SUMMARYNatural water sources used as drinking-water supplies by rural settlements in Sierra Leone were examined monthly over a one-year period to detect any seasonal variations in bacterial quality. The 37 'C colony count, levels of selected faecal indicator bacteria and the incidence of Salmonella spp. were monitored. A seasonality was demonstrated for all the variables, counts generally increasing with the progression of the dry season, culminating in peaks at the transition from dry to wet season. Some complications with respect to the interpretation of counts of faecal indicator bacteria from raw tropical waters are noted.

SUMMARYThe survival of various faecal bacteria used as indicators of the faecal contamination of water supplies has been investigated in a tropical environment (Sierra Leone). Isolates representing the thermotolerant coliform (TtC) and faecal streptococcus (FS) groups,Clostridium perfringensandSalmonellaspp. were studied over a 48 h period of immersion in water from three different sources. Survival patterns varied according to source type, but some general observations were made: a portion of the TtC group was apparently capable of substantial regrowth; FS organisms died off at a faster rate than TtC organisms initially, but survived longer; vegetative cells ofC. perfringensdied off rapidly; andSalmonellaspp. could survive for as long as the other faecal organisms tested. The implications of results for the analysis of tropical waters for faecal contamination are discussed.

SUMMARYThe levels of faecal coliforms (FC), indole-positive FC (presumptive Escherichia coli), faecal streptococci (FS), Streptococcus faecalis and Clostridium perfringens in the natural water sources used by 29 rural settlements in Sierra Leone were investigated. Levels of the same indicators in human faeces were also investigated. The incidence of Salmonella spp. in both habitats and the temperature, pH and conductivity of water sources were also recorded. All water sources were contaminated with the indicator bacteria, mean numbers of which occurred in the relationship FC > presumptive E. coli FS C. perfringens > S. faecalis. FC were also predominant in human faeces, the relationship of means being FC presumptive E. coli > FS > S. faecalis > C. perfringens. The need for confirmation of FC counts obtained from water sources was indicated by the large number of positive tubes produced in the FC multiple-tube dilution test from some samples which could not be confirmed as presumptive E. coli. Salmonella spp. were isolated from 13 water sources and 6 % of faecal samples. Mean water temperature was high (26-2 'C), pH low (5 04) and conductivity low (34 ,sS cm-1). Presumptive E. coli was considered the most appropriate indicator of faecal pollution of the types of water investigated.

Fecal streptococci in frozen foods. II. Effect of freezing storage on Escherichia coli and some fecal streptococci inoculated into green beans. III. Effect of freezing storage on Escherichia coli, Streptococcus faecalis and Streptococcus liquefaciens inoculated into orange concentrate. Appl. Microbiol. 3:102-106.