Sanitary quality improvement of fish produced in the northern Benin cotton basin water reservoirs by cage culture and fish transfer in agricultural contaminant-free water: human health implications.

Northern Benin water reservoirs may remain valuable resources for fish production if the ecotoxicological risks related to agricultural pesticides are eradicated. The present work was undertaken (i) to evaluate sanitary quality and human health implications of fish (Clarias gariepinus and Oreochromis niloticus) reared in cages compared with those produced in pens installed in a contaminated water reservoir (Batran) and a reference water reservoir (Songhaï) and (ii) to test the efficacy of fish transferring to water without agricultural contaminants on fish health status. Pathogenic bacteria and pesticide residues were analyzed by phenotypic and biochemical identification and gas chromatography coupled with mass spectrometry, respectively. For both species, Aeromonas species occur in fish reared in pens at Batran. In Batran, regardless of infrastructure and species, residues of 4,4'-DDE (Dichlorodiphenyldichloroethylene) (1.4-4.9 µg/kg) and Chlorpyriphos (ethyl) (2.8-12.1 µg/kg) were measured, while only the last molecule was found in C. gariepinus from Songhaï (8.9-8.10 µg/kg). Irrespective of the species in the Batran water reservoir, Chlorpyriphos (ethyl) concentration was higher in cages and lower in pens, while 4, 4'-DDE was more concentrated in fish farmed in pens. Levels of these pesticide residues were well below World Health Organization/Food and Agriculture Organization permissible limits and the risk analyzed indicates no potential adverse health implications in consumption of these fish. Also, fish bacteriological quality was in compliance with the international standards. The fish decontamination approach used herein results in a reduction of the splenic macrophage phagocytic activity in both studied fish species.

Establishment of loop-mediated isothermal amplification method (LAMP) for the detection of Vibrio nigripulchritudo in shrimp.

LAMP is a novel method that amplifies DNA with high specificity and rapidity under isothermal conditions. In this study, using the LAMP method, a diagnostic protocol was developed for the detection of Vibrio nigripulchritudo in shrimps. Vibrio nigripulchritudo is associated with distinct shrimp diseases (vibriosis) and is considered one of the threatening pathogens in shrimp industry. After initial cloning and sequencing of the intergenic spacer region (ITS) between 16S and 23S rRNA genes of V. nigripulchritudo, a set of four primers - two inner and two outer - were designed for use in the LAMP reaction. Reaction time and temperature were optimized for 60 min at 63 degrees C, respectively. The detection limit of V. nigripulchritudo by LAMP was 10(2) CFU mL(-1) but PCR could detect up to 10(3) CFU mL(-1). The LAMP method could detect the presence of V. nigripulchritudo from heart, lymphoid organ, and muscle of experimentally infected shrimps with V. nigripulchritudo. This study established a highly sensitive and a rapid diagnostic procedure for detection of V. nigripulchritudo in shrimps. The method developed in this study could be very useful for routine shrimp disease diagnostics.