Keeping a child home from school to prevent the spread of disease has been shown to work when the child has which of the following?

Chickenpox, or varicella virus infection, manifests as a febrile illness with numerous vesicles (generally 250-500) on an erythematous base. It is a highly communicable infection at the time that skin lesions are present. Exclusion from school is recommended until all lesions have crusted over and the patient is considered noninfectious.

“No nit” policies, by excluding children with nits (empty egg casings) from attending classes, do not diminish the spread of head lice in schools. According to the American Academy Pediatrics Redbook, “Children should not be excluded or sent home early from school because of head lice. Parents of children who are infested (i.e. with at least 1 live, crawling louse) should be notified and informed that their child needs to be treated. The presence of nits alone does not justify treatment.”

The communicability of molluscum warts is small, however, some studies suggest an increased risk in children attending swimming lessons.

Tinea capitis, or ringworm is commonly caused by a dermatophyte, Trichophyton tonsurans in the vast majority, which is ubiquitous in school-age children, and attending school does not affect the spread of this fungal infection.