KOLKATA: A fatal microbe that invades the body through the nose and travels through nerve fibres into brain where its feeds on cerebral tissues could be active in Kolkata. Even though extremely rare -with less than 150 cases recorded worldwide since 1965 -primary amoebic meningoencephelitis or PAM struck a 14-year-old boy in Kolkata earlier this month.Doctors suspect he contracted the bacteria while swimming and have warned that pools and other fresh waterbodies in the city may be harbouring the bacteria which has the macabre name 'brain-eating amoeba'.The mortality rate for PAM is a staggering 98% but the boy survived.It was touch and go for three weeks because his kidneys were also badly affected, but a team of doctors at CMRI Hospital refused to give up on him and tried out-of-the-box techniques which pulled him back from the brink. He is extremely lucky to be alive, said one of the doctors, adding that they had to seek a rare drug with the help of the state health department to save the boy . It is only the fifth known PAM survival in India.“The principal drug -amphotericin B -is very toxic. It was used along with three other drugs but the child suffered a kidney failure, a common side effect. Then, we had to act very fast. The principal drug was discontinued and we decided to try three other drugs that have been used in recent PAM cases elsewhere. One of these was Miltefocin, a new drug not yet widely available in the market but very effective,“ said Sushmita Banerjee, paediatric nephrologist at CMRI.The health department was approached for the drug and the directorate of health procured it quickly .After two weeks of being used in combination, the cocktail of medicines managed to control the infection. His kidneys stabilized and other symptoms like headache and vomiting gradually re ceded. By the end of the third week, he was declared fit to leave the hospital.“Initially , it seemed like meningitis. But we were worried when the lumbar puncture report indicated that his cell counts and the CSF protein count were worryingly high,“ recalled Banerjee.The doctors were surprised by the findings and spoke with family members to find out more about the boy .The feedback revealed that the youngster was a regular swimmer. This prompted doctors to dig deeper and ask for a test to detect PAM.A rare kind of meningitis associated with swimming in fresh water lakes, rivers and pools, it is a devastating infection caused by a free-living microscopic amoeba called naegleria fowleri. It enters the body through the nose, makes its way to the brain and causes PAN. In the brain, it feeds on nerve tissues and multiplies, causing necrosis and bleeding. Cases of PAM are extremely few and research on the infection is also rare, said a doctor.In USA, only 135 cases have been recorded in the last two decades -of whom merely four survived.Four cases of survival have been reported in India.According to a tropical medicine expert, swimming pools are the principal source of the infection. “While PAM could be triggered by either an amoeba or protozoa, usually pools are the source.It could be risky to use a pool that has not been properly chlorinated,“ he said.But PAM could even spread through other sources of water, said Indranil Ray , consultant microbiologist, CMRI, who was a part of the team treating the youngster. “When we checked recent cases, we found that it had even affected people who never swam in a pool. But pools and ponds remain the principal sources. We have also observed that patients in India, including this one, were probably struck by a less virulent strain.In the West, the common strain is more aggressive and hence more fatal,“ explained Ray .