2. INTRODUCTION
• Susceptible host (animal or person) is the potential future
host who is recipient of the pathogen /microbes.
• The future host is the person who is next exposed to the
pathogen. The person who is at risk for developing an
infection from the disease.
• It is the final link in the chain of infection and is someone
at risk of infection.
• Example of susceptible host are Children who are very
young ,People who are very old , People on inadequate
diets , People who are chronically ill , People receiving
medical therapy such as chemotherapy or high doses of
steroids ,People who are already ill , People with open
wounds
3. Cont….
• Individual who are likely to develop a
communicable disease after exposure to the
infectious agents are called susceptible host.
• Different individual are not equally susceptible
to infection for a variety of reason.
• Factor that increase the susceptibility of a
host to the development of a communicable
disease are called risk factor.
4. Cont…
• Some risk factors arise from outside of
environment which recalled outsider risk factor
.E.g poor personal hygiene or poor control of
reservoir of infection in the environment.
• Factor such as these increase the exposure of
susceptible host to infectious agent , which
makes the disease more likely to develop.
• Some people who cannot resist a microorganism
invading the body , multiplying and resulting in
infection.
5. Cont…
• The host is susceptible to disease , lacking immunity or
physical resistant to overcome the invasion by
pathogenic microorganism. Which are called insider
risk factors. Such Low level of immunity could be due
to :
Disease like HIV/AIDS which suppress immunity.
Poorly developed or immature immunity as in very
young children.
Not being vaccinated.
Poor nutritional status(malnourished child).
Pregnancy
6. Cont….
• The microorganism may spread to another
person but does not develop into an infection
if the person’s immune system can fight it off.
• They may however become a ‘carrier’ without
symptoms, able to then be the next ‘mode of
transmission’ to another ‘susceptible host’.
• Once the host is infected, he/she may become
a reservoir for future transmission of the
disease.
7. Cont…
• Susceptible hosts abound in health care
settings, as those accessing the health care
system often have compromised immune
systems.
• This may be due to other illnesses processes,
treatments or medications.
• This ineffective immune system leaves them
vulnerable to infectious agents that may be in
the health care environment.
8. Cont….
• Several factors make a person more susceptible
to disease including age (young people and
elderly people generally are more at risk),
underlying chronic diseases such as diabetes or
asthma, conditions that weaken the immune
system like HIV, certain types of medications,
invasive devices like feeding tubes, and
malnutrition.
• Infection does not occur automatically when the
pathogen enters the body of a person whose
immune system is functioning normally.
9. Cont….
• When a virulent pathogen enters an immune-
compromised person, however, infection generally
follows.
• Whether exposure to a pathogen results in infection
depends on several factors related to the person
exposed (the host), the pathogen (the agent), and the
environment..
• Host factors that influence the outcome of an exposure
include the presence or absence of natural barriers, the
functional state of the immune system, and the
presence or absence of an invasive device.
