How old is your brother chicken pox
is a viral disease and rash is maculopappular on face scalp and trunk, do not touch them they heal without scarring. If get infected and can form spots and continue to take supportive medication
as advised by treating physician.
Please keep him in isolation to pevent spread of disease.
In patients with poor immunity anti viral drug may be given (Acyclovir
for chicken pox is available can be given to childeren.
Good Luck to him