Diarrheal Disease

Department of the Navy
Bureau of Medicine and Surgery

Diarrhea and dysentery have had an important impact on military operations throughout history. Early in Operation Desert Shield an epidemic of diarrhea occurred with attack rates of 10 percent of the force strength per week in some units, with 50 percent of all troops affected. In general, estimates of diarrheal disease in travelers to the developing world range from 20 to 55 percent.

The etiology of diarrhea associated with foreign deployments is the same as "traveler’s diarrhea" in civilians (called Turista). The most common causative agents are enterotoxigenic strains of E. Coli (ETEC). They are responsible for 40 to 50 percent of all cases, and result in a self limited, noninvasive watery diarrhea (3 to 5 days). Invasive diarrhea is caused by Shigella (5 to 15 percent) of cases, Salmonella (5 to 10 percent) and Campylobacter (5 percent). These bacterial pathogens are more likely to cause a severe invasive diarrhea with bloody stools (i.e., dysentery), severe abdominal cramping, and smaller volume stools. Campylobacter is the most common pathogen in SE Asia, ahead of ETEC. Aeromonas is a common pathogen in this region as well. In Japan and Thailand, Vibrio parahemolyticus may be a significant problem, especially in association with seafood consumption. Protozoal disease due to Giardia may occur in 2 to 5 percent and produces a chronic intermittent diarrhea with malabsorption, weight loss and excessive flatulence. Amebiasis is responsible for only 1 percent of cases, but can cause a severe dysenteric picture.

Diarrhea at sea

Diarrhea at sea is generally associated with port calls when crewmembers consume local food. Port of call associated diarrhea usually begins on the 2nd day in port and a cluster of cases will usually peak on the 1st day back at sea and end by the 7th day at sea. In 80 percent of cases, there are 5 or less bowel movements during the entire episode (i.e., self-limited) and only about 10 percent of cases will require binnacle listing and 3 percent hydration in sick bay.

Diarrhea in the field

Provision of ice for cooling fluids in a field environment is particularly problematic. Despite the best training and intentions, fomites in field conditions rapidly contaminate ice machines or vats of ice and act as a point source for epidemic outbreaks.

The diagnostic approach to diarrheal disease in the field can be both simple and effective. The most important decision is to divide the cases into two broad categories: invasive and noninvasive. This can be done with an exam of the stool for fecal leukocytes using a methylene blue stain. Under field conditions, a stool guaiac test can be performed with similar sensitivity to the fecal leukocyte test. A positive test suggests invasive diarrhea. The stool culture is one of the most cost ineffective diagnostic tests available with only 2 percent of samples positive at a cost of $2000.00/positive. If available, stool cultures should be obtained in cases of invasive diarrhea, those who do not respond to empiric therapy, and in symptomatic food workers. Stool for ova and parasites would be most reasonable for patients with diarrhea of more than a week duration and in cases of invasive diarrhea.

The clinical evaluation should focus on the degree of dehydration, skin turgor, vital signs, and orthostatic changes. Monitoring of urine output and specific gravity may be critical important in patients requiring significant rehydration.

The treatment for all cases of diarrhea includes rehydration. For mild cases, this can be as simple as fruit drinks and soda crackers. For moderate to severe diarrhea, oral rehydration can be highly effective using prepackaged oral rehydration salts (ORS) to replace the approximate 135 mEq of sodium, 45 mEq of bicarbonate, and 15 mEq of potassium lost in each liter of stool. In the absence of ORS packets, a balanced electrolyte solution for moderate diarrhea can be concocted from the following home brewed method; five tsp. sugar, one teaspoon of salt, and one liter of potable water, ideally with the juice of two oranges to replete potassium losses. More severe cases or those with vomiting may require intravenous rehydration with Lactated Ringers solution and supplemental potassium and bicarbonate. Kaopectate has minimal to no effect on fluid losses or resolution of diarrhea. The use of loperamide (imodium) alone for noninvasive diarrhea (fecal leukocyte or stool guaiac negative, not systemically toxic) can reduce the duration of diarrhea by about 50 percent.

Prevention of diarrhea can be accomplished by providing safe water and food. Education before high-risk port calls should emphasize avoidance of fresh vegetables and salads, tap water, ice, street vendors, fresh dairy products, and buffets. For those determined to try the local cuisine, admonish accepting only food that comes to you steaming hot, and fruits and vegetables that you peel yourself. Encourage use of bottled water and beverages, and for especially high-risk ports, consider providing box lunches. Antibiotic prophylaxis is generally not indicated due to cost and logistical problems. However, for small groups on missions of limited duration, prophylaxis with Ciprofloxacin can be highly efficacious. Campylobacter strains in SE Asia are increasingly resistant to quinolones, particularly underscoring the need for preventive measures when deploying to this region