The North Korean soldier drove a jeep into the Joint Security Area, one of the most heavily guarded portions of the Demilitarized Zone, on Monday. He then ran across the border to defect to the South while fellow North Korean troops unleashed a hail of rifle and pistol shots trying to stop him.

He collapsed about 55 yards south of the border, bleeding profusely. South Korean officers pulled him to safety, and a United States Black Hawk military helicopter rushed him to a hospital near Seoul, where he underwent a series of surgeries.

His was the most dramatic defection from the North in years, making headlines in South Korea.

But more startling news came from the doctors who were working to clean and patch up his digestive ietary tract, which was torn by bullets.

The soldier’s condition was particularly noteworthy because North Korean soldiers, especially those deployed near the border with South Korea, receive priority in food rationing. Yet, in addition to the parasitic worms, doctors found kernels of corn in his stomach.

South Korea itself was afflicted with widespread parasitic infections through the 1970s, when more than 80 percent of the population carried parasitic worms. After a 9-year-old girl died in 1963 and doctors found more than 1,000 parasitic worms in her body, the country launched a national campaign to eradicate parasites.

Schools collected stool samples from students and distributed anti-parasitic pills. The campaign succeeded: Parasitic infections have become rare in South Korea as hygiene and economic conditions have improved.

More than 30,000 North Koreans have fled to South Korea since a famine killed more than a million people in the North in the 1990s. Since then, international relief agencies have reported widespread malnutrition and stunted growth among many children in the North.

The wounded soldier, who is believed to be in his late 20s, is 5 feet 5 inches tall and weighs 132 pounds. In contrast, an average high school male senior in South Korea is 5 feet 8 inches tall and weighs 154 pounds.