Download Epidemiology and Management of Diarrheal Diseases

Diarrhea
E Rahimi, MD
Assiatant Professor
Department Of Internal Medicine
MUK
DEFINITION
Diarrhea and constipation are exceedingly
common and， together，exact an
enormous toll in terms of mortality，
morbidity， social inconvenience， loss of
work productivity， and consumption of
medical resources.
W orldwide， > 1 billion individuals suffer
one or more episodes of acute diarrhea
each year.
DEFINITION
 Among the 100 million persons affected annually
by acute diarrhea in the United States， nearly
half must restrict activities, 10% consult
physicians, -250000 require hospitalization， and 5000 die (primarily the elderly) .
 The annual economic burden to society may exceed
$20 billion.
 Acute infectious diarrhea remains one of the most
common causes of mortality in developing
countries， particularly among impoverished
infants， accounting for 1 .8 million deaths per
year.
INTESTINAL FLUID ABSORPTION
AND SECRETION
 On an average day, 9 L of fluid enter the (GI)
tract, - 1 L of residual fluid reaches the colon，
and the stool excretion of fluid constitutes about
0.2 L/d.
 The colon has a large capacitance and functional
reserve and may recover up to four times its usual
volume of 0.8 L/d, provided the rate of flow
permits reabsorption to occur.
 Thus, the colon can partially compensate for
excess fluid delivery to the colon
• that may result from intestinal absorptive or
secretory disorders.
DEFINITION
 Diarrhea is loosely defined as passage of
abnormally liquid or unformed stools at an
increased frequency.
 For adults on a typical Western diet， stool
weight >200 g/d can generally be considered
diarrheal.
 Diarrhea may be further defined as acute if <2
weeks， persistent if 2-4 weeks， and chronic if
>4 weeks in duration
DEFINITION
 Two common conditions， usually associated with
the passage of stool totaling <200.
 Pseudodiarrhea， or the frequent passage of small
volumes of stool， is often associated with rectal
urgency， tenesmus， or a feeling of incomplete
evacuation， and accompanies IBS or proctitis.
 Fecal incontinence is the involuntary discharge of
rectal contents and is most 0fen caused by
neuromuscular disorders or structural anorectal
problems.
DEFINITION
 Diarrhea and urgency， especially if severe， may
aggravate or cause incontinence.
 Pseudodiarrhea and fecal incontinence occur at
prevalence rates comparable to or higher than
that of chronic diarrhea and should always be
considered in patients complaining of "diarrhea."
 Overflow diarrhea may occur in nursing home
patients due to fecal impaction that is readily
detectable by rectal examination.
 A careful history and physical examination
generally allow these conditions to be iscriminated
from true diarrhea.
Acute Diarrhia
 More than 90% of cases of acute diarrhea are
caused by infectious agents; these cases are often
accompanied by vomiting， fever， and abdominal
pain.
 The remaining 10% or so are caused by
medications，toxic ingestions， ischemia， food
indiscretions， and other conditions.
Acute Diarrhia
 Most infectious diarrheas are acquired by fecal
oral transmission or， more commonly， via
ingestion of food or water contaminated with
pathogens from human or animal feces.
 In the immunocompetent person， the resident
fecal microflora， containing >500 taxonomically
distinct species， are rarely the source of diar
Acute Diarrhia:
5 high risk groups
 1. Travelers
 Nearly 40% of tourists to endemic regions of
Latin America， Afica， and Asia develop socalled trave1er's diarrhea.
 Most common1y due to enterotoxigenic or
enteroaggregative Escherichia coli as well as to
Campylobacter， Shigella， Aeromonas，norovirus
， Coronavirus， and Salmonella.
 Visitors to Russia (especially St. Petersburg) may
have increased risk of Giardia-associated
diarrhea.
Acute Diarrhia:
5 high risk groups
 Travelers
 visitors to Nepal may acquire Cyclospora.
 Campers， back packers， and swimmers in
wilderness areas may become infected with
Giardia.
 Cruise ships may be affected by outbreaks of
gastroenteritis caused by agents such as
norovirus.
Acute Diarrhia:
5 high risk groups
 2. Consumers of certain foods.
 Diarrhea close1y following food consumption at:
 a picnic， banquet， or restaurant may suggest
infection with Salmonella
 Campylobacter， or Shigella from chicken
 enterohemorrhagic E. coli (01 57:H7) from
undercooked hamburger
 Bacillus cereus from fried rice or other reheated
food
 Staphylococcus aureus or Salmonella from
mayonnaise or creams
Acute Diarrhia:
5 high risk groups
 2. Consumers of certain foods.
 Salmonella from eggs
 Listeria from uncooked foods or soft cheeses
 Vibrio species， Salmonella， or acute hepatitis A
from seafood，especially if raw.
