Dr. Priyamadhaba BeheraReferences WHO Document, 5th edition OTPH, 18th edition Harrison principle of medicine, Articles however applicable

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Cholera

Cholera-Introduction

MIASMA THEORIES versus

• 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

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

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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.

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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

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Where are modern-day epidemics of cholera?

• HAITI

What Is the Current Situation?An outbreak of cholera has been ongoing in 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

Cholera : Causal Agent

• Species: Vibrio Cholerae• Serogroup: O139 & O1• Biotypes :EL Tor Classic• Serotypes Hikojima, Ogawa& Inaba

Reservoir

• 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 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

Transmission • Cholera is transmitted by the fecal –oral route through contaminated

water & food• 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

Period 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.

Incubation period-6hr to 5 days

RISK 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: internally displaced or

refugee Camps and slum populations• Inhabitants of rural areas, particularly along rivers

and lake shores• Diaster had took place

Case 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 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)

The stool has a characteristic appearance: a nonbilious, gray, slightly cloudy fluid with flecks of mucus, no blood, and a somewhat fishy, inoffensive odor. -"rice-water“Clinical symptoms parallel volume contraction At losses of <5% of normal body weight, thirst develops

5–10%, postural hypotension, weakness, tachycardia, and decreased skin turgor are documented

>10%, oliguria, weak or absent pulses, sunken eyes (and, in infants, sunken fontanelles), wrinkled ("washerwoman") skin, somnolence, and coma are characteristic

Complications -include renal failure due to acute tubular necrosis. Muscle cramps are common d/o electrolyte imbalanceFever is usually absent

Symptoms and signs

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

• 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 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

illnessSelection of transport media

Most reliable, currently available transport medium is carry-blair

Collection 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)

Antibiotics

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

• 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 hospital1

(Ref: Lancet 1996; 348: 296-300 and Lancet 2005; 366: 1085-93)

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 1

1.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

Age group Dose Duration

Infants under 6 months old

10 mg per day 10-14 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

What is the mortality rate of cholera?

• Untreated cases: Average- 50% Epidemics- 90%

• Treated cases: Less than 1%

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

Current priority activities of WHO Global 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

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

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

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

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

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

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

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)

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

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