This presentation is prepared as part of the Course assignment of " EPI 521: Epidemiology of Disease and Health Problem" for the Master's Degree of Public Health (MPH), Pokhara University and can be used as reference materials for Typhoid Fever

1. Epidemiological
Perspective of Typhoid
Presenter:
Jagat Prasad Upadhyay
MPH 2nd Semester
SHAS, Pokhara University
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2. Presentation Outline
• Background
• Distribution of Disease
• Epidemiological Determinant
• Prevention and control measures
• Government Response
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3. Background
• Typhoid fever is a life-threatening infection caused by the
bacterium Salmonella Typhi.
• It is usually spread through contaminated food or water.
Once Salmonella Typhi bacteria are eaten or drunk, they multiply and
spread into the bloodstream.
• Urbanization and climate change have the potential to increase the global
burden of typhoid.
• In addition, increasing resistance to antibiotic treatment is making it easier
for typhoid to spread through overcrowded populations in cities.
• Symptoms include prolonged fever, fatigue, headache, nausea, abdominal
pain, and constipation or diarrhoea. Some patients may have a rash. Severe
cases may lead to serious complications or even death.
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4. Distribution of Disease
• Epidemics of typhoid fever and high endemic disease rates have been
reported in India and countries in South Asia, the Middle East,
Central Africa, and South America.
• An estimated 11–20 million people get sick from typhoid and between
1,28,000 and 1,61,000 people die from it every year.
• In previous five year in Nepal average 4,50,000 infected cases were
identified.
• According to HMIS data, typhoid is the top three water and food borne
disease, and top fourth cause of OPD visit and hospitalization.
• A study conducted by Patan academy of health sciences (PAHS) shows
that around 1062 cases per 1,00,000 were infected, likewise in age
group 0-4 years 764 cases, 5-9 years 6713 and 10-14 years 3750 cases
per lakh.
• Highly Infectious: ≥100 cases per 1,00,000 incidence.
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Source: Guideline For Typhoid Vaccination Campaign And Launching Typhoid Vaccine Into Routine Immunization Programme and WHO

5. Epidemiological Determinant of Typhoid
• Agent: Typhoid and paratyphoid fevers are caused by the bacteria
Salmonella Typhi and Salmonella Paratyphi with serotypes A, B, and C
respectively.
• Reservoir: Human is the only reservoir (Cases and carriers) of Salmonella.
Almost 1-5% of patients have been seen to be chronic carriers
(asymptomatic).
• Sources of infection:
Primary source: feces (more frequent) and urine
Secondary sources: Contaminated water, food, fingers and flies
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6. Epidemiological Determinant of Typhoid
Host
• Age: Occurs at any age but highest incidence among under 15 yrs age
group
• Sex: More cases of typhoid have been seen among males than females
while more carrier rate among females have been observed.
• Immunity: S.Typhi is intracellular organism so cell mediated immunity
plays major role in combating the infection. Immunosuppression such as
HIV infection and inflammatory bowel disease or alteration of the intestinal
flora by antibiotic administration increase susceptibility to Salmonella
infection.
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7. Epidemiological Determinant of Typhoid
Environmental Factors
• Typhoid fever regarded as ‘Index of general sanitation’. Typhoid incidence
increases during monsoon season and peaks during July-September.
• S. Typhi can remain in polluted drinking water supplies up to 2 to 7 days while
soil irrigated with sewage can contain the bacteria up to 35-70 days.
• Similarly, Low standards of food and personal hygiene and health ignorance e.g.,
Milk, Vegetables grown in sewage plants. In milk S. Typhi can grow rapidly
without altering its taste
Incubation period: Usually 10 to 14 days but it may be as short as 3 days or as
long as 21 days depending upon the dose of ingested bacilli. For paratyphoid
fever, incubation period is usually 1-10 days.
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8. Mode of Transmission
• Primarily: Direct
finger-to-mouth
contact with feces,
urine of infected
people.
• Secondary: Ingestion
of contaminated water
and food (especially
dairy products and
shellfish)
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9. Laboratory Diagnosis
• Blood Culture
• Antigen-Antibody Test (Widal Test)
• Stool Culture
• Urine test
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10. WHO Response towards Typhoid
• In December 2017, WHO prequalified the first conjugate vaccine for typhoid. This new
vaccine has longer-lasting immunity than older vaccines, requires fewer doses and can be
given to children from the age of 6 months.
• This vaccine has been prioritized for countries with the highest burden of typhoid disease so
will help to reduce the frequent use of antibiotics for typhoid treatment, which will slow the
increase in antibiotic resistance in S. typhi.
• In October 2017, the Strategic Advisory 6 Group of Experts (SAGE) on immunization,
advised WHO to recommended typhoid conjugate vaccines for routine use in children over 6
months of age in typhoid endemic countries.
• SAGE called for the introduction of typhoid conjugate vaccines to be prioritized for countries
with the highest burden of typhoid disease or of antibiotic resistance to S. Typhi. Shortly after
SAGE’s recommendation, the Gavi Board approved US$ 85 million in funding for typhoid
conjugate vaccines starting in 2019.
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11. Typhoid Vaccines
Vaccine Name Route
Recommended
Number of doses
Time
between
doses
Min age for
vaccination
Booster needed
Vi capsular
polysaccharide
vaccine (Vi-PS)
IM 1 - 2 years Every 2 years
Live attenuated
Ty21a
vaccines
Oral 4 2 days 6 years Every 5 years
Typhoid
Conjugated
Vaccines (TCV)
IM 2 - 6 months 3 years
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12. Government Response
• Introduction of Typhoid Conjugate Vaccine (TCV) into
routine immunization through catch-up campaign from April
2022. The Government is also prioritizing TCV campaign to
identify zero-dose children - children who haven’t received
a single dose of the basic diphtheria, tetanus and pertussis-
containing vaccines (DTP) vaccine.
• Health Education and Promotion Activities and Social
Behaviour Change Communication on Typhoid.
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13. P3CE Activities against Typhoid
• Health Promotion and Education on Typhoid Prevention and
Control
• Environmental Modification; Provision of safe water, Sanitary
latrines, Improvement of housing and sewage management
system, fly control
• Lifestyle and behavioural changes; use of purified drinking
water, personal hygiene, food safety (5 Keys to food safety)
• Vaccination against Typhoid
Prevention
• Promotion of healthy life style and behaviour
• Environmental cleanliness and fly control
• Personal Hygiene and sanitation
• Health Education on Typhoid signs, symptoms and
transmission
Promotion
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14. P3CE Activities against Typhoid
• Specific Protection; Vaccination against Typhoid
• Inactivated Typhoid Vaccine, ViCPS
• Live Typhoid Vaccine (Oral)
Protection
• Reservoir Control; Case detection and treatment, Excreta
management, Carrier identification
• Transmission Control; Breaking chain of transmission,
Food and water sanitation, Safe excreta disposal and
control flies
• Case Identification in Endemic areas
• Rolling vaccination for high-risk populations and for
endemic areas
Control
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15. P3CE Activities against Typhoid
• Community participation in Sewage
management
• Involvement of Media for Public
Awareness
• Public involvement and public health
programs should be including School
Health Programs
Encouragement
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16. Typhoid Guidelines
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17. 2/24/2023 Epidemiological Perspective of Typhoid 17

18. Thank You
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