Cholera patient having stool output 1000-1500 mL/day is known as:
Correct Answer: Cholera gravis
Description: Ans. D. Cholera gravisExplanationVibrio choleraThey are curve (comma-shaped) gram negative, bacilli that are actively motile (single polar flagellum).Classification:Based on salt requirementHalophilic vibrios: They can't grow in the absence of salt. They can tolerate salt at 7-10%. examples are V. parahaemolyticus, V. alginolyticus, V. vulnificus.Non-halophilic vibrios: They can grow without salt but 1% salt is needed. Examples are V. cholerae, V. mimicus.Heiberg classification (1934)EIGHT GROUPS based on fermentation of mannose, arabinose and sucrose. V. cholerae placed in GROUP I.Gardner and Venkatraman classification.Based on serogrouping, biotyping, serotyping and phage typing.Pathogenesis of cholera: Toxin mediatedMode of transmission: Ingestion of contaminated water and food.Infective dose: extremely acid labile, hence high infective dose is needed to bypass gastric >> barrier (108 bacilli).Factors promoting transmission: Hypochlorhydria, use of antacids.The bacilli penetrates mucous layer - Adheres to the epithelium - Cholera toxin is produced - Toxin has fragment B and fragment A - Fragment B is binding fragment, that binds to GM1Ganglioside receptors - Fragment A, causes ADP-ribosylation of G protein - Upregulates the activity of adenylate cyclase - Intracellular accumulation of camp - water moves out due to osmolality, which leads to watery diarrhea - Loss of fluids and electrolytes leads to shock.Clinical features of cholera:Asymptomatic infection (75% cases)Mild diarrhea or cholera (20% cases)Sudden onset of explosive and life threatening diarrhea (Cholera gravis, in 5% of cases).Watery diarrhea, rice water stools, vomiting, fever usually absent, muscle cramps due to electrolyte imbalance.Complications of cholera:Loss of body weight bySymptoms<5%Increased thirst5-10%*. Postural hypotension*. Weakness*. Tachycardia*. Decreased skin turgor>10%Renal failure (acute tubular necrosis) and fluid loss results in:*. Oliguria*. Weak or absent pulse*. Sunken eyes*. Sunken fontanelles in infants*. Wrinkled skin*. Somnolence*. ComaEpidemiologyHistory of pandemics:Home land is DELTA REGION of Ganges and Brahmaputra in West Bengal. And Bangladesh.First 6 pandemics caused by classical biotype of V.cholerae, had spread from Bengal to all over world.Seventh pandemic-only pandemic originated outside india(in Indonesia),caused by El Tor biotype.0139 (Bengal strain) -- first isolated in Chennai in 1992It was not agglutinated by antisera (01 to 0138), hence designated as 0139.It is capsulated, invasive causes bacteremia and extraintestinal manifestations.Cholera is a notifiable disease.National reference center for cholera is located at national institute of cholera and enteric diseases (NICED), Kolkata.Reservoir: Humans.Source: Asymptomatic cases or carriers.Carriers: (1) Incubatory carriers (1-2 days), (2) Convalescent carriers (2-3 weeks), (3) Contact or healthy carriers (<10 days), (4) Chronic carriers.Factors determining severity: People with O blood group, malnutrition, lack of preexisting immunity.Habitat: Natural habitat of coastal sea salt water and brackish estuaries, associated with crustaceans, copepods, crabs, plankton.Lab diagnosisSpecimens: Watery stool or rectal swab for carriers.Transport media: Venkataramana Ramakrishna media, Cary-Blair medium.Direct microscopy:Gram-negative rods, short curved, comma shaped (fish in stream appearance)Hanging drop demonstrates darting motility.Culture:Enrichment broth: Alkaline peptone water, Monsur's taurocholate tellurite peptone water.Selective media: Bile salt agar, Monsur's GTTT agar, TCBS agar (yellow colonies)MacConkey agar-translucent non-lactose fermenting colonies.Culture smear and motility testing to be done.Biochemical identification:Catalase and oxidase positive.ICUT: Indole (+), Citrate (+/-), Urease (-), TSI: A/A, gas (-), H2S (-)Cholera red reaction is positiveString test is positiveSalt tolerance test is positiveFerments glucose and sucrose Biotyping: To differentiate Classical and El Tor Serogrouping: To differentiate 01 and 0139.Serotyping: To differentiate Ogawa, Inaba, Hikojima serotypes of serogroup 01TreatmentFluid replacement: ORS solution, ringer's lactateAntibiotics has minor role, WHO recommends antibiotic use only in severely dehydrated cases.Adults: doxycycline or tetracycline Children/pregnancy erythromycin/azithromycin.Prevention:General measures: Safe water, improved sanitary disposal of feces, notification, health education.Chemoprophylaxis: TetracyclineVaccine:Injectable killed vaccines: No longer in useOral cholera vaccines (OCV)Killed whole-cell vaccineOral live-attenuated vaccine.Killed whole-cell vaccineOral live-attenuated vaccine1. Whole-Cell (WC) vaccine: Composed of killed whole cells of V. cholerae 01 (Classical and El Tor Inaba and Ogawa)They use mutant strains that lack gene encoding for cholera toxin.2. Whole-cell recombinant B subunit cholera vaccine (WC/RBS) (Dukoral): Same composition as above plus recombinant cholera toxin B subunits.*.CVD103-hgr, (Orochol-contains live attenuated strain derived from reference strain 569B< classical, 01, inaba > Schedule-single dose)*. Peru-15*. V. cholerae 638 for classical and/or El Tor for biotypes of V. cholerae 1.Schedule 2 oral dose, at 7 days gap*. 3 doses for 3-5 years children*. Not given for <2 years.CVD-112 and Bengal-15 vaccine trials for V. cholerae 0139
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