Cholera: WHO & Lancet statements.

Cholera | 11 April 20231 |

Cholera Prevention and ControlCholera Prevention and Control

WHO Iraq Epidemiologist

+ Lancet 2012


Introduction:Introduction:

Cholera is an acute, secretory diarrhoea caused by infection with Vibrio choleraeof the O1 or O139 serogroup.

It is endemic in more than 50 countries &causes large epidemics.

Since 1817, seven cholera pandemics have spread from Asia to much of the world.

The seventh pandemic began in 1961 &affects 3–5 million people each year, killing 120 000.

Although mild cholera can be indistinguishable from other diarrhoeal illnesses, the presentation of severe cholera is distinct, with pronounced diarrhoeal purging.


Introduction:Introduction:

Management of patients with cholera involves aggressive fl uid replacement; eff ective therapy can decrease mortality from more than 50% to less than 0·2%.

Antibiotic treatment decreases volume & duration of diarrhoea by 50% &recommended for patients with moderate to severe dehydration.

Prevention of cholera depends on access to safe water & sanitation.

Two oral cholera vaccines are available&the most eff ective use of these in integrated prevention programmes is being actively assessed.


History of CholeraHistory of Cholera

Cholera Epidemics in England

– 1831-1832: 22 000 deaths

– 1848-1849 : 54 000 deaths

– 1853-1854 : John Snow’s work


EPIDEMIOLOGY EPIDEMIOLOGY

Cholera continues to be an important public health problem among many communities

It is one of the oldest diseases affecting humans.

It is caused by the gram-negative bacteria Vibrio cholerae.

About 20% of those who are infected develop acute, watery diarrhoea – 10–20% of these individuals develop severe watery diarrhoea with vomiting

Can cause as high as 20 to 50% mortality if case management is not adequate.

Conversely, the death rate can be low (<1%) if well treated.


Cholera: Causal agentCholera: Causal agent

While over 100 vibrio species have been isolated, only the “cholerae” species are responsible for cholera epidemics.

Vibrio cholerae species are divided into 2 serogroups:

1. V. cholerae O1, subdivided into Classical and El Tor biotypes, (Is the causal agent for 7th pandemic)

2. V. cholerae O139 sero– group, was first identified in 1992 in India


Cholera : Causal AgentCholera : Causal Agent

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Both El Tor and Classic biotypes are divided into 3 serotypes: Ogawa, Inaba and Hikojima

The three serotypes can co-exist during an epidemic because the bacteria can mutate between serotypes


Cholera : Causal AgentCholera : Causal Agent

Species: Vibrio Cholerae

Serogroup: O139 & O1

Biotypes :EL Tor Classic

Serotypes Hikojima, Ogawa& Inaba


ReservoirReservoir

Humans are the main reservoir of Vibrio cholerae. Other potential reservoirs are water,

Vibrios grow easily in saline water and alkaline media. They survive at low temperatures but do not survive in acid media;


Carriers and transmissionCarriers and transmission

The reservoir is mainly human, asymptomatic (healthy) carriers and patients carry huge quantities of vibrio in faeces and in vomit; up to 108 bacteria can be found in 1 ml of cholera liquid.

The infective dose depends upon individual susceptibility, but in general a 108 doses is needed.

Cholera is transmitted by a faecal-oral route


TRANSMISION TRANSMISION

Cholera is transmitted by the fecal –oral route through contaminated water & food

Person to person infection is rare

The infection dose of bacteria required to cause clinical disease varies with the source

If ingested with water the infective dose should be higher;

When ingested with food fewer organism are required to cause the disease


RISK FACTORSRISK FACTORS

Poor social and economic environment, precarious living conditions associated with Insufficient water supply (quantity and quality)

Poor sanitation and hygiene practices

High population density: camps and slum populations are highly vulnerable.

Underlying diseases such as malnutrition, chronic diseases and AIDS are thought to increase susceptibility to cholera, but this has not been proven.

Environmental and seasonal factors


Period of communicabilityPeriod of communicability

Infected persons (symptomatic or not) can carry and transmit vibrios during 1-4 weeks

A small number of individuals can remain healthy carriers for several months.


