Incubation period is the time elapsed between exposure to a pathogenic organism, a chemical or radiation, and when symptoms and signs are first apparent. The period may be as short as minutes to as long as thirty years in the case of variant Creutzfeldt-Jakob disease.
While Latent or Latency period may be synonymous, a distinction is sometimes made between Incubation period, the period between infection and clinical onset of the disease, and Latent period, the time from infection to infectiousness. Which is shorter depends on the disease.
A person may be a carrier of a disease, such as Streptococcus in the throat without exhibiting any symptoms. Depending on the disease, the person may or may not be contagious during the incubation period.
During clinical latency, an infection is subclinical. With respect to viral infections, in clinical latency the virus is actively replicating. This is in contrast to viral latency, a form of dormancy in which the virus does not replicate.
Clinical latency occurs in:
Examples of incubation periods
Incubation periods vary greatly, and are generally expressed as a range. When possible, it is best to express the mean and the 10th and 90th percentiles, though this information is not always available. The values below are arranged roughly in ascending order by number of days, although in some cases the mean had to be inferred.
For many conditions, incubation periods are longer in adults than they are in children or infants.
- Window period, the time between infection and when lab tests can identify the infection. The window period may be longer or shorter than the incubation period.
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