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| TYPHOID FEVER |
Disease
Typhoid fever is systemic disease characterized by fever and abdominal pain and is caused by dissemination of S typhi or S para typhie. The infection is transmitted by consumption of contaminated food or drink. Incubation period is between 5-14 days. The infection localizes primarily in the lymphoid tissue of the small intestine but may disseminate to lungs, gall bladder, kidneys or CNS. The incubation period for S typhie averages 10-14 days. The most prominent symptom is prolong fever which ascends in a stepwise fashion. Other features include headache, chills, cough, sweating, myelgia, malaise, arthregia, anorexia, abdominal pain, nausea and vomiting. The rash (rose spots) commonly appears during the second week and found principally on the trunk. These rashes disappear within 3-4 days after the appearance.
Occurrence
The incidence is highest in developing countries which lack adequate sewage disposal and water treatment.
Risk for travellers
All travellers to endemic areas are at potential risk of typhoid fever, although the risk is generally low in tourist and business centers where standards of accommodation, sanitation and food hygiene are high. The risk is particularly high in the Indian subcontinent. Even vaccinated individuals should take care to avoid consumption of potentially contaminated food and water as the vaccine does not confer 100% protection.
Vaccine
Typhoid immunization is advised for travellers to areas where sanitation standards may be poor, although it is not a substitute for scrupulous personal hygiene. Immunization is also advised for laboratory workers handling specimens from suspected cases.
Capsular polysaccharide typhoid vaccine is usually given by intramuscular injection in a single dose and produces protection 7 days after the injection. Young children may respond sub optimally to the vaccine, but children aged between 1-2 years should be immunized if the risk of typhoid fever is considered high (immunization is not recommended for infants under 12 months). Booster doses are needed every 3 years on continued exposure.
An oral typhoid vaccine is also available. The duration of protection following oral vaccine is not well defined and may vary with vaccine dose and possibly subsequent exposure to S-Typhi infection. It is a live attenuated vaccine contained in an enteric-coated capsule. It is taken by mouth as 3 doses of one capsule on alternate days, providing protection 7-10 days after the last dose. Protection may persist for up to 3 years in those constantly (or repeatedly) exposed to Salmonella typhi, but occasional travellers require further courses at intervals of 1 year.
Oral typhoid vaccine is contra-indicated in individuals who are immunosuppressed (whether due to a disease or its treatment) and in acute gastro-intestinal illness. Oral typhoid vaccine is inactivated by concomitant administration of antibacterial or antimalarials. Administration of a dose of oral typhoid vaccine should be coordinated so that mefioquine is not taken for at least 12 hours before or after a dose; vaccination with oral typhoid vaccine should preferably be completed at least 3 days before the first dose of mefloquine or other antimalarials (except proguanil hydrochloride with atovaquone, which may be given concomitantly).
These vaccines are not recommended for use in infant immunization programmes:
There is insufficient information on their efficacy in children under 2 years of age. |
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