"Deadly diseases, such as typhoid or cholera, are unlikely to break out after hurricanes and floods in areas where these diseases do not already naturally occur," says Ruth Berkelman, MD, Chair of the Public and Scientific Affairs Board of the American Society for Microbiology. "The greatest threats to the people in the affected areas are going to be from diseases that were already there."
Dr. Berkelman is the Rollins Professor and Director of the Center for Public Health Preparedness and Research at the Rollins School of Public Health at Emory University. She is a former Assistant Surgeon General of the United States and former deputy director of the CDC's National Center for Infectious Diseases (NCID).
Common infectious disease problems in New Orleans in the coming weeks are likely to be skin and soft-tissue infections, most likely from cuts, abrasions and wounds. The primary culprits will be Staphylococcus and Streptococcus bacteria, both of which can generally be treated with available antibiotics. Diseases caused by consumption of contaminated food or water as well as diseases caused by mosquitoes or other insect bites are also a threat.
Vibrio vunificus can also cause serious infections, either wound infections or blood poisoning (septicemia); V. vulnificus is a bacterium that is normally present in Gulf Coast waters and is usually contracted by eating tainted seafood. It is primarily a threat to people with weakened immune systems or liver dysfunction. The CDC has confirmed 15 infections with V. vulnificus, 3 of which were fatal. These cases have occurred in areas other than New Orleans where the water has greater salinity.
Another concern is diarrhea and gastrointestinal illnesses from the flood waters. Short bouts of diarrhea and upset stomachs sometimes occur after natural disasters and can be caused sewage contamination of the water. Although at high levels in floodwaters, the E. coli found in New Orleans is the type commonly associated with fecal contamination and is not the E. coli H7:O157 strain that can cause serious kidney disease and bloody diarrhea.
"At this point in time, I think it is just common sense to continue drinking only bottled water unless authorities have tested the water now being piped into some facilities and have declared it safe to drink," says Berkelman. "To also prevent risk of infection, people should practice basic hygiene, frequently washing their hands with soap and clean water or disinfecting hands with an alcohol-based hand cleaner. Individuals should not eat food that has been exposed to flood waters or that has not been properly refrigerated."
One common misperception is that the body of a person who died as the result of the hurricane and is still in the city poses a risk of infection.
"Decaying bodies pose very little risk for major disease outbreaks," says Berkelman. Furthermore, mosquitoes do not spread disease by feeding on dead bodies. There is, however, a risk of mosquito-borne diseases such as West Nile because mosquitoes breed in standing water. Appropriate pest management, including addressing the need to get rid of standing water, is an important public health measure, she said. A bacterial disease, leptospirosis, may be caused by exposure to water contaminated by rodent urine and can be treated successfully with antibiotics.
Over the long term, mold may also pose a threat. Mold growth is an indicator of excess moisture, and much will need to be done to dry out New Orleans and clean up mold growth. Some environmental molds can cause allergic reactions.