vibrio infections illustrates an infectious disease risk from exposure to flood water, especially in persons with chronic disease.

Sources: CDC. Vibrio Illnesses After Hurricane Katrina—Multiple States, August-September 2005. MMWR Morb Mortal Wkly Rep. 2005;54:928-931; CDC. Infectious Disease and Dermatologic Conditions in Evacuees and Rescue Workers After Hurricane Katrina—Multiple States, August-September, 2005. MMWR Morb Mortal Wkly Rep. 2005;54:961-964.

Hurricane Katrina struck the US Gulf Coast on August 29, 2005, and led to a disaster involving multiple states, particularly Louisiana, Mississippi, and Alabama. Surveillance of illnesses during the 2 weeks following Hurricane Katrina identified 22 Vibrio infections in residents or evacuees from Louisiana, Mississippi, and Alabama. Eighteen of these were wound infections: 14 V. vulnificus, 3 V. parahaemolyticus, and one was not speciated. Five patients with Vibrio wound infections died: 3 with V. vulnificus, 2 with V. parahaemolyticus. Age of patients ranged from 31 to 89 years, and 15 (83%) were male. Thirteen of the patients had underlying conditions including heart disease, diabetes mellitus, renal disease, alcoholism, liver disease, peptic ulcer disease, immunodeficiency, and malignancy.

Four patients were reported to have non-wound-associated Vibrio infections. Two of the patients had gastroenteritis and nontoxigenic V. cholerae (non-01, non-0139) was identified, but speciation in the other 2 patients was not reported. The Gulf States reported 11-18 cases of noncholeragenic Vibrio infections during the month of September from 2000 to 2004, including 4-8 cases of wound infections. Therefore, Vibrio gastrointestinal disease did not appear to have increased after Hurricane Katrina. However, the 18 wound-associated Vibrio infections represent a clear increased incidence, and occurred in patients who had exposure to flood water.

By the end of September, 24 cases of V. vulnificus and V. parahaemolyticus wound infections were reported among evacuees, with 6 deaths. Surveillance also found methicillin-resistant Staphylococcus aureus in 30 evacuees from the New Orleans area at a facility in Dallas, Texas. Clusters of diarrheal diseases were reported, and identified norovirus and nontyphoidal Salmonella, in addition to nontoxigenic V. cholerae 01. Respiratory diseases reported include pertussis, tuberculosis, streptococcal pharyngitis, and respiratory syncytial virus. Additionally, about 200 cases of presumed viral conjunctivitis were reported in evacuees. Among rescue workers, tinea corporis, folliculitis, arthropod bites (likely mite bites), and prickly heat were reported.

Commentary

Vibrio vulnificus is a Gram-negative rod described as a "halophilic (salt-requiring) Vibrio", and has been recognized as a marine organism associated with wounds and consumption of raw oysters.1 The organism is present in temperate estuarine and coastal waters, especially when water temperatures are > 20 C.2 Most cases occur in the warm season, usually from May to October.1 Infection can present as wound infection, gastroenteritis, or primary septicemia. In wound-associated infections, symptoms usually begin within 4 hours to 4 days with swelling, erythema, and pain. The wounds progress rapidly into cellulitis, vesicles, or bullae, and can necrose; other signs and symptoms include fever, chills, mental status changes, ecchymosis, hypotension, diarrhea, vomiting.2,3 In one study from Florida, the median age of patients with wound-associated V. vulnificus infections was 61 years, with a male predominance; case fatality rate was 24%.2 Individuals with underlying chronic diseases, such as liver disease, diabetes, alcoholism, congestive heart failure, and malignancy appear to be more susceptible to developing septicemia with V. vulnificus.1-3 V. vulnificus septicemias are associated with the ingestion of raw or contaminated seafood, and infection can also manifest as osteomyelitis, pneumonia, endometritis, fallopian tube infections, or corneal ulcerations.3 A tetracycline antibiotic is considered the drug of choice for V. vulnificus infection, although cefotaxime, ciprofloxacin, chloramphenicol, and gentamicin may also be effective; early treatment greatly improves outcome.2

Similar to V. vulnificus, V. parahaemolyticus is also a marine pathogen, occurring after exposure to seawater, with warm-season predominance. The epidemiology of Vibrio infections in Florida from 1981 to 1993, showed that V. parahaemolyticus and V. vulnificus were the leading Vibrio species causing wound infections.2,4 V. vulnificus was the most frequent Vibrio species associated with primary septicemia, whereas V. parahaemolyticus was the most common Vibrio species to be associated with gastroenteritis.4 In addition, V. parahaemolyticus is the most common cause of seafood-associated gastroenteritis in the United States, recently implicated in an outbreak following consumption of Alaskan oysters.5

In comparison, the tsunami that devastated southern Asia on December 26, 2004, also led to many cases of wound infections. Interestingly, Aeromonas species, organisms associated with fresh or brackish water, were the most commonly identified organisms in skin and soft-tissue infections among survivors in southern Thailand.6 Among the total of 641 isolates identified, 145 were Aeromonas species compared to 10 Vibrio species (7 V. parahaemolyticus, 2 V. vulnificus, 1 V. alginolyticus).6

A norovirus outbreak was also associated with Hurricane Katrina. From September 2-12, 18% of 6500 evacuees that visited the Reliant Park medical clinic in Houston, Texas, reported acute gastroenteritis.7 Acute gastroenteritis reported in medical personnel, police, and volunteers who had direct contact with patients led to suspicion of secondary spread. Norovirus was found in 50% of stool samples tested by reverse transcription-polymerase chain reaction; approximately 1000 evacuees and relief workers in the Houston area may have been affected.7 The norovirus outbreak highlights transmission of this virus in environments with crowding and with suboptimal sanitation.

Finally, carbon monoxide poisoning is an additional health hazard that occurred in Alabama, Louisiana, and Mississippi after Hurricane Katrina.8 The predominant cause was exposure to exhaust from portable generators, and could have been prevented by appropriate ventilation of the generators.

References:

  1. Blake PA, et al. Disease Caused By a Marine Vibrio. Clinical Characteristics and Epidemiology. N Engl J Med. 1979;300:1-5.
  2. Klontz KC, et al. Syndromes of Vibrio vulnificus Infections. Clinical and Epidemiological Features in Florida Cases, 1981-1987. Ann Intern Med. 1988;109:318-323.
  3. Oliver JD. Wound Infections Caused By Vibrio vulnificus and Other Marine Bacteria. Epidemiol Infect. 2005;133:383-391.
  4. Hlady WG, Klontz KC. The Epidemiology of Vibrio Infections in Florida, 1981-1993. J Infect Dis. 1996;173:1176-1183.
  5. McLaughlin JB, et al. Outbreak of Vibrio parahaemolyticus Gastroenteritis Associated With Alaskan Oysters. N Engl J Med. 2005;353:1463-1470.
  6. Hiransuthikul N, et al. Skin and Soft-Tissue Infections Among Tsunami Survivors in Southern Thailand. Clin Infect Dis. 2005;41:e93-96.
  7. CDC. Norovirus Outbreak Among Evacuees From Hurricane Katrina—Houston, Texas, September 2005. MMWR Morb Mortal Wkly Rep. 2005;54:1016-1018.
  8. CDC. Carbon Monoxide Poisoning After Hurricane Katrina—Alabama, Louisiana, and Mississippi, August-September 2005. MMWR Morb Mortal Wkly Rep. 2005;54:996-998.