What is the recommended treatment and prevention for typhoid fever, including the use of the typhoid injection (Vi polysaccharide vaccine)?

Typhoid Vaccination Recommendations

Typhoid vaccination is recommended for travelers to endemic areas, persons with intimate exposure to typhoid carriers, and laboratory workers who frequently work with S. typhi, but is not recommended for routine use in the United States. 1

Types of Typhoid Vaccines Available

There are two main types of typhoid vaccines currently available in the United States:

1. Oral live-attenuated Ty21a vaccine:

   • Dosage: One enteric-coated capsule taken on alternate days for a total of four capsules
   • Administration: Take with cool liquid (no warmer than 37°C), approximately 1 hour before meals
   • Storage: Must be kept refrigerated
   • Efficacy: Approximately 50-67% effective for up to 3 years 1, 2
   • Booster: Required every 5 years for continued protection 1

2. Injectable Vi polysaccharide vaccine:

   • Dosage: Single 0.5 mL intramuscular injection
   • Efficacy: Prevents around two-thirds of typhoid cases in the first year (69%, high-certainty evidence) 2
   • Protection: Efficacy decreases to approximately 59% in the second year 2
   • Booster: Required every 2 years for continued protection 1

Who Should Receive Typhoid Vaccination

Typhoid vaccination is specifically indicated for:

• Travelers to areas with recognized risk of S. typhi exposure, particularly those visiting developing countries in Latin America, Asia, and Africa who will have prolonged exposure to potentially contaminated food and drink 1
• Persons with intimate exposure to a documented typhoid fever carrier, such as household contacts 1
• Microbiology laboratory workers who frequently work with S. typhi 1

Vaccine Administration Guidelines

Adults and children ≥10 years of age:

• Oral Ty21a vaccine: One capsule every other day for a total of four capsules
• Vi polysaccharide vaccine: 0.5 mL intramuscular injection (single dose)

Children <10 years of age:

• Oral Ty21a vaccine: Same dosage as adults, but experience is limited in children under 5 years
• Vi polysaccharide vaccine: Can be used in children ≥2 years of age 1

Important Considerations and Precautions

1. Vaccine efficacy is not 100%:

   • Careful selection of food and drink remains essential even after vaccination 1
   • Protection can be overwhelmed by large inocula of S. typhi 1

2. Contraindications:

   • Live-attenuated Ty21a vaccine should not be used in immunocompromised persons, including those with HIV 1
   • Theoretical concerns exist about immunogenicity when used concurrently with antimicrobials, viral vaccines, or immune globulin 1

3. Adverse reactions:

   • Vi polysaccharide vaccine: Swelling and pain at injection site are common but fever and erythema are not significantly increased 2
   • Ty21a vaccine: Generally well-tolerated with minimal gastrointestinal side effects 2

Treatment of Typhoid Fever

For confirmed typhoid fever cases, ciprofloxacin is FDA-approved for treatment:

• Dosage: 500 mg orally every 12 hours for 10 days 3
• Caution: Increasing resistance to fluoroquinolones has been observed, particularly among travelers to South and Southeast Asia 1

Key Points to Remember

• Typhoid vaccination is not a substitute for careful food and water hygiene in endemic areas
• Neither vaccine protects against Salmonella Paratyphi A, B, or C infection 1
• Increasing antibiotic resistance, including to fluoroquinolones, is a growing concern 1
• The Vi polysaccharide vaccine has higher efficacy in the first year (69%) compared to subsequent years 2
• Booster doses are essential for maintaining protection: every 5 years for oral vaccine and every 2 years for injectable vaccine 1

Common Pitfalls to Avoid

1. Assuming vaccination provides complete protection: Even vaccinated individuals can contract typhoid fever if exposed to large bacterial loads
2. Neglecting food and water precautions: Vaccination should complement, not replace, careful selection of food and drink
3. Missing booster doses: Protection wanes over time, requiring boosters at appropriate intervals
4. Using typhoid vaccine for inappropriate indications: Not recommended for routine use in the United States, during natural disasters, or for rural summer camp attendees 1