What are the features of rabies during the incubation period?

Updated: Jun 21, 2019
  • Author: Sandra G Gompf, MD, FACP, FIDSA; Chief Editor: Michael Stuart Bronze, MD  more...
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The rabies virus is segregated from the immune system during this period, and no antibody response is observed. The infected individual remains asymptomatic during this period. The average duration of incubation is 20-90 days. In more than 90% of cases, incubation is less than 1 year. A person whose inoculum occurs with a scratch on the hand may take longer to develop symptoms of rabies than a person who receives a bite to the head. The incubation period is less than 50 days if the patient is bitten on the head or neck or if a heavy inoculum is transferred through multiple bites, deep wounds, or large wounds. Infected patients may not recall exposure because of the prolonged incubation period.

Rarely, incubation has been reported many years following exposure. In cases of salivary exposure, incubation has been estimated based on molecular, phylogenetic, and epidemiologic evidence to be greater than 6-8 years. [22, 23, 24, 25] A suspected prolonged incubation of 25 years was reported in India with no identifiable risk factors other than a dog bite occurring in a time frame and location coincident with the likelihood of rabies in local dogs. [6]

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