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• Enteric fever is a systemic disease characterised by fever and abdominal pain.

• It is caused by S. Typhi or S. parathyphi.

Transmission

• Food borne or water borne transmission from fecal contamination by ill or asymptomatic chronic carriers.

Incubation period : 10 -14 days.

Clinical feature

• The hallmark of the disease is fever and abdominal pain.

• Documented fever will be present in >75% of cases whereas abdominal pain may be present only in 30-40% of cases.

• The classical history of typhoid fever : Rise in temperature in a step ladder fashion for 4-5 days with malaise, increasing headache, drowsiness and aching in limbs. Constipation may be present although diarrhoea and vomiting may be prominent in early illness. Relative bradycardia.

• At the end of first week, a rash may appear on the upper abdomen and on the back as sparse, slightly raised, rose red spots which fade on pressure. Cough and epistaxsis occur.

• Around 7^th – 10^th day the spleen becomes palpable. Constipation is succeeded with diarrhea and abdominal distension and tenderness. Bronchitis and delirium will develop.

• If, untreated by the end of 2^nd week patient will become profoundly ill.

Complication

Diagnosis

• Isolation of S. typhi or S. paratyphi from blood, bone marrow, other sterile sites, rose spots, stools.

• Stool cultures are negative in first week ;can become positive during third week of infection.

• WIDAL Test :

  • It is tube agglutination test . Serial two fold dilution of patient serum (1/10, 1/20, 1/40 and so on.) is mixed with antigen.

  • O Antibodies starts to appear by 6-8 days & H antibodies by 10-12 days.

  • Demonstration of rising titre of antibody by testing two or more sample is diagnostic.

  • A single test of 1/100 titre of O antigen & 1/200 or more titre of H is significant.

• Drawback

  • It can be negative in upto 30% of culture proven typhoid.

  • Can be blunted due antibiotic usage

  • False positive results due to cross reaction with other serotypes of salmonella, malaria, typhus etc.

• Newer methods like Typhidot -M, IgM dipstick test. Studies have shown better sensitivity and specificity than WIDAL.

• WBC : Leucopenia is more common

• LFT : midly elevated.

Treatment

Antibiotics

• Fluroquinolnes

• They are the most effective agents. Cure rate is 98% and relapse and fecal carriage rates <2%.

• Nalidixic acid strains

  • Persons with nalidixic acid resitant strains are treated with azithromycin, ceftriaxone or high dose ciprofloxacin.

Vaccination

• Ty 21a , an oral live attenuated S. typhi vaccine given on 1, 3, 5 and 7^th day. Booster dose every 5 years.

• Vi CPS, a purified Vi Polysaccharide parenteral vaccine from bacterial capsule. Given as single dose. Booster dose every 2 years.

• Minimal age for vaccination is 6 years for Ty21a and 2 years for Vi CPS.

Updated on 9/6/2013.

Reference

• Harrison

• Background document: The diagnosis, treatment and prevention of typhoid fever. WHO 2003.

• Medical Microbiology ; By Gupte

• Davidson