Acute Diarrhia:
5 high risk groups
 3. Immunodeficient persons.
 primary immunodeficiency (e.g.， IgA deficiency
， common variab1e hypogammag1obulinemia，
chronic granu1omatous disease)
 secondary immunodeficiency states
 Common enteric pathogens:
 Mycobacterium species
 cytomegalovirus
 Adenovirus
 herpes simplex
Acute Diarrhia:
5 high risk groups
 3. Immunodφcient persons.
 Protozoa
 Cryptosporidium
 Isospora belli
 Microsporida
 Blastocystis hominis
Acute Diarrhia:
5 high risk groups
 3. Immunodφcient persons.
 In patients with AIDS agents transmitted
venereally per rectum (Neisseria onorrhoeae，
Treponema pallidum， Chlamydia) may contribute
to proctocolitis.
 Persons with hemochromatosis are especially prone
to invasive， even fatal， enteric infections with
Vibrio species and Yersinia infections and should
avoid raw fish.
Acute Diarrhia:
5 high risk groups
 4. Daycare attendees and their family members.
 Infections with Shigella， Giardia， Cryptosporidium
， rotavirus， and other agents are very common and
shou1d be considered.
• 5. Institutionalized persons. Infectious diarr
Acute Diarrhia:
5 high risk groups
 5. Institutionalized persons.
 Infectious diarrhea is one of the most frequent
categories of nosocomial infections in many hospita1s
and long-term care facilities; the causes are a
variety of microorganisms but most common1y
C. difficile.
 C. difficile can affect those with no history of
antibiotic use and may be acquired in the community.
Other Causes
 Side effects from medications:
 the most common noninfectious causes of acute
diarrhea
 Antibiotics
 cardiac antidysrhythmics
 Antihypertensives
 nonsteroidal anti-inflammatory drugs (NSAIDs)
 certain antidepressants
 chemotherapeutic agents，
Other Causes
 Side effects from medications:
 Bronchodilators
 Antacids
 laxatives.
Other Causes
 Occlusive or nonocclusive ischemic colitis typically
occurs in persons >50 years; often presents as acute
lower abdominal pain preceding watery， then bloody
diarrhea; and generally results in acute inf1ammatory
changes in the sigmoid or left colon while sparing the
rectum.
Other Causes
 colonic diverticulitis
 graft-versus-host disease.
 toxins including organophosphate insecticides;
amanita and other mushrooms; arsenic
 preformed environmental toxins in seafood，such as
ciguatera and scombroid.
 Acute anaphylaxis to food ingestion can have a similar
presentation.
 Conditions causing chronic diarrhea can also be
confused with acute diarrhea early in their course.
Other Causes
 This confusion may occur with inflammatory bowel
disease (IBD) andsome of the other inflammatory
chronic diarrheas that may have an abrupt rather
than insidious onset and exhibit features that mimic
infection.
APPROACH TO THE PATIENT
 The decision to evaluate acute diarrhea depends on
its severity and duration and on various host factors.
 Most episodes of acute diarrhea are mild and selflimited and do not justify the cost and potential
morbidity rate of diagnostic or pharmacologic
interventions.
APPROACH TO THE PATIENT
 Indications for evaluation
 profuse diarrheawith dehydration
 grossly bloody stools
 fever 38
 duration > 4 8 h without improvement
 recent antibiotiι use
 new community outbreaks
 associated severe abdominal pain in patients >50
years
 elderly (70 years)
 immunocompromised
APPROACH TO THE PATIENT
 Indications for evaluation In some cases of
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moderately severe febrile diarrhea
associated with feιal leukocytes (or inιreased feιal
levels of the
leukocyte proteins， such as calprotectin) or with
gross blood， a
diagnostic evaluation might be avoided in favor of an
empirical
antibiotic trial (see below) .
The cornerstone of diagnosis.
Chronic Diarrhia
 Diarrhea lasting >4 weeks warrants evaluation to
exclude serious underlying pathology.
 In contrast to acute diarrhea， most of the causes of
chronic diarrhea are noninfectious.
 The classification of chronic diarrhea by
pathophysiologic mechanism facilitates a rational
approach to management， although many diseases
cause diarrhea by more than one mechanism.
Chronic Diarrhia
 Diarrhea lasting >4 weeks warrants evaluation to
exclude serious underlying pathology.
 In contrast to acute diarrhea， most of the causes of
chronic diarrhea are noninfectious.
 The classification of chronic diarrhea by
pathophysiologic mechanism facilitates a rational
approach to management， although many diseases
cause diarrhea by more than one mechanism.
Chronic Diarrhia
Chronic Diarrhia
Chronic Diarrhia
Chronic Diarrhia
Chronic Diarrhia
Chronic Diarrhia
Chronic Diarrhia