infectious diseases

1. Cholera

2. Cholera-Introduction
MIASMA
THEORIES versus

3. • Are gram-negative rods that are facultativel
word cholera is a derivative of the Greek word “choler” meaning bile
•
• First discovered by Filippo Pacini in Italy in 1854, Pacini’s results
were published under the title, “Microscopic observation and
pathological deductions on cholera
Robert Koch independently discovered a bacillus, the same that Pacini
discovered 30 years back

6. Epidemiology
• Cholera likely has its origins in the Indian Subcontinent;
it has been prevalent in the Ganges delta since ancient
times
• The disease first spread by trade routes (land and sea)
to Russia in 1817, then to the rest of Europe, and from
Europe to North America
• Seven cholera pandemics have occurred in the past
200 years, with the seventh originating in Indonesia in
1961
6

7. Continued
• The first cholera pandemic occurred in the Bengal
region of India starting in 1817 through 1824.
• The disease dispersed from India to Southeast Asia,
China, Japan, the Middle East, and southern Russia.
• The second pandemic lasted from 1827 to 1835 and
affected the United States and Europe.
• It killed 150,000 Americans during the second
pandemic.
• The third pandemic erupted in 1839, persisted until
1856, extended to North Africa, and reached South
America, for the first time specifically infringing upon
Brazil.
7

8. Continued
• In Russia alone, between 1847 and 1851, more than one
million people perished of the disease
• Cholera hit the sub-saharan african region during the
fourth pandemic from 1863 to 1875
• The fifth pandemic raged from 1881–1896 Sixth
pandemics raged from 1899-1923
• Between 1900 and 1920, perhaps 8 million people died
of cholera in india
• These epidemics were less fatal due to a greater
understanding of the cholera bacteria
8

12. Where are modern-day
• HAITI
What Is the Current Situation?
An outbreak of cholera has been ongoing in epidemics of cholera?
Haiti since October 2010. According to the
Ministere de la Sante Publique et de la Population
(MSPP), as of August 4, 2013, 669,396 cases and
8,217 deaths have been reported since the cholera
epidemic began in Haiti. Among the cases
reported, 371,099 (55.4%) were hospitalized1

13. cholera
Cholera is an acute diarrhoel diseases caused
by V.cholerae 01
Cholera is both an epidemic and endemic
disease
The force of infection in an epidemic is
composed of 2 components namely the force
of infection through water and the force of
infection through contacts

14. Agent factors
Vibrio cholerae 0 Group 1/ epidemic strains
Non-0 group 1 V.cholerae/ non epidemic
strains
Within 0 group 1 two biotypes are classical
and El Tor
Classical and El Tor are further divided into 3
serological types namely Inaba,Ogawa and
Hikojima

15. Agent
Resistance
Killed within 30 min by heating at 56 C or
within few seconds by boiling
They are destroyed by cresol, bleaching powder
Toxin production
The vibrios multiply in the small intestine and
produce exotoxin(enterotoxin)

16. Reservior of infection
Human is the only reservoir of cholera infection
in the form of case or carrier
Infective material
Stools and vomit of cases and carriers
Infective dose
Cholera is dose related 1011 organisms required
to produce clinical disease
Period of communicability
7-10days

17. Carriers in cholera
Four types
1)Preclinical or incubatory carriers:
2)Convalescent carriers:
patients excrete vibrios for 2-3 wks who have
not received effective antibiotic treatment
3)Contact or healthy carrier-result of subclinical
infection. gall bladder is not infected and stool
culture is +ve .
4)Chronic carrier-gall bladder is infected
.antibody titre against vibrio rises

18. Host
Age and sex
All ages and both sexes
Gastric acidity
Destroyed in pH of 5 or lower
Population mobility
Risk increases
Economic status
Highest in lower S-E groups
Immunity
Mainly local intestinal immune system.
vaccination gives only temporary immunity

19. Environmental factors
Poor environmental sanitation
Contaminated water and food
Mode of transmission
Via man to man
a) Faecally contaminated water
b) Contaminated food and drinks
c) Direct contact
Incubation period
Few hrs to 5 hrs

20. Clinical features
Three stages
a) Stage of evacuation-rice water appearance
b) Stage of collapse-
c) Stage of recovery
The classical form of cholera appears in 5-10%
of cases and in the rest the disease tends to be
mild

21. Laboratory diagnosis of cholera
a) Collection of stools
b) Vomitus
c) Water
d) Food samples
e) Transportation
f) Direct examination-dark field illumination
g) Culture methods-peptone water tellurite
h) bio-chemical test

22. Control of cholera
1)Verification of diagnosis
It is important to identify V.ch in the stools of
the patient
2)Notification
Cholera is a notifiable disease locally,
nationally and internationally
3)Early case finding
Search for cases

23. 4)Establishment of treatment centers
Mild cases –ort
Severe- i.v fluids
5)Rehydration therapy
6)Adjuncts to therapy
Antibiotics should be given as soon as vomiting
has stopped
Doxycycline is DOC in adults
TMP-SMX is DOC in children
Furazolidine is DOC in pregnant women

