The border between North and South Korea is one of the most dangerous in the world. Soldiers face each other on both sides of the demilitarized zone. But South Korea is facing another threat from the North.
As American entomologist Terry Klein makes his way to the border between North and South Korea, he doesn't think twice about the thousands of landmines or soldiers patrolling the demilitarized zone, or DMZ.
The researcher is studying the effects of mosquitoes carrying malaria and Japanese Encephalitis. A former soldier, the retiree was contracted by the US Army to carry out his research in South Korea, which he has been doing for the past 22 years.
Klein was originally tasked with preventing US soldiers contracting a viral disease in Korea and spreading it to other parts of the world.
While South Korea is technically considered malaria-free today, there is an exception. The border region separating the two Koreas is a battlefield for malaria carrying mosquitoes.
The area, Klein says, "is composed of grasses and low lying areas that provide for mosquito habitats," which only encourage population growth.
Living in the zone
Major General Urs Gerber, the head of the Swiss delegation to the Neutral Nations Supervisory Commission that oversees the armistice between North and South Korea, lives just meters from the North Korean border - right inside the malaria zone.
Gerber says he has learned to live with the threat posed by the mosquitoes. But, he adds, one must be prepared.
Closing doors at sunset, covering exposed body parts and wearing special uniforms treated with mosquito-proofing are just some of the ways, Gerber says, of how best to avoid being bitten.
Despite his advice, each year thousands of South Koreans contract a non-deadly, nevertheless exhausting, malaria variant around the zone. According to the United Nations, the situation north of the border isn't much different. But statistics for North Korea are not available.
"Mosquitoes don't stay in one spot," researcher Klein says. "You find that winds are prevailing to the south. So, mosquitoes can get up into the system of the wind direction, they could actually come from over the DMZ to South Korea."
International health experts are not confident the virus can be eradicated from the DMZ.
Jerome Kim, director of the International Vaccine Institute likens the situation in the DMZ to the current spread of the Zika virus in the Americas. In a recent opinion piece in a leading South Korean newspaper, Kim emphasized the importance of coordinating efforts to identify outbreak risks, and the need for sufficient funding for research and development.
Leaving his mark
In almost a quarter of a century, researcher Klein has left his mark on the Korean peninsula. He discovered the Korean mosquito which carried the malaria virus in the East Asian country, and it was aptly named after him: the Anopheles Kleini.
The mosquito turned out, Klein says, "to be a probable primary vector of malaria in the DMZ."
When spring comes again, and temperatures across Korea begin to rise, Klein will again be back on mosquito duty heading northward to the DMZ to trap and test the insects.