- 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
- Man – Only known reservoir.
- Most common among males
- Incubation period: 7 – 14 days, but ranges from 3 days to 3 weeks.
- 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”
- 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 base – Black 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.
- GI bleeding -Most common complication.
- Guillain-Barre syndrome
- 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.
- Leucopenia with neutropenia.
- 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:
- Shed bacilli in feces for 3 weeks to 2 months after clinical cure.
- Shed bacilli for more than 3 months but less than 1 year.
- 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.
- Carriers of avirulent organisms in typhoid.
In breastfed infant less chance of enteric infection –
- Due to Ig & nutrients in breast milk
- 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 test – Investigation of choice in 3rd week.
- Dreyer’s tube – Conical bottom, H agglutination[DCH].
- Felix tube – Round bottom, O agglutination [FOR].
- 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.
- 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