Typhoid Fever

Typhoid fever is a febrile systemic illness caused by Salmonella typhi.  Paratyphoid fever is a pathologically and clinically similar illness caused by many species of salmonellae.

Typhoid and paratyphoid fever are found throughout the world, but are most common in the developing countries of the tropics and subtropics.  Both are primarily transmitted by fecally contaminated food and water.  S.typhi only infects humans.

The incubation period is generally 7-14 days, but may range from 3 to 60 days, even if you have no symptoms.  Both typhoid and paratyphoid fever present as a febrile, systemic illness, generally within a disturbance of bowel function (diarrhea or constipation).  During the first week of the illness it is clinically indistinguishable from any other febrile illness.  Anyone with a fever lasting more than a week with exposure to typhoid should be evaluated.

Diagnosis can only be confirmed by culture of Salmonella sp., most commonly from bone marrow aspirate, blood, duodenal aspirate, or stool, in that order.  The Widal and other serologic tests are sometimes useful for diagnosis.

A number of antimicrobials including chloramphenicol, ampicillin, trimethoprimsulfa-methoxazole, quinolones, and third generation cephalosporins are effective for treatment.  Patients with abnormal level of consciousness or shock should be admitted to an ICU and treated with antimicrobials and high doses of dexamethasone.

Travelers should exercise caution regarding ingestion of food and water.

Vaccines

A parenteral inactivated and an oral live vaccine for typhoid, but not for paratyphoid fever, are available and effective.  Neither of these vaccines provides complete protection, but they can be expected to protect the majority of travelers.  The oral vaccine, Ty21a (Vivotif) is the preferred vaccine.  It should be given every other day until four doses are administered.  Ideally, the vaccine should NOT be given for at least 7 days after antibiotics, nor should antibiotics be started for at lest 7 days after completing the oral typhoid vaccine. If even this is not feasible OR if mefloquine is to be used within 24 hours of a dose of the oral typhoid vaccine, the injectable vaccine should be used instead.  Oral vaccine is effective for 5 years; injectable vaccine is effective for 2 years total. 

Both vaccines are 80% protective in 14 days and 100% protective in 30 days.

Make your appointment at the SHS Travel Clinic by calling (858) 534-8089.