Typhoid in East Africa - tips - Diani Beach Hospital

Risk for travellers
Typhoid vaccination is not required for international travel, but it is recommended for travelers to areas where there is a recognized risk of exposure to S. typhi. Risk is greatest for travelers to the Indian subcontinent and to other developing countries (in Asia, Africa, and Central and South America) who will have prolonged exposure to potentially contaminated food and drink. Vaccination is particularly recommended for those who will be traveling in smaller cities, villages, and rural areas off the usual tourist itineraries. Travelers should be cautioned that typhoid vaccination is not 100% effective and is not a substitute for careful selection of food and drink.

Preventive Measures
Vaccine
Two typhoid vaccines are currently available for use

an oral, live-attenuated vaccine (Vivotif BemaTm vaccine, manufactured from the Ty21 a strain of S. typhi by the Swiss Serum and Vaccine Institute) and
a capsular polysaccharide vaccine (VICPS) (Typhim Vi, manufactured by, Pasteur Merieux) for parenteral use. Both vaccines have been shown to protect 50% to 80% of recipients. The parenteral heat-phenol-inactivated vaccine (manufactured by Wyeth-Ayerst) has been discontinued.

Adverse Reactions
Information is not available on the safety of these vaccines when they are used during pregnancy; it is prudent on theoretical grounds to avoid vaccinating pregnant women. Live, attenuated Ty2 I a vaccine should not be given to immunocompromised travelers, including those infected with human immunodeficiency virus (HIV). The parenteral vaccine presents theoretically safer alternatives for this group. The only contraindication to vaccination with VICPS vaccine is a history of severe local or systemic reactions following a previous dose. Neither of the available vaccines should be given to travelers with an acute febrile illness.

Precautions and Contraindications
Theoretical concerns have been raised regarding the immunogenicity of live, attenuated Ty21 a vaccine in people concurrently receiving antibiotics, immune globulin, antimalarials, or viral vaccines. The growth of the live Ty2la strain is inhibited in vitro by various antibacterial agents and by the antimalarial prophylactic agent mefloquine. Simultaneous administration of the antimalarial prophylactic agent proguanil with Ty2 I a vaccine resulted in significantly lower combined IgG or IgA anti-S. typhi lipopolysaccharide antibody response. The anti-S. typhi lipopolysacchaiide antibody response was not significantly decreased when mefloquine was administered concurrently with Ty2 Ia. Vaccination with Ty2Ia should not be administered concurrently with proguanil prophylaxis and should be delayed for more than 24 hours after the administration of any antibacterial agent or mefloquine. Chloroquine does not significantly inhibit the growth of Ty21a or the antis typhi antibody response, and can be given concurrently. Available data do not suggest that simultaneous administration of oral polio or yellow fever vaccine decreases the immunogenicity of Ty2la. If typhoid vaccination is warranted, it should not be delayed because of the administration of viral vaccines. Simultaneous administration of Ty2l a and immune globulin does not appear to pose a problem.

The side effects of Ty2la are rare and mainly consist of abdominal discomfort, nausea, vomiting, and rash or urticaria.