This is Diane Griffin, Professor of Johns Hopkins Bloomberg School of Public Health,
and we're going to be talking about measles.
So measles is typically a childhood rash disease.
Despite the fact that we have an excellent vaccine about which we'll talk more later,
it remains one of the 10 most important causes of death due to infectious disease.
So the earliest understanding of the epidemiology of measles which
has been very important and carries through to our current understanding of measles,
although we understand much more about the basis for this epidemiology now,
occurred due to the work of Peter Panum,
who was a Danish physician who was sent to the Faroe Islands in 1846.
This is well before we knew measles was caused by a virus,
it was well before we knew measles was even an infectious disease.
The last time that the Faroe Islands,
which are quite away from the continent of Europe but are a protectorate of Denmark,
had had a measles outbreak was 60 years before.
What Peter Panum observed was that the disease was contagious,
that you didn't get measles unless you'd been exposed to somebody who had it,
that it had a 14-day incubation period between
the time of exposure and the onset of the rash disease,
and importantly observed that all the people
who lived on the island at the time of the previous outbreaks,
60 years before, were protected from
disease and essentially everybody else got the disease.
So it was very infectious.
But if you had it, you develop lifelong immunity to reinfection.
So the virus that we now know causes measles belongs to
the family of paramyxoviridae and morbilliviruses.
There's a group of morbilliviruses,
some of which you may be familiar with,
particularly canine distemper virus.
Dogs usually get vaccine against canine distemper,
but these viruses are fairly species specific.
So many species have their own morbillivirus,
and the human morbillivirus is measles virus.
It also infects non-human primates,
although they're not an important reservoir,
and it's most closely related to rinderpest virus.
Rinderpest is a disease of cattle,
very serious disease of cattle,
and it's likely that measles virus arose
from rinderpest to become adapted to become a human virus.
Another interesting feature of rinderpest is that it was actually
eradicated fairly recently in the last few years through vaccination.
So that raised the hope that we might be able to do the same thing for measles virus,
and one of the things we'll discuss is why we're having trouble accomplishing that.