Hurricane Katrina sparks fears of disease outbreaks

Sep 2, 2005 (CIDRAP News) – Amid the devastation left by hurricane Katrina on the US Gulf Coast, fears of infectious disease outbreaks have added to the distress. Some of those concerns are solidly grounded, while others are less so, disease experts say.

The biggest immediate concern is the threat of gastrointestinal illness brought by the floods of contaminated water and lack of clean water in beleaguered New Orleans and other hurricane-struck areas. Other worries include infected wounds in people lacking medical care, a possible increase in West Nile virus as mosquitoes breed in waters left by the storm, infections from spoiled food, and the risk of common infectious diseases spreading rapidly in crowded refugee shelters.

But despite some official statements to the contrary, there is little risk that exotic diseases like cholera will erupt, experts say. And while corpses on the streets of New Orleans are a wrenching sight, they actually pose little danger of spreading disease.

Dr. Glenn Morris, an epidemiolgist at the University of Maryland in Baltimore, said the biggest worry is sewage-contaminated water. Quoted in a Reuters report, he said, "Just simply splashing around in the water, if there is sewage contamination there is a risk you could get it onto your hands and get it into your mouth."

The most likely contaminants are the usual culprits in water- and food-borne disease outbreaks in this country, such as Salmonella, Escherichia coli, Shigella, Campylobacter, Cryptosporidium, and hepatitis A virus, said Michael T. Osterholm, PhD, MPH. He is director of the University of Minnesota Center for Infectious Disease Research and Policy, publisher of this Web site.

Some officials this week have said the foul water could spark outbreaks of cholera and typhoid fever, but Osterholm and other experts say that's not likely.

"Because we don't have a population of people with typhoid or cholera, we don't expect to see that," Osterholm said.

The Centers for Disease Control and Prevention (CDC) says the same thing in a hurricane-related advisory: "Unless a disease is brought into a disaster area from elsewhere, any outbreaks that occur are almost always from diseases that were already in the disaster-affected area before the disaster struck."

On the other hand, hurricane-related wounds can pose serious risks, according to Osterholm. If someone with a wound goes without medical care for 3 or 4 days, as have many in New Orleans, an infected wound can become serious or life-threatening, he said. That happened to a number of people who were hit by the tsunami in Indonesia last December, he added.

Another worry is the likelihood of a plague of mosquitoes rising from waters left by the hurricane. "Mosquito populations are likely to take off dramatically in the next 7 to 10 days," Osterholm said. He explained this will be a bigger problem in rural areas, where the storm has left behind many pools of stagnant water, than in New Orleans.

"There'll be a tremendous nuisance mosquito situation occurring that will make life very difficult for people living there or going there to help," he said.

Rising with the clouds of mosquitoes will be the risk of West Nile virus infection, Osterholm added. Louisiana has already had 52 cases this summer, 40 of them involving encephalitis or meningitis, according to a CDC report published yesterday.

The CDC is working with Louisiana officials on a mosquito-control program in an effort to head off the West Nile threat, the Department of Health and Human Services (HHS) said in a news release 2 days ago. Osterholm said mosquitoes on the Gulf Coast generally stop biting about mid-October because of an adaptation that protects them in case of frost. Until then, using insect repellent will be important.

Hurricane-related flooding brings other health risks as a result of increased contact between people and animals, but most do not involve infectious diseases, according to Osterholm.

Reports of corpses lying on New Orleans streets—besides dramatizing the depth of the tragedy—have sparked fears of disease. But those fears are overblown, authorities say.

"Decaying bodies create very little risk for major disease outbreaks," says the CDC advisory.

Osterholm explained that a few infectious organisms can survive for a while after their host dies, but the vast majority die soon after the infected individual dies. "The process of decomposition actually degrades the pathogens in the body," he said. The presence of bodies "is not an important means of transmitting an infectious agent in a situation like this."

Because of hurricane threats, federal agencies have been posting recommendations about food safety in the aftermath of disasters, especially the need to discard perishable food that has been warmer than 40˚F for 2 hours or more. The CDC and the US Department of Agriculture's Food Safety and Inspection Service (FSIS) disagree on one point: what to do with canned foods that have been exposed to floodwaters. The FSIS says such cans should be thrown out, but the CDC says the food can still be used if one washes the can and dips it in bleach solution before opening it.

Osterholm said the concern is possible contamination on the outside of the can. "In most cases what's inside the can will be safe. If you're down to not having any other food, and you can disinfect the can, I'd eat that food," he said.

So far, infectious diseases have not emerged as a major problem in Katrina's wake, according to an online report by the New Orleans Times-Picayune today. Kristen Meyer, a spokeswoman for the Louisiana Department of Health and Hospitals, told the newspaper, "We haven't seen a lot of diseases because the things that put people at risk are being in floodwater and cleaning up after floodwater. Most evacuees haven't had a chance to go back home."

Osterholm said the Katrina disaster offers lessons for other potential public health emergencies, such as pandemic influenza.

For example, he said, "It's very hard to bring public health services to a population when the overall mental health of the community is so compromised. How do you get people to, say, get in line for vaccines or to quarantine themselves, when they have that sense of despair and helplessness?"

The disaster also hints at the magnitude of the problems that a major pandemic could bring, he said. "While an influenza pandemic wouldn't unfold with such speed, all 50 states will be dealing with it virtually simultaneously; there won't be 47 other states to help the three affected states. If there was ever a time to better understand the need for preparedness and surge capacity, this should be it."

See also:

CDC information on infectious disease risks after a hurricane

USDA FSIS guidelines on food safety after a hurricane

Aug 31 HHS news release

Sep 1 CNN report on infectious disease risks in aftermath of hurricane Katrina

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