Storm Surge: Microbes in the Wake of a Hurricane
- Heather McSharry, PhD
- 2 days ago
- 11 min read
Summary
Hurricanes don't create pathogens—but they radically rearrange exposure.
In this episode of Infectious Dose, Heather explores how severe weather, flooding, and storm recovery can increase infectious disease risks long after the wind dies down. From contaminated floodwater and wound infections to mold exposure and mosquitoes, the greatest health risks often emerge after the storm has passed.
Drawing on personal experiences during Hurricane Ike and her background as a virologist, Heather explains why hurricanes are also infectious disease events and how understanding exposure pathways can help communities prepare more effectively.
The episode also includes practical guidance for building an infectious disease-informed hurricane preparedness kit, along with a downloadable preparedness guide featuring safety tips, emergency formulas, and a personal medical information worksheet.
Because the storm isn't always the biggest health risk. Sometimes it's the week after.
Listen here or scroll down to read full episode.
Full Episode
The storm passes first. That’s the strange part. Not the sirens. Not the radar. Not the hours spent watching weather maps and wondering whether it’s finally time to leave.
The storm passes……and then people step outside into water that shouldn't be there.
Warm floodwater. Standing for days in neighborhoods, garages, living rooms, and streets.
During Hurricane Ike, Sep 13, 2008, I was living in Galveston near Offatt’s Bayou. I was in graduate school at the time with a year-and-a-half-old baby, and my now ex-husband and I were in the middle of renovating a serious fixer-upper ourselves. The house was raised. Garage below. Living space above. The renovation meant the upstairs was torn apart and most of our belongs, certainly our keepsakes and such, were in boxes in the garage. And the garage took on about nine feet of water. It came within an inch of the floor of our living space.
We evacuated late because the storm shifted toward Galveston at the last minute. By the time we drove out of the neighborhood, roads were already flooding. Some of our neighbors got stranded trying to leave. Before evacuating, we moved everything we could onto shelves and tables in the garage thinking maybe we could save some of it.
It didn’t matter. The water covered everything.
And then there was the trash can. Trash pickup hadn’t happened yet that week, so before evacuating, we had rolled our large outdoor trash can into the garage so it wouldn’t blow through the neighborhood during the storm. The garage flooded. The trash can tipped over underwater.
Diapers. Food waste. Floodwater. Tools. Furniture. Boxes of our belongings. Everything mixed together, marinating until the water finally receded.
Weeks later, when we were finally allowed back onto the island, the streets of Galveston had become mountains of debris. Entire lives piled curbside in the Texas heat.
Hurricanes aren't just about wind and flooding. they're about what happens when infrastructure collapses and the boundaries that normally separate humans from microbes collapse with it. Because hurricanes are not just weather events. They are infectious disease events.
They mix systems that are supposed to stay separate.
Natural disasters don’t create pathogens. But they radically rearrange exposure.
This is Storm Surge: Microbes in the Wake of a Hurricane.
And if the risks change after a storm…then preparedness has to change too.
Today, we’re talking about the infectious disease risks that follow severe weather and flooding—and how to supplement your hurricane preparedness kit to mitigate microbial exposure after a storm.
Storms as Infectious Disease Events
When most people think about infectious disease, they imagine transmission between people. Someone coughs. Someone gets sick. An outbreak spreads. But many infectious disease risks aren’t really about infected people at all. They’re about exposure environments. And severe weather can transform an environment incredibly fast.
Often, the microbes are already there. In the soil. In drainage systems. In standing water. In sewage infrastructure. In warm coastal environments. In rodent populations. In mold spores waiting inside walls. What changes is how often and how intensely people come into contact with them.
Flooding mixes systems that are normally separated. Stormwater overwhelms sewage systems. Contaminated water enters homes. Standing water accumulates in neighborhoods. Power failures interrupt refrigeration and sanitation. Healthcare systems become harder to access. People crowd into shelters. Cleanup crews begin tearing apart water-damaged buildings. That sounds very official and professional, and it might be true for larger buildings. But for most homes, it’s the homeowners and renters themselves who end up doing the majority of the demolition after a storm. After Ike, we did our own demo and clean up. Our staircase leading up to the front door which was on the second floor, remember, had been torn away from the house. My husband at the time, slid the refrigerator over to the front door, wrapped it in layers of duct tape, then pushed it out. There was no cleaning that after the power had been off for weeks. It joined the rest of the debris in our front yard. The point is, exposures that would normally be rare become common during storm recovery.
