15-month-old Lillian Becker presents with a vesicular rash to her trunk and arms, itchiness, and fever. Onset of symptoms occurred after being picked up from daycare 2 days ago.
After being brought in to the pediatric clinic by her father, Ray, Lillian is diagnosed with chickenpox. Varicella, more commonly referred to as chickenpox, is an infectious disease caused by the varicella-zoster virus, or VZV for short, also known as human herpesvirus 3 or HHV-3 for short.
This is a highly contagious airborne virus, meaning it’s transmitted from person to person through respiratory droplets; for example, when a person sneezes or coughs.
But the virus can also be transmitted by direct contact with the skin or oral mucosa of an infected person. Because of that, an important risk factor for varicella involves going to crowded or poorly ventilated public places, such as day-care centers, as well as being immunocompromised.
Now, once a person inhales the virus-containing droplets, these travel down the respiratory mucosa, and the virus starts replicating in the epithelial cells. This is called the incubation period, where the client is asymptomatic, and lasts 14 to 21 days.
Then, the virus gets picked up by nearby immune cells and gets transported to a nearby lymph node, so the client may start to experience prodromal symptoms, such as fever, headache, and malaise.
Prodromal symptoms are more likely in clients over the age of 10, and more severe in adults. About 36 to 48 hours later, the immune cells reach the skin and release the virus. At this point, clients typically develop skin lesions, usually involving the scalp, face, and trunk.
Initially, skin lesions appear as flat, red, and very itchy spots called macules. Over time, macules become elevated and progress into papules, and then into small fluid-filled vesicles.
Within 1 to 2 days, these vesicles begin to crust over and form scabs. After 5 days the scabs fall off, typically without leaving a scar, unless the client picks or scratches their skin.
Now, every 3 to 5 days, new crops of lesions form in different places on the body, so it’s possible to see skin changes in different phases at the same time. Additionally, clients might present with painful sores on mucosal membranes, like inside the mouth.
Finally, it’s important to note that these clients are contagious from 1 to 2 days before skin rash until all lesions have crusted. Now, most clients have chickenpox only once, and will develop immunity against it for the rest of their lives.