Schools in the United States, Canada, and Australia commonly exclude infested students, and prevent return of those students until all lice, eggs, and nits are removed.
This is the basis of the "no-nit policy".
Data from a primarily American study during 1998–1999 found that no-nit policies were present at 82% of the schools attended by children suspected of louse infestation.
A separate 1998 survey revealed that 60% of American school nurses felt that "forced absenteeism of any child who has any nits in their hair is a good idea."

A number of health researchers and organizations object to the no-nit policy.
Opponents to the no-nit policy mention that visible nits may only be empty egg casings which pose no concern as transmission can only occur via live lice or eggs.
This has led to the perception that the no-nit policy serves only to ease the workload of school nurses and punish the parents of infested children.

Proponents of the no-nit policy counter that only a consistently nit-free child can be reliably shown to be infestation-free.
That is, the presence of nits serves as an indirect proxy for infestation status.
Proponents argue that such a proxy is necessary because lice screening is prone to false negative conclusions (i.e., failure to find lice present on actively infested children).
For example, a 1998 Israeli study found that 76% of live lice infestations were missed by visual inspection (as verified by subsequent combing methods).
Although lice cannot fly or jump, they are fast and agile in their native environment (i.e., clinging to hairs near the warmth of the scalp), and will try to avoid the light used during inspection.
Louse colonies are also sparse (often fewer than 10 lice), which can contribute to difficulty in finding live specimens.
Further, lice populations consist predominantly of immature nymphs, which are even smaller and harder to detect than adult lice.
Schools in the United States, Canada, and Australia commonly exclude infested students, and prevent return of those students until all lice, eggs, and nits are removed. This is the basis of the "no-nit policy". Data from a primarily American study during 1998–1999 found that no-nit policies were present at 82% of the schools attended by children suspected of louse infestation. A separate 1998 survey revealed that 60% of American school nurses felt that "forced absenteeism of any child who has any nits in their hair is a good idea."
A number of health researchers and organizations object to the no-nit policy. Opponents to the no-nit policy mention that visible nits may only be empty egg casings which pose no concern as transmission can only occur via live lice or eggs. This has led to the perception that the no-nit policy serves only to ease the workload of school nurses and punish the parents of infested children.
Proponents of the no-nit policy counter that only a consistently nit-free child can be reliably shown to be infestation-free. That is, the presence of nits serves as an indirect proxy for infestation status. Proponents argue that such a proxy is necessary because lice screening is prone to false negative conclusions (i.e., failure to find lice present on actively infested children). For example, a 1998 Israeli study found that 76% of live lice infestations were missed by visual inspection (as verified by subsequent combing methods). Although lice cannot fly or jump, they are fast and agile in their native environment (i.e., clinging to hairs near the warmth of the scalp), and will try to avoid the light used during inspection. Louse colonies are also sparse (often fewer than 10 lice), which can contribute to difficulty in finding live specimens. Further, lice populations consist predominantly of immature nymphs, which are even smaller and harder to detect than adult lice.
Treatment of human lice