Table 1.

Comparison of average ct values obtained by conducting multiplex real-time PCR on parasite-positive stool samples stored on Whatman protein saver cards for 48 hours using Qiagen or Chelex DNA extraction protocols

Sample type	DNA extraction method	Average ct values ± standard deviation (min-max)
		Giardia lamblia (N = 20)	Cryptosporidium (N = 20)	Entamoeba histolytica (N = 20)
Whole stool	Qiagen	30 ± 4 (22–35)	29 ± 5 (19–35)	30 ± 3 (22–34)
Whole stool directly on Whatman cards	Qiagen	31 ± 3 (23–36)	32 ± 4 (26–38)	33 ± 4 (24–38)
	Chelex	33 ± 3 (27–39)	36 ± 2 (31–39)	33 ± 3 (25–36)
Stool suspension on Whatman cards	Qiagen	31 ± 4 (23–39)	33 ± 4 (28–40)	33 ± 3 (25–36)
	Chelex	32 ± 3 (25–37)	33 ± 4 (27–39)	33 ± 3 (26–36)

ct = cycle threshold.