According to Shayan T. Vyas, MD (2017), “Chickenpox often starts without the classic rash, with a fever, headache, sore throat, or stomachache. These symptoms may last for a few days; with the fever in the 101°–102°F (38.3°–38.8°C) range.” The disease can show up inside the genital area, eyelids, and mouth. 1-2 days before the rash symptoms that may occur include fever, tiredness, loss of appetite, and headaches (National Center for Immunization and Respiratory Diseases, 2016).
The virus spreads easily from people with chickenpox to others who have never had the disease or been vaccinated. The virus spreads mainly by touching or breathing in the virus particles that come from chickenpox blisters, and possibly through tiny droplets from infected people that get into the air after they breathe or talk, for example. It is most contagious on the day before the rash appears.
The Canadian Paediatric Society (2005)