Abridged validation of charm II screening tests for the detection of veterinary drug residues in fish farmed in Cameroon.

The intensification of aquaculture in Cameroon requires efficient screening methods to control veterinary drug residues in fish. This is why the charm II radio receptor technique for the detection of antimicrobial residues in aquaculture fish initiated in Belgium was transferred to Cameroon according to Commission Decision 2002/657/EC. The validation parameters included the following tests: repeatability, reproducibility and robustness in addition to the mandatory characteristics, detection capability and specificity. Selected veterinary drug-free fish samples of tilapia (Oreochromis niloticus), catfish (Clarias gariepinus), carp (Cyprinus Carpio) and kanga (Heterotis niloticus) were spiked at different target concentrations with different antimicrobials (ß-lactams, tetracycline, sulfonamides, macrolides and chloramphenicol). The detection capabilities (CCß) were at MRPL (0.3 µg/kg for chloramphenicol), or below the regulatory limits in a range of 0.25-0.5 MRL with 0% false-negative results. ß-lactams (penicillin G), tetracyclines (tetracycline, chloretetracycline and oxytetracycline) and macrolides (erythromycine A) were detected at half MRL (25, 50 and 100 µg/kg respectively), while sulfonamides (sulfamethazine) was detected at 25 µg/kg (0.25 MRL). The detection capabilities (CCß) obtained were satisfactory as the cut-off factors (Fm) were less than the mean values of blank fish readings (B) (Fm < B). Furthermore, the method was applicable since the cut-off factor was less than the positivity threshold (Fm < T). The variability of the data under repeatability and reproducibility conditions was acceptable, with a relative standard deviation less than 15%. Results were unaffected by delaying the reading time from 0 h to 24 h after the addition of scintillation fluid, with a precision below 16%. Likewise, non-target drugs were not detected even at high concentrations (100 MRL) in a cross-reactivity study. From the overall results, the performance characteristics (detection capabilities, precision, robustness and specificity) were suitable and comparable to the initial validation results, indicating that the transfer to Cameroon laboratory was valid, the method was reliable and could be used in aquaculture fish quality monitoring programs in Cameroon.

Occurrence of Total Aflatoxins, Aflatoxin B1, and Ochratoxin A in Chicken and Eggs in Some Cameroon Urban Areas and Population Dietary Exposure.

Consumption of chicken and eggs contaminated by mycotoxins could lead to a public health concern. This study was conducted to evaluate the dietary exposure of populations to aflatoxins (AFs) and ochratoxin A (OTA) through these poultry products in the three most urbanized regions of Cameroon (Centre, Littoral, and West). A survey was firstly carried out to know about the consumption frequency by the different population age groups as well as their awareness about mycotoxins. Chicken feed, broiler, and eggs were collected from modern poultry farms. AFs and OTA were analysed using the enzyme-linked immunosorbent assay (ELISA), and dietary exposure was evaluated using a deterministic approach. From the 900 households questioned, a daily consumption frequency of chicken and eggs was the most reported (41% and 69%, respectively), with populations having a very weak knowledge of mycotoxins and their associated health risk (18%). Mean concentrations of AFs, AFB1, and OTA in poultry tissues were below the established regulated limits (20 µg/kg for AFs, 10 µg/kg for AFB1, and 5 µg/kg for OTA) in feeds. These toxins were detected at average concentrations of 1800 and 966.7 ƞg/kg for AFs in chicken muscle and egg, respectively, and 1400 and 1933.3 ƞg/kg for OTA in muscle and egg, respectively. Based on the survey, their estimated daily intakes through these poultry products tended to be lower than the limits 1 and 100 ƞg/kg bw/day for AFB1 and OTA, respectively). The margins of exposure (MOE) of the different population age groups to AFB1 and OTA obtained suggest that the public health concern associated with the presence of mycotoxins in poultry products shall not be underestimated.