Infectious diseases: host-pathogen interactions
Lecture 1
“Old” infectious diseases – like malaria, tuberculosis, and cholera - are still a big problem.
Tuberculosis causes more deaths worldwide than HIV; both are leading causes of death.
Infectious diseases are a major cause of death worldwide:
To improve treatment and preventions a better understanding of infection processes – per
example the host-pathogen interactions - is necessary.
Epidemiological triangle (interplay between these factors):
The human body contains 10 times more microorganisms (mo’s) than human cells; these are
called the commensals or microbiota or microbiome (synonyms) – the microorganisms in
our body with beneficial effects.
, The central question of this course: why and how is one microorganism able to make us ill,
while another is not? Why and how is one pathogen more lethal than the other?
Disease depends on the load of infection, the pathogenicity, and our immunity; it’s a battle
between pathogen and our immune system.
Different classes of pathogens: bacteria (prokaryotes), viruses, fungi, parasites (worms and
protozoa (eukaryotes)).
The classes can be ordered by size:
From big to smaller: worms (helminths) – protozoa (unicellular) – fungi – bacteria – viruses
(DNA or RNA and protein) – prions
The underlined classes of pathogens belong to the microorganisms. Although viruses are
debatable because they don’t really meet the requirements of a (micro)organisms. One of
the criteria of being a (micro)organism is to be able to reproduce itself independently, and
viruses are not able to do so; they need the host to replicate themselves. But in this course,
we do call them microorganisms.
Lecture 1
“Old” infectious diseases – like malaria, tuberculosis, and cholera - are still a big problem.
Tuberculosis causes more deaths worldwide than HIV; both are leading causes of death.
Infectious diseases are a major cause of death worldwide:
To improve treatment and preventions a better understanding of infection processes – per
example the host-pathogen interactions - is necessary.
Epidemiological triangle (interplay between these factors):
The human body contains 10 times more microorganisms (mo’s) than human cells; these are
called the commensals or microbiota or microbiome (synonyms) – the microorganisms in
our body with beneficial effects.
, The central question of this course: why and how is one microorganism able to make us ill,
while another is not? Why and how is one pathogen more lethal than the other?
Disease depends on the load of infection, the pathogenicity, and our immunity; it’s a battle
between pathogen and our immune system.
Different classes of pathogens: bacteria (prokaryotes), viruses, fungi, parasites (worms and
protozoa (eukaryotes)).
The classes can be ordered by size:
From big to smaller: worms (helminths) – protozoa (unicellular) – fungi – bacteria – viruses
(DNA or RNA and protein) – prions
The underlined classes of pathogens belong to the microorganisms. Although viruses are
debatable because they don’t really meet the requirements of a (micro)organisms. One of
the criteria of being a (micro)organism is to be able to reproduce itself independently, and
viruses are not able to do so; they need the host to replicate themselves. But in this course,
we do call them microorganisms.
