Table 1.

IFA end-point titers for six Rickettsia species in horses experimentally infected with Rickettsia rickettsii

Horse	Days post-infection	IFA titers for Rickettsia antigens
		R. rickettsii	R. parkeri	R. amblyommii	R. rhipicephali	R. bellii	R. felis
1	0	–	–	–	–	–	–
1	12	128	128	64	–	64	–
1	18	2,048	256	256	256	256	128
1	86	128	128	64	64	64	–
1	177	64	64	–	–	–	–
2	0	–	–	–	–	–	–
2	12	512	256	256	128	256	–
2	20	8,192	4,096	2,048	2,048	4,096	1,024
2	611	512	256	–	–	–	–
2	772	256	128	–	–	–	–
3	0	–	–	–	–	–	–
3	10	256	256	64	64	64	–
3	20	8,192	2,048	1,024	2,048	512	2,048
3	366	256	128	128	128	–	128
4	0	–	–	–	–	–	–
4	12	128	64	–	–	–	–
4	24	512	256	128	128	128	256
4	100	256	128	64	–	–	–
4	254	64	64	64	64	64	64

Abbreviations: IFA, indirect immunofluorescence assay–, nonreactive at titer ≥ 64