Which condition requires exclusion from school until no more open lesions are observed?

Scabies is a condition caused by the infestation of the skin by tiny mites known as Sarcoptes scabiei. It leads to intense itching and a rash, which can result in the formation of open lesions due to scratching. In a school setting, individuals with scabies need to be excluded until all open lesions have healed. This exclusion is necessary to prevent the spread of scabies, as the mites can easily be transmitted through direct skin-to-skin contact or sharing of infested items like clothing and bedding.

Maintaining a scabies-free environment in schools is crucial for the health and safety of all children, which is why complete healing of any open lesions is a requirement for returning to school. Other conditions listed, like rubella and rubeola (measles), have their own exclusion criteria primarily related to infectiousness and vaccination status, rather than the presence of open lesions. Paralytic shellfish poisoning, on the other hand, is not a communicable condition related to school attendance and does not have open lesions as a symptom, thereby not fitting the criteria for exclusion based on the presence of open lesions.