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There were 86 water samples from open drains tested for E. coli and 42 for coliphage. The concentrations of coliphage in the open drain water samples were consistently lower than the E. coli concentrations across all drain types (Table 6). Water samples from drains that were originally rivers/lagoons had E. coli concentrations that were significantly lower than water samples that were taken from drains that only functioned as drains (geometric mean, 7.93 cfu log10/100 mL vs. 8.72 cfu log10/100 mL; P < 0.01). There was no significant difference in coliphage concentrations between drains that were originally rivers/lagoons and those that were not. To assess differences in microbial concentrations between other neighborhood and drain characteristics, samples from drains that were originally rivers/lagoons were removed from the analysis. For remaining samples, E. coli and coliphage concentrations in drain water samples did not significantly differ by neighborhood, drain size, construction type, or cover (Table 6).

Table 6

Coliphage and E. coli concentrations from open drain water samples by neighborhood and drain characteristics

 Coliphage (pfu log10/100 mL)
E. coli (cfu log10/100 mL)
NGeo meanSDP-valueNGeo meanSDP-value
Overall 42 5.56 1.18   86 8.60 1.00   
River/lagoona       0.40       <0.01 
 No 35 5.63 1.17   72 8.72 0.99   
 Yes 5.21 1.25   14 7.93 0.77   
Neighborhoodb       0.19       0.08 
 Alajo 5.21 1.45   18 8.62 0.71   
 Bukom 13 6.13 1.10   19 8.95 0.98   
 Old Fadama 5.63 1.01   16 8.23 0.85   
 Shiabu 5.12 1.06   19 9.01 1.22   
Sizeb,c       0.72       0.05 
 Small 10 5.42 1.44   13 8.55 0.73   
 Medium 18 5.63 1.04   45 8.93 1.03   
 Large 5.91 1.19   14 8.23 0.92   
Constructionb,d       0.92       0.15 
 Formal 25 5.61 1.28   56 8.81 1.00   
 Ecological 10 5.66 0.90   16 8.41 0.93   
Coverb       0.80       0.05 
 Some cover 25 5.66 1.16   54 8.85 0.94   
 No cover 10 5.54 1.25   18 8.33 1.07   
 Coliphage (pfu log10/100 mL)
E. coli (cfu log10/100 mL)
NGeo meanSDP-valueNGeo meanSDP-value
Overall 42 5.56 1.18   86 8.60 1.00   
River/lagoona       0.40       <0.01 
 No 35 5.63 1.17   72 8.72 0.99   
 Yes 5.21 1.25   14 7.93 0.77   
Neighborhoodb       0.19       0.08 
 Alajo 5.21 1.45   18 8.62 0.71   
 Bukom 13 6.13 1.10   19 8.95 0.98   
 Old Fadama 5.63 1.01   16 8.23 0.85   
 Shiabu 5.12 1.06   19 9.01 1.22   
Sizeb,c       0.72       0.05 
 Small 10 5.42 1.44   13 8.55 0.73   
 Medium 18 5.63 1.04   45 8.93 1.03   
 Large 5.91 1.19   14 8.23 0.92   
Constructionb,d       0.92       0.15 
 Formal 25 5.61 1.28   56 8.81 1.00   
 Ecological 10 5.66 0.90   16 8.41 0.93   
Coverb       0.80       0.05 
 Some cover 25 5.66 1.16   54 8.85 0.94   
 No cover 10 5.54 1.25   18 8.33 1.07   

cfu denotes colony forming units; pfu denotes plaque forming units.

aDrain was originally a river or lagoon but now functions as a large, terminal drain.

bOnly drains that were not originally rivers or lagoons were included.

cSmall drain (<0.5 m across), medium drain (0.5–1 m across), large drain (1–3 m across).

dEcological drains were dirt lined with no formal planning. Formal drains were cement or stone lined and were intentionally constructed.

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