Lecture 21

Question 1

Describe distance from entrance to focus of action by giving an example

Answer 1

The organism must travel from the site of infection to where in the body it affects

for example someone who is bit by a dog carrying rabies will have a longer period of incubation than somebody bit in the neck [because the focus of action of rabies is the brain]

Question 2

How long is the incubation period for most childhood infections (such as chicken pox)?

Answer 2

1 to 3 weeks

Question 2

How could virulence increase?

Answer 2

passing through susceptible hosts

Question 3

Name some inanimate objects which can spread disease through the genito-urinary tract

Answer 3

bubble baths

catheters

thongs

improper wiping with toilet paper

Question 3

What does herpes simplex 1 cause? herpes simplex 2?

Answer 3

simplex 1 causes cold sores simplex 2 causes genital herpes

Question 3

How long is the incubation period for AIDS?

Answer 3

8 years on average now (although it used to be 9.8 years)

Question 4

What does Rubella cause?

Answer 4

german measles

Question 5

What does Rubeola cause?

Answer 5

measles

Question 6

What factors can affect the period of incubation? (5)

Answer 6

1. nature of the organism
2. virulence of the organism
3. resistance of the host
4. distance from entrance to focus of action
5. amount of infectious agent

Question 8

Portal of entry

Answer 8

the organisms must gain entrance into you in the correct way

Question 8

How long is the incubation period for TB?

Answer 8

6 months

Question 9

What is a healthy carrier?

Answer 9

someone who spreads the disease while remaining without symptoms themselves

Question 10

What is a sub-clinical dose?

Answer 10

the load of the organism when the host can transmit the disease although they appear healthy

Question 11

How does incubation period change as virulence changes?

Answer 11

generally, as virulence increases, incubation period decreases

Question 13

What is another name for venereal disease?

Answer 13

Sexually Transmitted Disease

Question 14

What does it mean for an infection to go clinical?

Answer 14

the infection becomes symptomatic

Question 16

How does the skin work to keep organisms out? How can an organism get past this?

Answer 16

epidermis and dermis are made of many interlocking layers

organisms which can find an opening through (such as an injury) would be able to infect you staph aureus and dermatophytic fungi can enter through the hair follicle

neisseria gonhorroea and chlamydia trachomatis can get through the conjunctiva (causing opthalmia neonatorum)

Question 17

How long is the incubation period for a cold, strep throat, and the flu?

Answer 17

1 to 3 days

Question 18

What is the ID50 of salmonella?

Answer 18

10^5 bacilli

Question 20

What does STORCH apply to? What does it stand for?

Answer 20

organisms which can cross the placenta from mother to child

Syphilis

Toxoplasmosis

Others (AIDS, Hep B, Chlamydia)

Rubella

Cytomegalovirus

Herpes simplex

Question 21

How long is the incubation period for leprosy?

Answer 21

2 to 5 years (although up to 40 years has been observed)

Question 22

What is the ID50 of anthrax?

Answer 22

8,000 to 10,000 spores or bacilli