Acute diarrheal diseases are a leading cause of illness and death worldwide, with over 4.6 billion cases per year. A wide variety of infectious agents can cause acute diarrhea, including viruses, bacteria, and parasites. The main pathogenic mechanisms are toxin production, invasion and destruction of intestinal cells, and penetration of the intestinal mucosa. Treatment focuses on oral rehydration and antibiotics depending on the suspected pathogen. Proper hygiene and vaccines can help prevent acute diarrheal diseases.

1. ACUTE DIARRHEAL DISEASES

2. INTRO
• leading cause of illness globally
• 4.6 billion episodes worldwide per year
• ranks second to LRI as the most common infectious cause of death
worldwide
• contributes to malnutrition and thereby reduces resistance to
other infectious agents - indirect factor in a far greater burden of
disease
• wide variety of infectious agents involved, including viruses,
bacteria, and parasitic pathogens

3. PATHOGENIC MECHANISMS
TOXIN PRODUCTION
• Enterotoxins - cause watery diarrhea by acting directly on secretory
mechanisms in the intestinal mucosa. cholera toxin, heat-labile enterotoxin,
heat-stable enterotoxin
• Cytotoxins - cause destruction of mucosal cells and associated inflammatory
diarrhea
• Neurotoxins - act directly on the central or peripheral nervous system -
produced by bacteria outside the host and therefore cause symptoms soon after
ingestion - staphylococcal and Bacillus cereus toxins

5. INVASION
• Dysentery - from bacterial invasion and destruction of intestinal mucosal cells
• Shigella and enteroinvasive E. coli - invasion of mucosal epithelial cells,
intraepithelial multiplication, and subsequent spread to adjacent cells
• Salmonella - inflammatory diarrhea by invasion of the bowel mucosa but generally is
not associated with the destruction of enterocytes
• Salmonella typhi and Yersinia enterocolitica - penetrate intact intestinal mucosa,
multiply intracellularly in peyer's patches and intestinal lymph nodes, and then
disseminate through the bloodstream to cause enteric fever

6. GASTROINTESTINAL PATHOGENS CAUSING
ACUTE DIARRHEA
NONINFLAMMATORY (ENTEROTOXIN)
• Vibrio Cholerae, ETE.Coli, EAE. Coli, Clostridium Perfringens, Bacillus Cereus,
Staphylococcus Aureus
• Rotavirus, Norovirus, Enteric Adenoviruses
• Giardia Lamblia, Cryptosporidium Spp
• Proximal small bowel
• Watery diarrhea
• Stool - no fecal leukocytes; mild or no increase in fecal lactoferrin

7. INFLAMMATORY (INVASION OR CYTOTOXIN)
• Shigella Spp., Salmonella Spp., Campylobacter Jejuni, Enterohemorrhagic E. Coli,
Enteroinvasive E. Coli, Yersinia Enterocolitica, Listeria Monocytogenes, Vibrio
Parahaemolyticus, Clostridium Difficile
• Entamoeba Histolytica
• Colon or distal small bowel
• Dysentery or inflammatory diarrhea
• Stool - Fecal polymorphonuclear leukocytes; substantial increase in fecal
lactoferrin

8. PENETRATING
• Salmonella Typhi, Y. Enterocolitica
• Enteric fever
• Stool - Fecal mononuclear leukocytes

9. TRAVELER'S DIARRHEA
• Most common travel-related infectious illness
• time of onset is usually 3 days to 2 weeks after the traveler's arrival in a
resource-poor area
• most cases begin within the first 3–5 days
• generally self-limited, lasting 1–5 days
• related to the ingestion of contaminated food or water
• enterotoxigenic and enteroaggregative strains of E. coli are the most common

11. BACTERIAL FOOD POISONING

14. • Bacterial disease caused by an enterotoxin elaborated outside the host -
staphylococcus aureus or b. cereus, has the shortest incubation period (1–6 h) and
generally lasts <12h
• staphylococcal food poisoning - caused by contamination from infected human
carriers
• B. cereus - syndrome with a short incubation period—the emetic form, mediated by
a staphylococcal type of enterotoxin—or one with a longer incubation period (8–16
h)—the diarrheal form, caused by an enterotoxin resembling E. coli LT
• emetic form - contaminated fried rice
• Clostridium perfringens - slightly longer incubation period (8–14 h) , results from
the survival of heat-resistant spores in inadequately cooked meat, poultry, or
legumes

15. APPROACH TO THE PATIENT: INFECTIOUS
DIARRHEA OR BACTERIAL FOOD
POISONING

17. PHYSICAL EXAMINATION
• Signs of dehydration - provides essential information about the severity of the
diarrheal illness and the need for rapid therapy
• Mild dehydration - by thirst, dry mouth, decreased axillary sweat, decreased
urine output, and slight weight loss
• Moderate dehydration - orthostatic fall in blood pressure, skin tenting, and
sunken eyes
• Severe dehydration - lethargy, obtundation, feeble pulse, hypotension, and
frank shock

18. LABORATORY EVALUATION
• Noninflammatory diarrhea - self-limited or can be treated empirically, no need
to determine a specific etiology
• Cholera - stool should be cultured on selective media such as thiosulfate–
citrate–bile salts–sucrose (TCBS) or tellurite-taurocholate-gelatin (TTG) agar
• rotavirus - latex agglutination test
• patients with fever and evidence of inflammatory disease - stool cultured for
Salmonella, Shigella, and Campylobacter

19. DIAGNOSTIC APPROACH

20. TREATMENT
• Mainstay of treatment is adequate rehydration - oral rehydration solution
• glucose-facilitated absorption of sodium and water in the small intestine remains
intact in the presence of toxin
• World Health Organization recommended a "reduced-osmolarity/reduced-salt" ORS
that is better tolerated and more effective
• 2.6 g of sodium chloride, 2.9 g of trisodium citrate, 1.5 g of potassium chloride, and
13.5 g of glucose (or 27 g of sucrose) per liter of water
• severely dehydrated or in whom vomiting precludes the use of oral therapy - IV
solutions such as Ringer's lactate

22. PROPHYLAXIS
• IMPROVEMENTS IN HYGIENE TO LIMIT FECAL-ORAL SPREAD OF ENTERIC
PATHOGENS
• ROTAVIRUS VACCINE
• VACCINES AGAINST S. TYPHI AND V. CHOLERAE ARE ALSO AVAILABLE

23. TREATMENT OF TRAVELER'S DIARRHEA
• loperamide: 4 mg initially followed by 2 mg after passage of each unformed stool,
not to exceed 8 tablets (16 mg) per day
• Loperamide should not be used by patients with fever or dysentery; its use may
prolong diarrhea in patients with infection due to Shigella or other invasive
organisms
• fluoroquinolone such as ciprofloxacin, 750 mg as a single dose or 500 mg bid for 3
days; levofloxacin, 500 mg as a single dose or 500 mg qd for 3 days; or norfloxacin,
800 mg as a single dose or 400 mg bid for 3 days
• Azithromycin, 1000 mg as a single dose or 500 mg qd for 3 days
• Rifaximin, 200 mg tid or 400 mg bid for 3 days