Table 3. Comparison of pathogen proportions between selected study periods.

Pathogen	Feb 2003-Feb 2004 Isolates# (n = 1332)**	Jul 2006-Jul 2008 Isolates# (n = 2845)**	p-value*
BACTERIA
Salmonella spp.	48 (4)	110 (4)	0.728
Escherichia coli	5 (<1)	17 (<1)	0.492
Campylobacter spp.	10 (<1)	12 (<1)	0.175
Shigella spp.	74 (6)	97 (3)	0.001
Total bacterial isolates:	137 (10)	236 (8)	0.041
PARASITES
Cryptosporidium spp.	10 (<1)	76 (3)	<.001
Isospora spp.	42 (3)	69 (2)	0.180
Giardia lamblia	21 (2)	10 (<1)	<.001
Other Parasites	5 (<1)	25 (1)	0.079
Total parasitic isolates:	78 (6)	180 (6)	0.582
NO PATHOGEN	1124 (84)	2450 (86)	0.143

# Number (and %) of specimens in selected study period.

*p-values calculated using two-tailed Fisher Exact Test.

**not all columns sum to 100% due to co-infection with multiple pathogens among some specimens.