People often think of floodwater as dirty rainwater. It’s usually much more complicated than that. Floodwater can contain sewage, fuel, chemicals, animal waste, sharp debris, bacteria from soil and surface water, and contaminants washed through entire communities. And after major flooding, people often spend hours inside it. Walking through it. Cleaning with it. Driving through it. Trying to salvage homes and belongings soaking in it.
Which brings us to one of the classic post-flood infectious disease risks: wound exposure. Because floodwater and broken skin are a bad combination and sometimes those infections are relatively minor. But sometimes they are very much not.
One of the organisms that gets attention after hurricanes is Vibrio vulnificus—a bacterium naturally found in warm coastal waters whose habitat is shifting north because of climate change. I have a whole episode on this guy if you want to know more. It's called No Boat Big Enough. Most people will never encounter it in a serious way. But after storms, conditions can shift: warmer water, flooding, disrupted infrastructure, people wading through contaminated water with cuts or abrasions. And in susceptible individuals, especially people with liver disease or immunocompromise, infections can become severe very quickly.
Another example is leptospirosis. Leptospira bacteria spread through the urine of infected animals—especially rodents—and flooding creates ideal conditions for human exposure. Heavy rain washes contamination into standing water. Rodents are displaced from nests and drainage systems. People wade through contaminated floodwater with cuts on their feet and legs. Again: same organism, different exposure environment.
Flood-damaged buildings can also become major mold exposure environments. Demolition and cleanup aerosolize spores and debris. Cuts become infected more easily. Heat stress and dehydration compound everything. The storm may be over. But biologically, the environment is still unstable.
At this point, you might be thinking: Okay, great. New fear unlocked. And that's not actually the goal. Because the point of understanding risk isn't anxiety. It's preparation. One of the reasons I wanted to do this episode is that most hurricane preparedness advice is focused on surviving the storm itself. And that's understandable.
Surviving matters. You need water. Food. Flashlights. Batteries. A way to charge your phone. But after living through Hurricane Ike, one of the lessons that stuck with me is that some of the biggest challenges don't happen while the storm is making landfall. They happen afterward. When you're cleaning up. When you're trying to decide whether a cut on your leg is something to ignore or something to pay attention to. When mosquitoes suddenly seem to be everywhere. When the walls you've spent years building are now sitting in a pile at the curb.
But what would an emergency kit look like if we also thought about infectious disease risk? What would we pack if we planned not just for wind and flooding, but for contaminated water, wound infections, mold exposure, disrupted medical care, and the long cleanup that often follows?
So let's talk about what an infectious disease-informed hurricane kit actually looks like.
The Infectious-Disease Hurricane Kit
The good news is that this isn't about building some elaborate survival bunker or spending thousands of dollars on specialty gear. Most of these items are relatively inexpensive.
Let's start with water and sanitation. Water is one of the most obvious needs after a storm, and you need clean water for hydration and cleaning is more effective if the water isn't filthy. So, having stored drinking water is essential. It can go fast though when systems take time to get back up and running so you need to have ways to purify water if normal infrastructure is disrupted. Depending on your situation, that might include water purification tablets, household bleach used according to public health guidance, or portable water filters. Hand sanitizer can help conserve water in a pinch but it's important to remember that it's not a complete substitute for soap and water when hands are visibly dirty.
We often underestimate the risk of dehydration during storm recovery, so something you should keep on hand that we often don't think of is oral rehydration solution—or the ingredients needed to make it. Dehydration can happen during cleanup when you're rationing water or hesitant to drink filtered or disinfected water. Combine that with prolonged power outages and days spent hauling debris in hot, humid weather, and dehydration happens easily.
OK, the next category is wound care. If there is one section of this kit I would emphasize more than any other, it's this one. As I mentioned, a surprisingly small cut can become a much bigger problem when it's exposed to contaminated water, mud, or debris. A good wound care kit should include waterproof bandages, sterile gauze, antiseptic wound cleanser, antibiotic ointment, medical tape, gloves, tweezers, and saline solution for rinsing debris from wounds. Also include waterproof markers and tape so you can label wound dressings with date or details so you can track changes.
And perhaps more importantly than having the supplies is using them. Many people spend days cleaning up after storms... collecting cuts and scrapes they barely notice or ignore because those kinds of cuts never matter. But those are exactly the injuries worth paying attention to when dealing with flood-contaminated debris and water. And make sure your tetanus booster is up to date before hurricane season. Dirty, flood‑contaminated cuts are exactly when you want that protection in place.
Next is exposure protection.
One of the simplest ways to reduce risk is to avoid direct contact with contaminated water whenever possible. That means sturdy closed-toe shoes or boots instead of sandals. It means work gloves during cleanup. It means eye protection when cutting, tearing, spraying, or removing damaged materials. Floodwater is not just water. It's whatever the water encountered on its way to where you're standing.
