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Paratyphoid Fever

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Reporting Obligations

Individuals who have or may have paratyphoid fever shall be reported to the local Health Unit.

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Aetiologic Agent

Paratyphoid fever is caused by Salmonella enterica  subspecies enterica serotype Paratyphi A, B and C (commonly S. Paratyphi).

Note that Salmonella Paratyphi B variant Java should be reported as a case of salmonellosis, not paratyphoid fever.

Clinical Presentation

Paratyphoid fever is a systemic bacterial disease which usually presents with fever, headache, and malaise. Other symptoms may include anorexia, constipation, which is more common than diarrhea, bradycardia, non-productive cough, enlargement of spleen, and rose spots on trunk, visible in 25% of light-skinned patients. The clinical picture varies from mild illness with low-grade fever to severe clinical disease with abdominal discomfort and multiple complications. Severity is influenced by factors such as strain virulence, quantity of inoculum ingested, duration of illness before treatment, and age.

Modes of Transmission

Transmitted by the fecal-oral route through the ingestion of food and water contaminated by feces and urine of cases and carriers. Common sources include contaminated milk and milk products, raw fruit and vegetables, and shellfish harvested from contaminated water. Flies may be vectors.

Incubation Period

1–10 days.

Period of Communicability

Communicable as long as organisms are excreted; from the appearance of prodromal symptoms, throughout illness and for periods of up to two weeks after onset.

Risk Factors/Susceptibility

Susceptibility is general and is increased in individuals with gastric achloryhdria and possibly in those who are HIV positive. Relative specific immunity follows recovery from clinical disease and in apparent infection.

Travellers should be referred to travel clinics to assess their personal risk and appropriate preventive measures.

Diagnosis and Laboratory Testing

Laboratory confirmation of infection with or without clinically compatible signs and symptoms (characterized by insidious onset of sustained fever, headache, malaise, anorexia, relative bradycardia, constipation or diarrhea):

  • Isolation of Salmonella Paratyphi A, B, or C (excluding S. Paratyphi B variant Java) from an appropriate clinical specimen (e.g., sterile site, blood, stool, urine).

Enteric culture specimens are accepted only from health units at Public Health Lab. If you are a clinician, please use a community laboratory to perform your testing. Confirmation and speciation however are performed at PH Lab.

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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. With appropriate antibiotic treatment, infected individuals with typhoid or paratyphoid fever usually recover within ten to 14 days. Educate the case about transmission of infection and proper hand hygiene.

Exclude all cases (regardless of symptoms) of S. Paratyphi from food handling, healthcare and daycare activities until provision of 3 consecutive negative stool samples 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). 1 negative urine sample from a confirmed case who has ever traveled to a schistosomiasis-endemic country and may have been exposed to schistosomiasis must also be collected.

Close contacts should be seen by their health care provider and screened for illness (stool specimens sent for testing).

If after 6 samples, a case continues to test positive, then he or she may be in an excreter state.

Patient Information

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Additional Resources

Centers for Disease Control and Prevention. “Typhoid and Paratyphoid Fever.”

Public Health Agency of Canada. “Canadian Immunization Guide. Paratyphoid Fever”


Ministry of Health and Long-Term Care, Infectious Diseases Protocol, 2022.