Typhoid Fever

Objective

At the end of the class the students will be able to

•       Explain typhoid fever

•       Describe the pathogenesis of typhoid

•       Discuss epidemiology of typhoid

•       Describe the treatment and diagnosis

Typhoid Fever

(Enteric Fevers)

Typhoid fevers are prevalent in many regions in the World

Etiology of Typhoid fever

•       Typhoid fever is a bacterial disease, caused by Salmonella typhi.

•        It is transmitted through the ingestion of food or drink contaminated by the faeces or urine of infected people.

•       Para typhoid fevers are produced by other species named

•       Paratyphi A, B, C

How a Typhoid fever spreads

•       Salmonella Typhi lives only in humans.

•       Persons with typhoid fever carry the bacteria in their bloodstream and intestinal tract. In addition, a small number of persons, called carriers, recover from typhoid fever but continue to carry the bacteria.

•       Both ill persons and carriers shed S. Typhi in their feces
(stool).

Epidemology of Typhoid

•       World largest outbreak of typhoid in SANGLI on December 1975 to February 1976. This disease is endemic in India

•       1992    :      3,52,980 cases with 735 deaths

•       1993    :      3,57,452 cases and 888 deaths

•       1994    :      2,78,451 cases and 304 deaths

•       Case fatality rate due to typhoid has been varying between 1.1% to 2.5 % in last few years.

Manifestations of Typhoid

•       Relative bradycardia

•       Hepatomegaly

•       Splenomegaly

Causes of Typhoid

Age group: Typhoid fever may occur at any age but it is considered to be a disease mainly of children and young adults. In endemic areas, the highest attack rate occurs in children aged 8-13 years. In a recent study from slums of Delhi, it was found that contrary to popular belief, the disease affects even children aged 1-5 years

Gender and race: Typhoid fever cases are more commonly seen in males than in females. On the contrary, females have a special predilection to become chronic carriers.

Occupation: Certain categories of persons handling the infective material and live cultures of S. typhi are at increased risk of acquiring infection.

Socio-economic factors: It is a disease of poverty as it is often associated with inadequate sanitation facilities and unsafe water supplies.

Environmental factors: Though the cases are observed throughout the year, the peak incidence of typhoid fever is reported during July – September.
This period coincides with the rainy season and a substantial increase in fly population.

Social factors:
pollution of drinking water supplies, open air defecation, and urination, low standards of food and personal hygiene, and health ignorance.

Pathogenesis of Typhoid

Caused by

•       S. typhi

•       S.paratyphi

•       The organisms penetrate ileal mucosa reach mesenteric lymph nodes via Lymphatics , Multiply,

•       Invade Blood stream via thoracic duct

•       In 7 – 10 days through blood stream infect

•       Liver, Gall Bladder,, spleen, Kidney, Bone marrow.

•       After multiplication bacilli pass into blood causing secondary and
heavier bactermia

Management of typhoid fever:

General: Supportive care includes

•       Maintenance of adequate hydration.

•       Antipyretics.

•       Appropriate nutrition.

Specific: Antimicrobial therapy is the mainstay treatment. Selection of antibiotic should be based on its efficacy, availability and cost.

•       Chloramphenicol , Ampicillin ,Amoxicillin , Trimethoprim &Sulphamethoxazole ,Fluroquinolones

•        In case of quinolone resistance – Azithromycin, 3rd generation cephalosporins (ceftriaxone)

Control of Typhoid fever

MEASURES DIRECTED TO RESERVOIR

a) Case detection and treatment

b) Isolation

c) Disinfection of stools and urine

d)Detection & treatment of carriers

MEASURES AT ROUTES OF TRANSMISSION

a) Water sanitation

b) Food sanitation

c) Excreta disposal

d) Fly control

MEASURES FOR SUSCEPTIBLES

a) immunoprophylaxis

b) Health education

Vaccines for Typhoid Prevention

•       Two types of vaccines are available Oral and Injectable

•       Oral – A live oral vaccine (typhoral) is a stable mutant of S.typhi strain Ty 21a lacking the enzyme UDP Galactose -4-epimerase.

•       One capsule given orally taken before food, with glass of water or milk, on 1, 3, 5 days ( three doses )

•       No antibiotics should be taken during the period of administration of vaccine

•       The injectable vaccine, ( typhim –vi) contains purified Vi polysaccharide antigen derived from S.typhi strain ty21

•       Given as single subcutaneous or intramuscular injection

•       Single dose is adequate.

Summary

•       Typhoid fever is a bacterial disease, caused by Salmonella typhi.

•        It is transmitted through the ingestion of food or drink contaminated by the faeces or urine of infected people

•       The organisms penetrate ileal mucosa reach mesenteric lymph nodes via Lymphatics , Multiply, Invade Blood stream via thoracic duct

•       Management: Antipyretics,Appropriate nutrition, Antimicrobial therapy

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