Cholera: Epidemiological Model
DJOKI Bahati, MBChB
Background
Cholera is an acute diarrheal infection caused by ingestion of food or
water contaminated with the bacterium Vibrio cholerae
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2.86 million cases per year (estimation)
95000 deaths worldwide per year
Incidence of 0.3/10000 in endemic settings (African sentinel network)
99% of cases in Africa and southern Asia
overall case fatality rate < 1%
case fatality in vulnerable settings up to 5%
half of cases in children ≤ 5 years old
EPIDEMIOLOGICAL MODEL OF CHOLERA
Incidence
0.3/10000 – endemic area
<20/10000 - epidemics
Not-infected/
Susceptible
Cholera
infection
Infectious,
asymptomatic
< 24H - 5 days
Mild/
Moderate disease
Recovered
Infectious,
symptomatic
Reservoir: human/ aquatic
Severe
disease
Death
CFR = 50 - 70%
Source of values:
Risk Factors
1. Risk factors increasing the likelihood of infection and a wide-spread transmission
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Environmental factors: increased sunlight and temperature
Dry season
Rainy season: disperse contaminated faeces
Poor and overcrowded living conditions : favoring wide-spread transmission
A decrease in gastric acidity
2. Risk factors increasing the risk of unfavorable outcome
• Pathogen specific factor
• Host specific factors
• O blood group
• Great inoculum
• Lack or depressed immunity
EPIDEMIOLOGICAL MODEL OF CHOLERA
Incidence
0.3/10000 – endemic area
<20/10000 - epidemics
Cholera
infection
Not-infected/
Susceptible
Infectious,
asymptomatic
< 24H - 5 days
Mild/
Moderate disease
Recovered
decrease in gastric acidity
Poor and
overcrowded living
conditions
Reservoir: human/ aquatic
Pathogen specific factor
Host specific factors
- O blood group
- Great inoculum
- Lack or depressed
immunity
Infectious,
symptomatic
Severe
disease
Death
CFR = 50 - 70%
Environmental factors
Source of values: