2. Introduction
• An acute diarrheal illness caused by infection of the intestine by
bacteria Vibrio cholerae.
• Has become an increasing public health concern around the world.
• Endemic in many countries in Africa and Asia
3. Introduction
• World wide estimates from the WHO 2020
- 1.3 to 4.0 million new cases of cholera each year
- 21,000 to 143,000 deaths each year
• Infects both male and females equally
• More severe in children and the elderly
5. History
• Cholera is an ancient disease.
• Records from Hippocrates (460-377 BCE) describe an illness that
might have been cholera
• Since 1817, 7 cholera pandemics have occurred.
• The first 6 occurred from 1817-1923.
• The seventh pandemic of cholera, and the first in the 20th century,
began in 1961; by 1991, it had affected 5 continents.
6.
7. Microbiology
• Comma-shaped
• Gram negative aerobic or facultative anaerobic bacillus
• Varies in size from 1-3 µm in length by 0.5-0.8 µm in diameter
• Single polar flagellum- erratic movement on microscopy
• Its antigenic structure consists of
- Flagella H antigen
- Somatic O antigen
• The differentiation of the latter allows for separation into pathogenic
(01) and nonpathogenic (non-01) strains.
8. Microbiology
• More than 200 serotypes have been identified based on the O antigen.
• Only O1 and O139 are responsible for epidemic cholera in humans.
• Other serotypes generally grouped as “non O strains” are associated with sporadic cases.
• O1 is divided into two biotypes, classical and El Tor, on number biochemical characteristics and
susceptibility to specific phages.
• Both biotypes are further divided into Inaba, Ogawa, and Hikojima based on subspecificity of the
O1 antigen
- Inaba (antigen A and C), Ogawa (antigen A and B) and Hikojima (antigen A, B and C)
Classic biotype - causes equal number of symptomatic vs asymptomatic
El Tor biotype - causes more asymptomatic infection
• Main virulence genes are ctxA , ctxB and tcpA
9. Pathogenesis/pathophysiology
• Pathogenic only to humans
• Humans and water are the only known reservoirs
• Mode of transmission
- contaminated water
- contaminated food
- direct contact ???
• To reach the small intestine, the organisms has to overcome the defense mechanisms of
the GIT (acidic media in the stomach)
• Infectious dose varies with the vehicle
-103 to 109 when water is the vehicle
-102 to 104 when food is the vehicle
• The organism does not invade the intestinal wall or reach the blood stream
11. Pathophysiology
• This high osmolality is balanced by water secretion, the result is
watery diarrhea.
• The colon usually is relatively insensitive to the toxin, but its
absorption capacity is overwhelm by the volume of fluid.
12. Risk factors
• Environmental factors
- certain human habits favoring water and soil pollution
- low standard of personnel hygiene
- lack of education and poor quality of life
- climatic change
• Host factors
- Raw or undercooked food i.e shellfish
- Blood group O patients
- Decreased gastric acidity
1) Use of antiacids
2) Histamine receptor blockers
3) Gastrectomy
4) Chronic gastritis induced by helicobacter pylori
13. Clinical findings
• Incubation period:
1 to 2 days on average, can be anywhere between 12hours to 5days
Variable depending on host factors
• Diarrhea
Watery, non-bloody (enterotoxin)
Bile and faecal matter can be seen in the early phase of infection
The diarrhea has fishy odor in the beginning, but became less smelly & like “rice
water” in few hours
In severe cases stool volume exceeds 250 ml /kg leading to severe dehydration,
shock & death if untreated
Diarrhea lasts for 4-6 days
• Vomiting
14. Clinical findings
• Cholera gravis- severe cholera
Very watery “rice water stool”
Up to 6liters of stool per hour in adult-rapid dehydration and shock
Rapidly lose more than 10%of body weight
Death within 12hours or less
107 vibriors per ml of stool
15. Clinical findings
• Cholera sicca
Rare atypical presentation that causes ileus with fluid swelling in the
intestines without diarrhea
Increased fatality, with death resulting from toxemia before the onset
of diarrhea
16. Clinical findings
• Signs and symptoms of dehydration
- dry mucous membranes
- decreased skin turgor
- sunken eyes
- dry axilla, no tears
• Washer woman's hand sign
• Lethargy
• Hypotension
• Fatigue
• Muscle cramps
17. Complications
• Pneumonia secondary to aspiration
• Renal failure
• Hyperglycemia
• Hypoglycemia mostly in children
• Seizures
• Mental alteration
18. Diagnosis
• Clinical diagnosis
- Cholera should be considered in all cases with severe watery
diarrhea and vomiting
- Travelling to affected areas or eating raw shellfish
- No distinguishing clinical manifestation
• Rapid diagnosis using Immuno-chromatographic dipstick test on fresh
stool specimen.
19. Diagnosis
• Organism can be seen in stool by direct microscopy after gram stain &
dark field exam is used to demonstrates motility
20. Diagnosis
• Cholera can be cultured on special alkaline media like triple sugar agar
or thiosulphate-citrate-bile salt-sucrose (TCBS) agar plate.
21. Diagnosis
• Serologic tests are available to define strains, but this is needed only
during epidemics to trace the source of infection.
• PCR
• Real-time nucleic acid sequence based amplification assays
22. Other laboratory findings
• Elevated blood urea and serum creatinine
• Increased haematocrit and WBC
• Metabolic acidosis with wide anion gap due to dehydration and
bicarbonate loss
• Total body K+ may be depleted but serum level may be normal due to
the effect of acidosis
24. Treatment-Rehydration
• Rehydration phase:
- restore normal hydration status
- should take not more than 4hours
- ringers lactate preferred over normal saline
- rate of 50-100mls/kg/hr
26. Treatment- Antibiotics
• Antibiotic treatment:
- prompt eradication of the vibrio
- diminished the duration of the diarrhea
- decreased fluid loss
• Antibiotics should be administered to moderate and severe cases
• Recommended antibiotic
- Ciprofloxacin 1g as a single dose
- Tetracycline 500mg qid for 3days
- Doxycycline 300mg single dose
- Co-trimoxazole 1tab bd for 3 days
- Azithromycin 1g as a single dose
- Furazolidone
31. Vaccination
• Dukoral
- oral inactivated whole cell of 4 strains plus recombinant B subunit
- 2 doses needed
- not licenced for children < 2years
• Sanchol
- bivalent cholera vaccine
- booster dose recommended after 2 years
• Vaxchora
- indicated for active immunization against V. cholerae serogroup 01
- approved for adult 18-64years of age
32. Chemoprophylaxis
• Advised only for close household contacts or a closed community in
which cholera has occurred
• Tetracycline is the drug of choice
33. Steps for epidemic control
• Verification of the diagnosis
• Notification of cases to MOH and WHO
• Early case finding and tracing source of infection
• Establishment of treatment centers
• Isolation and barrier nursing
