Enteroaggregative Escherichia coli: a public health hazard in Yaounde; Cameroon?

The prevalence of various pathotypes of Escherichia coli was investigated during a case-control study conducted in children diarrhoea in Yaounde. Isolates obtained from the stools samples of children aged 6 months to 5 years were selected on phenotypic basis; and identified by virulence genes detection using polymerase chain reactions. The most prevalent pathotype was enteroaggregative Escherichia coli (25.8). Enteropathogenic Escherichia coli (3.6); enterotoxigenic Escherichia coli (1); and enteroinvasive Escherichia coli (0.2) followed. No shiga toxin-producing Escherichia coli were identified. Enteroaggregative Escherichia coli was not associated with diarrhoea (cases 26.1; controls 25.5; P=0;887); unlike enteropathogenic Escherichia coli (cases 6.7; controls 1; P=0.003). Investigations into documented potentials of enteroaggregative Escherichia coli in causing diarrhoea and other related pathologies indicated that it could be a major public health threat in Cameroon despite the fact that it was not found associated with clinical diarrhoeal cases in this study

Recovery of metals from Cuban nickel tailings by leaching with organic acids followed by precipitation and magnetic separation.

The percolation leaching of the Cuban nickel tailings containing 0.34% Ni, 0.08% Co and 44.2% Fe was investigated by using tartaric and oxalic acids at different concentrations. About 70% Ni, 80% Co and 30% Fe were extracted after 5 days of leaching with the mixture of 0.15 mol/L tartaric acid and 0.05 mol/L oxalic acid at ambient temperature and normal pressure. Nickel and cobalt extraction of 80% as well as iron extraction of 50% were achieved from the pregnant solution by means of precipitation at 80 degrees C for 2h. The precipitation at ambient temperature led to a similar result after 16 days. Cobalt, nickel and iron oxalates were found in the precipitate by using the X-ray diffraction method. The regeneration of acids during the precipitation step made possible the reuse of the raffinate at the leaching step. Heating of the precipitate at 200 degrees C increased the metal concentration to 1.22% Ni and 0.33% Co, which can be fed in the existing nickel plant in Moa, Cuba. The magnetic processing of the leaching residues led to a non-magnetic product containing less than 20% Fe and a magnetic product containing more than 50% Fe.