CHOLERA

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CHOLERA

• Presenter Dr. J.J. Kambona

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Case definition

• Cholera outbreak should be suspected when a
  patient older than 5 years develops severe
  dehydration or die from acute, severe, watery
  diarrhoea. Or
• If there is a sudden increase in the daily number
  of patients with acute watery diarrhoea,
  especially patients who pass rice-water stools
  typical of cholera.

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Systemic routine

1. Verification of the cholera.
2. Confirmation of the existence of the cholera
   epidemic.
3. Identification of the affected persons and their
   characteristics.
4. Definition and investigation of the population at
   risk.
5. Formulation of a hypothesis as to source and
   spread of epidemic.
6. Management of the epidemic.
7. Prevention of spread and commencement of control
   measures.
8. Writing a report.
9. Continued surveillance of the population.

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Verification of the cholera

• Once the epidemic is notified
• Take the a detailed history from the informants.
• Make a tentative differential diagnoses
• Type of diagnostic specimen.
• Kind of equipments.
• Alert the laboratory which will process the
  specimens.

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Verification of the cholera.....

• Special arrangement
• Stakeholders meeting.
• Transport from the epidemic area at awkward hours
  of the day or night.

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Confirmation of the existence of cholera epidemic

• Obtain an approximate estimate of previous
  incidence of acute watery diarrhoea, both from
  clinics and hospital data and by questioning the
  local people.
• Demonstrate the existence of the epidemic by a
  graph of incidence against time and by mapping
  its geographic extent.

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Identification of the affected persons and their
characteristics

• Case histories
• Details of each confirmed or suspected case
  must be taken in order to obtain a complete
  picture of the epidemic.
• Name.
• Age.
• Sex.
• Occupation.
• Place of residence.
• Recent movements.
• Details of symptoms (including time of onset).

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Identification of the affected persons and their
characteristics.....

• The details of what they have been eating or
  drinking , when and its source.
• Contact with a person with similar symptoms.
• Record all information on specially prepared
  forms.
• If large numbers of cases (gt 1,000) are
  involved the data will require coding and
  analysis by computer.

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Identification of the affected persons and their
characteristics.....

• Search for addition cases.
• The initial notification may come from the
  hospital, but visit
• Dispensaries.
• Health centers.
• Further inquiry in the villages.

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Definition and investigations of the population
at risk

• Definition
• Analyse case histories to get a profile of
  patients characteristics.
• Epidemiological description
• Relate the profile to the characteristics
  and distribution of the entire population at
  risk.
• Attack rates Number of cases
• population at risk
• If possible age/sex-specific attack rates should
  be calculated.

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Definition.....

• Point source epidemic
• Compare the characteristics of the cholera
  cases with those of people seemingly exposed to
  cholera source but not affected.

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Investigations

• Microscopic stool examination
• Direct Vibrio cholerae are gram-negative and
  curved (coma shaped) or straight bacillus.
• Dark-field of the wet mount of fresh stool
• The organisms are mobile by means of a
  single flagellum. It can be confirmed by adding
  vibrio antisera, which results into cessation of
  motility of only the homologous organism.

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Vibrio cholerae
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Investigations..

• Stool analysis
• Vibrio cholerae do not elicit an
  inflammatory response and therefore, stool
  contains few leucocytes and no erythrocytes.
• Haematological tests
• Full blood picture Shows neutrophil leucocytosis
  without a left shift when patients are first
  observed.

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Stool culture and sensitivity

• Routine differential media
• Triple sugar iron agar
• Gives the non-pathogenic pattern of an
  acid (yellow) slant, because of fermentation of
  sucrose contained in the media.
• Alkaline enrichment media
• Peptone water (pH 8.5-9.0).
• Media containing bile salts e.g.
  thiosulphatecitrate bile-sucrose agar (pH 8.6).
  Sucrose fermenting vibrio cholerae grow as large,
  smooth, round yellow colonies that stand out
  against the blue-green agar.

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Formulation of a hypothesis as to source and
spread cholera

• Aims at knowing why, when and how the cholera
  occurred.
• Establish changed relevant previous conditions
  related the outbreak of cholera
• Rains.
• Water supply.
• Sewage disposal.
• Refuse collection.
• Behavioural change.

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Formulation of a hypothesis as to source and
spread cholera.....

• Establish the
• Reservoir of vibrio cholerae.
• Mode of exit from this reservoir or Source.
• Mode of transmission to the next host.
• The mode of entry.
• The susceptibility of the host.

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Treatment

• Look and establish cholera emergency treatment
  centre.
• Look for additional staff and trained them very
  rapidly. Health auxiliaries medical students or
  even the army may be available for this.
• Estimate the amount of drugs and other medical
  supplies and order them urgently.

