Summertime Dangers: Water Related Illnesses

Dr. David J. Holcombe
Dr. David J. Holcombe

Summer fun often includes water and that can be in public pools, water parks, ponds, rivers or bayous.  Fresh water fun, however, does have its share of potential hazards beyond the risk of drowning.  The list of potential infectious illnesses that can come from fresh water exposure includes Cryptosporidia, Giardia, Shigella, norovirus, E. Coli and the much publicized, albeit rare, Naegleria fowleri.


Cryptosporidia is a parasitic infection transmitted by the fecal-oral route, and is the leading cause of pool-related outbreaks of diarrhea.  The oocysts of Cryptosporidia are highly resistant to chemicals and can survive in treated water.  “Crypto” causes acute watery diarrhea and abdominal cramping which can lead to dehydration or even death in immunocompromised hosts.


Giardia, a protozoan or one-celled organism, also includes cysts and trophozoites as part of its life cycle, both of which can be infectious. While infected individuals may be asymptomatic, Giardiasis can cause acute or chronic diarrhea, especially in children.  It is most common in untreated bodies of water such as lakes, ponds and streams (or bayous) where it can be transmitted by fecal contamination by either humans or animals (beavers).  While it can be treated with metronidazole (Flagyl), it is often self-limiting (resolving by itself).


Shighella, a bacterial disease, also causes an acute self-limiting diarrhea of variable intensity.  Transmission can occur through contaminated water or by fecal-oral transmission within a household, where 40% of household members may be infected.  Antibiotics may be useful, depending on the sensitivity of the organism.


Norovirus, the cruise ship nemesis, is a highly contagious viral infection.  Outbreaks of norovirus can sweep through nursing homes and cruise ships alike.  And, as with most viral diseases, treatment remains symptomatic during the week or so of acute diarrhea.  Adequate cleaning of any infected facility (or cruise ship) remains the mainstay of preventing re-infections.


  1. Coli 0157-H7 is one of the main serotypes of E. Coli and causes 90% of the cases of Hemolytic Uremic Syndrome (HUS), a very serious complication of infection with this organism. HUS occurs in less than 8% of E. Coli 0157-H7 infections, but can be life-threatening since it causes destruction of red cells and associated renal failure. Most causes of E. Coli 0157-H7 occur with infected food, but water contaminated either with human or cattle feces can also be a source.


Last, but not least, Naegleria fowleri, an amoeba (or amoeba-flagellate, a single-celled free-living organism), can also be found in untreated or inadequately treated water.  Several highly publicized cases in Louisiana resulted in death by meningoencephalitis.  Public health changes subsequently occurred, resulting in more stringent chlorination standards.  Naegleria fowleri also occurs naturally in fresh water lakes and bayous.  Getting water, especially untreated, up the nose should be avoided since the bony separation between the roof of the nasal cavity and the brain is razor thin and perforated by tiny holes (cribriform plate), easily penetrated by an amoeba.


While most of these infectious agents cause diarrhea (with the exception of Naegleria fowleri), the other symptoms they cause resemble one another.  Differentiating one from another, while often unnecessary, generally requires a stool sample (or, as Dr. Raoult Ratard puts it, “The proof is in the poop”).  Not drinking untreated fresh water, hand washing and not allowing soiled diapers in public pools go a long way to reducing outbreaks.  If symptoms of diarrhea develop, be sure to remain hydrated, since dehydration poses the most common risk, especially to infants and the elderly.


Speaking of children, besides the aforementioned infections, drowning remains the greatest danger.  As a state, Louisiana has the 3rd highest rates of childhood drowning in the U.S.  For children aged 1 to 4 years old, drowning is the leading cause of unintentional injury in our state.  Most of the drownings were in pools, tubs or spas (47%), while only 26% occurred in lakes, rivers, ponds, creeks or bayous.  Lack of supervision was a contributing risk factor in 42% of drowning deaths.  While around 12 children die of drowning in Louisiana each year, another 28 young children (1 to 4 years old) are hospitalized.  A proportionately higher percentage of African-American children die from drowning than Whites.


You can still have fun in the water this summer, but remember the hidden dangers that may be lurking there from infections for adults and children, the latter of whom always require strict supervision and should be taught to swim as early as possible.