If a child in your class or school has lice, here is a sample template you can use to write a parent notification letter for lice.
To,
[Concerned parent]
Dear, [Name]
It has come to our attention that your ward, [Student name] belonging to class [Class and section] is a carrier of lice. We request you to give him/her the appropriate treatment at the earliest.
He/she can stay at home until you receive a certificate of health from a medical practitioner. These measures are followed to prevent the spread of lice amongst our students.
Sincerely,
[Name of school]