Chickenpox is caused by the varicella zoster virus and causes a blistering rash. Symptoms include fever, fatigue, and a rash that leaves scabs. It is usually diagnosed based on symptoms but lab tests on fluid from blisters can confirm. Antiviral drugs like acyclovir are prescribed to reduce symptoms and complications which can include bacterial infections or pneumonia. The varicella vaccine protects against chickenpox but is not recommended for those with weak immune systems. Treatment focuses on reducing fever and itching while the rash heals in 7-10 days.