Host Parasite Interaction

Question 1

Host

Answer 1

an animal (human) or plant on or in which a parasite or commensal organism lives

Question 2

Parasite

Answer 2

an organism that lives in or on an organism of another species (its host) and benefits
by deriving nutrients at the other’s expense

Question 3

Pathogen

Answer 3

a microorganism capable of causing an infectious disease

Question 4

Primary Pathogen

Answer 4

microorganism that regularly causes infection and disease when it enters a
non-immune host.

Question 5

Opportunistic Pathogen

Answer 5

microorganism that rarely causes disease in healthy humans but may
in a host whose defense mechanisms have been compromised or weakened

Question 6

Commensal

Answer 6

or colonization): an organism living in or on a host where neither derives benefit
or harm

Question 7

Symbiosis

Answer 7

an organism living in or on a host where both derive mutual benefit

Question 8

Parasitism

Answer 8

an organism living in or on a host where the organism gains benefit at the expense
of the host.

Question 9

Infection

Answer 9

invasion and multiplication of microorganisms in or on a host. A disease process
may or may not be present. It may cause an immune response. Symptoms may be sub-
clinical

Question 10

Virulence

Answer 10

the degree of pathogenicity and extent to which a microorganism can cause
damage to the infected host (variable due to individual host, infectious dose, and portal of
entry)

Question 11

Carrier

Answer 11

an infectious host that, because of inherited genetic traits, either does not develop
symptoms of disease or carries an organism in a latent state. (Symptoms may develop later,
such as Herpes reactivation following stress).

Question 12

Microbial factors leading to disease

Answer 12

evade immune response, antibiotic cleaving, ability to attach, can inhibit chemotaxis/phagocytosis, exotoxins, endotoxins, enterotoxin, elicit production of tumor necrosis factor, elicit production of tumor necrotic factor, tissue tropism, excrete enzymes, collagenase

Question 13

How do organisms invade our bodies and survive?

Answer 13

Pathogens enter the body through various routes, including the respiratory tract, digestive system, skin, and mucous membranes.
They overcome our defenses by adhering to cells, producing enzymes, using capsules, or surviving inside cells.
Pathogens survive and multiply by acquiring nutrients, replicating, producing toxins, or forming biofilms.

Question 14

How do we defend or protect ourselves from infection?

Answer 14

Our bodies have multiple layers of defense, including physical and chemical barriers, the innate immune system, and the adaptive immune system.
The innate immune system provides immediate, non-specific protection, while the adaptive immune system provides targeted, long-term protection.
Mechanisms of resistance include genetic resistance and acquired immunity.

Question 15

Host factors- what makes someone susceptible to infection?

Answer 15

Host factors are characteristics of an individual that can increase their susceptibility to infection.
These factors include age, nutritional status, pre-existing conditions, lifestyle factors, environmental factors, and medications.

Question 16

To establish an infectious disease, an organism must:

Answer 16

1. reach the host and find a portal of entry
2. Overcome host defenses
3. invade and proliferate in the host tissues and produce toxins or other virulence factors
4. be capable of resisting host defenses