Prevention of measles is difficult because the most contagious period
is that which precedes the eruption. At this time the child is usually
supposed to have a cold and mixes freely with other children. To
prevent the further spread, each patient must be isolated until fever
has been absent two or three days. Children who have not had measles
may be allowed to go about freely for a week after exposure, and then
should be isolated until 15 days after exposure. Fortunately we are now
able to prevent measles in young children even after exposure. This
is accomplished by drawing a little blood from one who has recently
recovered from the disease and injecting it into the exposed one. This
usually prevents the disease entirely or at any rate renders it mild if
it occurs. Blood drawn from a parent and injected into the child soon
after exposure renders the disease mild. The drawing of the required
amount of blood is devoid of any danger.