Studies have concluded that 75% to 90% of the cases of chickenpox were encountered in children aged less than 10. Every year, 10% of those between 5 and 9 years old and 2% of those aged 10 to 14 develop chickenpox every year. All these percents will decrease in a few years, when the young vaccinated children will get older.
It seems that the disease appears in late winter and early spring months and is transmitted through saliva, sneezing and coughing. Generally towels, bed sheets, and clothes are not responsible for the transmission of the disease.
The spreading of the disease is possible within two days before the spots appear on skin and the end of the blister stage. This means five to seven days of possible contamination. After the dry scabs form the rate of contamination decreases. Therefore, it is best to keep away your child from any contacts, including from going to school, for about 10 days.
Once your child has had chickenpox he is exposed to shingles too for the rest of his life. 10 to 20% of those who have had chickenpox will suffer from shingles later. In US, 600,000 to 850,000 people develop shingles every year and the number of affected people is increasing every year.
It seems that the risk of getting shingles (herpes zoster) is increasing with the age. More rarely, children can get herpes zoster too. 5% of those aged under 15 have developed shingles. It seems that this happens if the child has a weakened immune system or if he had chickenpox before he was one years old.
The risk of developing shingles is increased for those who have problems with their immune system like those who have AIDS, cancer, diabetes. Those who follow a treatment for AIDS containing protease inhibitors are also exposed to shingles. 15% of those who have Hodgkin's disease, lymphomas and other cancers and are following chemotherapy are at risk of having shingles. Drugs called immunosuppressant are exposing patients to herpes zoster and other infections too. These drugs are: Azathioprine (Imuran), Chlorambucil, Cyclophosphamide, Cyclosporine, and Cladribine. These drugs are generally used in those who have suffered an organ transplant but they can also be used in treating systemic lupus erythematosus, Crohn's disease, rheumatoid arthritis, and multiple sclerosis.
Only those who have a good immune system response and those who have been vaccinated against chickenpox and shingles are spared from developing them.