Typhoid and Cholera

Typhoid and Cholera

1. Typhoid/enteric fever

   • i.e
     • Salmonella typhi
       • typhoid, enteric fever
     • Salmonella paratyphi A,B C
       • paratyphoid fever
     • Non- typhoidal Salmonellae
       • gastroenteritis
     • Gram -ve motile bacilli
     • Facultative anaerobes
   • Character
     • Pathogens for humans only
     • One serotype
       • O antigens - somatic, heat stable
       • H antigen (flagella), immunogenic
       • Vi antigen
   • Transmission
     • Oral (via healthy carrier)
       • Bacteria shed thru stool
       • Contaminated food/beverages
       • 1/30 of survivors -> carrier
     • Oral
       • H-to-M
       • Sewage contaminated water or shellfish
       • Contaminated toilet, poor hygiene
   • Pathogenesis
     • 1. Penetrate GI mucosa [ileum for S.typhi]
       • Fimbriae -> adhesion near Peyer's patches
       • Epithelial cells, macrophages,T-cells, neutrophils
       • All interact – inflammation
       • Vi antigen supresses neutrophil response
     • 2. Mesenteric LN -> multiply inside macrophages
     • 3. Travel via Thoracic duct -> bacteraemia
     • 4. Replication in BM, liver, GB, spleen, kidney (7-10 days)
     • 5. 2nd invasion blood → heavier bacteraemia → fever
     • 6. Invade GB
     • 7. Re-infect GIT & Peyer’s patches
   • Clinical features
     • 7-14 days incubation
     • 1st w of illness
       • Rise in temperature over 4–5 days
       • Cough, Headache
       • Abdominal pain, Constipation (gut lumen narrow by inflammation)
       • Malaise, Delirium
     • 2nd week
       • Day 7-10
         • Mild hepatosplenomegaly
         • Bradycardia
       • Day 9 -12
         • Rose spots
           • Pink, blanching
           • Abdominal wall/ trunk
     • 3rd week
       • "Typhoid state"
         • • Toxic • Anorexic, Weight loss • Prolonged apathy • Delirium, disorientation, psychosis, coma • Diarrhoea – pea-soup • Conjunctival injection • Cough, tachypnoea, crackles
         • If untreated high risk of intestinal hemorrhage and perforation from necrotic Peyer’s patches
   • Diff. dx
     • Malaria
     • Dengue
     • Rickettsial, typhus
     • Leptospirosis
   • Dx
     • Blood culture
       • Highest yield in early sympt. phase , b4 Ab
       • Including
         • BM, Blood, Duodenal fluid, Faeces, Urine
       • S&E media
       • May take 2-3 w
       • only 20-30% sensitive later in disease
       • Non-specific supporting findings
         • Anemia ,ESR ^, leucopenia, lymphopenia
         • Mildly ^ fibrin degradation products
         • ^ ALT, AST, bilirubin - 2x normal
     • Rapid dx test (IgM, IgG)- not musch used
   • Tx
     • Antibiotics
       • Chlorapmphenicol
       • Ciprofloxacin
       • 2nd line - 3rd generation cephalosporinf
   • Mx
     • Mild
       • outpatient
       • hygiene precautions
     • Severe
       • Hospitalise
       • Contact isolation during acute illness
     • Surgery
       • If perforate
       • If chronic shedding via GB, (if Ab tx fails)
   • Control of typhoid fever
     • Reservoir
       • Case detection and tx
       • Isolation
       • Disposal of stools and urine
       • Detection and trx of carriers
     • Route of transmission
       • Water and food sanitation
       • Excrete disposal
       • Fly control
     • Susceptibles
       • Immunisation
       • Health edu.
       • Ab prophylaxis x recemended

2. Cholera

   • Characteristic
     • Profuse secretory diarrhea
     • caused by Vibrio vholerae
       • El Tor 1 is the predominant cholera pathogen
     • Antacids , histamine receptor blockers, and PPI
       • < gastric aciddity
       • > risk of cholera infection
       • Predispose pt to more severe disease
   • Transmission
     • Faecal-oral
     • Survives in water
     • 200 serogroups
   • Pathogenesis
     • 1. Enterotoxin.promotes secretion of F&E into SI
     • 2. → Fluid loss in duodenum & upper jejunum.
     • 3. The absorptive capacity of the colon is overwhelmed by the > vol. of fluid produced in upper intestine
     • 4. → Severe diarrhoea – “rice water” stools
     • 5. Death related to water & electrolyte depletion
   • Malnutrition, overcrowding, diseasters
   • Clinical
     • 24-48 hr incubation
     • Sudden onset of painless watery diarrhoea
     • Abdominal cramps
     • no fever
     • Asymptomatic - facilitates transmission
     • F&E
   • Mx
     • Infection control
       • Human excrement from drinking water
       • Prepare surrounding areas if epidemic
     • Case finding
       • Rapid dx test
     • F&E correction - oral, IV, zinc
     • Ab
       • Half duration of illness
       • Decrease stool volume
       • < duration of excretion of V.cholerae
     • Vaccine