Table 2.

Serial antibody titers to plague F1 antigen in three survivors of a cluster of five cases of severe pneumonia, Yulong County, China, November 2005*

Patient A			Patient D			Patient E
Days after onset	ELISA	IHI	Days after onset	ELISA	IHI	Days after onset	ELISA	IHI
13		< 1:20	9		< 1:20	8		< 1:20
16	1:2560	1:40	12	1:40000	1:80	11	1:2560	1:160
			18	> 1:40000	1:640
34	> 1:40000	1:320				29	> 1:40000	1:640

^*ELISA = enzyme-linked immunosorbent assay; IHI = indirect hemagglutination inhibition.