Chickenpox is an infectious disease that results in blister-like rashes, itching, tiredness, and fever. It is caused by the varicella-zoster virus. In most cases, the condition can be treated at home through close monitoring of the symptoms. However, you may need to visit a healthcare provider if more serious symptoms of chickenpox occur. A few of these more serious symptoms include vomiting, diarrhea, headache, and dehydration. Chickenpox is transmitted through direct contact with a person who is infected with the chickenpox virus or through the air from an infected person's coughing or sneezing.