PATHOGENESISPATHOGENESIS

V.cholerae cause clinical disease by producing an enterotoxin that promotes the secretion of fluid and electrolytes into the lumen of the gut


Case Definitions for CholeraCase Definitions for Cholera

Suspected

In an area where the disease is not known to be present: severe dehydration or death from acute watery diarrhoea in a patient aged 5 years or more;

In an area where there is cholera endemic: acute watery diarrhoea, with or without vomiting in a patient aged 5 years or more

Epidemic ongoing: acute watery diarrhoea with or without vomitting


Case definition for choleraCase definition for cholera

Confirmed

A suspected case that is laboratory-confirmed.( Isolation of Vibrio cholerae O1 or O139 from stools in any patient with diarrhoea is the laboratory criteria for diagnosis)


CLINICAL FEATURE CLINICAL FEATURE

Cholera is an acute enteric disease characterized by the sudden onset of profuse painless watery diarrhoea or rice-water like diarrhoea, often accompanied by vomiting;

Can rapidly lead to severe dehydration and cardiovascular collapse

Clinical features are the same whatever the strain. Regardless the strain, the response is the same


Clinical features Clinical features

No fever

Dehydration appears within 12 to 24 hours.

Asymptomatic and/or minor forms: in more than 80% of the cases, infection is asymptomatic or causes simple diarrhoea

In moderate forms there are frequent watery stools, however, fluid loss and dehydration are moderate.

In severe forms there is intense diarrhoea and vomiting with significant fluid loss

Cholera | 11 April 202321 |2


Role of laboratory test Role of laboratory test

Bacteriological confirmation is compulsory on the first suspected cases, in order to:

Confirm cholera Identify the strain, biotype and serotype Assess antibiotic sensitivity


Laboratory Test Laboratory Test

Confirmation on 10 to 20 stool samples is sufficient. Samples can be taken using different methods : filter paper, Cary Blair medium or rapid tests

Rapid tests can give a quick confirmation of a cholera diagnosis, however, rapid tests Do not provide information on antibiotic sensitivity nor can

they be used for biotyping,and therefore must always be followed by sampling.


Selection of cases for bacteriologic samplingSelection of cases for bacteriologic sampling

For confirmation of an outbreak, stool samples should be collected from up to 10-20 previously “untreated” cases who meet all of the following criteria:

– onset of illness less than four days before sampling;– currently having watery diarrhoea;– have not received antibiotic treatment for this illness;


Selection of transport mediaSelection of transport media

The most reliable, currently available transport medium is Carry-Blair. The CB transport medium should be refrigerated for one hour before collecting the stool specimen. (It can be used for 18 months or longer under proper conditions of storage, provided there is no loss of volume and no evidence of contamination or colour change)


Collection of specimensCollection of specimens

Stool should be collected either by:

Collecting a swab from a freshly passed stool specimen (fresh stool should be less than 1 hour old) or from

A swab of the rectal contents (rectal swab)


CASE MANAGEMENT CASE MANAGEMENT

The main stay of case management of correction of dehydration status


Clinical Management of CholeraClinical Management of Cholera

Aim for case fatality ratio of 1% or less

80-90% of patients can be treated with ORS

Initiate treatment promptly

intravenous therapy (Ringers/Hartmann's) only for severely dehydrated


What type of Dehydration is this ?What type of Dehydration is this ?


Severe DehydrationSevere Dehydration

Loss of at least 10% of body weight

Hypovolemic shock

Low blood pressure

Rapid, weak, or undetectable peripheral pulse

Skin has lost normal turgor (“tenting”)

Mouth is very dry

Thinking is dulled


What type of Dehydration is this ?What type of Dehydration is this ?

.


What type of dehydration is this ?What type of dehydration is this ?


Moderate DehydrationModerate Dehydration

Loss of 5-10% of body weight

Normal blood pressure

Normal or rapid pulse

Increased thirst, drinks eagerly

Mucosal membranes are dry

Restless, irritable

Skin goes back slowly after skin pinch


Step-2: Maintenance of hydration and monitoring the

hydration status Step-2: Maintenance of hydration and monitoring the

hydration status

Reassess the patient for signs of dehydration for first 6 hours

– Number and quantity of stool and vomit in order to compensate for the body fluids;

– Radial pulse: If remains weak, rehydration should be continued;

Provide frequent small meals with familiar foods during the first two days

Provide food orally as soon as the patient is able to swallow

Breastfeeding infants and children should continue


Step-3: Giving antibiotics if neededStep-3: Giving antibiotics if needed

Why give antibiotic in cholera patients ?

– Reduces the volume and duration of cholera related diarrhoea by half (50%); important adjunct to fluid treatment

Benefits of giving antibiotics– Shortens hospital stay and reduction of need for intravenous

fluid; Reduces the management cost


Which Antibiotics ?Which Antibiotics ?


