Pacific Unit Battles Infectious Diseases
By Douglas J. Gillert
American Forces Press Service
PEARL HARBOR, Hawaii, Jul. 30, 1996 They don't carry weapons, but they do wage constant war. They don't hold sick call, but they help keep service members healthy and ready to perform their duties.
Their enemy: infectious diseases, the kind that at best knock troops out of action for a few days or weeks and at worst cause physical agony and death.
Their territory: the vast Pacific Theater, including most of Asia.
From here, the medical officers of Navy Environmental and Preventive Medicine Unit Six do battle against microorganisms, bacteria and viruses that can lay low the strongest, healthiest troops.
Some maladies are as old as war itself diarrhea, for example. After visiting his brother on the Civil War battlefield at Fredericksburg, Va., poet Walt Whitman wrote, "War is 99.9 percent diarrhea." The Navy medics here devote much of their time trying to wipe out the causes of this traditional enemy of the soldier in the field.
"Over the last six years, we've studied the causes of diarrhea among American troops training in Thailand," said Navy Dr. (Capt.) H. James Beecham III, head of the unit's Department of Tropical Medicine. "Our goal is an oral vaccine to prevent a high percentage of the diarrhea that occurs in our ground troops."
Because more than one bacteria causes diarrhea, researchers are looking at a vaccine "cocktail" that can be administered rapidly to deploying troops and would protect them three to six months, Beecham said.
Less common but potentially deadly to U.S. forces in the Pacific are malaria and various tropical diseases endemic to the region. They are tough enemies, conceded Dr. (Capt.) Ben S. Mitchell, officer in charge of the Pearl Harbor unit. "Malaria, for example, has proven highly resistant to drugs," Mitchell explained.
Besides malaria, Japanese encephalitis, dengue fever, uncontrollable bleeding and typhus top the medics' "enemies list." Also high on that list: mosquitoes and ticks, prime carriers of such diseases.
"Japanese encephalitis is one of approximately 100 viruses spread by mosquitoes, ticks and a few other insects," said Dr. (Lt. Cmdr.) Stanton E. Cope, the preventive medicine team's entomologist.
There's no accepted treatment for the disease, which progresses from fever and headaches to delirium, coma and death, Cope said. Onethird of those who contract the disease die from it, while a third of survivors suffer permanent brain damage.
Service members and their families headed for the region receive vaccinations against the disease. Other preventive efforts include personal protection against insect bites and insect eradication programs.
Fortunately, these efforts have proven successful only 11 U.S. citizens are known to have contracted Japanese encephalitis since 1981. Eight of them, however, were service members, and all acquired the disease in Southeast Asia.
"That's not many, but the potential is real for high numbers," Cope said. "Many people were infected during World War II and the Korean War," he explained. It could, however, happen again.
Dengue fever provides a broader threat, because it is present in tropical climates worldwide, said Dr. (Lt. Cmdr.) Laurel May, the Navy's sole epidemiologist in the Pacific Theater.
"We've had cases of dengue fever in active duty personnel in Cobra Gold [a major annual combined forces exercise in Thailand], Haiti and Somalia," May said. Because dengue's a virus, she added, antibiotics won't help, and currently, there's no vaccine and no treatment. "The only way to keep people from getting dengue is to convince them to protect against mosquito bites."
Dengue fever symptoms include fever, headaches, eye pain, severe muscle pain and joint pain, Cope said. The severity of the latter symptom give dengue its nickname, "breakbone fever."
It gets worse. Dengue may cause hemorrhagic disease, May said uncontrolled bleeding that most certainly leads to death. "Bleeding from the nose, mouth, gastrointestinal tract," Cope added. "You try to put an IV [needle] in them and they bleed through it."
Compared to Japanese encephalitis, a higher proportion of people infected with dengue come down with the basic symptoms, Mitchell said. And because dengue occurs throughout the world, it could more greatly affect military operations. "You could expect a high portion of troops to be disabled [by the disease]," he said.
A long recovery period follows after the fever subsides, Cope said. Sailors who contracted the fever last year during Cobra Gold in Thailand were listless and fatigued for at least a week. "They had difficulty just getting off their cots," he said.
The World Health Organization, DoD and other agencies are working to develop a vaccination for dengue fever, Mitchell said.
The Navy advises three levels of protection during field deployment: applying insect repellent containing diethyltoluamide, commonly known as DEET, to the skin; applying permethrin spray to field uniforms, which will last through six washes; and using bed netting that also has been sprayed with permethrin.
In addition to personal protection, Mitchell said, the services actively work to eradicate mosquito breeding sites.
May challenges service members who dismiss the protection efforts as ineffectual. "The military takes insectborne diseases like malaria and dengue fever seriously," she said. "We've done a lot of research to make sure this is the best system for preventing insect bites."
Chiggers are the culprits behind scrub typhus, another disease unique to Southeast Asia and Korea. The insects crawl under clothing, bite and infect their victims with tiny organisms called rickettsia, Beecham explained. In about 10 days, infected persons comes down with a fever, headaches, skin rash and swollen lymph nodes.
Chiggers infected a lot of victims with scrub typhus during the Vietnam War. Early on, American doctors misdiagnosed their patients as having mononucleosis because of the similarity of symptoms and their unfamiliarity with scrub typhus. Once they correctly diagnosed the disease, they determined it could be effectively, cheaply treated by the drug doxycycline.
However, a U.S. Army researcher in Thailand recently discovered a new strain of typhus resistant to the drug, and this has people worried, Beecham said.
More worrisome, however, is the existence of infectious diseases on the Korean Peninsula, including the unknown factor of what's occurring north of the demilitarized zone. "There was a lot of hemorrhagic fever during the Korean War that may still be a problem we can't gather data on," Beecham said. Korean hemorrhagic fever attacks the kidneys and can cause death, he said.
Fourteen U.S. Marines contracted the fever during its last major outbreak, in 1983. Two died. New cases occur every year. The virus comes from the excrement and urine of field mice. It turns to dust that its victims breathe in.
Fortunately, the fever is treatable, and prevention measures mostly involve good field hygiene, Beecham said.
These, of course, aren't the only infectious disease threats to U.S. service members deployed in the Pacific. Mitchell said his unit conducts site surveys ahead of troops to detect the threat in any given region. In addition, they search medical literature, the Internet even travel brochures for health information.
Underdeveloped countries pose a greater challenge to collecting useful data, he said. "You can't go to countries that don't have any type of infrastructure and expect them to be able to identify what types of diseases we may encounter there," he said. American Army and Navy medical research laboratories in Bangkok, Thailand and Jakarta, Indonesia, help, and DoD has contracted with commercial laboratories to look at contagious diseases, he added.
"Given the sense of urgency caused by the ebola outbreaks," he said, "people are increasingly willing to share information and resources."
(Dr.) Rear Adm. William J. McDaniel, U.S. Pacific Command surgeon, said cooperation between the United States and Asian nations is paramount to successfully combating tropical disease and maintaining military readiness.
"Our access and ability to put teams in there to do preventive medicine and disease studies allows us to better prepare our people to deploy in this theater or anywhere in the world," McDaniel said.