CDC REPORT ON DANGEROUS WATER SCUM

FROM:  CENTERS FOR DISEASE CONTROL AND PREVENTION 

Freshwater Algal Bloom–Associated Disease Outbreaks Among Users of Untreated Recreational Waters — United States, 2009 –2010 

Harmful algal blooms commonly occur in freshwater bodies. They can create bad odors, they can discolor the water or accumulate as a scum on the surface of the water. People should avoid, and animals should be kept from, and neither should drink directly from lakes and ponds that have a scum on the water. People should also observe any local water advisories. Eleven waterborne disease outbreaks reported to CDC in 2009–2010 were linked to harmful algal blooms (HABs) in freshwater lakes during summer months. The outbreaks most often affected people less than 20 years old. HABs tend to occur in warm bodies of water that are rich in nutrients and often produce a visible algal scum on the water. HABs might generate toxins that can make humans sick and cause death among fish, birds and dogs. Ill people report a range of health effects, including neurologic symptoms (for example, confusion), diarrhea, cough, rash, and earache. Health-care providers should consider HAB—toxin exposure as a possible cause of illness in people who have been in or alongside freshwater bodies with algal blooms. Future increases in water temperature and nutrient pollution are expected to result in an increase in the number of HABs in freshwater lakes.