TABLE 1.

Characteristics of samples and serological assays used^a

Country	No. of samples that were			Total	ELISA description		IFAT description	IHAT description	Antigen used	Definition (per in-country guidelines) of:			Reference(s)
	Positive	Negative	From patients with other infections		I	II				Positive sample	Negative sample	Discordant samples
Argentina	40	51	10	101	In-house protocol (cutoff, 0.2 + SD)		In-house protocol (cutoff, 1:32)	In-house protocol (cutoff, 1:32)	T. cruzi epimastigotes, Tulahuén strain	A sample was considered seropositive if at least two serological tests were positive following testing by ELISA, IHAT, and IFAT	Readings were negative following testing by three different tests (ELISA, IFAT, and IHA)	Readings were discordant following testing by three different tests (ELISA, IFAT, and IHAT)	9, 19
Ecuador	51	8	41	100	Chagas III (BiosChile Ingeniería Genética S.A., Santiago, Chile) (cutoff, [CPos + CNeg]·0.35)	Chagatek ELISA (bioMérieux, Buenos Aires, Argentina) (cutoff, CNeg·0.100)	ND	ND	Commercial kit antigen	Readings were positive following testing by two different ELISAs	Readings were negative following testing by two different ELISAs	Readings were discordant following testing by two different ELISAs, or one reading was close to the test's cutoff (±10%); the third reading by either test was considered definitive	1
Mexico	40	50	10	100	Kit Chagas III (BiosChile Ingenieria Genetica S.A., Santiago, Chile) (cutoff, [CPos + CNeg]·0.35)		ND	ND	Commercial kit antigen	Readings were positive following testing by two different ELISAs	Reading was negative following testing by one ELISA	Readings were discordant following testing by two different ELISAs, or one reading was close to the test's cutoff; the third reading by either test was considered definitive	N. Pavia-Ruzb
Venezuela	40	25		65	In-house protocol (cutoff, 0.2 + 2 SD)		ND	In-house protocol (cutoff, 1:4)	T. cruzi epimastigotes, PM strain locally isolated from a patient in 1985	Readings were positive by serological testing of two patient samples taken 1 month apart	Reading was negative following testing by one ELISA	Readings were discordant following testing by two different ELISAs, or one reading was close to the test's cutoff; the third reading by either test was considered definitive	10, 13

^aPositive and negative samples included samples that had previously tested positive and negative by serological methods, as per in-country Chagas disease diagnostic guidelines. Abbreviations: CPos and CNeg, optical density value of positive and negative controls, respectively; ND, not done.

^bPersonal communication.