TABLE 3.

Prevalence of BTPC in virgin soils and nonvirgin soils^a

Region	Nonvirgin soil samplesb			Virgin soil samplesc
	No. positive	Total no.	%	No. positive	Total no.	%
Central	89	397	22.4	31	88	35.2
Northeast	9	151	6.0	3	119	2.5
Northwest	60	174	34.5	25	109	22.9
South	59	288	20.5	13	202	6.4
West	147	338	43.5	36	143	25.2
Total	364	1,348	27.0	108	661	16.3

^aDifferences in the prevalence values for virgin soils and nonvirgin soils were significant (P < 0.001) in all cases.

^bNonvirgin soils were defined as soils that had been changed by people (cultivated, urbanized, and industrialized soils).

^cVirgin soils were defined as soils that had not been changed by people.