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| The three stages in the life cycle of Naegleria fowleri ― cyst, trophozoite, and flagellated forms ― are displayed in this image. Courtesy of Centers for Disease Control and Prevention |
By Lee Hyo-jin
Korea has identified its first case of Naegleria fowleri infection. A man in his 50s, who died 10 days after displaying symptoms of the rare but highly lethal infection, is suspected of being exposed to the brain-eating amoeba in Thailand.
The Korea Disease Control and Prevention Agency (KDCA) confirmed, Monday, that the Korean man who had stayed in Thailand for four months before entering Korea on Dec. 10, died after being infected with Naegleria fowleri.
The patient began to show symptoms of meningitis, such as headaches, fever, vomiting, slurred speech and stiffness of the neck on the evening of his arrival, and was transferred to an emergency room the next day.
After he was pronounced dead on Dec. 21, health authorities conducted further tests to confirm the exact cause of death, which was found to be a Naegleria fowleri infection.
This is the first official case of a Naegleria fowleri infection in Korea. The KDCA has yet to discover the exact route of transmission, but noted that swimming in contaminated water or nasal rinsing with unsafe water are the leading causes of infection.
Naegleria fowleri is a single-celled amoeba, commonly found in warm fresh water such as lakes, rivers, and ponds. It can enter the human body through the nose and causes a rare, life-threatening infection of the brain called primary amebic meningoencephalitis (PAM). The fatality rate of PAM exceeds 97 percent, but the infection does not spread between humans.
After the protozoa was first discovered in 1965 by Australian pathologist Malcom Fowler, a total of 381 Naegleria fowleri infection cases have been identified around the world as of 2018. In the United States, only four out of 151 total known infected individuals have survived as of 2020.
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| Illustration of the life cycle of the parasitic agent Naegleria fowleri / Courtesy of Centers for Disease Control and Prevention |
Local microbiology experts said Koreans do not have to be excessively worried about the first brain-eating amoeba case as the parasite is unlikely to exist in the country. But they warned that the number of cases worldwide is rising.
Shin Ho-joon, a microbiologist at Ajou University said once a patient gets infected with Naegleria fowleri, the chances of survival are extremely low as the disease progresses rapidly.
"Preemptive diagnosis of the infection is very difficult since the early symptoms are similar to that of the common cold. And by the time a patient displays more visible symptoms such as a stiff neck, unconsciousness, coma or death can occur in the following days," he told The Korea Times. "That is why in most cases, the infection is detected post-mortem."
"There is no effective treatment or vaccine against it," Shin added.
His research team has been working to develop potential vaccines against the water-borne pathogen with initial trials on mice showing promising results. But the effectiveness on humans has yet to be proven.
An investigation on 52 samples collected from the water supply in 2017 led to Naegleria fowleria DNA being extracted from six of them. But this does not pose immediate threats to public safety, Shin said.
"There should be additional studies to verify the distribution of the amoeba in the country," he said.
However, he warned that people travelling overseas should take caution as there are rising numbers of infections in countries such as the United States, Southeast Asian nations and some European countries.
"As temperatures rise in lakes and rivers due to global warming, cases are more frequently identified in southern states in the U.S. such as Florida and Texas. Also, a significant number of cases are presumed to be occurring in South America and China, but they are rarely officially reported," he added.
