Types of trematodes infecting freshwater snails found in irrigation canals in the East Nile locality, Khartoum, Sudan

Table 2 Associations between snail counts for 3 snail species or infections in these and various factors tested one by one together with site so as to adjust for variation among sites

Factor (coding first category base)	Snail density (Count ratios)			Infections in snails (Odds ratios)
Factor (coding first category base)	Biomphalaria pfeifferi	Bulinus truncatus	Melanoides tuberculata	Schistosoma mansoni (B. pfeifferi)	Xiphidio cercariae (B. pfeifferi)	Xiphidio cercariae (B. truncatus)	Parapleurolo-phocercous cercariae (M. tuberculata)
Year (2004 - 2005)	0.13***	0.85	0.30**	0.35	0.29*	1.43*	0.63***
Season (Summer - Winter)	1.74	2.61*	0.55	0.67	0.75	1.65**	0.95
Water temperature (°C)	0.92	0.97	1.09*	0.97	1.26***	0.98	0.98
Water temperature (previous month)	0.95	0.99	1.02	0.96	1.22***	1.16***	0.99
Depth (≤0.10 m - >0.10 m)	0.33*	0.81	0.32*	0.33	0.32***	1.28	0.63
Flow speed (≤0.40 m/s - >0.40 m/s)	2.24	1.02	3.05*	0.85	0.55***	0.61***	0.68
Turbidity (Clear-turbid)	1.09	0.49	1.84	1.52	0.61**	0.56**	1.13
Vegetation cover (≤40 % - >40 %)	2.26	1.39	0.89	3.12	3.98***	1.24*	1.30*

Numbers are exponentially transformed regression confidents from negative binomial regression on snail counts (count ratio) or from logistic regression on infection status of these snails (odds ratios)
*)p < 0.05; **)p < 0.01; ***)p < 0.001

ISSN: 2049-9957