Is chickenpox contagious?

There is a saying among the common people that a person will get chickenpox once in his life no matter how old he is. From an immunological perspective, this statement can be considered correct. Chickenpox is caused by the varicella zoster virus, which is a herpes virus. It can be transmitted through direct contact and respiratory saliva. Preschool children are easily infected and are a susceptible population. And it can easily spread to other places.

Varicella (chickenpox) is an acute infectious disease caused by the primary infection of varicella-zoster virus. It mainly occurs in infants and preschool children, and the symptoms in adults are more severe than in children. It is characterized by fever and the appearance of widespread red maculopapular rashes, vesicles, and scabs on the skin and mucous membranes. The rash is distributed centripetally, mainly occurring on the chest, abdomen, and back, and rarely on the limbs. It is common in winter and spring and is highly contagious. Chickenpox patients are the only source of infection. It is contagious from 1 to 2 days before the onset of the disease until the rash dries and crusts over. It can be transmitted through contact or inhalation of droplets. The incidence rate in susceptible children can reach over 95%. The disease is a self-limiting disease and generally does not leave scars. If it is combined with bacterial infection, scars will be left. Lifelong immunity is obtained after the disease. Sometimes the virus remains in a dormant state in the ganglia, and the infection recurs after many years, resulting in shingles.

The incubation period of the disease is 12 to 21 days, with an average of 14 days. The onset is relatively acute. Older children and adults may have prodromal symptoms such as fever, headache, general fatigue, nausea, vomiting, abdominal pain, etc. before the rash appears. In children, the rash and systemic symptoms appear at the same time.

The rash appears within 24 hours of onset, first on the scalp and compressed parts of the trunk, with a centripetal distribution. At first, it is a small pink macule, which quickly turns into a round tense blister the size of a rice grain to a pea, with a noticeable red halo around it, and the center of the blister is umbilical. Mucous membranes are also often invaded, such as the oral cavity, pharynx, conjunctiva, vulva, and anus.

During the eruption period of 1 to 6 days, the rash appears in batches one after another. The skin lesions evolve from small red maculopapules → blisters → scabs → descending, and no scars are left after descending. There is obvious pain and itching during the blister stage, and if secondary infection occurs due to scratching, slight indentations may be left. Weak people may develop high fever, and about 4% of adults may develop disseminated varicella and varicella pneumonia.

The clinical manifestations of varicella include bullous varicella, hemorrhagic varicella, neonatal varicella, adult varicella, etc. In addition, if chickenpox is infected during pregnancy, it can cause fetal malformation, premature birth or stillbirth.