Incubation period, also called the latent period or latency period, is the time elapsed between exposure to a pathogenic organism, or 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 able to give the disease to others during the incubation period. Examples of incubation periodsIncubation periods can 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.