#Typhoid Fever
Parajuli SB, 2026 (www.suryaparajuli.com.np)
Community Medicine (Kathmandu University) | MBBS 6th Semester |
#๐น Specific Learning Outcomes (SLOs)
#At the end of the session, the learner will be able to:
State the โGolden 3โ basics of typhoid fever
Describe the problem statement of typhoid fever
Explain the epidemiological determinants of typhoid fever
Identify the clinical features, diagnostic approaches, and treatment options for typhoid fever
Discuss the prevention and control measures
Describe the principles and importance of typhoid fever surveillance
#Golden 3 Basic of Typhoid Fever
Typhoid fever is an acute systemic infectious disease caused by Salmonella enterica serovar Typhi, transmitted through contaminated food and water via the fecalโoral route.
It presents with prolonged fever, headache, abdominal pain, weakness, relative bradycardia, and may lead to intestinal hemorrhage or perforation if untreated.
Management includes appropriate antibiotics (e.g., ceftriaxone or azithromycin), hydration, and supportive care; prevention involves safe water, sanitation, hand hygiene, safe food practices, and typhoid vaccination.
#๐ Global Burden of Disease
๐ฆ Typhoid fever occurs worldwide, predominantly in regions with inadequate water supply and poor sanitation.
It has become uncommon in developed countries due to improved living conditions and antibiotic availability, with most cases being imported.
#๐ According to WHO estimates:
๐ฅ 11โ20 million cases annually
โฐ๏ธ 128,000โ161,000 deaths per year
๐ Majority of cases occur in Asia
๐ถ Children of school age and younger are disproportionately affected
๐ Since the 1950s, antimicrobial resistance has emerged as a major challenge, particularly in Asia and the Middle East. Multidrug-resistant (MDR) S. Typhi strains have caused outbreaks in India and Pakistan and are associated with increased severity, complications, and mortality.
โ ๏ธ Without treatment, case fatality may reach 10โ20%
#Typhoid Fever in Nepal
๐ Typhoid fever is endemic in Nepal.
๐ Global Burden of Disease estimates indicate a high disease burden, particularly among children and adolescents.
๐๏ธ Community-based studies have reported high incidence rates, especially in Kathmandu Valley and peri-urban areas.
๐ฐ The burden is higher in areas with poor water supply, inadequate sanitation, and overcrowding.
โ ๏ธ Typhoid fever remains underreported and is considered an important indicator of sanitation, water safety, and socioeconomic development in Nepal.
#Typhoid Fever in India
๐ Typhoid fever is endemic in India.
๐ National Health Profile 2021 data (2020):
๐ฅ 1.069 million cases
โฐ๏ธ 126 deaths
๐ Highest burden reported from:
๐บ๏ธ Uttar Pradesh
๐บ๏ธ West Bengal
๐บ๏ธ Karnataka
๐บ๏ธ Telangana
#๐งฌ Epidemiological Determinants
#Agent Factors
๐ฆ Causative agent: Salmonella Typhi
๐งช Paratyphoid fever: S. Paratyphi A and B (less common)
#๐งฉ Antigens:
๐งฑ O (somatic)
๐ H (flagellar)
๐ก๏ธ Vi (capsular)
๐งซ Intracellular survival in reticuloendothelial system
๐งฌ Multiple phage types (useful for outbreak investigation)
โ ๏ธ Disease severity influenced by infecting dose and virulence
#๐ง Reservoir of Infection
๐ฅ Humans are the only reservoir
#๐ Cases
๐ก Mild, severe, or missed
๐ Infectious as long as bacilli are excreted in stool or urine
#๐ถ Carriers
โณ Temporary: incubatory or convalescent
๐ฐ๏ธ Chronic: excretion >1 year
๐ Chronic carrier rate: 2โ5%
๐ซ Gall bladder is the common site of persistence
๐ฉ Faecal carriers more common than urinary carriers
๐ Classic example: Typhoid Mary
#๐งช Source of Infection
๐ข Primary: feces and urine of cases or carriers
๐ Secondary: contaminated water, food, fingers, flies
๐ซ No evidence of excretion in sputum or milk
#๐ค Host Factors
๐ Age: Highest incidence in 5โ19 years
๐๏ธ High incidence also documented in children <5 years in urban slums
๐ป Sex: Higher incidence in males; higher carrier rate in females
#๐ก๏ธ Immunity
๐งฌ Cell-mediated immunity plays a major role
๐งช Antibodies (O and H) are not protective
๐ Natural infection does not always confer lasting immunity
โ๏ธ Other factors: Gastric acidity and local intestinal immunity
#๐ Environmental and Social Factors
๐ Occurs year-round with peak during JulyโSeptember
๐ง๏ธ Coincides with rainy season and increased fly density
#๐งซ Survival of bacilli:
๐ฐ Water: up to 7 days
๐ง Ice and ice cream: >1 month
๐ฑ Soil: up to 70 days
๐ฅ Milk: rapid multiplication without change in taste
#โ ๏ธ Contributing factors:
๐ฑ Unsafe drinking water
๐ฝ Open defecation
๐ฝ๏ธ Poor food hygiene
๐ Low health awareness
๐ Typhoid fever is regarded as an index of general sanitation.
#โฑ๏ธ Incubation Period
๐ Usually 10โ14 days
๐ Range: 3 days to 3 weeks
โ๏ธ Depends on infecting dose
#๐ Modes of Transmission
๐ฉโก๏ธ๐ Fecalโoral route
๐ฝโก๏ธ๐ Urineโoral route
โ Direct: contaminated hands
๐ฐ Indirect: water, food, milk
๐ชฐ Mechanical transmission by flies
๐ Transmission is influenced by social, cultural, and economic factors affecting quality of life.
#๐ฉบ Clinical Features
โณ Insidious onset (abrupt in children)
๐ Step-ladder rise of fever
๐ค Malaise, headache, cough, sore throat
๐คข Abdominal pain, constipation or pea-diarrhea
๐ง Splenomegaly, abdominal distension
โค๏ธ Relative bradycardia, dicrotic pulse
๐น Rose spots during second week
๐งช Leukopenia common
๐ Relapse may occur within 2 weeks of treatment completion
#โ ๏ธ Complications
๐ Seen in up to 10% of cases, especially if untreated:
๐ฉธ Intestinal hemorrhage
๐ณ๏ธ Intestinal perforation (usually 3rd week)
๐ซ Pneumonia
โค๏ธ Myocarditis
๐ง Psychosis
๐ซ Cholecystitis
๐ฉบ Nephritis
๐ฆด Osteomyelitis
#๐งช Laboratory Diagnosis
#Microbiological
๐ฉธ Blood culture: Gold standard
๐ฆด Bone marrow culture: Highest sensitivity
๐ฉ Stool culture: Positive later in illness
#๐งซ Serological
๐งช Widal test
๐ก O antibodies: day 6โ8
๐ต H antibodies: day 10โ12
โ๏ธ Moderate sensitivity and specificity
โ ๏ธ False positives and false negatives common
#โก Rapid Diagnostic Tests
๐งฌ Tubexยฎ
๐งช Typhidotยฎ and Typhidot-Mยฎ
๐งท IgM dipstick tests
๐ Useful for rapid diagnosis but do not replace culture.
#๐ก๏ธ Control of Typhoid Fever
#๐ Three main strategies:
๐ง Control of reservoir
๐ฐ Control of sanitation
๐ Immunization
โ ๏ธ Sanitation is the weakest and most critical link.
#๐ง Control of Reservoir
#Cases
๐ Early diagnosis
๐ข Notification
๐ช Isolation until 3 consecutive negative stool and urine cultures
๐ Antibiotic treatment (fluoroquinolones, azithromycin, cephalosporins)
๐งผ Disinfection of stools, urine, linen
๐ Follow-up cultures at 3โ4 months and 12 months
#Carriers
๐งช Identification by culture and Vi antibodies
๐ Prolonged antibiotic therapy
๐ช Cholecystectomy in refractory cases
๐จโ๐ณ Surveillance and restriction from food handling
๐ Health education
โ ๏ธ Carrier management remains a major challenge in elimination.
#๐ฐ Control of Sanitation
๐ง Safe drinking water
๐ฝ Proper sewage disposal
๐ฝ๏ธ Food hygiene
๐งผ Personal hygiene
๐ข Health education
๐ Sanitation combined with education produces sustained reduction in disease burden.
#๐ Immunization Against Typhoid
#Vi Polysaccharide Vaccine
๐งฌ Subunit vaccine
๐ Age โฅ2 years
๐ Single dose
๐ Booster every 3 years
โ Safe, minimal adverse effects
๐ซ Not effective in children <2 years
#Ty21a Oral Vaccine
๐ฆ Live attenuated
๐ Age โฅ5 years
๐ 3 doses on days 1, 3, 5
๐ Booster every 3 years (annually for travelers)
๐ Avoid antibiotics around vaccination
โ Contraindicated in immunodeficiency
#๐งช Typhoid Conjugate Vaccine (TCV)
Introduced in Nepal: 2022 into National Immunization Programme (EPI)
Routine Schedule: Single dose at 15 months of age
Co-administered with: MR (Measles-Rubella) vaccine at 15 months
Catch-up Campaign (2022): Given to children 15 monthsโ15 years
Purpose: Protects against Typhoid fever and reduces disease burden among children
#๐ Key Take-Home Messages
๐ Typhoid fever is a preventable but persistent public health problem
๐ฅ Humans are the sole reservoir
๐ฐ๏ธ Chronic carriers sustain transmission
๐ MDR S. Typhi complicates treatment
๐ฐ Sanitation is the cornerstone of control
๐ Vaccines are effective adjuncts, not substitutes
#References
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World Health Organization. Fact sheet. 31 Jan 2018.
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Ramesh Kumar, et al. Ann Nat Acad Med Sci (India). 1988;24(4):255โ257.
Government of India. National health profile 2021. New Delhi: Directorate General of Health Services, Ministry of Health and Family Welfare; 2021.
Basu S, et al. Bull World Health Organ. 1975;52(3):333.
Christie AB. Infectious diseases: epidemiology and clinical practice. 2nd ed. Edinburgh: Churchill Livingstone; 1974.
Mangal HN, et al. Indian J Med Res. 1967;55:219.
World Health Organization. Public health papers No. 38. Geneva: WHO; 1969. p.78.
World Health Organization. Background document: the diagnosis, treatment and prevention of typhoid fever. Geneva: WHO; 2003.
Cvjetanovic B, et al. Bull World Health Organ. 1978;56(Suppl 1):45.