An amoeba that lives in warm water can cause a deadly inflammation of the brain.

The children, aged 9 and 7, died after being infected with Naegleria, an amoeba that lives in warm water and can cause a deadly inflammation of the brain, the Tulsa Health Department said.

The boys, who live in the Tulsa area, came to doctors with symptoms of fever, hallucinations and headaches, health department spokesman Melanie Christian said. The boys did not know each other and appear to have contracted the disease independently.

The 9-year-old died Friday morning. The 7-year-old succumbed about 5:30 p.m., Christian said.

Avoid Swimming In Area Ponds

The children were believed to have been swimming in area ponds in recent days. Christian said family members of the 7-year-old are avid fishermen and have visited a number of ponds and lakes in recent weeks.

Three city pools where the boys were known to have swum were closed for testing and reopened after authorities said tests and records indicated appropriated levels of chlorine had been maintained. Chlorine kills the amoeba.

Of the 200 known cases of Naegleria in the past 40 years, only two people have survived, health officials said.

The amoeba enters the body through the nose. The health department will work with the US Army Corps of Engineers to post warning signs if the investigation indicates the boys contracted the infection from a natural body of water.

Most Infections End In Death

A 3-year-old girl who died in 1998 was the last known victim of the disease in Oklahoma. This case was also from the Tulsa area. She had been swimming in Kaw and Fort Gibson lakes before she became sick.

Several drugs are effective against Naegleria in the laboratory, the federal Centers for Disease Control and Prevention said, but most infections continue to end in death.

People can avoid getting the infection by not swimming in bodies of warm fresh water, or by holding the nose shut or using nose clips.

A total of 24 Naegleria infections were documented in the United States between 1989 and 2000.