But experts say the extremely rare killer only exists in rivers and lakes and cannot survive in chlorinated water
Children learn how to swim at the Dai Dong swimming pool in Ho Chi Minh City. Many people have been avoiding swimming pools for fear of a brain-eating amoeba that killed a Vietnamese man in late July, despite experts' assurances that the deadly protozoon cannot survive in chlorinated water.
Pham Nguyen Long has not taken his family to the swimming pool since the first fatality caused by Naegleria fowleri, a protozoon known as the "brain-eating amoeba," was reported in Vietnam.
"Local media have reported that properly-disinfected pools are safe for swimming. But I am not sure whether they use enough chlorine," said the 43-year-old teacher in Ho Chi Minh City.
A lifeguard at the Hoa Binh Swimming Pool in HCMC's District 8 told Vietweek that there have been fewer people at the pool, even on weekends and on Independence Day (September 2), when it is typically overloaded.
On August 31, the Ministry of Health confirmed the country's first casualty to primary amoebic meningoencephalitis, a rare but usually fatal disease which attacks the central nervous system.
The victim, a 24-year-old man from Phu Yen Province in central Vietnam, got infected with Naegleria fowleri after going swimming in a local lake.
While emphasizing that the possibility of contracting the deadly disease remains highly unlikely, the ministry warned people not to swim in high-risk rivers, lakes or ponds, but failed to define what qualifies a body of water as high-risk.
Furthermore, the ministry advised people who must enter rivers and lakes for work to keep their heads above water when swimming, to use nose clips when diving and to rinse their sinuses with nasal antiseptics after being submerged in freshwater.
The protozoon can survive in rivers, lakes, ponds and reservoirs in tropical and subtropical regions, and the ideal water temperature for their development is 46 degrees Celsius, said Nguyen Van Binh, director of the Preventative Health Department at the health ministry, in an August 31 statement issued by the department.
The amoeba can penetrate mucous membranes in the nose and enter the brain of human beings.
"People should be examined at medical facilities for timely diagnosis and treatment if they show symptoms like headache, high temperature, nausea and vomiting," it said.
On August 29, the Hospital of Tropical Diseases said a male patient, identified only as T., died from primary amoebic meningoencephalitis.
T., a peanut vendor in HCMC, returned his hometown in Phu Yen's Tuy Hoa District in mid-July. He and his friends swam in a lake to catch oysters in a rural village near his home.
He then developed a fever and headache and was admitted to Gia Dinh People's Hospital in HCMC. He was diagnosed with meningitis and transferred to the Hospital of Tropical Diseases on July 30.
Tests there showed the patient was infected with Naegleria fowleri. His fever continued to rise and he suffered respiratory failure, dying the following day.
Dr. Nguyen Hoan Phu, who treated T., said anyone swimming or working in open bodies of freshwater should be tested for the protozoon if symptoms such as high fever, headache and disorientation arise.
"However, people should not be overly anxious because such infections are exceedingly rare," he said, adding that there had been only 144 reported cases worldwide between 1965 and 1990.
The World Health Organization (WHO) in Vietnam said it received the notice from Vietnam's health ministry alerting them to the Naegleria fowleri fatality on August 31.
"This is a single case of a very rare cause of meningoencephalitis," the WHO said in an emailed statement.
It said the health ministry has instituted a number of measures aimed at reducing the risk of acquiring the disease, by spreading information on how to stay safe while swimming or bathing in lakes and rivers.
"This is especially important during periods of high water temperature and low water levels," it said.
Swimming pools: safe if clean
Despite the fact that experts have said that the protozoon cannot live in chlorinated swimming pools, people have been afraid nonetheless.
Dang Thi Kim, a small trader in HCMC, said she had registered her eight-year-old son for swim lessons, but has requested that the second-grader switch to another activity, due to her fear of the brain-eating amoeba.
"Many swimming pools are contaminated," she said. "Who knows if they contain that amoeba?"
Dr. Phu of the HCMC-based Hospital of Tropical Diseases said swimming pools should maintain proper levels of chlorine.
"Naegleria fowleri is very sensitive to chlorine and they are killed by water with a chlorine concentration of 1mg per liter in the environment of 26 degrees Celsius," he said, adding that higher concentrations of chlorine were required in hotter water.
Phu said people who swim and work in rivers and lakes should take preventive measures against the protozoon, but that people need not worry about visiting their local swimming pool.
According to the US Centers for Disease Control and Prevention, people cannot contract Naegleria fowleri from a properly cleaned, maintained and disinfected swimming pool.
However, swimming pools are not always properly maintained. From 2002 to 2011, 32 infections were reported in the US, of which 28 people were infected by contaminated recreational water. Two people were infected from water which came from a contaminated, geothermal (naturally hot), untreated supply of drinking water; the other two victims irrigated their nasal passages with contaminated tap water, it said.
Dr. Hoang Phu Manh Sieu, director of the HCMC Preventive Health Center, said the protozoon would not be likely to appear in the city's swimming pools because they have been disinfected with high concentrations of chlorine.
However, Sieu also questioned whether T. was truly the first Vietnamese person to die from meningoencephalitis caused by Naegleria fowleri.
"We don't know how many people have died from this disease because it takes only between three to five days from infection to fatality and the protozoon cannot be identified if no tests are conducted," he said, adding that while the disease is fatal more than 90 percent of the time, it cannot cause a pandemic.
"What we should do now is to take water samples from the suspected lake [in which T. swam] for tests so we may find solution to the problem," he said.
KEEP AWAY THE BRAIN-EATERS!
The World Health Organization recommends that the public follows the precautionary measures recommended by the Ministry of Health's General Department of Preventive Medicine:
- Do not bathe or swim in high risk areas (people should avoid swimming or diving in polluted water, warm bodies of freshwater and poorly maintained swimming pools, particularly during periods of high water temperature and low water levels.)
- While bathing and swimming in pools, lakes, ponds and springs, minimize water into the nose by not submerging the head below water or using nose clips.
- After bathing and swimming, clean the nose, using distilled, sterilized, filtered, or previously boiled water.
- In the case of headache, fever, nausea or vomiting, within one week after swimming or bathing in potentially contaminated freshwater, seek immediate healthcare for timely diagnosis and treatment.
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