ppt on Cholera (Etiopathogenesis & diagnosis)

Description of Cholera for MBBS graduates

1. TOPIC: CHOLERA

2. Historical perspective The name ‘ Vibrio ’ is derived from its characteristic vibratory motility Robert Koch isolated the organism in 1886, and named it as Komma bacillus Family Vibrionaceae : Four genera Vibrio Aeromonas - Aeromonadaceae Pleisomonas - Enterobacterales Photobacterium – plant pathogen

3. Characteristics of Vibrio Vibrios are curved , Gram negative bacilli , motile with single polar flagellum (Darting motility ) Fermentative, aerobic, Oxidase positive (ex. V.metschnikovii ) Non- capsulated (except…..?) Growth is stimulated in presence of SALT Habitat: marine waters, surface waters, river, sewage

4. Epidemiology Cholera is a notifiable disease WHO estimated that more than 1.3-4 million cases of cholera occur every year Homeland of Cholera : Delta region of Ganges and Brahmaputra in West Bengal and Bangladesh

5. Epidemiological Determinants Reservoir: Humans are the only reservoir of infection There is no known animal reservoir Source : The source of the infection may be either asymptomatic cases or carriers Carriers : Asymptomatic carriers play an important role in transmitting cholera over long distances Cholera season : high temperatures , heavy rainfall and flooding Habitat: V. cholerae is a natural inhabitant of coastal sea salt water and brackish estuaries

6. Monitoring NICED: National reference Center for cholera in India is located at National Institute of Cholera and Enteric Diseases (NICED), Kolkata In October 2017, the WHO Global Task Force on Cholera Control (GTFCC) launched aiming for the elimination of the disease as a public threat by 2030

7. Classification 1) Based on Salt Requirement : Nonhalophilic vibrios : V . cholera and V. mimicus Halophillic vibrios : V. parahaemolyticus , V. alginolyticus and V. vulnificus . 2) Heiberg Classification : (Mannose, Arabinose, Sucrose) 3 ) Gardner and Venkatraman Classification This classification of V. cholerae (1935) was based on serogrouping (based on O antigen), biotyping , serotyping & phage typing

8. Classification

9. O139 (Bengal Strain) It was isolated first from Chennai in 1992 I t spread rapidly along the coastal region of Bay of Bengal up to West Bengal, then to the adjacent areas of Bangladesh With distinct LPS and being CAPSULATED , can cause bacteremia and extraintestinal infections O139 appears to be a derivative of O1 El Tor Currently, O139 still causes a minority of cases in India and Bangladesh

10. Cholera Pandemics

11. Classical & El Tor V.cholerae

12. Pathogenesis Only host: humans Grows in brackish estuaries and coastal seawaters Also grows in water with low salinity when it is warm and adequate organic matter is available Patients of cholera excrete 20 L of rice water stool laden with ~10 9 vibrio cholera cells/ml/day  this facilitates propagation. TRANSMISSION: - Contaminated food - Contaminated water - feco -oral route Reference: Mandell, Douglas and Bennetts Principle And Practice of Infectious Disease 8 th edition page 2472

13. V. Cholerae secrete Cholera toxin (CT) Pentameric B subunit of CT binds to GM1 (glycosphingolipid) on epithelial cell surface CT-GM1 transports toxin to cytoplasm In cytoplasm, A subunit mediates transfer of NAD to G protein G protein regulates Adenyl cyclase level and increases cAMP level - Increase Cl - secretion by crypt cells -Decrease absorption by villous cells Pathogenesis

14. Clinical manifestations Asymptomatic infection ( 75% of cases) Mild diarrhea or cholera (20 % of cases) Sudden onset of explosive and life-threatening diarrhea ( cholera gravis , in 5% of cases ) Painless Rice- watery diarrhea that may become voluminous Vomiting may be present but fever is usually ABSENT

15. Lab diagnosis of V.cholerae Specimens: Watery stool or rectal swab (for carriers) Direct microscopy Hanging drop-demonstrates darting motility Enrichment broth : Alkaline peptone water, Monsur’s taurocholate tellurite peptone water

16. Mac- Conkey agar- translucent NLF colonies TCBS Agar: Yellow colonies Blood Agar: Hemodigestion Culture Characteristics

17. Identification Identification is made either by MALDI-TOF or VITEK; or by conventional biochemical tests Species identification Agglutination with V. cholerae polyvalent O antisera NEGATIVE : Test with O139 POSITIVE WITH O1 ANTISERA If agg . with OGAWA: OGAWA SEROTYPE If agg . with INABA: INABA SEROTYPE If agg . with Both: HIKOGIMA SEROTYPE

18. Non O1/O139 V. cholerae Gastroenteritis: following sea food consumption (raw oysters) Stool is watery or partly formed, less voluminous and bloody or mucoid A bdominal cramps, nausea, vomiting and fever Extraintestinal manifestations: Such as otitis media, wound infection and bacteremia

19. Management Fluid replacement Antibiotics: MINOR ROLE Preferred Condition: Hastens clearance of organism from stool & prevents the development of carrier stage DOC: Erythromycin/Azithromycin (10mg/kg) – Pregnancy & Children Doxycycline (300mg) in Adults

20. Vaccination Killed whole-cell vaccine Oral live attenuated vaccines Whole-cell recombinant B subunit vaccine (WC/ Rbs ) Dukoral Vaxchora (CVD 103-HgR) licensed in U.S. & Europe >2 year age: 2 doses 1 week apart, 3 rd dose b/w 2-5 yrs 18-64 years traveling to an area with active cholera transmission Protective immunity: 2 yrs Protective immunity: 3 -6 months

21. Halophilic vibrio infections Halophilic vibrios can withstand higher salt concentration (> 6%) in contrast to V. cholerae , which can tolerate up to 6% Features V. parahemolyticus V. vulnificus V.alginolyticus First reported in Japan in 1953; ( India (Kolkata) “ WOUND MAKER ” MOST SALT TOLERANT Clinical features Food-borne gastroenteritis, watery diarrhea Wound infections, sepsis Eye, ear and wound infections Lab diagnosis Pleomorphism Gram negative Gram negative Culture TCBS: GREEN colonies BA: SWARMING WAGATSUMA AGAR: KANAGAWA PHENOMENON Ferments LACTOSE ------

22. Halophilic vibrio infections Features V. parahemolyticus V. vulnificus V.alginolyticus Identification Salt tolerance test: resist upto 8% Salt tolerance test: upto 8% Salt tolerance test: upto 10% Treatment GE is self-limiting Doxycycline or macrolide are the drug of choice Wound debridement, and general supportive care Self-limiting Severe infection: Tetracycline & drainage

23. Aeromonas Infections Aeromonas was earlier placed in the family Vibrionaceae A. hydrophila causes red leg disease in frog Clinical Features: Gastroenteritis (watery diarrhea, vomiting, fever and rarely dysentery) Bacteremia & Respiratory tract infections, such as epiglottitis, pharyngitis and pneumonia H uman infections are caused by A. hydrophila , A. caviae and A. veronii Aeromonas is susceptible to ciprofloxacin and levofloxacin

24. MCQ 1 Which laboratory test is most useful in confirming Cholera diagnosis? Stool occult blood test Widal test Blood culture Stool culture on TCBS

25. MCQ 2 Mechanism of action of Cholera toxin? Inhibition of Protein synthesis Lysis of enterocytes Inhibition of cyclic GMP Activation of adenylate cyclase & increase cAMP

26. MCQ 3 KANAGAWA Phenomenon is seen in? V. vulnificus V. cholera V. parahaemolyticus V. alginolyticus

27. Thank you