Diarrheal Disease
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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 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. 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. A reasonable approach to noninvasive diarrhea is two tablets after the
first loose bowel movement, followed by one tablet after each successive bowel movement up
to a maximum of 8 tablets/day. Keep in mind that imodium may exacerbate invasive diarrhea
when used alone, and that up to 30 percent of invasive pathogens may have fecal leukocyte
negative stools. Prescribing a fluroquinolone like Cipro one tab twice a day for 3 days
combined with imodium has been shown to further decrease the duration to a mean of 1 hour
for noninvasive ETEC diarrhea. Due to increasing worldwide resistance to Septra among
shigella and salmonella, the mainstay of treatment for invasive diarrhea has become a quinolone, such as Norfloxacin or Ciprofloxacin 500 mg bid x 3d or alternatively a single
one gram dose. In summary, it would be reasonable to treat all cases of invasive diarrhea
with a quinolone antibiotic. For those patients who do not respond within 24 to 48 hours
to a quinolone, other etiologies should be considered including Clostridium difficile
(often associated with the use of antibiotics) or amebiasis. Both of these diseases
respond well to Metronidazole
(Flagyl) 250mg TID for C. difficile and giardiasis, and 750
mg TID x 10 days for amebic dysentery. If a patient does not respond to empiric
antibiotics, noninfectious etiologies such as ulcerative colitis or regional enteritis
should be considered in conjunction with a more intensive evaluation. In considering synchronous, simultaneous treatment of troops,
consultation with the flight surgeon may be valuable. Air crewmembers may be grounded for
24 hours after use of Ciprofloxacin. This makes a 3 day course of therapy a 4 day mission
crippler whereas a single dose of one gram may only affect flight status for the next 24
hours. 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 Previous review by LCDR James C. Pile MC, USNR, Infectious Disease
Department, National Naval Medical Center, Bethesda, MD. Latest review by CDR Doug
McNeill, MC, USNR, Senior Medical Officer, USS Saipan, LHA-2 (1999). |
Preface · Administrative Section · Clinical Section
The
General Medical Officer Manual , NAVMEDPUB 5134, January 1, 2000
Bureau
of Medicine and Surgery, Department of the Navy, 2300 E Street NW, Washington, D.C.,
20372-5300
This web version of The General Medical Officer Manual, NAVMEDPUB 5134 is provided by The Brookside Associates Medical Education Division. It contains original contents from the official US Navy version, but has been reformatted for web access and includes advertising and links that were not present in the original version. This web version has not been approved by the Department of the Navy or the Department of Defense. The presence of any advertising on these pages does not constitute an endorsement of that product or service by either the Department of Defense or the Brookside Associates. The Brookside Associates is a private organization, not affiliated with the United States Department of Defense. All material in this version is unclassified. This formatting © 2006 Medical Education Division, Brookside Associates, Ltd. All rights reserved.
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