Texans throughout the Brazos River basin are beating the heat by taking trips to nearby rivers and lakes. The Brazos River Authority encourages visitors to enjoy the water, while keeping in mind the health risks associated with swimming in or around stagnant or slowmoving water.

Most prevalent during the summer months, primary amebic meningoencephalitis is a rare disease caused by an ameba found in soil and in almost all untreated, fresh surface water.

The disease-causing ameba thrives in fresh water that is above 80 degrees and is stagnant or slowmoving. The PAM infection occurs when water containing the organism is forced into the nasal passages -- usually from diving or jumping into water. Upon making its way into the brain and spinal cord, the ameba destroys brain tissue.

Symptoms of the almost-always fatal infection include severe headache, high fever, stiff neck, nausea, vomiting, seizures and hallucinations as the condition worsens.

Although PAM is rare -- affecting about one to three people a year in Texas -- those infected usually succumb to the disease within a week.

To prevent infection, it is recommended that those taking part in warm, fresh water-related activities use nose clips or hold their nose shut while jumping into the water.

With the ameba often found in soil, it is best to avoid stirring up the sediment under the water.

The Texas Department of Health recommends that people avoid stagnant or polluted water and take "No Swimming" signs seriously. PAM cannot be spread person to person or by drinking water. Swimming pools that are properly cleaned, maintained and chlorinated are generally safe, as is salt water.

For more information contact the Texas Department of State Health Services Public Information Office at (512) 458-7400.