by Karen Fleming-Michael
FORT DETRICK, Md. (Army News Service, Dec. 17, 2002) -- The runs. The trots. The quick step. Montezuma's revenge. Whatever it's called, diarrhea can debilitate deployed soldiers.
In fact, during Operations Desert Shield and Storm 57 percent of troops had at least one bout with diarrhea; 20 percent reported they were temporarily incapacitated by it, according to the 1998 Army Science and Technology Master Plan.
To combat the ailment, researchers in the Walter Reed Army Institute of Research's Department of Enteric Infections are developing new vaccines to help deployed warfighters fight bacteria that cause diarrhea.
Less-than-sanitary living conditions and foreign diets, teamed with few opportunities to wash after using the bathroom, let diarrhea-causing bacteria with names like Shigella flexneri, Shigella sonnei, Shigella dysenteriae and Escherichia coli flourish in the field, quickly disabling thousands and upending readiness.
So far, the institute has four vaccines in the works to combat diarrhea.
"Ideally, the goal would be to have one vaccine that will protect against multiple pathogens that can easily be given to deploying soldiers," said Maj. David Katz, a senior clinical investigator at WRAIR. "So soldiers can take it before they deploy to an area, and they'll be protected."
A vaccine to combat Shigella flexneri, called SC602, was developed along with The Institute Pasteur. Since 1992 it has undergone clinical trials in the United States and Bangladesh.
"The wonderful thing about the shigella vaccines is... the bacteria (used in them) are alive but weakened to diminish the amount of symptoms," Katz said. "The body thinks it's infected and gives an immune response, but you don't get infected like a natural infection because the bacteria don't spread from cell to cell."
Receiving the oral vaccine before deploying is key, Katz said. "Most of the soldiers will get hit right when they arrive in a new area," Katz said, "either because they're eating on the economy or they're in a new area and their system has not been primed."
Another reason to give the vaccine ahead of time is because of potential side effects, said Dr. Thomas Hale, chief of the Department of Enteric Infections at WRAIR.
"The vaccine can cause some short-term fevers and mild diarrhea in 20 percent of the people who receive it," Hale said, "so soldiers need to take it well before they get on a plane."
A vaccine for Shigella sonnei, which often attacks travelers and stateside daycare centers, is a possible stand-alone product, Hale said. "This one vaccine could make a significant difference in the health of soldiers deployed to the Middle East (where 90 percent of outbreaks occur) and the developing world," Hale said.
Drs. Malabi Venkatesan and Antoinette Hartman from WRAIR developed the oral vaccine, called WRSS1, that is currently in clinical trials in conjunction with the University of Maryland Medical School and the National Institute of Allergy and Infectious Diseases.
The Department of Enteric Infections at WRAIR has teamed up with the Israel Defense Force for a vaccine trial evaluating WRSS1 this winter.
"Israel has cities that are very westernized, but almost everyone has a compulsory military obligation, so they go from cities to field posts and the incidence of diarrheal disease is significant," Katz said.
To combat the deadly form of diarrhea, dysentery -- also called bloody diarrhea -- WRAIR researchers are working with the Bloomberg School of Public Health at Johns Hopkins University to test the oral Walter Reed Shigella-Dysentery-1 vaccine, WRSD1.
The other diarrhea-causing bacteria WRAIR and the Navy Medical Research Unit researchers are trying to disable is E. coli. Whereas shigella bacteria invades a cell's wall and moves from cell to cell to spread the disease, E. coli prefers to stick to the intestine's lining, homestead and crank out toxins that cause diarrhea. To outsmart the unwanted tenant, researchers are trying to make antibodies that will prevent squatters from colonizing because they can't stick to the intestine. The vaccine's been tested in a time-release capsule form as well as a transdermal patch,
"It should be easy for the soldier to use: Just pop the patch on and that's it," Katz said.
Though having one vaccine to combat all major forms of infectious diarrhea is a ways off, he said.
(Editor's note: Karen Fleming-Michael is a staff writer for the Fort Detrick Standard newspaper.)