Epidemiology and Management
of Diarrheal Diseases
Amal Mitra, MD, MPH, DrPH
Professor
University of Southern Mississippi
Readings: Diarrhoeal Diseases
DEFINITION
• Watery Diarrhea: 3 or more liquid or watery
stools in 24 h
• Dysentery: Presence of blood and/or mucus
in stools
• Persistent Diarrhea: Diarrhea lasting for 14
days or more
TYPES OF DIARRHEA
Diarrhea
Watery diarrhea
Dysentery
Persistent diarrhea
Rota virus diarrhea
E. coli diarrhea
Cholera
Shigellosis
Amebiasis
Causes are mostly unknown
COMMON CAUSES OF
DIARRHEA- BACTERIA
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Vibrio cholera
Shigella
Escherichia coli
Salmonella
Campylobacter jejuni
Yersinia enterocolitica
Staphylococcus
Vibrio parahemolyticus
Clostridium difficile
COMMON CAUSES OF
DIARRHEA- VIRUS
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Rotavirus
Adenoviruses
Caliciviruses
Astroviruses
Norwalk agents and Norwalk-like viruses
COMMON CAUSES OF
DIARRHEA- PARASITE
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Entameba histolytica
Giardia lamblia
Cryptosporidium
Isospora
COMMON CAUSES OF
DIARRHEA-OTHERS
• Metabolic disease
Hyperthyroidism
Diabetes mellitus
Pancreatic insufficiency
• Food allergy
Lactose intolerance
• Antibiotics
• Irritable bowel syndrome
TRANSMISSION
• Most of the diarrheal agents are transmitted
by the fecal-oral route
• Some viruses (such as rotavirus) can be
transmitted through air
• Nosocommial transmission is possible
• Shigella (the bacteria causing dysentery) is
mainly transmitted person-to-person
SEASONALITY
Disease
Common season
Cholera
Winter
Rotavirus diarrhea Winter
Shigellosis
Dry summer
PERSON-AT-RISK
• Cholera: 2 years and above, uncommon in
very young infants
• Shigellosis: more common in young
children aged below 5 years
• Rotavirus diarrhea: more common in young
infants and children aged 1-2 years
• E. coli diarrhea: can occur at any age
• Amebiasis: more common among adults
TYPES OF VIBRIO CHOLERA
• Two major biotypes of Vibrio cholera that
cause diarrhea are:
Classical
ElTor
• Two common serotypes of Vibrio cholera
that cause diarrhea are:
Inaba
Ogawa
Vibrio cholerae O139
• Vibrio cholerae in O-group 139 was first isolated
in 1992 and by 1993 had been found throughout
the Indian subcontinent. This epidemic expansion
probably resulted from a single source after a
lateral gene transfer (LGT) event that changed the
serotype of an epidemic V. cholerae O1 El Tor
strain to O139.
• More information:
http://www.cdc.gov/ncidod/EID/vol9no7/020760.htm
Vibrio vulnificus
• The organism Vibrio vulnificus causes wound infections, gastroenteritis
or a serious syndrome known as "primary septicema."
• V. vulnificus infections are either transmitted to humans through open
wounds in contact with seawater or through consumption of certain
improperly cooked or raw shellfish.
• This bacterium has been isolated from water, sediment, plankton and
shellfish (oysters, clams and crabs) located in the Gulf of Mexico, the
Atlantic Coast as far north as Cape Cod and the entire U.S. West
Coast.
• Cases of illness have also been associated with brackish lakes in New
Mexico and Oklahoma.
