This presentation is prepared by:Dr -Safia Al_rezami

Definition Causes Mechanism Symptoms

&signs Diagnosis Treatment Prevention

The contents

Defination Cholera is an acute diarrhoeal disease can

kill within hours if left untreated. Cholera is caused by ingestion of food or water contaminated with the bacterium “ Vibrio cholerae”.

cause

Two serogroups of V. cholerae – O1 and O139 – cause outbreaks.

V. cholerae O1 causes the majority of outbreaks, while O139 –– is confined to South-East Asia .

non-O139Non-O1 V. cholerae can cause mild diarrhoea but do not generate epidemics .

Recently, new variant strains have been detected in several parts of Asia and Africa. Observations suggest that these strains cause

more severe cholera with higher case fatality rates .

Cholerae strains

The main reservoirs of V. cholerae are people and aquatic sources such as brackish water and estuaries, often

associated with algal blooms. Recent studies indicate that global warming

creates a favourable environment forthe bacteria.

cause

Mechanism ingestion of food or water contaminated with the bacterium stomach

The small intestine (thick mucus to get to the intestinal walls,that lines the small intestine )cholerae bacteria start up production of the hollow cylindrical protein flagellin to make flagella , the curly whip-like tails, cholerae start producing the toxic proteins that give the infected person a watery diarrhea. This carries the multiplying new generations of V. The cholera toxin (CTX or CT) is an oligomeric complex made up of six protein subunits: a single copy of the A subunit (part A), and five copies of the B subunit (part B), connected by a disulfide bond.

symptoms & signs

Among people who develop symptoms ,

80% have mild or

moderate symptoms ,

while around 20% develop acute watery diarrhoea with severe dehydration. This can lead to death if

untreated.

People with low

immunity – such as

children or people

living with HIV – are at

a greater risk of death

if infected

malnourished

Diagnosisclinical diagnosis may be made by taking a history and doing a briefexamination

A rapid dip-stick test is available to determine the presence of V. choleraeStool and swab samples collected in the acute stage of the disease

The special media have been employed for the cultivation for cholera vibrios. are classified as follows:

Enrichment mediaAlkaline peptone water at pH 8.6 Monsur's taurocholate tellurite peptone water at pH 9.2

Plating mediaAlkaline bile salt agar (BSA): The colonies are very similar to those on nutrient agar

.Monsur's gelatin Tauro cholate trypticase tellurite agar (GTTA) medium: Cholera

produce translucent colonies with a greyish black center .TCBS medium: This the mostly widely used medium; it contains thiosulphate,

citrate, bile salts and sucrose. Cholera vibrios produce flat 2–3 mm in diameter, yellow nucleated colonies .

Direct microscopy of stool is not recommended, as it is unreliable.

Diagnosis can be confirmed, as well, as serotyping done by agglutination with specific sera.

TreatmentCholera is an easily treatable disease . Up to 80% of people can be treated successfully through prompt administration of oral rehydration salts ,There are an estimated 3–5 million cholera cases and 100 000–120 000 deaths due to cholera every year. Treatment is usually started without or before confirmation by laboratory analysis.

Treatment

Electrolytes

Antibiotics

Fluids

1)Fluids

In most cases, cholera can be successfully treated with oral rehydration therapy (ORT), which is highly effective, safe, and simple to administer. Rice-based solutions are preferred to glucose-based ones due to greater efficacy. In severe cases with significant dehydration, intravenous rehydration may be necessary. Ringer's lactate is the preferred solution

If commercially produced oral rehydration solutions are too expensive or difficult to obtain, solutions can be made. One such recipe calls for 1 liter of boiled water, 1 teaspoon of salt, 8 teaspoons of sugar, and added mashed banana for potassium and to improve taste]

Fluids

http://en.wikipedia.org/wiki/File:Cholera_hospital_in_Dhaka.jpg

Electrolytes

ElectrolytesAs there frequently is initially acidosis, the potassium level may be normal, even though large losses have occurred.As the dehydration is corrected, potassium levels may decrease rapidly, and thus need to be replaced.

Antibiotics

Antibiotic treatments for one to three days shorten the course of the disease and reduce the severity of the symptoms.

People will recover without them, however, if sufficient hydration.

Doxycycline is typically used first line, although some strains of V. cholerae have shown resistance.

Other antibiotics that have been proven effective include

1-cotrimoxazole, erythromycin, 2-tetracycline, chloramphenicol,3- furazolidone. 4-Fluoroquinolones, such as norfloxacin.In many areas of the world, antibiotic resistance is

increasing ,New generation antimicrobials have been discovered which are effective against in in vitro studies.

Antibiotics

Prevention and control

Oral cholera vaccinesThere are two types of safe and effective oral cholera vaccines currently available on the market. Both are whole-cell killed vaccines, one with a recombinant B-sub unit, the other without. Both have sustained protection of over 50% lasting for two years in endemic settings . One vaccine (Dukoral) is WHO prequalified and

licensed in over 60 countries. has been shown to provide short-term protection of 85–90%against V. cholerae O1 among all age groups at 4–6 months following immunization

The other vaccine (Shanchol) is pending WHO prequalification and provides longer-term protection against V. cholerae O1 and O139 in children under five years of age.

Both vaccines are administered in two doses given between seven days and six weeks apart.

Prevention and control

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