KARACHI, July 19: Three young men between 22 and 27 years of age admitted to a private hospital in the city during the past two weeks have died due to what doctors described as a “free-living amoeba capable of causing human disease”, it emerged on Thursday.

The doctors, who treated the three patients at the Liaquat National Hospital, named the pathogenic amoeba as Naegleria fowleri, which causes an acute and usually lethal central nervous system (CNS) disease called primary amebic meningoencephalitis (PAM).

Initially, it was assumed that the deceased persons had contracted the Naegleria fowleri amoeba through water sources, including swimming pools. However, Dawn’s investigation revealed that only one of the three amoeba victims had swum in a recreational place swimming pool along the Superhighway.

Such opportunistic free-living amoebae are capable of causing granulomatous amebic encephalitis (GAE) in individuals with compromised immune system, a senior consultant for infectious diseases at a private medical university said.

The doctor said that brain, skin, lung and eyes infections due to these amoebae had increased significantly during the past 12 years all over the world.In the meantime, following some media reports, Sindh Health Minister Dr Sagheer Ahmad on Thursday ordered a team of health officers to ascertain the reasons behind the three young men’s death, who died on July 6, July 11 and July 14, consecutively.

The inquiry team included newly appointed EDO-Health Karachi Dr Imdadullah Siddiqui and deputy secretary of the health department Dr Nadeem Sheikh.

Dr Shobha Luxmi, who treated two of the three patients, told Dawn that one of the patients was brought to the hospital with a history of fever and headache followed by drowsiness and comma.

The 22-year-old patient died after about 24 hours of his admission to the hospital, she said, adding that the patient, as she was told, had swam in a pool at a farm house a few days before his illness.

A relative of another patient, who was a government employee and lived in Gulshan-i-Iqbal, said that his brother-in-law had complained about continued high fever but he had no exposure to any swimming pool or farm house, nor had he cleaned any water reservoir or overhead tank at his place of living.

Since he was not responding to a physician’s treatment, he was taken to hospital where a few hours before his death on July 11 doctors declared him a Naegleria fowleri infected patient, the relative said, adding that the young man only got married last year and had a son.

According to family sources of the third victim, a resident of Korangi, the doctors at the LNH had declared him a Naegleria fowleri positive case.

After initial complaints of a high fever and pain, the 27-year-old patient was given treatment at a local hospital and finally he was taken to the LNH where he died in two days after his admission there on July 15. He too had never swum in any pool.

According to a medical researcher, the knowledge that the free-living amoebae are capable of causing human disease dates back to some 55 years, prior to which they were regarded as harmless soil organisms or, at most, commensals of mammals.

Naegleria fowleri, then Acanthamoeba spp. and Balamuthia mandrillaris, and finally Sappinia diploidea have been recognised as etiologic agents of encephalitis.

Freshwater, soil, thermal discharges of power plants, heated swimming pools, hydrotherapy and medicinal pools, aquariums and sewage are considered as reservoirs of Naegleria fowleri.

According to infectious disease researchers at a medical university in the city, Naegleria fowleri is present all around the world and its presence in freshwater is directly related to water temperature.

Pathogenic species proliferate at higher temperature with growth occurring at up to temperatures of 40°C to 45°C, while the infections have been registered in countries in every continent.

The factors that protect most individuals from infection are not understood yet, while on the other hand, the results of treatment on the whole have been disappointing, it is further added.

The first confirmed case of primary amebic meningoencephalitis (PAM) was reported in Karachi in a 22-year-old male with no known chronic illness, admitted to the Aga Khan University Hospital Karachi, in July, 2005, with complaints of cough for 15 days, fever for 4 days and generalised tonic-clonic seizures for one day. The patient died within 12 hours of admission.

Further history from the patient’s family revealed that the patient had gone for a picnic with his friends to Sakran, a lake slightly further than Hub Choki, three weeks earlier before his illness and spent a good time in swimming in the lake waters.

Another lake frequented by him regularly was Northern Bypass pool, close to Sohrab Goth, said an AKUH source.

Experts said that the signs and symptoms of the disease included severe headache and other meningeal signs, fever, vomiting, and focal neurologic deficits which progressed rapidly (less-than 10 days) to coma and death.

EDO health Karachi Dr Siddiqui said that he and his team had already collected information from the LNH and a comprehensive report on the deaths, along with the awareness, preventive and curative aspects would be finalised in a day or so.

The authorities may also be suggested to have all recreational farms and swimming pools surveyed or regulated for proper chlorination of water or for the sake of quality water there.

A doctor, however, commented that the risk factor for the PAM, included use of un-chlorinated water from any source.