TyphoidTyphoid fever is a systemic infection caused by the gram-negative bacterium (Salmonella enterica, subspecies enterica, serotype typhi) that penetrates the intestine, replicates and enter the bloodstream. The Salmonella bacteria only colonise humans. The case fatality rate is less than 1% if promptly treated with antibiotic therapy but mortality rate can be as high as 20% if untreated. Strains of S. typhi have become increasingly resistant to antibiotics, particularly in South Asia (Threlfall and Ward, 2001). In 2000, the global incidence of typhoid fever was estimated to be 21.7 million with 216,510 deaths per year. About 10% of affected individuals will suffer for at least 3 months excreting the bacteria and 2-5 % become long term carriers (more than 1 year).
SymptomsClinical features ranges from mild fever, diarrhoea, headache, significant body pain to severe disseminated disease with multi-organ involvement in 10-15% cases. Incubation period is from 1- 3 weeks.
TransmissionPrimarily via the oral route following ingestion of food or water contaminated by faeces and occasionally the urine of persons acutely ill with typhoid or those who are chronic carriers. Direct faecal–oral transmission can also occur.
PrevalencePredominant in countries with inadequate sanitation and poor standards of personal and food hygiene. It can be found anywhere in the world but the disease is endemic in Southeast Asia, Middle East, Central and South America, Africa and outbreaks in Easter Europe were reported. Typhoid in the UK are usually imported diseases associated with foreign travel or contact with somebody who has travelled.
VaccinationThere are 2 types of vaccine currently used in the UK. A purified Vi capsular polysaccharide from S. typhi given through injection and an oral typhoid vaccine in an enteric coated capsule.
The injectable is an inactivated, do not contain live organisms and cannot cause the diseases against which they protect. The oral typhoid vaccine is a live, attenuated form, but these have been weakened enough to produce immunity without causing disease.