Last year saw some of the worst recreational water illness outbreaks on record. And that could be just a taste of things to come especially when it comes to the virulent bug, cryptosporidium.

In fact, crypto infections have increased substantially, jumping 41 percent in 2005 and 24 percent in 2006, according to preliminary reports from the Centers for Disease Control and Prevention.

The 2007 figures are still incomplete, but several states saw unusually large crypto outbreaks, including Utah, which reported more than 1,700 cases, vs. a typical year of approximately 30. The outbreak was so severe that officials took the extraordinary step of banning children under age 5 from pools.

Idaho, which has averaged approximately 23 cases annually since 1995 and last year, reported about 230. And South Dakota recorded more than 100 compared with a five-year average of 31 cases per year.

This increase in infections likely resulted in an increase in detected outbreaks. CDC logged an average of five crypto outbreaks per year, but already has received 29 outbreak reports for 2007.

?We are, indeed, seeing an increase and there are several factors for this trend,? said Michael Beach epidemiologist, acting associate director for Healthy Water at the National Center for Zoonotic, Vector-Borne and Enteric Diseases at the CDC.

According to Beach and his colleagues at the CDC, the increase in the number of reported cases of RWIs may be due to a number of factors.

?There are a lot of variables as to why we might be seeing more outbreaks,? agreed Diane Raccasi, epidemiologist at the Utah Department of Health, Salt Lake City. ?In 2007 we had a much hotter summer than normal, so we had more swimmers in recreational water and pools.?

Another reason for the increase in reported cases may be fact that Nitazoxanide (brand name Alinia), the first drug approved to treat adults with crypto, became available in 2004. The availability of the treatment probably has caused more health-care providers to test patients suffering with severe diarrhea for the parasite.

Increased awareness also might be playing a part because more health-care providers and public health departments consider patients? last dip in the pool, rather than their last meal. And when a crypto case in confirmed, more public health agencies may be opening outbreak investigations.

But regardless of the causes, Beach and Raccasi agree that operators will have to work with the public to prevent future outbreaks.

?What we learned from our outbreak is that more than anything, public responsibility has to be key,? Raccasi said. ?I think operators are going to have to become more vigilant in changing behavior patterns, educating patrons and enforcing good practices such as showering before entering. They may have to also look at more mechanical solutions, such as additional filtration in the pool and limiting the bather load depending on the capabilities of the filtration system.?