24. 7)Epidemiological investigation
8)Sanitation measures
a)Water control
b)Excreta disposal
c)Food sanitation
d)Disinfection
9)Chemoprophylaxis
Tetracycline is DOC

25. 10)Vaccination
a)Parenteral vaccine
b)Oral vaccine-2 types
i)Killed whole cell V.cholerae 01
ii)Live attenuated classical V.cholerae strain
11)Health education

27. WHO Global Task Force on
Cholera
• Launched in 1992, 44th world health
assembly
• Aim -reduce mortality and morbidity
associated with the disease and to address the
social and economic consequences of cholera
• Partnership brings together governmental and non-
governmental organizations, UN agencies, and
scientific institutions
• Develop technical guidelines and training
materials for cholera control

28. Current priority activities of WHOGlobal
Task Force on Cholera
• Encouraging improved surveillance , to identify high risk
areas and guide intervention
Providing evidence based support to countries for
preparedness and response
Gaining evidence on the use of oral cholera vaccines as an
additional public health tool to diminish incidence of cholera
in high risk areas and vulnerable groups
Linking health and management of the environment in order
to improve access to safe water for vulnerable populations
and diminish incidence of waterborne diseases

29. Prevention and control of cholera outbreaks:
WHO policy and recommendations
Main tools for cholera control
• Proper and timely case management in cholera treatment centres
• Specific training for proper case management, including avoidance
of nosocomial infections
• Sufficient pre-positioned medical supplies for case management
(e.g. Diarrhoeal disease kits)
• Improved access to water, effective sanitation, proper waste
management and vector control
• Enhanced hygiene and food safety practices Improved
communication and public information

30. Cholera vaccines
•WHO recommends that immunization with currently
available cholera vaccines be used in conjunction with the
usually recommended control measures in
-Areas where cholera is endemic
-Areas at risk of outbreaks
•Vaccines provide a short term effect while longer term
activities like improving water and sanitation are put in
place

31. Cholera vaccines
• Parenteral cholera vaccine not recommended by WHO (low
protective efficacy and adverse reaction)
•Two types of safe and effective oral cholera vaccines
currently available
➢Both are whole-cell killed vaccines
➢Both have sustained protection of over 50% lasting for two years in
endemic settings.
➢Both vaccines are WHO-prequalified and licensed over 60
countries.
➢Both vaccines are administered in two doses given between seven
days and six weeks apart
➢Recently, however, researchers have suggested that oral cholera
vaccines induce “herd immunity”1
1.Ali M, Emch M, von Seidlein L, Yunus M, Sack DA, Rao M, Holmgren J, Clemens JD.Herd immunity conferred by killed oral cholera
vaccines in Bangladesh: areanalysis.Lancet. 2005 Jul 2-8;366(9479):44-9

32. Dukoral
• Vaccine with the b-subunit
• Given in 150 ml of safe water
• Short-term protection of 85–90% against V. Cholerae
O1 among all age groups at 4–6 months following
immunization
Shanchol
• Provides longer-term protection against V. Cholerae
O1 and O139 in children under five years of age

33. International Health Regulations
• 194 countries across the globe, including all the
Member States of WHO
• Aim- the international community prevent and
respond to acute public health risks that have the
potential to cross borders and threaten people
worldwide
• Surveillance for prevention, preparedness and early
warning
• Imposing travel and trade restrictions have proven
inefficient and risk to divert useful resources.
• WHO has no information -imported food from
affected countries has ever been implicated in
outbreaks of cholera in importing countries

34. WHO recommendations to unaffected
neighbouring countries
• Improve preparedness to rapidly respond to an
outbreak, should cholera spread accross
borders, and limit its consequences
• Improve surveillance to obtain better data for risk
assessment and early detection of outbreaks,
including establishing an active surveillance system

35. Measures should be avoided,
(ineffective, costly and
counter-productive)
• Routine treatment of a community with antibiotics,
or mass chemoprophylaxis (no effect on the spread
of cholera, can increase antimicrobial resistance and
provides a false sense of security)
• Restrictions in travel and trade between countries or
between different regions of a country (hampers
good cooperation spirit between institutions and
countries instead of uniting efforts)

36. Key messages
• Cholera is an acute diarrhoeal disease that can kill within hours if
left untreated
• There are 100 000–120 000 deaths due to cholera every year of
which only a small proportion are reported to WHO
• Up to 80% of cases can be successfully treated with oral
rehydration salts (ORS)
• About 75% of people infected with Vibrio cholerae O1 or O139 do
not develop any symptoms
• Typical at-risk areas of cholera include peri-urban slums with
limited access to safe drinking water and lack of proper sanitation

37. Key messages
• Surveillance is paramount to identify vulnerable populations living
in hotspots
• Cholera is a preventable disease provided that safe water and
proper sanitation are made available
• Cholera is a preventable disease provided that safe water and
proper sanitation are made available
• Safe and effective oral cholera vaccines are now part of the cholera
control package
• Today, no country requires proof of cholera vaccination as a
condition for entry