Typhoid Vaccine

TYPHOID VACCINE

Typhoid

Typhoid fever is present worldwide and is endemic in the major part of Central America, of South America, of Mexico, of Africa and Asia. It is caused by a bacterium, Salmonella typhi.

Symptoms include intermittent fever, headache, digestive upset, abdominal pains and a skin rash.

Transmission

Typhoid fever is propagated by the ingestion of food or water that is by faeces. Drinking water is probably the most frequent source of contamination. Dairy products and oysters can also be contaminated by the bacterium. The incubation period for Typhoid fever is 3 to 60 days and varies according to the importance of the inoculum. The bacterium initially penetrates the intestinal mucous membrane, multiplies in the intestinal lymphoid follicles , enters various organs (liver, spleen, bone marrow, gall bladder). Reinvasion of the intestine occurs through bile. The bacterium is excreted in the feces.

Prevention

The disease does not confer lasting immunity. Travellers likely to be exposed in countries where the endemicity is high, travelling "off the beaten tourist track, who are immunosuppressed, taking antacids, who have undergone gastrectomy or who are visiting friends abroad, must be vaccinated. Vaccination, albeit imperfect, offers some protection.

Vaccination does not replace precautions regarding water and food. Food distributed by the itinerant salesman is particularly at risk.

Vaccines

Immunization must ideally be started 2 weeks before exposure. 4 capsules of the oral vaccine must be taken, one capsule per day on days 1,3,5,7. The capsule must be taken one hour before a meal with a small amount water and must not be chewed.

The attenuated live oral vaccine can be administered at the same time as other vaccines but must not be taken at the same time as antibiotics. In the case of concurrent antibiotic treatment, immunization must be deferred at least 48 hours after the last antibiotic taken. Mefloquine can also harm the immune response and must be taken at least 8 hours following oral typhoid vaccine. Likewise oral vaccination will have to be deferred 48 hours in the event of diarrhea or vomiting.

A subcutaneous or intramuscular vaccine is also available in the face of inflammatory disease of the intestine, pregnancy or other special situations.

In the majority of cases, the vaccine does not cause any reaction.