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Typhoid fever is a life-threatening illness caused by S typhi .

Epidemiology. Typhoid fever is a life-threatening illness caused by S typhi . In the United States about 400 cases occur each year. 75% of these are acquired while traveling internationally . Common in the developing world , where it affects about 21.5 million persons each year.

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Typhoid fever is a life-threatening illness caused by S typhi .

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  1. Epidemiology Typhoid fever is a life-threatening illness caused by S typhi. In the United States about 400 cases occur each year 75% of these are acquired while traveling internationally. Common in the developing world, where it affects about 21.5 million persons each year.

  2. Salmonella Gram negative bacteria Motile except S gallinarum pullorum MAC NLF colonies Selective medium Wilson & Blair bismuth sulphite Jet black colonies due to H2S S paratyphi A green colonies ( no H2S) Enrichment media Selenite F & tetrathionate broth

  3. Diseases Enteric fever Exclusively or primarily human parasite S typhi (Typhoid fever) S paratyphi A, B, C (Paratyphoid fever) Food poisoning Essentially animal parasite also infect human S typhimurium S enteritidis Septicemia S choleraesuis

  4. Pathogenesis Cases Source Carriers Poultry, diary Transmission Ingestion of contaminated water or food High infectious dose (108 CFU) IP 7-14 days Virulence factors Invasiveness Intracellular survival & multiplication Endotoxin

  5. Infection pattern of Salmonella Salmonella are ingested in contaminated food or water Organisms reach the terminal ileum Enteritis Organisms invade the gut wall & cause ulcertion, perforation & hemorrhage Organisms spread to intestinal lymphatics & are phagocytosed by macrophages Organisms disseminate to bones, kidneys, lungs,liver, brain & blood Enteric fever or typhoid fever

  6. Clinical Syndromes of Salmonella Salmonellosis = Generic term for disease Enteric fever (prototype is typhoid fever and less severe paratyphoid fever) Septicemia (particularly S. choleraesuis, S. typhi, and S. paratyphi) Asymptomatic carriage (gall bladder is the reservoir for Salmonella typhi)

  7. Clinical features Nausea & vomiting Fever (Step ladder) Bradycardia Toxemia Soft palpable spleen Hepatomegaly ? Rose spots on skin (2nd - 3rd week)

  8. Lab diagnosis of Enteric fever Specimens Blood, Bone marrow, urine, stool, pus, csf Blood culture BHI broth 1st week 2nd week Antibody detection (serum) Widal test 3rd week Urine culture 4th week Stool culture Use selective & enrichment medium

  9. Lab Diagnosis of Enteric fever Specimens Blood, urine, stool, Culture NLF colonies MAC W & B Jet black colonies (Stool culture) TSI agar K-/ A +(H2S) AST Report & Interpretations

  10. Serology - Widal Test Tube agglutination test To detect antibodies in patient serum Test is performed after 2 wks To diagnose Enteric / typhoid fever Antigens used TO O antigen of S typhi TH H antigen of S typhi H antigen of paratyphi A AH BH H antigen of paratyphi B CH H antigen of paratyphi C O is group specific Enteric fever H is species specific Typhoid or paratyphoid

  11. Widal test - interpretation Test is carried by double dilution of serum Anamnestic response with TAB vaccine Demonstration of rise in titre Cases treated early may show poor antibody response TO 1: 320 TH 1: 160 Typhoid fever Titre suggestive of AH 1: 20 1: 20 BH CH 1: 20

  12. Carriers Food handlers & Cooks Repeated stool cultures Widal test no value in endemic countries Vi agglutinins indicates carrier status Sewer swab technique tracing carriers in cities Vaccines TAB Typhoral Typhim

  13. Treatment & drug resistance 1948 Availability of Chloramphenicol (choice) 1972 Chloramphenicol resistance Epidemic in Mexico Epidemic in Calicut (Kerala India) Endemic & confined to Kerala till 1978 Alternative – ampicillin, co-trimoxazole (ACOT), furazolidone Multi-drug resistance (MDR-S typhi) 1980 late Resistance to ACCOT Current choice Fluoroquinoles (ciprofloxacin) or 3 GCs (Third-Generation Cephalosporins)

  14. If you know you are traveling to an at risk location: Avoid Ice Drink Only Bottled Water & pasteurised milk Consume cooked food Vaccination ?

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