Varicella

Chickenpox is caused by the varicella-zoster virus also known as human herpesvirus 3 (HHV-3), which primarily spreads through respiratory droplets and direct contact with skin lesions.

Upon entering the upper respiratory tract, the virus infects respiratory epithelial cells and replicates intracellularly.

The immune cells capture the virus and carry it to the nearby lymph nodes, then enter the bloodstream, causing primary viremia.

This allows the virus to reach organs like the liver, where it undergoes further replication, leading to secondary viremia.

At the same time, humoral and cellular immune responses activate to control the infection.

During secondary viremia, the virus travels to the skin, producing a characteristic rash that progresses from spots to blisters.

Once the infection resolves, the virus remains dormant in the dorsal root ganglia, establishing lifelong latency.

In some individuals, reactivation of the latent virus later in life can cause herpes zoster, also known as shingles.