ANTIBIOTICSANTIBIOTICS

Should be given only in severe cases to reduce the duration of symptoms and carriage of the pathogen

Selective chemoprophylaxis may be useful for members of a household who share food and shelter with cholera patient


Use of Ciprofloxacin : Offers short course for cholera treatment

Use of Ciprofloxacin : Offers short course for cholera treatment

Offers short course for cholera treatment– Ease of administration: Single dose– Assurance of patients compliance;– Reduction of cost of treatment;

Evidence: Single dose Ciprofloxacin (500 mg) is shown to be effective in both adults and children (Cure rate was 94% in adults and 60% in children: Resolution of diarrhoea within 48 hours of the start of treatment and no recurrence during 5 day stay in the hospital (Ref: Lancet 1996; 348: 296-300 and Lancet 2005; 366: 1085-93)


Zinc Supplementation in Cholera : What is the evidence ?

Zinc Supplementation in Cholera : What is the evidence ?

Supplementation of zinc to the children with cholera reduces both stool volume and duration of diarrhoea, an effect that was more pronounced in malnourished children (Ref: S.K. Roy, K E Islam, et al. Impact of Zinc on Children with Cholera. Presented during 10th Annual Scientific Conferences (ASCON) of

ICDDR,B, Dhaka)


WHO and UNICEF’s Recommendation for Zinc Supplementation

WHO and UNICEF’s Recommendation for Zinc Supplementation

Age groupDoseDuration

Infants under 6 months old

10 mg per day10-14 days

Children above 6 months old

20 mg per day 10-14 days

Ref: WHO/UNICEF Joint Statement on Clinical Management of Acute Diarrhoea, May 2004


Cholera Prevention Measures Other Than Rehydration

Cholera Prevention Measures Other Than Rehydration

Antibiotics are not necessary for patient recovery, but are used as a public health measure.

Vaccination (mass chemoprophylaxis) and cordon sanitaire are NOT effective in controlling epidemics.

Selective chemoprophylaxis is rarely practical.


Cholera CotCholera Cot


ComplicationsComplications

Pulmonary edema if excessive IV fluid has been given

Renal failure if too little IV fluid is given;

Hypoglycaemia

Hypokalaemia in children with malnutrition rehydrated with Ringer lactate only


IV Fluid TherapyIV Fluid Therapy

Ringer’s lactate is the preferred IV fluid

Normal 9% saline or half –normal saline with 5% glucose can also be used

ORS solution must be given at the same time to replace the missing electrolytes


Composition of Standard andReduced Osmolarity ORS

Composition of Standard andReduced Osmolarity ORS

Standard ORS(mEq or mmol/l)

Reduced Osmolarity ORS

Glucose11175

Sodium9075

Chloride8065

Potassium2020

Citrate1010

Osmolarity311245


Proper preparation of ORSProper preparation of ORS


Home based ORSHome based ORS

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CHOLERA TREATMENT CENTRE (CTC)CHOLERA TREATMENT CENTRE (CTC)

The organization of the CTC is meant to offer the best care to patients but also to protect other people from contamination

Fences around the CTC are often necessary to reduce the number of visitors


Cholera Treatment CentreCholera Treatment Centre


Infection control Infection control

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Cholera | 11 April 202365 |Infection PreventionInfection Prevention

Assume infectious agent could be present in the patient’s

– Blood – Body fluids, secretions, excretions– Non-intact skin– Mucous membranes

Hand hygiene and PPE are critical


Personal Protective Equipment (PPE) Personal Protective Equipment (PPE)

When used properly can protect you from exposure to infectious agents

Know what type of PPE is necessary for the duties you perform and use it correctly


Key Infection Control PointsKey Infection Control PointsKey Infection Control PointsKey Infection Control Points

Minimize exposures

– Plan before entering room

– Minimize number of visitors

– Separation of Cholera patients

– Flow of patients

Avoid adjusting PPE after patient contact

– Do not touch eyes, nose or mouth!

Avoid spreading infection

– Limit surfaces and items touched

Change torn gloves

– Wash hands before donning new gloves


DISINFECTION OF PATIENT’S BEDDING AND CLOTHING

DISINFECTION OF PATIENT’S BEDDING AND CLOTHING

Patient’s bedding and clothing can be disinfected by stirring them for 5 minutes in boiling water

Bedding including mattresses can also be disinfected by thorough drying in the sun

Can we all now manage a cholera patient ?

Yes?Yes!

Cholera: WHO & Lancet statements.

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