Then there are mosquitoes. Because eventually the floodwater recedes. And what's left behind is often a perfect breeding environment. Standing water can produce enormous mosquito populations in the days and weeks following heavy rainfall. So insect repellent belongs in this kit too. Whether you prefer DEET, picaridin, or another EPA-registered repellent, the important thing is having something available before you need it.
Now let's talk about something people often forget entirely: respiratory protection.
After Hurricane Ike, what I remember almost as vividly as the flooding itself were the
debris piles. Walls have to come down. Carpet has to come out. Damaged materials have to be handled. And every one of those activities can generate dust, debris, and mold exposure. Entire neighborhoods became mountains of wet drywall, insulation, flooring, furniture, and belongings. So even after you’ve pulled everything out of your house, it often stays in 10‑foot‑high piles all along your street, growing mold and who‑knows‑what in the heat. That's why you need N95 respirators in your storm supplies. Plural. A respirator may be one of the most useful infectious disease and respiratory health tools in your entire hurricane kit. Plan for power and services to be out longer than you expect. And if you don’t end up needing all those respirators, fantastic. One other note about N95s. When we evacuated from Ike, the power was out for weeks and rodents made our place their own while we were away. By the time we got back the water had receded so dried rodent debris was a real issue. You all know about hantaviruses now and the truth is, we have hantaviruses in the US and the rodents that carry hantaviruses live in all the states that are vulnerable to hurricanes. So if rodents moved in after you evacuated, N95s are non-negotiable for clean-up.
Let's talk about medications and medical continuity. Power outages and evacuations have a way of exposing how dependent we are on systems we rarely think about. If you take prescription medications, try to maintain an emergency supply when possible and discuss contingency planning with your healthcare provider before hurricane season begins. Keep a printed medication list. Have copies of important medical information. Think ahead about refrigeration needs for medications that require temperature control. And don't assume you'll have reliable internet access when you need it most. Because one of the lessons storms teach over and over again is that resilience often comes down to preparation done before anyone sees a storm on the radar.
Oh and if you have pets, your kit should cover them too—food, water, medications, and a way to keep them out of floodwater.
None of these items are particularly dramatic. But that's the point. Preparedness rarely looks dramatic. It's a box in a closet. A pair of boots in a garage. It's a packet of oral rehydration salts you'll hopefully never need.
And because I know nobody is going to remember all of this while they're listening to a podcast, I've put together a downloadable Infectious Disease Hurricane Preparedness Guide
It's free to download and includes the complete checklist, infectious disease safety tips for flood recovery, refrigerator and freezer safety guidance, quick-reference instructions for oral rehydration solution and bleach disinfection, a personal medical information worksheet, pet preparedness recommendations, and a collection of hyperlinked resources for hurricane preparedness and recovery. It's a practical resource you can review and keep with your emergency supplies.
Closing
We can’t stop the storm. We can’t stop the rain from falling, the water from rising, or the power from going out. But we can change what happens afterward. And that’s really what preparedness is about. Not fear. Not panic. Not trying to anticipate every possible disaster scenario. Preparedness is simply recognizing that when severe weather changes our environment, we can take steps to reduce our exposure and improve our resilience.Some of those steps are individual. Keeping supplies on hand. Protecting wounds. Planning for medications. Having a way to safely clean up after flooding.
But some of the most effective preparedness strategies aren't things you can buy at all.
After living through extended post-storm power outages, one of my favorite preparedness strategies is talking with neighbors before hurricane season. In some situations, sharing generator resources for refrigeration, medications, device charging, and limited lighting can be more realistic than every household trying to power everything on their own. Because resilience isn't just about equipment. It's about relationships and knowing who might need help and who might be able to help you. The storm may be a weather event but recovery is a community event. And that's especially true when it comes to health.
The infectious disease risks we talked about today aren't inevitable consequences of severe weather. They're often the result of disrupted systems, delayed cleanup, unsafe exposures, and lack of preparation. The good news is that many of those risks can be reduced. Through things like a pair of boots. A box of bandages. An N95 respirator. A bottle of insect repellent. A printed medication list. A conversation with a neighbor before hurricane season begins.
Preparedness is understated. It's a box in a closet. A checklist tucked into a hurricane kit. A medical worksheet you hope you never need. Until one day, a hurricane makes a last minute jog west and it isn't just a collection of supplies anymore. It's the difference between a difficult recovery and an even harder one.
And while we can't stop the storm, with a little planning, we can protect ourselves a little better when the water recedes.
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