Your diarrhea risk after swimming in a public pool has grown every year over the past decade, according to a report released by the CDC in late June. Studying public health reports between 2009 and 2017, the agency found that each year outbreaks of the Cryptosporidium parasite have increased by about 13%.
People infected with crypto are very contagious, writes Charles P. Davis, MD, PhD, a doctor of emergency medicine. They "need to practice good hygiene with soap and water" and avoid public swimming pools and other recreational water sources, he says.
According to Dr. Davis, Crypto infection causes watery diarrhea and other stomach problems. The parasite is resistant to chlorine, a characteristic that lets it live longer than a week in treated water.
A single outbreak is thought to cause hundreds or even thousands of infections, according to the CDC. More than 400 outbreaks were identified in the study, and one in three outbreaks occurred at a recreational water facility. Those outbreaks peaked in July and August.
There are ways to stay safe, though. William C. Shiel Jr., MD, FACP, FACR, chief editor of MedicineNet, offers the following tips:
- Never allow diaper changing at poolside. Don't bathe your baby in the pool either.
- Use the toilet and wash hands with soap and hot water before entering the pool.
- Take a hot, soapy shower before entering the pool.
- If you are infected with a disease that can be transmitted through water, or if you have had diarrhea in the previous two weeks, you should not use the pool.
Keeping Pools Clean
Maintaining your pool can also prevent the spread of recreational water illnesses that include Crypto.
When you find feces in your pool, you need to take special maintenance steps. Here are Dr. Shiel's recommendations:
- Remove and dispose of any feces in the pool, then disinfect any removal equipment.
- When possible, run the filtration system for three to four turnovers, which usually takes 24 hours. Next, backwash the filter to a sanitary sewer.
- For small pools and spas, the pool should be drained and disinfected. Refill the pool, restart the filtration system and balance the water.
If feces contaminates your pool water, you must understand how pool disinfection works, Dr. Shiel says. Not only do you need enough chlorine, but the chlorine also needs to be in the water long enough to disinfect.
You can determine this by knowing your pool's CT value. Determine your CT value by multiplying the concentration of chlorine (C) in parts per million by the time in minutes (T) it has been in your pool. The CT value for proper chlorination is 9,600.