Pathogenic microorganisms are extremely small organisms that may cause disease, and include:bacteria, viruses, parasites. Many different kinds can be present in the water and sand at recreational water areas. Most come from human and animal waste that enters waterways from: swimmers, runoff from farms, discharges of sewage and stormwater. Some pathogens can cause more serious illnesses. For example, Naegleria fowleri causes an extremely rare meningitis that is almost always fatal. It occurs when a person inhales water containing the microorganism. It's commonly found in warm lakes and ponds in tropical and subtropical climates. Most cases are in the southern US, but some have occurred in northern states where water temperatures are similar to those found in parts of Canada. No cases have been reported in Canada to date.