Chapter 2

Question 1

What is an infectious agent?

Answer 1

An infectious agent is a microorganism that can cause disease, including bacteria, viruses, and fungi.

Question 2

What is a reservoir?

Answer 2

A reservoir is the habitat in which the infectious agent lives, grows, and multiplies.

Types of reservoirs include human, animal, and environmental.

Question 3

What are the types of human reservoirs?

Answer 3

Diseases with only human reservoirs
Disease transmitted from person to person without intermediate
include sexually transmitted diseases,
measles,
mumps,
smallpox, and
streptococcal infections.

Question 4

What is a carrier?

Answer 4

A carrier is an infected person who shows no signs or symptoms of a disease but can transmit the infection to others.

Question 5

What is an asymptomatic carrier?

Answer 5

An asymptomatic carrier is someone who never experiences symptoms of the disease.

Question 6

What is an incubatory carrier?

Answer 6

An incubatory carrier can transmit the agent during the incubation period before clinical illness begins.

Question 7

What is a convalescent carrier?

Answer 7

A convalescent carrier is someone who has recovered from the disease but can still transmit the infection to others.

Question 8

What is a chronic carrier?

Answer 8

A chronic carrier continues to harbor a pathogen for long periods, such as months or years
. Hbv
typhoid fever

Question 9

What is zoonosis?

Answer 9

Zoonosis is an infectious disease that is transmissible from vertebrate animals to humans.

Examples include brucellosis (cows), anthrax (sheep), plague (rodents), rabies (dogs, bats, camel), HIV (monkey), and Ebola & SARS (bats).

Question 10

What is an environmental reservoir?

Answer 10

An environmental reservoir is a nonliving environment where some organisms can survive and multiply, such as plants, soil, and water.

For example, the reservoir of Clostridium botulinum is soil, but the source of most botulism infections is improperly canned food containing spores.

Question 11

What is the chain of infection?

Answer 11

The chain of infection describes how transmission of infection occurs when the agent leaves its reservoir through a portal of exit, by some mode of transmission, and enters through an appropriate portal of entry to infect a susceptible host.