It seems like your brother is suffering from Scabies
and he has spread the infestations in the house.
But not to worry at all you just have to use Permethrine 5% cream as directed on the literature of the medication.The important thing to be noted here is that all the family members have to apply the cream once at the same time and then have to reapeat it after a week.
The itch will be there for a week or so thats why i have told you to reapeat the application again after a week,but in the mean time you can apply Calamine
lotion only on the affected areas for three times aday along with some oral anti allergics and everything will be fine.
I hope this will help.
thanks very much and all the best.