The Centers for Disease Control and Prevention warns the public of the potential health hazards of swimming in untreated recreational waters such as lakes, river, and beaches this swimming season.

A newly released report details just how many outbreaks have been associated with such activities in recent years.

140 Outbreaks

On Friday, the CDC released a report detailing the untreated recreational water-related outbreaks between the years of 2000 and 2014. Evidently, between those years alone, there were 140 such outbreaks reported by the governments of 35 states and Guam, which resulted in nearly 5,000 illnesses and two deaths.

Of the outbreaks with a confirmed etiology, 84 percent were linked to enteric or gastrointestinal pathogens such as E.coli, norovirus, Shigella, and Cryptosporidium, while 11 percent or 345 of the cases were linked to bacteria from birds that are also present in the waters.

Meanwhile, the two reported deaths came from a single outbreak linked to Naegleria fowleri, a brain-eating amoeba.

July Swimmers

In particular, the CDC report reveals that a majority of the outbreaks occurred between June and August, 58 percent of which started in July. Most of the outbreaks were recorded in locations such as lakes, ponds, and reservoirs, but cases were recorded in beaches as well.

According to the CDC, many of the pathogens that were recorded in the untreated recreational waters are actually rarely recorded in treated recreational waters such as pools. A well-maintained, treated, and disinfected waters decrease the chances of pathogen transmission and recreational water illnesses.

On the other hand, the pathogens that were found in the untreated recreational waters likely came from animal waste, sewage system discharge, flooding, septic systems, sewage overflows, or even from the swimmers themselves. This is particularly true if they have a fecal incident in the water, or when fecal material washes off of their bodies and goes straight into the water.

Safety Measures This Swimming Season

As such, people who are planning to go for a swim in untreated waters soon should heed advisories of closed swimming facilities. They should not swim if they have diarrhea or are ill and should limit the amount of water entering the nose or swallowed.

Waters that are smelly, scummy, or foamy should also be avoided. People are also advised not to go into the water if there is a discharge pipe on the beach, if the fish or the other animals near the water are dead, and if there was recent heavy rainfall.

On the part of the organizations that maintain swimming areas, they are also advised to keep wildlife from the swimming areas and to regularly monitor the aquatic bacteria levels as well.