A<unk>  is a<unk>  held by parents for the purpose of infecting their children with childhood diseases, here chicken<unk>  virus. Similar ideas have applied to other diseases eg Measles but are now strongly discouraged by doctors and health services.  The reasoning behind this now largely historical practice is that guests are exposed to the varicella virus and contract the  disease, developing strong and persistent immunity at an age before disaster is likely, from Chickenpox or Rubella<unk> cularly.
Since 1995 Chickenpox immunisation has been routine in the U.S. and<unk>  of Canada, but not the UK.  (See Chickenpox
Efficacy: The vaccine adequately immunises 70-90% of recipients, attenuating symptoms in those who do later contract the disease.
Children have a milder course of the disease than adults, for whom the disease can often be fatal.  (See Chickenpox)
Pox party
Firefighter
Unitaid
Sultiame
Cypress
Chigger
SureSmile
Ventouse