1. gastrointestinal block week 3 Vibrio cholera
By Abdallah Mohamed

2. Objective Know the epidemiology of cholera and history of cholera
Recognize the microbiological characteristics of cholera
Define the pathogeneses of cholera
Describe the clinical features of cholera
Outline the methods for laboratory diagnosis
Discuss the management of cholera
List major strategies for prevention and control of outbreak

3. Morphology of vibrio cholerae

4. Epidemiology of the cholera and history of the cholera
Cholera is an acute diarrheal disease that can kill within hours if left untreated. Cholera affects millions, in endemic areas and causes thousands of deaths especially during seasonal epidemics. Robert Koch, the famous microbiologist of Germany, discovered Vibrio cholera, the causative organism. Because of its characteristic shape he originally referred to it as comma bacilli. Cholera likely has its origins in the Indian

5. Where is cholera found?
The cholera bacterium is usually found in water or food sources That have been contaminated by feces from a person infected with cholera. Cholera is most likely to be found and spread in places with inadequate water treatment, poor sanitation, and inadequate hygiene. The cholera bacterium may also live in the environment in Brackish rivers and coastal waters. Shellfish eaten raw have been a source of cholera, and a few persons in the U.S
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6. Serogroups of V.cholera
Two serogroups of V. cholera, O1 and O139, cause outbreaks of cholera. ... Only toxigenic strains of serogroups O1 and O139 have caused widespread epidemics. Mild diarrhea to severe deadly diarrhea –Depends on how much toxin produced Vomiting can also occur Lose liters a day, sometimes 1 liter/hour

7. Transmission
Infection occurs through ingestion of food or water contaminated directly or indirectly by faeces or vomitus of infected individuals. Cholera affects only humans; there is no insect vector or animal reservoir host.
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8. Nature of the disease
An acute enteric disease varying in severity. Most infections are asymptomatic ( do not cause any illness). In mild cases, acute watery diarrhoea occurs without other symptoms. In severe cases, there is sudden onset of profuse watery diarrhoea with nausea and vomiting and rapid development of dehydration. In severe untreated cases, death may occur within a few hours due to dehydration leading to circulatory collapse.
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9. Microbial characteristics of the cholera
V. cholerae is Gram-negative and comma-shaped. Initial isolates are slightly curved, whereas they can appear as straight rods upon laboratory culturing. The bacterium has a flagellum at one cell pole as well as pili. V. cholerae is a facultative anaerobe, and can undergo respiratory and fermentative metabolism

10. Pathogeneses of the cholera
Vibrio Cholerae enterotoxin activates the stimulatory Gs protein via ADP-RiboRylation. This stimulates secretion of chloride ions and water from enterocytes into the small intestines, and causing watery diarrhea.

11. Pathology
Cholera is not an invasive infection • Organisms do not reach blood, only act locally • Virulent V.cholrae organism attach to the microvillus of the brush border of epithelial cells • They multiply and liberate cholera toxin

12. Clinical feature of the cholera
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 No fever Dehydration appears within 12 to 24 hours. The incubation period is 1 – 4 days for person who develop symptoms, depends on the size of the inoculums ingested

14. The method for laboratory diagnosis
Bacteriological confirmation is compulsory on The first
suspected cases, in order to:
Confirm cholera
Identify the strain, biotype and serotype
Assess antibiotic sensitivity
Stool specimen appear as Rice water • On Microscopy contain Mucus, epithelial cells and large number of Vibrio's.

15. The morphology of vibrio under microscope

16. Stool culture
Use Cary Blair Transport media if available – Viable for many days at room temperature • Use TCBS media(Thiosulfate- citrate-bile salts-sucrose agar) for culture it's selective media for vibrio cholera Alkaline peptone water is ideal enrichment medium

17. When you suspect Cholera
The diagnosis of cholera should be considered in patients with watery diarrheal who have recently (within 7 days) returned from cholera-affected countries. Patients with suspected cholera should be reported immediately to local and state health departments.

18. The management of the cholera
The primary goal of therapy is to replenish fluid losses caused by diarrhea & vomiting.
Fluid therapy is accomplished in 2 phases: rehydration and maintenance
Rehydration should be completed in 4 hours & maintenance fluids should replace ongoing losses & provide daily requirement
Ringer lactate solution is preferred over normal saline because it corrects the associated metabolic acidosis.

19. DRUG THERAPY
The goals of drug therapy are to eradicate infection, reduce morbidity and prevent complications.
The drugs used for adults include tetracycline, doxycycline, cotrimoxazole & ciprofloxacin
For children erythromycin, cotrimoxazole and furazolidone are the drugs of choice

20. DRUG THERAPY
Drug therapy reduces volume of stool & shortens period of hospitalization. It is only needed for few days (3-5 days).
Drug resistance has been described in some areas & the choice of antibiotic should be guided by the local resistance patterns
Antibiotic should be started when cholera is suspected without waiting for lab confirmation

21. Prevention and control of out break
Needs improvement of Sanitation associated with water treatment and food.
Patients infected preferably isolated .
Excreta disinfected
All contacts to be followed up

22. Chemoprophylaxis with antibiotics is effective
Chemoprophylaxis with antibiotics is effective. Repated injection of vaccine containing either Lipopolysaccharides extracted from Vibrio's or dense Vibrio's Vaccines not useful in Epidemic controls

23. Authors: Kenneth Ryan, C.G.Ray. chapter 66. Publisher: Mc Graw Hill.
Recommended Books:
-Sherris Medical Microbiology ,An Introduction to Infectious Diseases
Authors: Kenneth Ryan, C.G.Ray. chapter 66.
Publisher: Mc Graw Hill.

24. End
Thank you four your attention
Any question