Incubation Period for Typhoid Fever
The typical incubation period for typhoid fever is approximately 2 weeks (14 days), with a range of 9.7 to 21.2 days depending on various factors including inoculum size, vaccination history, and host immune response. 1, 2
Standard Incubation Timeline
The median incubation period is 2 weeks (14 days) based on outbreak investigation data from the United States spanning 1960-1999. 2
The mean incubation period ranges from 9.7 to 21.2 days across different outbreak subgroups, with significant heterogeneity between studies. 1
The average duration of fever before diagnosis is 14.1 days (range up to 30 days), though this represents time to diagnosis rather than true incubation period. 3
Factors That Influence Incubation Period
Previous vaccination history may prolong the incubation period, with vaccinated individuals clustered in subgroups reporting the longest incubation periods (up to 21.2 days). 1
Attack rates during outbreaks may be associated with incubation period length, though this relationship requires further investigation with individual patient data. 1
The ingested inoculum size, strain virulence, and host immune response all influence the pathogenesis and likely affect the incubation period duration. 4
Clinical Surveillance Implications
79% of US typhoid cases report foreign travel within 30 days before symptom onset, which aligns with the typical 2-week incubation period plus illness duration. 5
Healthcare workers and laboratory personnel exposed to S. Typhi should be monitored for symptom development for at least 2-3 weeks post-exposure. 5
Important Clinical Pitfalls
Do not rule out typhoid fever based solely on timing if the patient has had potential exposure within the past month, as incubation can extend beyond the typical 2-week period. 1
Consider that vaccinated individuals may have longer incubation periods, potentially delaying diagnosis if clinicians expect symptoms within the standard 2-week window. 1
The incubation period represents time from exposure to symptom onset, not time to diagnosis—patients often present much later due to non-specific initial symptoms. 3