A study was conducted in agricultural and urban areas in Cambodia to assess the presence of hantaviruses in rodent populations. In 1998, rodents were trapped in two villages and in Phnom Penh city around market places and a rubbish dump. IgG antibodies to Hantaan virus were detected in 54 (8.2%) rodents among 660 tested: 6.4% (13/203) among roof rats (Rattus rattus), 20.9% (39/187) among Norway rats (R. norvegicus), 16.7% (2/12) among unidentified Rattus species and none in 183 Polynesian rats (R. exulans) or in 75 bandicoot rats (Bandicota sp.). The presence of the viral genome was detected by a reverse transcription-PCR amplifying part of the sequence coding for the nucleoprotein in the S segment, in 87% of the seropositive rodents. Thirty-one representative cDNAs were sequenced. Phylogenetic studies of the sequences indicated a close relationship with Seoul virus. However, the Cambodian Seoul virus sequences clustered within two different phylogenetic lineages, one associated with R. rattus and the other with R. norvegicus.

An international multicenter study of ready-to-eat foods, sandwiches, and ice creams or sorbets sold in the streets and their vendors was carried out to assess the microbiological quality of these foods and to identify characteristics of the vendors possibly associated with pathogens. Thirteen towns in Africa, America, Asia, and Oceania were involved in the study. A single protocol was used in all 13 centers: representative sampling was by random selection of vendors and a sample of foods bought from each of these vendors at a time and date selected at random. Microbiological analyses were carried out using standardized Association Française de Normalisation methods, and the use of a standardized questionnaire to collect data concerning the characteristics of the vendors. Fifteen surveys were carried out, with 3,003 food samples from 1,268 vendors. The proportion of unsatisfactory food samples was between 12.7 and 82.9% for ice creams and sorbets and between 11.3 and 92% for sandwiches. For ice creams and sorbets, the sale of a large number of units (>80 per day) increased the risk of unsatisfactory food by a factor of 2.8 (95% confidence interval [CI]: 1.5 to 5.1), lack of training in food hygiene by 6.6 (95% CI: 1.1 to 50). and by a factor of 2.8 (95% CI: 1.4 to 5.4) for mobile vendors. These risk factors were not identified for sandwiches, this difference may be due to the presence of a cooking step in their preparation. These results show that the poor microbiological quality of these street foods constitutes a potential hazard to public health, that the extent of this hazard varies between the cities studied, and that vendors' health education in food safety is a crucial factor in the prevention of foodborne infections.

Genomic analysis of Salmonella enterica revealed the existence of a variable number of tandem repeats (VNTR) at multiple loci. Some S. enterica strains are considered as references (Typhi Ty2, Typhi CT18, Typhimurium LT2, Enteritidis LK5, PT4, and Enteritidis 07-2642, and Newport). These allowed the selection of markers to develop the genotyping technique, multiple-locus VNTR analysis (MLVA). These markers were used to discriminate S. enterica isolated from humans, food, or the environment. In this report, the characteristics and specifications of 58 salmonella markers described from 2003 to 2009 are analyzed. Some VNTR loci were used as markers. The markers were used to discriminate S. enterica isolates from different sources and geographical localizations. Among the VNTR loci described in the published reports, eight presented with a high diversity index (DI) of polymorphism of more than 0.80. The selection of several markers within a single locus validated their polymorphism characteristic. Despite unequal DI values, the use of a panel of markers is a powerful discriminatory tool for the surveillance and identification of the source of salmonella outbreak. Depending on the markers selected, MLVA should be used either for macro- or microepidemiological purposes. The main challenge in the future for this technique is standardization.

BackgroundSalmonella (S.) enterica is the main cause of salmonellosis in humans and animals. The epidemiology of this infection involves large geographical distances, and strains related to an episode of salmonellosis therefore need to be reliably discriminated. Due to the limitations of serotyping, molecular genotyping methods have been developed, including multiple loci variable number of tandem repeats (VNTR) analysis (MLVA). In our study, 11 variable number tandem-repeats markers were selected from the S. enterica Typhimurium LT2 genome to evaluate the genetic diversity of 206 S. enterica strains collected in Cambodia between 2001 and 2007.FindingsThirty one serovars were identified from three sources: humans, animals and food. The markers were able to discriminate all strains from 2 to 17 alleles. Using the genotype phylogeny repartition, MLVA distinguished 107 genotypes clustered into two main groups: S. enterica Typhi and other serovars. Four serovars (Derby, Schwarzengrund, Stanley, and Weltevreden) were dispersed in 2 to 5 phylogenic branches. Allelic variations within S. enterica serovars was represented using the minimum spanning tree. For several genotypes, we identified clonal complexes within the serovars. This finding supports the notion of endemo-epidemic diffusion within animals, food, or humans. Furthermore, a clonal transmission from one source to another was reported. Four markers (STTR3, STTR5, STTR8, and Sal20) presented a high diversity index (DI > 0.80).ConclusionsIn summary, MLVA can be used in the typing and genetic profiling of a large diversity of S. enterica serovars, as well as determining the epidemiological relationships of the strains with the geography of the area.

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