Short Answers to Hard Questions about Health Threats from Hurricane Harvey

What about other diseases spread by mosquitoes, like West Nile?

West Nile virus is endemic in the United States and outbreaks are triggered by several factors, including the concentrations of culex mosquitoes, humans who are not immune, and birds who are not immune. (The virus builds up to higher concentrations in bird blood than in human blood, so mosquitoes tend to pick it up from them to give to humans.) Birds were also probably driven away from coastal Texas by Hurricane Harvey’s winds.

In 2005, in the wake of Hurricane Katrina, there was initially no increase in cases of West Nile virus or St. Louis encephalitis, which is also spread by mosquitoes, noted Dr. Peter J. Hotez, dean of the National School of Tropical Medicine at Baylor College of Medicine in Houston. But a year later, there was a surge in dangerous “neuroinvasive” West Nile disease in the affected regions of Louisiana and Mississippi: Cases of encephalitis and meningitis more than doubled. Researchers from Tulane University’s School of Public Health and Tropical Medicine speculated that more people were bitten that year because they were outside doing reconstruction work or living inside partially-destroyed houses that mosquitoes could invade easily.

What about disease transmission in shelters?

“The big thing I’m worried about is norovirus,” said Dr. Persse, Houston’s chief medical officer. “That’s the ‘cruise ship virus’ – with a lot of people in a small space, it can spread really quickly.”

The disease causes vomiting, diarrhea and dehydration. It is not normally fatal to otherwise healthy people, but severe dehydration can kill frail older adults.

In shelters, it can be hard to control. Health officials try to stop outbreaks by quickly taking the sick to separate rooms where they are given food and entertainment, there is no wait for toilets and the floors are washed frequently with bleach.

Dr. Persse’s medical teams are walking through shelters now looking for people vomiting. Shelter populations are thinning out as people return home or find other places to stay, so the danger is decreasing.

After Hurricane Katrina, 200,000 refugees ended up in 750 shelters in 18 states, and there were scattered outbreaks of various diseases, the C.D.C. said.

About 1,000 cases of diarrhea in more than 20 shelter clusters were reported. One Dallas-area shelter had 30 skin infections with MRSA, an antibiotic-resistant form of staphylococcus bacteria.


Matthew Trent moved a flood-damaged refrigerator in front of his home in Port Aransas.

Christopher Lee for The New York Times

Officials worried about tuberculosis transmission, one new case was found in a shelter. Health authorities were able to trace about 70 percent of the patients they knew had previously been on TB treatment so they could be kept on it, the C.D.C. said. TB patients who are taking their antibiotics are usually not infectious.

Can I sick from exposure to a corpse?

That is not likely, but dead bodies may leak feces that will contaminate the water and could lead to gastrointestinal infections.

What should I do when I get home?

First, make sure that your electrical system is safe and there are no gas leaks. Check for structural damage.

Once inside, there is likely to be toxic sludge. Throw out any food that has come into contact with floodwaters, unless it’s well packaged in metal, waterproof glass or hard plastic containers. Even then, wash it off first.

Don’t run gas-powered electrical generators indoors or use gas or charcoal grills indoors. These can cause carbon monoxide to build up and kill you.

“Many people are already back into their homes that have been flooded with two or three feet or more of water,” said Winifred J. Hamilton, director of the environmental health service at Baylor College of Medicine. “We are already seeing piles of carpet and sofas on the curb.

“As the water dries,” she said, “you are going to have mold spores made airborne.”

She advised anyone who has asthma, respiratory disease or is immune-compromised not to take on the cleanup. “You should get someone else to do it if possible,” she said. “And wear personal protection equipment so that you are not breathing in toxins.”

Any other advice?

Yes, watch out for snakes. Humans aren’t the only creatures who were seeking dry ground.

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