Typhoid

TYPHOID


INTRODUCTION

  • Typhoid fever is caused by Salmonella typhi.
  • Paratyphoid fever is caused by Salmonella paratyphi A, B & C.
  • The term “Enteric fever” encompasses both typhoid & paratyphoid fevers.
  • Infection acquired by ingestion of faecally contaminated food/water
  • ManOnly known reservoir.
    • Most common among males
  • Incubation period: 7 – 14 days, but ranges from 3 days to 3 weeks.

CLINICAL FEATURES:

  • Coated tongue
  • Stepladder pyrexia
  • Relative bradycardia
  • Soft palpable spleen
  • Rose spots (appears at 2nd week on trunk).
  • Are bacterial emboli to skin & occur in 1/3 of typhoid fever cases.
  • Marked constipation in early stage or “pea-soup diarrhea”

Typhoid ulcers:

  • Longitudinal & without subsequent strictures formation.
  • Note: Tuberculous ulcers are transverse that lead to stricture formations.
  • Multiple ulcers found in terminal ileum.
  • Ulcer margins – Slightly raised.
  • Ulcer baseBlack due to sloughed mucosa.
  • Microscopically ulcers show erythrophagia & mononuclear cell infiltration.
  • Perforation appears clinically as Pyrexia for
  • Acute pain in peri-umbilical region spreading all over abdomen.
  • Paratyphoid fever caused by S.paratyphi C more often leads to septicemia with suppurative complications
  • Infection spread prevented by isolating patient till three bacteriologically negative stools.
  • Urine reports are obtained on three separate days.

COMPLICATIONS:

  • GI bleeding -Most common complication.

Neurologic manifestations: 

  • Meningitis
  • Guillain-Barre syndrome
  • Neuritis

Neuropsychiatric symptoms:

  • Muttering delirium or Coma vigil, with picking at bedclothes or imaginary objects.

Commonest complications in 3rd or 4th week – 

  • Intestinal perforation (less common in children below 5yrs) & hemorrhage.
  • Cholangiocarcinoma
  • Splenomegaly
  • Leucopenia with neutropenia.

CARRIERS

  • Carrier state occurs due to persistence of bacilli in gallbladder resulting in passage of organism in feces & via urine.
    • Fecal carriers – Most common
    • Healthy carriers – Emerge from subclinical cases
    • Urinary carriers – More dangerous, common in patients with calculi or schistosomiasis.
  • More common in women, infants, older age groups (> 40 years) and biliary abnormalities.

Types of carrier state:

Convalescent carriers: 

  • Shed bacilli in feces for 3 weeks to 2 months after clinical cure.

Temporary carriers: 

  • Shed bacilli for more than 3 months but less than 1 year.

Chronic carriers: 

  • Shed bacilli for more than a year
  • This state associated with bacilli presence in gall-bladder.
  • 2 – 4% become chronic carriers at end of 1 year.

Pseudo-carriers:

  • Carriers of avirulent organisms in typhoid.

In breastfed infant less chance of enteric infection – 

  • Due to Ig & nutrients in breast milk

LAB DIAGNOSIS

  • Blood culture (gold standard) – 90% positive in first week.
  • Clot culture – Higher rate of isolation.
  • Urine culture – Positive in 2nd & 3rd week.
  • Bile culture – detection of carriers.
  • Bile – Good culture medium for Bacillus.
  • Fecal & bone marrow culture – Valuable in patients on antibiotics.
  • Typhoid perforation diagnosed by plain X-ray abdomen in erect posture.
  • Vi antibody – Used for detecting carrier.
  • Demonstrated of circulating antigen – staphylococcal agglutination test (Staph.aureus-Cowan I strain).

New diagnostic tests:

  • IDL tubex test – Detects IgM09 antibodies in few minutes.
  • Typhidot test – Detects IgM & IgG antibodies.
  • Leukopenia & neutropenia in 25% cases
  • Leukocytosis – Children during first 10 days of illness, cases complicated by intestinal perforation or secondary infection.

WIDAL REACTION:

  • Widal test – Investigation of choice in 3rd week.

Instrumentation:

  • Dreyer’s tube – Conical bottom, H agglutination[DCH].
  • Felix tube – Round bottom, O agglutination [FOR].

Antigens titre:

  • H & O antigens of S.typhi and H antigens of S.paratyphi are employed.
    • Paratyphoid 0 antigens not used.
  • Most immunogenic in typhoid is H antigen.
  • H-antigen titre remains positive for several months after infection.
    • Usually positive at end of 1st week, titre increases till 4th week & then declines.
  • Demonstration of rise in titers is more meaningful than a single test.
    • Significant titres > 1/320 for O; 1/640 for H is considered positive.
  • Widal positive should not be taken as proof of typhoid fever.
    • As agglutinins may be present due to prior disease, inapparent infection or immunization.
    • Those who had prior infection or immunization develop anamnestic response (transient rise in antibody titers) during an unrelated fever.

Exam Important

  • Healthy carriers in typhoid emerge from subclinical cases
  • In  typhoid  fever,  the  urinary  carrier  is  more dangers than an intestinal carrier
  • Carriers of avirulent organisms in typhoid are called pseudo-carriers
  • Typhoid is Most common among males
  • IP: 7 – 14 days, but ranges from 3 days to 3 weeks
  • Chronic  case of typhoid carrier is a risk factor for cholangiocarcinoma
  • To prevent the spread of infection, the patients are kept in isolation till three bacteriologically negative stools and urine reports, are obtained on three separate days.
  • Widal test is the investigation of choice in 3rd week.
  • Step ladder pyrexia, Rose spots on trunk & pea-soup diarrhea are the common findings of typhoid fever
  • Chronic carrier state is associated with presence of bacilli in gall bladder 
  • Convalescent carriers excrete the organism for 3 – 8 weeks
  • Chronic carriers excrete bacilli for many years
  • Splenomegaly , neutropenia & positive urine & stool culture after 2weeks of infection may be seen in Typhoid in children
  • Vi antibody  can be used  for detecting carrier
  • Blood culture (gold standard) – 90% positive in the first week
  • H-antigen titre remains positive for several months after infection
  • Person with prior infection or immunization may show anamnestic response
  • Infection acquired by ingestion of faecally contaminated food or water
  • Culture of feces, Bile, urine is useful in detection of carrier state in Typhoid
  •  Man is the only known reservoir
  • Multiple ulcer found in terminal ileum
  • Perforation in typhoid ulcer occurs in 3rd week
  • Intestinal Perforation in typhoid is less common in children below 5yrs
  • Erythrophagia and Mononuclear cell infiltration ulcers are seen in typhoid ulcer
  • Perforation,Haemorrhage,Sepsis are the complications of typhoid ulcers
  • In breast fed infant less chance of enteric infection is due to Ig & nutrients in breast milk
  •  Perforation appears clinically as Pyrexia for greater than ten days ,acute pain in periumblical region spreading all over the abdomen.
  • Typhoid perforation is diagnosed by Plain X-ray of abdomen in erect posture
  •  Enteric Fever is caused by salmonella typhi & paratyphi
  • Enteric fever diagnosis in 2nd week is best made by widal test
  • Most immunogenic in typhoid is H antigen
  • Rose spots are bacterial emboli to the skin and occur in 1/3 of cases of typhoid fever
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