Lecture 21 Flashcards
Portals of Entry and Incubation
Describe distance from entrance to focus of action by giving an example
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]
How long is the incubation period for most childhood infections (such as chicken pox)?
1 to 3 weeks
How could virulence increase?
passing through susceptible hosts
Name some inanimate objects which can spread disease through the genito-urinary tract
bubble baths
catheters
thongs
improper wiping with toilet paper
What does herpes simplex 1 cause? herpes simplex 2?
simplex 1 causes cold sores simplex 2 causes genital herpes
How long is the incubation period for AIDS?
8 years on average now (although it used to be 9.8 years)
What does Rubella cause?
german measles
What does Rubeola cause?
measles
What factors can affect the period of incubation? (5)
- nature of the organism
- virulence of the organism
- resistance of the host
- distance from entrance to focus of action
- amount of infectious agent
Portal of entry
the organisms must gain entrance into you in the correct way
How long is the incubation period for TB?
6 months
What is a healthy carrier?
someone who spreads the disease while remaining without symptoms themselves
What is a sub-clinical dose?
the load of the organism when the host can transmit the disease although they appear healthy
How does incubation period change as virulence changes?
generally, as virulence increases, incubation period decreases
What is another name for venereal disease?
Sexually Transmitted Disease
What does it mean for an infection to go clinical?
the infection becomes symptomatic
How does the skin work to keep organisms out? How can an organism get past this?
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)
How long is the incubation period for a cold, strep throat, and the flu?
1 to 3 days
What is the ID50 of salmonella?
10^5 bacilli
What does STORCH apply to? What does it stand for?
organisms which can cross the placenta from mother to child
Syphilis
Toxoplasmosis
Others (AIDS, Hep B, Chlamydia)
Rubella
Cytomegalovirus
Herpes simplex
How long is the incubation period for leprosy?
2 to 5 years (although up to 40 years has been observed)
What is the ID50 of anthrax?
8,000 to 10,000 spores or bacilli
