Typhoid Fever
Reporting Obligations
Confirmed and suspected cases shall be reported to the local Health Unit.
Epidemiology
Aetiologic Agent
Typhoid fever is caused by the Gram negative bacillus known as Salmonella enterica subspecies enterica serotype Typhi (commonly S. Typhi).
Clinical Presentation
The clinical presentation of typhoid fever is highly variable. Typically, symptoms include fever, headache, constipation or diarrhea, fatigue, abdominal pain or discomfort, and loss of appetite. In more severe cases, symptoms may worsen and cause life threatening complications involving many body systems, such as enlargement of the liver and spleen or intestinal bleeding. Constipation is more common than diarrhea in adults. In up to 25% of light-skinned people small erythematous maculopapular lesions (rose spots) on the trunk are seen in the first week of fever. Severity is influenced by factors such as strain virulence, quantity of inoculum ingested, duration of illness before treatment, age, and previous exposure to typhoid vaccination.
Modes of Transmission
Transmitted by the fecal-oral route mainly through the ingestion of food and water contaminated by feces and urine of patients and carriers. Common vehicles include contaminated water, beverages and ice made with contaminated water, shellfish (particularly oysters), contaminated milk and milk products, raw fruit and vegetables grown in fields fertilized with sewage. Sexual transmission of typhoid fever from an asymptomatic carrier has been documented. Other established risk factors include history of contact with other cases especially contact with feces and contact with urine of persons infected from schistosomiasis endemic areas. The risk of transmission increases with improper hand hygiene and poor sanitation. Flies may act as vectors.
Incubation Period
From 3 days to over 60 days; usual range is 8–14 days depending on innoculum size and on host factors.
Period of Communicability
Typhoid fever is communicable as long as S. Typhi is being excreted in stools or urine, usually from one week after symptom onset, through convalescence, and for a variable period thereafter. About 10% of untreated typhoid fever cases have detectable bacteria in their stool for three months after onset of symptoms. Both treated and untreated patients can become chronic carriers (carriage for more than one year following illness).
Risk Factors/Susceptibility
Susceptibility is general and is increased in individuals with gastric achlorhydria and possibly in those who are HIV positive. Relative specific immunity follows recovery from clinical disease, inapparent infection and active immunization. In endemic areas, typhoid fever is most common in preschool children and children 5–19 years of age. Travellers should be referred to travel clinics to assess their personal risk and appropriate preventive measures.
Diagnosis and Laboratory Testing
A confirmed case of Salmonella Typhi is based upon laboratory confirmation of infection with or without clinically compatible signs and symptoms: Isolation of Salmonella Typhi from an appropriate clinical specimen (e.g., sterile site, stool, urine, bone marrow).
Enteric culture specimens are accepted only from health units at the Public Health Lab. If you are a clinician, please use a community laboratory to perform your testing. Confirmation and speciation performed at Public Health Lab.
Treatment and Case Management
Treatment with antibiotics and follow up is under the direction of the attending health care provider. Where possible, physicians should be encouraged to request antibiotic sensitivity testing due to resistant strains.
Inform cases of Inform cases of S. Typhi that they will be excluded from certain activities/occupations including food handling, healthcare and daycare activities until 3 consecutive negative stool samples are collected at least 48 hours apart AND at least 48 hours after completion of antibiotic treatment (for ciprofloxacin) OR at least 2 weeks after completion of antibiotic treatment (for ceftriaxone and azithromycin). With appropriate antibiotic treatment, infected individuals with typhoid or paratyphoid fever usually recover within 10–14 days. Close contacts should be seen by their health care provider and screened for illness.
Patient Information
Additional Resources
Public Health Agency of Canada. “Canadian Immunization Guide, Evergreen edition: Typhoid Vaccine.”
Centers for Disease Control and Prevention. “Typhoid Fever.”
References
Ministry of Health and Long Term Care, Infectious Diseases Protocol, 2022.