TABLE 1.

Comparison of frozen banked serum specimens from persons with documented and undocumented cases of syphilis^a

Syphilis category	No. of serum samples
	Total	Reactive with:
		Synthetic VDRL antigen	Natural VDRL antigenb	TP-PA
Undocumented	100	100c	88c	99
Documented
Untreated
Primary	9	9	9	8
Secondary	20	20	20	20
Latent	6	5	5	6
Treated
Primary	15	12	11	13
Secondary	30	30	30	30
Latent	20	18	17	19
Total	200	194	180	195

^aAll specimens were tested with CDC synthetic VDRL antigen. Undocumented sera were tested using the CDC reference VDRL antigen; documented sera were tested with BDMS VDRL antigen. 

^bNatural VDRL antigen was either CDC reference VDRL (undocumented serum samples) or BDMS VDRL antigen (documented sera). 

^cOne sample was reactive with both VDRL antigens but nonreactive with TP-PA.