12 Scary Diseases You Didn’t Know You Could Catch at the Beach

Updated: Mar. 30, 2022

Sunburn isn't the only concern at the shore this year. Keep your family safe by protecting them against these scary diseases you didn't know you could pick up at the beach.

Air bubbles in clear blue water in pool


You may have heard horror stories about Cryptosporidium outbreaks at the local beach or pool and with good reason. Crypto causes watery diarrhea, abdominal cramps, and vomiting for up to two weeks. There is nothing like two weeks of diarrhea to put a damper on your summer travel plans. The Cryptosporidium parasite has a protective outer layer that allows it to survive outside the body and on surfaces or water. Beachgoers can be infected by swimming in or accidentally drinking contaminated water.

Vibrio vulnificus infections

If you’re planning to have a cookout while enjoying your beach day, make sure your seafood is fully-cooked. Eating undercooked seafood, especially oysters, could lead to a Vibrio vulnificus infection. While this condition is rare, people with underlying medical conditions could be more at risk. Swimming with an open sore or wound can also encourage the infection. “A superficial wound in such a person can become contaminated and a rapidly progressive skin/soft tissue infection could occur,” says Amesh A. Adalja, MD, senior scholar at Johns Hopkins Center for Health Security. “These infections require prompt treatment with antibiotics and sometimes even amputation.” Fortunately, this infection will not affect the vast majority of people, says Dr. Adalja.

Soft pastel landscape photo of waves breaking on a pristine, peaceful, unpopulated beach.

Legionnaires’ disease

Legionnaires’ disease is a serious lung infection caused by the bacteria Legionella, which can survive in pools, the ocean, or lakes. Breathing in the mist or accidentally inhaling a bit of contaminated water can lead to an infection. While most people can manage a little exposure, smokers and people with lung conditions are at higher risk. Don’t miss these other hidden beach dangers you need to take seriously.

The first step
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Pseudomonas infection

This bacteria lives in water or sand and will trigger a mild reaction in most people—usually spots, redness, or an open wound. However, if the bacteria enters your bloodstream, the infection can be much more serious, with symptoms such as a fever, chills, and muscle pain. If you think you were exposed, see your doctor—you may need antibiotics.

Tasty cutlets from beef on the grill


Catching hepatitis is probably not front of mind when you’re packing your hat and sunscreen for a fun beach day—but it is possible. The most common way to contract Hepatitis A is by eating contaminated food, but you can also catch it by eating undercooked shellfish and being exposed to polluted water. Hepatitis A causes severe gastric distress including symptoms like nausea, vomiting, abdominal pain, and even jaundice. Keep you and your family safe by following these 9 beach safety rules.

A man foot in the stream line of deep dark water

Swimmer’s itch

Swimmer’s itch is just as uncomfortable as it sounds. It’s a reaction to certain parasites that live on birds and other animals; the bugs get washed off and can survive in salt or freshwater, where you can pick them up. They burrow into the skin and cause small raised red bumps that can turn into blisters. Swimmers itch (officially, cercarial dermatitis) is possible when exposed to parasites in certain freshwaters, says Alexander Evens, DO, an infectious disease specialist at Marin General Hospital. “It presents about 48 hours after exposure with these parasites that irritate the human skin but fortunately do not cause invasive disease.”

Close-up of tick filled with blood crawling on white paper

Lyme disease

You might remember to check for ticks after a stroll through the woods—but after a beach trip? “When you walk along the beach, you expect to run into some crabs or birds, but it’s definitely possible to find ticks on the beach hanging out in long strands of beach grass,” says Mayla Hsu, PhD, director of Research and Science at the Global Lyme Alliance. “That’s why people should always stay off dunes and away from tall grass.” Dr. Hsu explains that ticks could also fall off seagulls onto the sand, so it’s best to bring along some insect repellant along with your shades and beach towels.

Ear infection

Ear infections don’t just affect toddlers and young kids. Adults can come down with them too, and a trip to the beach could put you at higher risk. “Otitis externa is a common bacterial infection acquired with persistent water exposure along the external ear canal,” says Dr. Evens. “It manifests by itchiness, pain, and swelling of the outer ear.” While the infection shouldn’t be serious, it will require antibiotics to treat. Find out the 17 sneaky ways summer is making you sick.

close-up partial view of african american man washing in bathroom
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If you need to use the public restroom at the beach, be vigilant about washing your hands. Germs like norovirus can live on surfaces like toilets, doorknobs, and sinks, and they can cause major stomach upset. Norovirus is responsible for what is commonly called the stomach flu, and that would definitely wreck your fun day at the beach. Washing hands with soap and water should be enough to kill the virus.

Fishing pier disappearing into the sea in foggy conditions.
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Nothing could make you regret a romantic stroll down the beach more than hookworm. You’ll want to watch where you step, says Cole Beeler, MD, an infection prevention specialist at Indiana University Health. “Dogs poop on the beach, and sometimes this poop has hookworm larvae in it,” warns Dr. Beeler. “If you step on this poop without knowing it, these larvae can penetrate through your skin and crawl around until they eventually die.” As if that visual isn’t enough to keep you up at night, hookworm can cause a rash and intense itching.

Steamed Crab serve on white disk for Steamed Crab or seafood buffet in Thailand.

Lung infection

When hosting a cookout on the beach, it may be safer to stick with s’mores instead of seafood. Undercooked fish and shellfish can pass on dangerous parasites. When Aileen M. Marty, MD, director of the FIU Health Travel Medicine program, examined a patient who had been vomiting blood for months, she discovered that he had eaten improperly cooked crabs on the beach. “He had gone on a canoe trip at a lakeside beach where he had cooked crabs (improperly) and eaten them,” says Dr. Marty. “When we examined his sputum, we found the golden brown eggs of a Paragonimus species.” Don’t miss these 8 health problems that totally feel worse in the summer.

Closeup of Green algae underwater in Moucha Island in Djibouti, East Africa
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Algal blooms

Before visiting the lake or ocean, consider checking to make sure there are no current health warnings. When certain algae are blooming, swimmers can come down with a variety of serious illnesses. “Tiny organisms called dinoflagellates may overgrow in the ocean and release toxins in the air that can cause fever, headache, rash, eye irritation, gastrointestinal disturbances, wheezing, numbness, and even confusion,” says Dr. Beeler. “Most beaches will warn you when algae are overgrowing, but be aware that the symptoms are nonspecific and the best treatment, if you are affected, is avoidance of the beach.”

kids running and jumping from pier
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How to stay safe

Don’t let this list make you cancel your beach excursions. According to the Centers for Disease Control and Prevention, there are a few simple steps to take to stay safe at the beach. First, never swim or allow your kids to swim with diarrhea, as this could lead to a crypto outbreak. While you’re swimming, take care to never swallow the water (and keep your mouth closed underwater). In addition to your sunscreen, toss some insect repellant and hand sanitizer in your beach bag as well. Next, find out the 18 healthy ways to prepare your body for summer.