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TYPHOID FEVER. TYPHOID FEVER. INTRODUCTION PROBLEM STATEMENT AGENT FACTORS HOST FACTORS ENVIRONMENTAL FACTORS INCUBATION PERIOD CLINICAL FEATURES DIAGNOSIS CONTROL AND PREVENTION. Introduction.
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TYPHOID FEVER • INTRODUCTION • PROBLEM STATEMENT • AGENT FACTORS • HOST FACTORS • ENVIRONMENTAL FACTORS • INCUBATION PERIOD • CLINICAL FEATURES • DIAGNOSIS • CONTROL AND PREVENTION
Introduction • Typhoid fever is the result of systemic infection mainly by S.typhi found only in man. The disease is clinically characterised by a typical continuous fever for 3 or 4 weeks, relative bradycardia with involvement of lymphoid tissues and considerable constitutional symptoms. • The term “enteric fever” includes both typhoid and paratyphoid fevers.
Problem Statement • World :- • Typhoid occurs in all countries where water supplies and sanitation are sub-standard. • Affects about 6 million people worldwide with 600,000 deaths a year. • 80% of cases & deaths are in Asia, Africa & Latin America. • Close to eradication in UK, with approximately 1 case per 1,000,000 population.
Problem Statement • INDIA :- • Typhoid is endemic in India. • Study in an urban slum showed 1% of children up to 17yrs of age suffer from typhoid every year.
AGENT • S.typhi is the major cause of enteric fever. • S.paraA and S.paraB are relatively infrequent. • S.typhi has three major antigens - O,H and Vi antigens. • S.typhi survives intracellularly in various organs. • It is readily killed by drying, pasteurisation & common disinfectants.
RESERVOIR OF INFECTION • Man is the only known reservoir of infection, viz cases and carriers. • A case is infectious as long as bacilli are in stools or urine. • Carriers :- • They may be temporary (incubatory or convalescent) or chronic. • Convalescent carriers excrete bacilli for 6-8 wks. • Chronic carriers excrete for more than 1yr. Eg: Typhoid Mary, who gave rise to 1300 cases in her lifetime.
SOURCE OF INFECTION • Primary sources of infection are faeces and urine of cases and carriers. • Secondary sources are contaminated water, food, fingers and flies.
Age :-It may occur at any age. Highest incidence occurs in the 5-19yrs of age group. • Sex :-More cases are reported among males, probably as a result of increased exposure to infection. Carrier state is more in females. • Immunity :-Antibody may be stimulated by infection or by immunization. However the antibody to somatic antigen (O) is usually higher in patient with disease & antibody to flagellar antigen (H) is more in immunized individuals. • Host factors that contribute to resistance against S.typhi are gastric acidity and local intestinal immunity.
Present throughout the year, peak incidence during July-September. • Survive for over a month in ice & ice-cream. • Up to 70 days in soil irrigated with sewage under moist winter conditions. • They may also survive and multiply in milk, vegetables and food. • Social factors such as pollution of drinking water supplies, open air defecation and urination, low standards of food personal hygiene and health ignorance.
Incubation Period:- It is usually 10-14 days. It may be as short as 3 days or as long as 3 weeks depending on the dose of bacilli ingested.
Modes of transmission Water Mouths of well persons Faeces and urine from cases and carriers Foods raw or cooked Soil Flies Fingers
Onset :- Usually insidious, but in children may be abrupt with chills & rigor. • Prodromal stage :- There is malaise, headache, cough & sore throat often with abdominal pain & constipation. • Fever ascends in a step ladder fashion. • After about 7-10 days, fever reaches plateau, patient is toxic, exhausted. • Marked constipation, especially in early stage or “pea soup” diarrhoea, abdominal distention. • If no complications, recovery in 7-10 days.
Diagnosis • Physical findings: • Splenomegaly • Abdominal distention & tenderness. • Relative bradycardia • Dicrotic pulse • Meningsmus (occasionally) • Rose spots
Complications • Occur in about 30% of untreated cases & account for 75% of all deaths due to typhoid fever. • Intestinal hemorrhage • Intestinal perforation • Less frequent are : • Urinary retention • Pneumonia • Thrombophlebitis • Myocarditis • Psychosis, nephritis, osteomyelitis
Control of typhoid fever can be done by • Control of reservoir • Control of sanitation • Immunization
Control of reservoir It consists of • Cases • Carriers
Cases • Early diagnosis : Culture of blood & stools are important as the symptoms are non-specific. • Notification : This should be done where such notification is mandatory. • Isolation : Cases are better transferred to a hospital for better treatment, as well as to prevent the spread of infection.
Treatment • Chloramphenicol is the drug of choice. For adults, dose of 500mg (50mg/kg body wt), 4hrly while febrile & thereafter 500mg 6hrly. • Cotrimoxazole, amoxycillin & trimethoprim are equally active. • Ciprofloxacillin is drug of choice now. • Patients seriously ill may be given an injection of hydrocortisone 100mg daily for 3-4 days.
Disinfection : • Stools & urine are disinfected with 5% cresol for 2hrs. • Soiled clothes & linen are disinfected with 2% chlorine & steam sterilized. • Nurses & doctors must disinfect their hands. • Follow up : • Examination of stools & urine must be done for S.typhi 3-4 months after discharge of patient & again after 12months.
Carriers • Identification : • Identified by culture & serological examinations • Duodenal drainage establishes presence of salmonella in biliary tract of carriers. • Vi antibodies are present in 80% of chronic carriers. • Treatment : • An intensive course of ampicillin (4-6g a day) together with probenecid ( 2g/day) for 6 wks.
Surgery : • Cholecystectomy with concomitant ampicillin therapy is regarded as most successful treatment for carriers with success rate of 80%. • Urinary carriers are easy to treat, but refractory cases may need nephrectomy when one kidney is damaged and the other healthy. • Surveillance : • Carriers should be prevented from handling food, milk or water for others. • Health education : • Health education regarding washing of hands with soap, after defecation & urination, before preparing food is an essential element.
Control of sanitation • Protection & purification of drinking water supplies. • Improvement of basic sanitation. • Promotion of food hygiene.
Immunization • Immunization is recommended to • Those living in endemic regions • Household contacts • Groups at risk of infection, such as hospital staff & school children • Travellers proceeding to endemic areas • Those attending melas & yatras
Anti-typhoid vaccines currently available in India are • Monovalent anti-typhoid vaccine : agar grown, heat killed & phenol preserved vaccine, contains 1,000 million of S.typhi per ml. • Bivalent anti-typhoid vaccine : contains 1,000 million & 500 million of S.typhi & S.paratyphi A, respectively, per ml. • TAB vaccine : contains S.typhi (1,000 million), S.paratyphi A (500-750 million), S.paratyphi B (500-750 million) organisms per ml.
Dosage & route of administration • Primary immunization : • 2doses ( each of 0.5ml), given subcutaneously, at an interval of 4-6 wks. • Children between 1-10yrs are given smaller doses (0.25ml). • Immunity develops in 10-21 days & lasts for 3yrs. • Booster doses : • They are recommended every 3yrs. • Storage : • stored in a refrigerator at 20-40C.
Typhoral • It is live oral Ty 21a vaccine • Contains about 109 S.typhi strain Ty 21a. • Indicated for immunization of adults and children more than 6yrs of age. • 1 capsule is administered on days 1,3,5, 1hr before a meal with lukewarm water or milk. • Protection commences 2wks later & lasts for 3yrs. • Booster doses are recommended once in 3yrs.
