By Emma Brown
Washington Post Staff Writer
Saturday, December 25, 2010; 6:47 PM
People began dying by the dozens in little coastal villages in the Philippines in the 1960s, and no one knew why. Some suspected a curse and hired two witch doctors to exorcise the area. The two toiled until one of them died of the very illness they were trying to drive out.
John Cross, a civilian parasitologist leading the U.S. Navy's efforts to prevent outbreaks of tropical diseases by understanding parasites' ecology and biology, sent two scientists to find out what was going on.
They quickly discovered that the villagers were suffering from acute infections of a worm that caused extraordinary diarrhea, emaciation and death. But it was years before anyone could say with certainty how the villagers had been infected and how the spread of disease could be stopped.
Dr. Cross, the sleuth who eventually solved that mystery with a combination of creative experimentation and stubborn endurance, died Nov. 19 of complications from diabetes at Shady Grove Adventist Hospital in Rockville. He was 85.
He had taught since 1984 at the Uniformed Services University of the Health Sciences in Bethesda, where he was admired by medical students for his engaging lectures highlighted by photographs and stories from more than two decades of studying tropical diseases in Asia.
The litany of diseases he studied included schistosomiasis, malaria and the plague. He was perhaps best known for his work on the mysterious, cholera-like illness that attacked Filipino villagers on the island of Luzon in the 1960s and has since appeared in Thailand, Iran and Egypt.
At the time of the outbreak, the worm that caused the illness was new to science and its life cycle was not understood. Capillaria philippinensis was first identified in 1964.
Navy scientists suspected that villagers, whose diet consisted of raw fish and shrimp, were ingesting the Capillaria worms with their food. But the scientists, working in a makeshift hospital and laboratory powered by a Honda generator, could not find evidence to show what other animals harbored the worm or how it was being delivered to villagers' intestines.
"We went through 30,000 necropsies, everything from shrimp and little fish to cattle and sheep, and we never could find anything," said K. Darwin Murrell, who was a young Navy parasitologist working under Dr. Cross at the time. "We were really puzzled."
After more than a year of that tedious work, Murrell was transferred back to the United States. He doubted that anyone would ever untangle the Capillaria outbreak, and he began to believe it was a freak occurrence that posed no enduring threat.
"I remember telling John I thought it was senseless to try to continue to do necropsies on everything under the sun down there, that this was an ephemeral event and we probably wouldn't see it again," Murrell said. "I could see he was skeptical of that."
Dr. Cross took his efforts into a laboratory, where he began a painstaking process of trying to infect various animals with the Capillaria eggs.
He even swallowed the eggs himself. When he did not become infected, he had good evidence that humans could not be sickened by exposure. He surmised that the worms could reproduce in a human only if that person had ingested larvae.
Those larvae, Dr. Cross discovered in the lab, were able to hatch in the guts of little freshwater and brackish-water fish that lived in lagoons along the coast of the Philippines.
Rather than continuing to experiment on himself, he tested his theory by exposing other mammals: monkeys, gerbils and rats. The mammals became ill, and their symptoms mimicked those of humans sick with Capillaria, suggesting that Dr. Cross had succeeded in recreating the worm's path from village lagoons to villagers' intestines.
People were becoming ill, he concluded, after eating raw fish that were infected with Capillaria larvae. Infection could be easily prevented by cooking food and could be effectively treated with the right drug.
Dr. Cross went on to show that fish-eating birds also could become infected with larvae, and surmised that such birds were the natural host for the Capillaria worm.
After learning that Dr. Cross had figured out the Capillaria puzzle, Murrell was "a little embarrassed," he said.
"I felt like I'd given up too early on this thing. It was a personal lesson to me," he said. "Don't quit."
John Henry Cross was born Sept. 25, 1925, in Lynn, Mass. He served in the Navy in the Solomon Islands during World War II. In 1945, as the war drew to a close, he joined the nascent United Nations Relief and Rehabilitation Administration in Shanghai, where he met his wife, Evelyn Chang. They married in 1952, after returning to the United States for school.
Besides his wife, survivors include a daughter, Kelley Cross Finn of Rockville, and a grandson. A son, John F. Cross, died in 1979.
Dr. Cross graduated in 1953 from Miami University in Oxford, Ohio, and received a master's degree there in 1955 in parasitology.
After receiving a doctorate in parasitology in 1958 from the University of Texas at Galveston, Dr. Cross taught at the University of Arkansas medical school until 1967, when he was asked to head up the new medical ecology department in the well-regarded U.S. Naval Medical Research Unit No. 2.
He worked for the Navy for the next two decades. Based in Taipei and Manila, he traveled widely, mentored many young scientists and was known in Southeast Asia as "Papa John."
His long history of working on that continent was honored in 2007 with an honorary doctorate from Mahidol University in Bangkok.
His daughter recalled watching slide shows he gave after returning from research trips. "It was never, 'Look at this beautiful countryside,'â" she said. Instead, his photographs featured villagers, often infected with a parasitic disease.
Unmoved by her father's passion, she did not become a parasitologist herself. "I became more of a hypochondriac," she said.