TABLE 2.

Epidemiological and serological data compiled from level 1 risk group

Sex	Age (yrs)	Access to the stable	Symptoms	Serology of blood extractionb				Case	Attack rate (%)
				1st		2nd
				IgMc	IgG	IgMc	IgG
Farm workers									78
Malea	57	No	Yes	1/128	1/128	1/256	1/1024	Yes
Male	57	No	Yes	Neg	Neg	Neg	Neg	No
Male	59	No	No	1/1024	1/512	NDd	ND	Yes
Male	34	Yes	Yes	Neg	1/512	Neg	1/1024	No
Female	35	No	Yes	1/64	1/64	1/128	1/512	Yes
Male	38	No	Yes	1/1024	1/2048	ND	ND	Yes
Female	29	No	Yes	1/128	1/2048	ND	ND	Yes
Male	22	Yes	No	1/512	1/128	ND	ND	Yes
Female	43	Yes	No	Neg	Neg	1/512	1/128	Yes
Visitors									31
Female	18	Yes	Yes	Neg	Neg	Neg	Neg	No
Male	21	Yes	No	Neg	Neg	Neg	Neg	No
Male	18	Yes	No	Neg	Neg	ND	ND	No
Male	25	Yes	Yes	Neg	Neg	Pos	1/256	Yes
Male	18	Yes	Yes	Neg	Neg	Neg	Neg	No
Male	18	Yes	No	Neg	Neg	Neg	Neg	No
Male	18	Yes	No	Pos	Neg	Pos	1/128	Yes
Male	20	Yes	Yes	Neg	Neg	Pos	1/128	Yes
Male	18	Yes	No	Neg	Neg	Neg	Neg	No
Male	19	Yes	No	Pos	Neg	Pos	Neg	No
Male	19	Yes	No	Neg	Neg	Pos	1/256	Yes
Male	30	Yes	Yes	Neg	Neg	Neg	Neg	No
Male	35	Yes	No	Neg	Neg	Neg	Neg	No

^aIndex case.

^bNeg, negative; Pos, positive.

^cIgM determined by IFAT (farm workers) or indirect chemiluminescent immunoassay (visitors).

^dND, not done.