This is Ian Lipkin; I'm the John Snow Professor
at Columbia University in the City of New York,
and I will be talking today to you about approaches to the diagnosis of viral infections.
In today's lecture, I'm going to go over the following items.
First, are the methods we have for implicating
not only all viruses but also all microbes in disease.
We'll talk a bit about mechanisms by which bacteria,
viruses, fungi, and microbes, in general, cause disease;
the methods we use for diagnosis and discovery;
the potential viral pool-
an estimate based on some empirical data that we've obtained in field studies;
and some thoughts about future perspectives.
Our focus will be on viruses but to some extent,
we have to talk about other microbes, as well.
The earliest efforts of which we have
record in investigating the implication microbes and disease,
dates from Koch's work presented and published in
1890 in the 10th International Congress of Medicine in Berlin.
His postulate was as follows,
that the microbe had to be present in every case of disease,
it had to be specific for that disease, that is to say,
it could not be implicated in any other disease;
it had to be isolated,
grown in culture, and shown to induce disease upon inoculation into an experimental host.
There frequently is a fourth postulate,
which was probably a part of Koch's original work
but suggested that you had to re-isolate the microbe
from that experimental host where you've demonstrated the capacity to reproduce disease.
These are what are known as famous Koch's postulates,
frequently called Koch's postulates, plural,
but there are problems with them particularly in
the molecular era and we'll go into those shortly.