• For more information:
http://hgic.clemson.edu/factsheets/HGIC3663.htm
TYPES OF SHIGELLA
• The major serotypes of Shigella that cause
diarrhea are:
Dysenteriae type 1 or Shigella shiga
Shigella flexneri
Shigella sonnei
Shigella boydii
TYPES OF E. COLI
• Six major types of Escherichia coli cause
diarrhea:
Enterotoxigenic E. coli (ETEC)
Enteroinvasive E. coli (EIEC)
Enteropathogenic E. coli (EPEC)
Enterohemorrhagic E. coli (E. coli O157:H7)
Enteroaggregative E. coli (EAggEC)
Diffuse adherent E. coli (DAEC)
CLINICAL FEATURE:
CHOLERA
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Rice-watery stool
Marked dehydration
Projectile vomiting
No fever or abdominal pain
Muscle cramps
Hypovolemic shock
Scanty urine
CLINICAL FEATURE:
E. COLI DIARRHEA
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Watery stools
Vomiting is common
Dehydration moderate to severe
Fever– often of moderate grade
Mild abdominal pain
CLINICAL FEATURE:
ROTAVIRUS DIARRHEA
• Insidious onset
• Prodromal symptoms, including fever,
cough, and vomiting precede diarrhea
• Stools are watery or semi-liquid; the color is
greenish or yellowish– typically looks like
yoghurt mixed in water
• Mild to moderate dehydration
• Fever– moderate grade
CLINICAL FEATURE:
SHIGELLOSIS
• Frequent passage of scanty amount of
stools, mostly mixed with blood and mucus
• Moderate to high grade fever
• Severe abdominal cramps
• Tenesmus– pain around anus during
defecation
• Usually no dehydration
CLINICAL FEATURE:
AMEBIASIS
• Offensive and bulky stools containing
mostly mucus and sometimes blood
• Lower abdominal cramp
• Mild grade fever
• No dehydration
LABORATORY DIAGNOSIS
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Stool microscopy
Dark field microscopy of stool for cholera
Stool cultures
ELISA for rotavirus
Immunoassays, bioassays or DNA probe
tests to identify E. coli strains
ASSESSMENT OF
DEHYDRATION
Dehydration
Mild
Moderate Severe
Appearance irritable, irritable, lethargy,
thirsty
very
coma, or
thirsty
unconscious
Anterior
normal
depressed markedly
Fontanelle
depressed
Eyes
normal
sunken
sunken
ASSESSMENT OF
DEHYDRATION (contd.)
Tongue
Mild
normal
Skin
normal
Breathing normal
Dehydration
Moderate Severe
dry
very dry,
furred
slow
very slow
retraction retraction
rapid
very rapid
ASSESSMENT OF
DEHYDRATION (contd.)
Pulse
Mild
normal
Urine
normal
Dehydration
Moderate Severe
rapid and feeble or
low
imperceptible
volume
dark
scanty
Weight
loss
< 5%
6 - 9%
10% or more
TREATMENT
• Rehydration– replace the loss of fluid and
electrolytes
• Antibiotics– according to the type of
pathogens
• Start food as soon as possible
COMPOSITION OF ORS
Ingredient
Sodium chloride
Amount (g/liter)
3.5
Trisodium citrate or
Sodium bicarbonate
2.9 or
2.5
Potassium chloride
1.5
Glucose
20.0
AMOUNT OF SALT LOSS
DURING DIARRHEA
Diarrhea
Cholera
(child)
Salt (mmol/L)
Na K Cl HCO3
88 30 86 32
Cholera
(adult)
135 15 100 45
E. coli
Rota
virus
53
37
37 24
38 22
18
6
ANTIMICROBIAL AGENTS
Type of diarrhea
Cholera
Antimicrobial agent
Tetracycline,
Doxycycline,
Ciprofloxacine
Shigellosis
Pivmecillinam
(Selexid), Nalidixic
acid, Ciprofloxacin,
Ceftriaxone
Metronidazole
Amebiasis
COMPLICATIONS:
WATERY DIARRHEA
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Dehydration
Electrolyte imbalances
Tetany
Convulsions
Hypoglycemia
Renal failure
COMPLICATIONS:
DYSENTERY
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Electrolyte imbalances
Convulsions
Hemolytic uremic syndrome (HUS)
Leukemoid reaction
Toxic megacolon
Protein losing enteropathy
Arthritis
Perforation
VACCINES
• An oral cholera vaccine is available, which
gives immunity to 50-60% of those who
take the vaccine, and this immunity lasts
only a few months.
• No vaccines are available against shigellosis
• A vaccine against rotavirus diarrhea has
been withdrawn recently from the market.
PREVENTION
• Safe drinking water and food
“Boil it, cook it, peel it, or forget it. "
• Hand washing
• Proper sanitation