Molecular identification of Yersinia enterocolitica isolated from pasteurized whole milk using DNA microarray chip hybridization.

A DNA microarray chip of four virulence genes and 16S ribosomal DNA gene conserved region among all Gram negative species, including Yersinia, as a positive control was developed and evaluated using 22 Yersinia enterocolitica isolates. Eight different oligonucleotide probes (oligoprobes) with an average size of 22 bp, complementary to the unique sequences of each gene, were designed and immobilized on the surface of chemically modified slides. Multiplex PCR was used to simultaneously amplify DNA target regions of all five genes, and single stranded DNA (ssDNA) samples for microarray analysis were prepared by using a primer extension of amplicons in the presence of one primer of all genes. The presence of genes in Y. enterocolitica was established by hybridization of the fluorescently labeled ssDNA representing different samples of the microarray gene-specific oligoprobes and confirmed by PCR. Results of the study showed specificity of genotyping Y. enterocolitica using multiple microarray-based assays. Final validation of the chip's ability to identify Y. enterocolitica genes from adulterated pasteurized whole milk was confirmed and successful. The limit of chip detection of virulence genes in pasteurized whole milk was found to be 1000 CFU per hybridization.

[Evaluation of eight diagnostic tests for HIV infection in Lome (Togo)]. / Evaluation de la performance de huit tests de diagnostic de l'infection à VIH à Lome (Togo).

This study to evaluate the performance of eight diagnostic tests for HIV/AIDS infection was conducted at the National Reference Center for HIV/AIDS/STD in Lomé, Togo. The tests were as follows: Enzymum test anti HIV Combi, Enzymum tests anti-HIV1 + 2 + subtype O, Genscreen HIV 1/2, Ice 1.0.2, Vironostika HIV Uni-Form II Plus O, Genie II HIV 1/2, SFD HIV 1/2 PA and DETERMINE HIV 1/2. A total of 238 serum specimens collected consecutively between January and April 1999 were studied. They were from 161 occasional blood donors and 77 patients. New Lav-Blot I and Ii (western blot) were used as reference tests. Test sensitivity ranged from 90 to 100%. Specificity ranged from 96 to 100%. The Enzymum test anti HIV Combi used only on serum samples from blood donors demonstrated a sensitivity and specificity of 100%. Tests based on Elisa (Emzymum Combi, Enzymum HIV 1 + 2 + subtype O, Genscreen, Ice 1.0.2 and Vironostika) allowed acceptable diagnosis of HIV/AIDS as alternatives to western blot. Two of the three rapid assays tested provided acceptable results, i.e., Genie II HIV 1/2 and SFD HIV 1/2. They are suitable for screening to prevent HIV transmission by blood transfusion in areas where Elisa is unfeasible.

The use of spatial analysis in mapping the distribution of bancroftian filariasis in four West African countries.

The geographical distribution of human infection with Wuchereria bancrofti was investigated in four West African countries (Benin, Burkina Faso, Ghana and Togo), using a commercial immunochromatographic test for filarial antigen. Efforts were made to cover each health-system implementation unit and to ensure no sampling point was >50 km from another, but otherwise the 401 study communities were selected at random. The aim was to enable spatial analysis of the data, to provide a prediction of the overall spatial relationships of the infection. The results, which were subjected to an independent random validation in Burkina Faso and Ghana, revealed that prevalence in the adult population of some communities exceeded 70% and that, over large areas of Burkina Faso, community prevalences were between 30% and 50%. Most of Togo, southern Benin and much of southern Ghana appeared completely free of the infection. Although there were foci on the Ghanaian coast with prevalences of 10%-30%, such high prevalences did not extend into coastal Togo or costal Benin. The prevalence map produced should be useful in prioritizing areas for filariasis control, identifying potential overlap with ivermectin-distribution activities undertaken by onchocerciasis-control programmes, and enabling inter-country and sub-regional planning to be initiated. The results indicate that bancroftian filariasis is more widely distributed in arid areas of Burkina Faso than hitherto recognized and that the prevalences of infection have remained fairly stable for at least 30 years. The campaign to eliminate lymphatic filariasis as a public-health problem in Africa will require significantly more resources (human, financial, and logistic) than previously anticipated.