Clinical Manifestations

For most of the enteric infections, a characteristic clinical illness is not produced by a given etiologic agent. When patients acquire enteric infection, a variety of symptoms other than diarrhea may result, including abdominal cramps and pain, nausea, vomiting, and fecal urgency and incontinence or the urge but inability to defecate. When patients experience fever as a predominant finding, invasive bacterial pathogens should be suspected (Salmonella, Shigella, and Campylobacter). Vomiting is the primary complaint in viral gastroenteritis (often due to rotavirus in an infant or Norwalk-like viruses in older children or adults), staphylococcal food poisoning, or foodborne illness due to Bacillus cereus. When dysentery (the passage of small-volume stools that contain gross blood and mucus) occurs, amebic Shigella or Campylobacter enteritis should be suspected. In salmonellosis, gatroenteritis stools are grossly bloody in just under 10 percent of cases. Other less common causes of dysentery are inflammatory bowel disease, Aeromonas, Vibrio parahemolyticus, Yersinia enterocolitica, Clostridium difficile, and Entamoeba histolytica.

Table VTII.35.1. Commonly identified etiologie agents in diarrheal disease

Table VIII.35.2. Etiologic agents of diarrhea, characteristically identified in special settings




Escherichia coli

Enteropathogenic E. coli (EPEC)

Enterotoxigenic E. coli (ETEC)

Enteroinvasive E. coli (EIEC)

Enterohemorrhagic colitis (EHEC)

Shigella, Salmonella, Campylobacter jejuni


Plesiomonas shigelloides

Vibrio parahemolyticus, other nonagglutinable vibrios Staphylococcus aureus, Bacillus cereus



Norwalk viruses

Caliciviruses and enteric adenoviruses


Giardia lamblia

Entamoeba histolytica


Causes infantile diarrhea; may cause chronic diarrhea

Major cause of infant and childhood diarrhea in developing tropical countries, and travelers' diarrhea

Occasionally causes foodborne febrile diarrhea

Causes colitis, low-grade fever associated with hamburger consumption; may result in hemolytic uremic syndrome

Common in all areas, especially during the summertime

Of uncertain importance

Causes diarrhea in travelers and those exposed to seafood

Causes diarrhea in those exposed to seafood

Associated with foodborne outbreaks of vomiting (± diarrhea)

Found in infants <2 years age; shows wintertime propensity in temperate climates; occurs in all seasons in tropical areas

Major cause of waterborne and shellfish-associated gastroenteritis

Of uncertain importance

Causes protracted diarrhea commonly in those exposed to mountainous areas or day-care centers Commonly causes recurrent diarrhea in persons living in tropical countries

Causes diarrhea in patients with AIDS, those in daycare centers, and in travelers to Leningrad


Commonly identified agents

Day-care centers

Person traveling from industrial to developing countries

Male homosexuals

Acquired immune deficiency syndrome

Rotavirus, Giardia, Shigella,

Cryptosporidium Enterotoxigenic Escherichia coli, Shigella, Salmonella, Campylobacter, Plesiomonas, Giardia

Herpes simplex, Chlamydia trachomatis, Treponema pallidum, Neisseria gonorrhoeae, Shigella, Salmonella, Campylobacter, Clostridium difficile, Giardia Cryptosporidium, Isospora belli, Herpes simplex, cytomegalovirus, Salmonella, Mycobacterium avium—intracellular

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