Question

21)

Which is false regarding sexually transmitted diseases (STD's)?

	A.	Since STD pathogens are susceptible to drying out, they require direct contact with mucous membranes for transmission.
	B.	Treponema pallidum: causative agent of syphilis
	C.	Secondary syphilis: latent period of infection characterized by periodic rashes
	D.	Tertiary syphilis: presence of chancres at site of infection containing pathogen
	E.	Preliminary diagnosis of syphilis: corkscrew-shaped spirochetes in chancre exudate

22)

A reservoir of infection

	A.	is the pathogen causing the disease
	B.	is the mechanism by which the disease is transmitted
	C.	is a virulence factor
	D.	is a vector
	E.	none of the above

Answer 1

Answer 21: Tertiary syphilis: presence of chancres at site of infection containing pathogen.

Chancre are painless ulcers. These are usually present in primary syphilis. These ulcers usually occur around labia or cervix ( female).

Answer 22: None of the above

An animal, plant, human in which infectious agent live without causing the harm to reservoir itself.

For example humans are reservoir of STD, smallpox. Animals such as bats are a reservoir of number of viruses.

The reservoir may or may not be the source from which an infectious agent is transferred to a host.

Vectors are living organism that carry the disease from one living organism to another living organism. For example Mosquitoes are vector of many disease such as malaria, west nile disease, dengue fever etc.