Hello, my name is Ron Fouchier,
Virologist at Erasmus Medical Centre in Rotterdam.
In this presentation, I will discuss
the discovery and characterization of four viral pathogens that
are associated with respiratory illnesses in
humans and that have been described since 2001.
The pathogens are first a paramyxovirus named
Human metapneumovirus, two human coronaviruses,
NL63 and HKU1, and a parvovirus named Human bocavirus.
It is well known that a wide range of
pathogens can cause respiratory tract illnesses in humans.
Viruses are the most frequently detected causative agents,
in particular, 40 acute respiratory tract illnesses.
As an example, this slide shows the result of diagnostic tests for 540 patients
with respiratory problems visiting
their general practitioner about 10 years ago in the Netherlands.
Several notorious pathogens were circulating this winter season with enteroviruses,
respiratory syncytial virus, influenza A and B virus,
and rhinoviruses as the most frequently detected viral pathogens.
The reason why I put this slide up is not so much the positive diagnostic results,
which can vary considerably between studies,
but to point out that in a significant proportion of the patients,
in this case 36 percent,
no known pathogen could be detected.
This proportion of respiratory tract illnesses with unknown etiology is highly variable,
for instance, for different patient populations, locations and timing.
But in most studies like this one,
an etiological agent cannot be identified in
a large proportion of patients under investigation.
I will discuss some of the viral pathogens that have been discovered in
the past six or seven years by research groups attempting
to reduce this proportion of illnesses with unknown etiology.
In 2001, a study by the Van der Hoek and others in the Netherlands described