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Treatment

• Treatment of cholera should start before the
  diagnosis is confirmed.
• Assess the dehydration and classify the degree of
  dehydration.
• Rehydrate the patient and monitor frequently.
  Then, reassess hydration status.
• Maintain hydration by replacing the ongoing fluid
  losses until diarrhoea stops.
• Administer oral antibiotics to the patient with
  severe dehydration.
• Feed the patient.

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Finding Mild (3-5) Moderate (6-9) Severe (10)
Pulse. Rate, volume is normal. Rapid. Rapid and weak.
Systolic pressure. Normal. Normal to low. Low.
Respirations. Normal. Deep, rate may be increased. Deep, tachypnoeia.
Buccal mucosa. Tacky or slightly dry. Dry. Parched.
Anterior fontanelle. Normal. Sunken. Markedly sunken.
Eyes. Normal. Sunken. Markedly sunken.
Skin turgor. Normal. Reduced. Tenting.
Skin. Normal. Cool. Cool, mottled, acrocyanosis.
Urine output. Normal or mildly reduced. Markedly reduced. Anuria.
Systemic signs. Increased thirst. Listlessness, irritability. Grunting, lethargy, coma.
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Cholera cot
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Severe dehydration

• Ringer lactate is the fluid of first choice or if
  not available, give isotonic sodium chloride
  solution.
• Amount of IV fluid 100 ml/kg in 3 hours
• 30 ml/kg as rapidly as possible (within 30
  minutes).
• 70 ml/kg in the next 2 hours.
• Re-assess the patient after 3 hours.

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Moderate dehydration

• Give 75 ml/kg of ORS solution for the first 4
  hours.
• If the patient passes watery stools or wants more
  ORS solution than indicated, give more.
• Discard the leftover solution after 24 hours.
• Re-assess the patient after 4 hours.

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Mild dehydration

• Give ORS packets to take at home, enough for 2
  days (2000 ml/day).
• Demonstrate to the patient or caretaker how to
  prepare and give the solution.
• If diarrhoea stops, discharged patient should
  return for follow-up in 2 days.
• Most patients absorb ORS solution to achieve
  hydration, even when they are vomiting.

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Mild dehydration..

• Instruct the patient or the caretaker to return
  if any of the following signs develop
• Increased number of watery stool.
• Marked thirst.
• Repeated vomiting.
• Any signs indicating other problems e.g. fever or
  blood in stool.

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Oral antibiotics

• Azithromycin 1 g PO stat. Or
• Tetracycline 2 g PO stat. Or
• Doxycycline 300 mg PO stat. Or
• Ciprofloxacin 250 mg PO OD for 3 days or 1 g stat
  (not to exceed 1 g/dose).

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Oral antibiotics..

• Norfloxacin 400 mg PO bid for 3 days. Do not to
  exceed 800 mg/day. Or
• Erythromycin 40 mg/kg PO divided TID for 3 days.
  Or
• Co-trimoxazole 960 mg PO BID for 3 days.

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Prevention

1. Early identification and case management.
2. Active surveillance and prompt reporting.
3. Water supply Ensure a safe water supply
   (especially for municipal water system).
4. Improve sanitation and sewage disposal.
5. Making food safe for consumption by thorough
   cooking of high risk foods especially seafood and
   protecting it against flies.

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Prevention..

• Health education through mass media Insisting
  on
• Importance of purifying water and cooking
  seafood.
• Washing hands after using the toilet and before
  food preparation.
• Recognition of the signs of cholera and location
  where treatment can be obtained to avoid delays
  in cases of illness.
• Cholera vaccine.

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Report writing and continued surveillance

• Categories of reports
• A popular account for laypeople.
• An account for planners in the ministry of health
  or local authority.
• A scientific report for publication in a medical
  journal.
• Continue surveillance of the population.

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Thank you for your attention
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References

1. Thaker V.V. Cholera. www.emedicine.com/ped/topic38
   2.htm Last updated May 1, 2006.
2. Todd W.T.A., Lookwood D.N.J., Nye F.J., Wilkins
   E.G.L and Carey P.B. infection and immune failure
   (cholera) Davidsons principles and practice of
   medicine, 19th edition, chapter 1, page 44.
3. Sack D.A., Sack R.B., Nair G.B and Siddique A.K.
   Cholera The Lancet, January, 17, 2004. 363
   (9404) 223-233.
4. Butterton J.R. Approach to the patient with
   vibrio cholerae infection. www.UpToDate.com
   Version 13.1 Last updated January 27, 2004.
5. Barker D.J.P and Hall A.J. Investigation of
   epidemics Practical epidemiology.4th edition