communicable disease

1. CHOLERA

2. BACKGROUND
Cholera, is a Greek word, which means the gutter of
the roof. It is caused by bacteria: Vibrio cholerae,
which was discovered in 1883 by Robert Koch.
Cholera is a acute infectious disease of the intestinal
tract characterized by sudden onset of severe
diarrhoea and vomiting leading to rapid dehydration
often resulting death of the patient.
Cholera is both epidemic and endemic disease.

3. Cholera is caused by Vibrio cholerae.
The organism is a comma-shaped, gram-negative,
aerobic bacillus whose size varies from 1-3 mm in
length by 0.5-0.8 mm in diameter.
CAUSATIVE ORGANISM
Its antigenic structure consists of a
flagellar H antigen and a somatic O
antigen. It is the differentiation of the
latter that allows for separation into
pathogenic and nonpathogenic
strains.

4. Cholera is transmitted through ingestion of water
contaminated with the cholera bacterium, usually
from faeces or other effluent.
The source of the contamination is typically other
cholera patients when their untreated diarrhoea discharge
is allowed to get into waterways or into groundwater or
drinking water supplies.
Cholera is rarely spread directly from person to person.
Flies act as mechanical carriers.
MODE OF SPREAD

5. MODE OF SPREAD

6. MODE OF SPREAD

7. INCUBATION PERIOD
 Incubation period is very short from few hours
to 5 days. (usually 1-2 days).

8. AT RISK GROUPS
All ages but children & elderly are more
severely affected.
Subjects with blood group “O” are more
susceptible; the cause is unknown.
Subjects with reduced gastric acid.

9. SIGNS AND SYMPTEMS
The primary symptoms of cholera are profuse
diarrhoea (rice water stools), severe dehydration,
abdominal pain and fever.
Cholera may also cause vomiting.
These symptoms start suddenly, usually one to five
days after infection.

10. LAB DIAGNOSIS
Organism can be seen in stool by direct microscopy
after gram stain and dark field illumination is used to
demonstrates motility.
Cholera can be cultured on special alkaline media
like triple sugar agar or TCBS (Thiosulphate-
citrate-bile salt-sucrose) agar
Serologic tests are available to define strains, but
this is needed only during epidemics to trace the
source of infection.

12. Oral rehydration therapy with sodium chloride
and glucose is done to stimulate water uptake by the
intestine.
The antibiotics of choice are tetracycline,
trimethoprim- sulfa methoxazole or ciprofloxacin
for 3 to 5 days.
TREATMENT
The severity of the diarrhoea and vomiting can lead
to rapid dehydration and electrolyte imbalance

13. O.R.S.
TheWorld Health Organization
recommendsa solution containing:
# 3.5 g sodiumchloride
# 2.9 g trisodiumcitrate/sodium
bicarbonate
#1.5 g potassiumchloride
#20 g glucoseor 40 g sucrose
•
Per literof water
•
Min. of 1.5 x thestool volumelosses
shouldbeadministered
•
Commerciallysold over-the-counteras
rehydrate.

14. ORS

15. PREVENTION
Education on hygiene practices.
Provision of safe, uncontaminated, drinking water
to the people.
Antibiotic prophylaxis to house-hold contacts of
index cases.
Vaccination against cholera to travellers to endemic
countries & during public gatherings.

16. CHOLERA VACCINES
The old killed injectable vaccine is obsolete now
because it is not effective.
Two new oral vaccines became available in 1997. A
Killed & a live attenuated types.
Both provoke a local immune response in the
gut & a blood immune response.
Cholera vaccination is no more required for
international travellers because risk is small.