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PRACTICE

132 JAMC 22 JUILL. 2003; 169 (2)

2003 Canadian Medical Association or its licensors

Background and epidemiology:Ty-phoid fever is a systemic bacterial infec-tion caused by Salmonella typhi. Typhoid

is usually acquired through ingestion ofwater or food contaminated by the urineor feces of infected carriers and, as such,is a common illness in areas where sani-tation is poor. One of the most famouscarriers was Typhoid Mary, a cook whoinfected at least 51 people.1Today, out-breaks of typhoid fever occur most oftenin developing countries, in refugeecamps and in overwhelmed areas with ahigh population density. In some areasthe annual incidence is as high as 198cases per 100 0002 and, contrary to a

previously held view, the disease causesconsiderable morbidity in children.3

Worldwide, at least 17 million newcases and up to 600 000 deaths are re-ported annually.4 The disease is lesscommon in North America: an esti-mated 400 cases are reported each yearin the United States, 70% occurring intravellers returning from endemic areas.5

The case-fatality rate of typhoid feveris 10%, but it can be reduced to 1% withappropriate antibiotic treatment.4

Infections with other Salmonella bac-

teria also occur. Paratyphoid fever isalso a systemic disease, caused by Sal-monella paratyphi. Its presenting symp-toms are similar to those of typhoidfever, but they are milder and the case-fatality rate is much lower.

The other pattern of Salmonella in-fection is primarily enteric (food poi-soning) and can occur with exposureto one of hundreds of different Salmo-nella species.

Clinical management:Although in most

cases a transient and mild episode of di-arrhea develops shortly after ingestingS. typhibacteria, most cases are asymp-tomatic during an incubation period of714 days. The disease manifests mostoften a week or so after ingestion andbegins with an intermittent fever thatbecomes high and sustained, severeheadache, poorly localized abdominaldiscomfort, malaise and anorexia. Theremay also be a nonproductive cough. Al-

though the focus of the infection is theintestine, constipation is more commonthan diarrhea in adults. The reverse is

true in AIDS patients and children.Physical signs are few. Bradycardia

in the presence of high fever, once con-sidered a hallmark of typhoid fever, isnot common. The abdomen may betender to palpation, with poorly local-ized discomfort. Rose-coloured spots(small maculopapular blanching lesions)appear on the trunk of about 25% ofpatients with light skin. The spots areless frequent and more difficult to lo-cate in people with darker skin. Labora-tory screening may reveal a normal

hemoglobin level, normal leukocyteand platelet counts, and elevated liverenzyme levels.6

Complications occur in 10%15%of cases; gastrointestinal bleeding, per-foration and typhoid encephalopathyare the most serious. Gastrointestinalbleeding can occur in up to 10% ofcases, most likely from intestinal ero-sion, but it is clinically significant inonly 2% of cases.6

Typhoid fever is diagnosed by meansof bacterial culture. Blood culture is usu-

ally done and is most sensitive in the firstweek of illness. Bone marrow culture ismore sensitive than blood culture, re-gardless of the duration of illness ortreatment with antibiotics, but it is tech-nically more difficult to perform. Fecalculture yields positive results in onlyone-third of cases. Serologic testing forSalmonella antibodies (Widals test) ispossible but shows cross-reactivity withsome other Salmonella species and has asensitivity of only 70%.

Treatment of typhoid fever is with

antibiotics, usually fluoroquinolones.Chloramphenicol, amoxicillin and tri-methoprimsulfamethoxazole remainreasonable choices when quinolones areunavailable. Unfortunately, resistanceof S. typhistrains to all of these drugs isbecoming more common, particularlyin Asia, the Middle East and Latin

America. As such, appropriate treat-ment varies with geographic distribu-tion of resistant strains. In resistant

cases, consideration is given to a longerduration of quinolone therapy or totreatment with azithromycin or a third-

generation cephalosporin.6

Prevention and control:Preventionmeasures target handwashing, sanitarydisposal of human feces, provision ofsafe public water supplies, controlling offlies, scrupulous food preparation, andpasteurization of milk and other dairyproducts. In addition, because manyseafood beds are contaminated withsewage, attention is given to limiting thecollection and marketing of shellfish toapproved sources, and to steaming or

boiling shellfish for at least 10 minutes.Immunity is conferred after infection

or through vaccination. In either case, itis only temporary. Typhoid fever vac-cine can be given orally or parenterally,and the efficacy of, and adverse reac-tions to, each type differ.7Vaccination isoften recommended for people travel-ling to endemic regions, although thecost-effectiveness of this strategy hasbeen questioned.7 The effectiveness ofmass vaccination in endemic regions isundergoing further study but should be

considered in high-risk situations, suchas disaster relief sites and refugee camps.

James MaskalykEditorial FellowCMAJ

Refererences1. Brooks J. The sad and tragic life of Typhoid

Mary. CMAJ1996;154(6):915-6.2. Lin FY, Vo AH, Phan VB, Nguyen TT, Bryla

D, Tran CT, et al. The epidemiology of typhoidfever in the Dong Thap Province, MekongDelta region of Vietnam. Am J Trop Med Hyg2000;62:644-8.

3. Sinha A, Sazawal S, Kumar R, Sood S, Reddaiah

VP, Singh B, et al. Typhoid fever in childrenaged less than 5 years.Lancet1999;354:734-7.

4. Typhoid fever [fact sheet N149]. Geneva: WorldHealth Organization; 1997. Available: www.who.int/inf-fs/en/fact149.html (accessed 2003 June 23).

5. Typhoid fever. Atlanta: US Centers for DiseaseControl and Prevention; 2001 June 20. Avail-able: www.cdc.gov/ncidod/dbmd/diseaseinfo/typhoidfever_g.htm (accessed 2003 June 23).

6. Parry CM, Hien TT, Dougan G, White NJ,Farrar JJ. Typhoid fever [review]. N Engl J Med2002;347(22):1770-82.

7. Engels EA, Falagas ME, Lau J, Bennish ML. Ty-phoid fever vaccines: a meta-analysis of studieson efficacy and toxicity. BMJ1998;316:110-6.

Typhoid fever

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