TABLE 4.

Comparative material costs

Parametera	SMAC plate ($)	ELISA ($)	RA plate ($)	ELISA-RA method ($)
Cost per item	0.46	9.00	1.80	NA
Cost per negative sampleb	0.46	9.00	1.80	10.80
Cost per positive sample	0.92c	9.00d	3.60c	39.60d

^aCosts do not include positive and negative controls. 

^bDoes not include the cost of additional materials for “rule-out” testing. 

^cTwo plates were used for primary isolation and subculture. 

^dBased upon an average of four ELISA tests (see the text).