Hurricane Epidemiology: The Dangers After The Storm Passes

by Erica Mitchell | September 14 2017 | 0 Comments

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These past two weeks have seen two record-breaking hurricanes barrel into the United States and its territories. Hurricane Harvey, which brought torrential rainfall and flooding (27 trillion gallons of water!), brought the city of Houston to a stand-still. Right on Harvey's tail, Irma battered islands in the Caribbean and kept southern Floridians guessing as to where it would make landfall, ultimately striking the Keys and the Gulf Coast. As with all hurricanes of this magnitude, the dangers to life and limb are not limited to the duration of the actual storm- the weeks that follow bring a whole new set of dangerous conditions. Today's post will explore the dangers that involve infectious disease and the overall access to medical care.


Whenever there is a cataclysmic weather event such as these recent hurricanes, news coverage includes the sobering statistic of deaths claimed by the storm. After the 24-hour news coverage stops, however, these storms continue to claim lives. While they may not make the nightly news, these fatalities and injuries - from lack of access to health care to an infectious disease - are directly related to the storm.

The first category of post-storm dangers comes from the water. Standing water, often several feet deep, serves as a perfect breeding ground for any number of waterborne pathogens. Often, sewage systems will be compromised, spewing human waste full of bacteria into the floodwaters. If Katrina serves as a model, cases of MRSA, Vibrio pathogens and E. coli will be the most likely culprits, leading to GI issues, skin rashes, and upper-respiratory infections. (Vibrio pathogens? Yes, that includes the toxigenic strains of cholera. However, the cases following Katrina were other members of the Vibrio family. For the toxigenic strain to become a problem, a person with that disease would have to be present in the area already. Thankfully, cases of toxigenic cholera are extraordinarily rare in the United States - under 5 cases per year.) Mosquitos tend to increase after extensive flooding, providing a vector for numerous diseases.  In Texas, the risk of West Nile virus will be elevated, as the virus has been endemic since 2002. But it turns out the organisms of greatest risk to humans after a hurricane are... other humans.

The second category involves outbreaks in the close quarters of hurricane shelters. In particular, "mega-shelters" housing thousands of evacuees pose significant dangers for the transmission of disease, especially norovirus. In a "perfect storm" of risks, these mega-shelters involve lots of people, limited access to showering and cleaning supplies, shared bathrooms, spoiling food, and tight quarters. In these conditions, a viral infection can quickly become an outbreak.

After a storm, access to medical care is often limited. Roads may be impassible, phone lines overburdened, and facilities (including pharmacies) might even have to be shut down. During Harvey, several hospitals evacuated patients to surrounding facilities out of harm's way, a herculean task involving ambulances, helicopters, and massive coordination with over 1o hospitals. Access to prescription medications can also be a challenge. From lessons learned during Katrina, several preventive measures were in place to stockpile medications in hurricane-prone areas, including Houston. These include medications needed for chronic conditions such as diabetes, but access to medications such as antibiotics and simple first-aid supplies will be out of reach to some evacuees for a time after storms of this magnitude.

Finally, after evacuees are cleared to return to their homes and cities start to rebuild, there is one more significant danger to face: Mold. Homes, businesses, and any other structure in the flooded areas will be waterlogged, creating an environment perfect for the quick growth and spread of mold. Spending time cleaning and rebuilding around mold has been linked to respiratory symptoms, allergies, asthma, and immunological reactions. After every major storm, including Katrina in New Orleans and Sandy in New York, mold posed a significant health threat for months and even years after the storm. The most dangerous type is known as "toxic mold," strains of mold that have developed toxigenic mycotoxins that can make anyone who inhales them sick. Ridding structures of any kind of mold infestation - toxic or otherwise - is expensive, time-consuming, and often not successful.


In a world where we are outnumbered by bacteria and other microscopic pathogens, we have to constantly work at keeping unwanted microorganisms in check. After a major disaster, however, those day-to-day efforts such as refrigeration, personal hygiene, and medical care are disrupted. And it's not just hurricanes - earthquakes, such as the one in Mexico last week, and any number of disasters can have the same effect. These opportunistic pests will take advantage of this chink in our armor, so we have to be prepared to fight back. 

On behalf of everyone at EOS, we send our hopes and prayers to those affected by Harvey and Irma, as well as the recent earthquake in Chiapas, Mexico.