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Protecting travelers from typhoid fever
1Department of Medicine, Shadyside Hospital, Pittsburgh, Pennsylvania 15232.
Infection Control and Hospital Epidemiology
|March 1, 1991
Summary
Typhoid fever cases from foreign travel are rising. Oral live attenuated vaccines offer improved efficacy and safety compared to older parenteral vaccines, but travelers must still practice food and water precautions.
Area of Science:
- Infectious Diseases
- Vaccinology
- Travel Medicine
Background:
- Domestic typhoid fever incidence is decreasing, but travel-related cases are increasing.
- Older heat-phenol-inactivated parenteral vaccines have moderate efficacy and significant adverse reactions.
- Newer oral live attenuated vaccines represent a significant advancement in typhoid fever prevention.
Purpose of the Study:
- To review the efficacy and safety of available typhoid fever vaccines.
- To inform healthcare providers and travelers about optimal vaccination strategies.
- To highlight the limitations of current vaccines and the importance of continued precautions.
Main Methods:
- Review of existing literature on typhoid fever vaccines.
- Comparison of efficacy, safety, and administration of parenteral and oral vaccines.
- Discussion of emerging vaccine candidates and their potential.
Main Results:
- Oral live attenuated Ty21a vaccine (three doses) shows 69% efficacy for at least four years.
- Parenteral purified Vi polysaccharide vaccine (not US-available) offers 64-72% protection over 21 months.
- New auxotrophic (Aro-, Pur-) S typhi vaccines are under evaluation.
Conclusions:
- Travelers to high-risk areas should be vaccinated but must maintain food and water safety.
- No typhoid vaccine is 100% effective; large bacterial inocula can overcome protection.
- Differential diagnosis is crucial as other febrile illnesses can mimic typhoid.