TABLE 2.

Serological cross-reaction with serum from patients with other documented diseases

Antigen source	Population tested (n)a	No. of specimens IgG positive/total no. tested	IgG titer(s)	No. of specimens IgM positive/total no. tested	IgM titer
PA	Acute MSF (10)	1/10	64	0	<32
	Acute Q fever (10)	0	<32	0	<32
	Acute CMV infection (3)	0	<32	0	<32
	Bartonella sp. endocarditis (10)	7/10	2,048, 1,024, 8,192, 256, 128, 512, 1,024	0	<32
	Q fever endocarditis (3)	0	<32	0	<32
	Systemic lupus erythematous (3)	0	<32	0	<32
IC	Acute MSF (10)	0	<32	0	<32
	Acute Q fever (10)	0	<32	0	<32
	Acute CMV infection (3)	1/3	64	0	<32
	Bartonella sp. endocarditis (10)	6/10	1,024, 1,024, 4,096, 128, 64, 128	1/10	64
	Q fever endocarditis (3)	2/3	256, 512	0	<32
	Systemic lupus erythematous (3)	1/3	64	0	<32
MRL	Acute MSF (10)	1/10	128	0	<20
	Acute Q fever (10)	1/10	256	0	<20
	Acute CMV infection (3)	0	<32	0	<20
	Bartonella sp. endocarditis (10)	7/10	512, 512, 2,048, 64, 256, 128, 256	0	<20
	Q fever endocarditis (3)	0	<32	0	<20
	Systemic lupus erythematous (3)	0	<32	0	<20

^aMSF, Mediterranean spotted fever; CMV, cytomegalovirus.