ABSTRACT
BACKGROUND: Introduced Wolbachia bacteria can influence the susceptibility of Aedes aegypti mosquitoes to arboviral infections as well as having detrimental effects on host fitness. Previous field trials demonstrated that the wMel strain of Wolbachia effectively and durably invades Ae. aegypti populations. Here we report on trials of a second strain, wMelPop-PGYP Wolbachia, in field sites in northern Australia (Machans Beach and Babinda) and central Vietnam (Tri Nguyen, Hon Mieu Island), each with contrasting natural Ae. aegypti densities. METHODS: Mosquitoes were released at the adult or pupal stages for different lengths of time at the sites depending on changes in Wolbachia frequency as assessed through PCR assays of material collected through Biogents-Sentinel (BG-S) traps and ovitraps. Adult numbers were also monitored through BG-S traps. Changes in Wolbachia frequency were compared across hamlets or house blocks. RESULTS: Releases of adult wMelPop-Ae. aegypti resulted in the transient invasion of wMelPop in all three field sites. Invasion at the Australian sites was heterogeneous, reflecting a slower rate of invasion in locations where background mosquito numbers were high. In contrast, invasion across Tri Nguyen was relatively uniform. After cessation of releases, the frequency of wMelPop declined in all sites, most rapidly in Babinda and Tri Nguyen. Within Machans Beach the rate of decrease varied among areas, and wMelPop was detected for several months in an area with a relatively low mosquito density. CONCLUSIONS: These findings highlight challenges associated with releasing Wolbachia-Ae. aegypti combinations with low fitness, albeit strong virus interference properties, as a means of sustainable control of dengue virus transmission.
Subject(s)
Aedes/microbiology , Dengue/prevention & control , Insect Vectors/microbiology , Pest Control, Biological/methods , Wolbachia/physiology , Aedes/physiology , Animals , Australia/epidemiology , Dengue/transmission , Environment , Female , Humans , Male , Pupa , Vietnam/epidemiologyABSTRACT
BACKGROUND: Contamination of food with multiantibiotic-resistant bacteria, particularly extended-spectrum ß-lactamase (ESBL)-producing Enterobacteriaceae, is considered a potential source for the wide dissemination of ESBL-producing bacteria in communities. However, little is known about the extent of contamination of food with ESBL-producing bacteria in Vietnam. OBJECTIVE: This study was conducted to assess the characteristics of ESBL-producing Escherichia coli isolated from retail meats and shrimp in Nha Trang, Vietnam. MATERIALS AND METHODS: A total of 350 food samples (poultry [n=143], pork [n=147], and shrimp [n=60]) were purchased in July and November 2013 from a local market. ESBL-producing E. coli were isolated, and ESBL genotypes, phylogenetic groups, and antibiotic resistance profiles were determined. RESULTS: The prevalence of ESBL-producing E. coli in retail foods was 40.6%. ß-Lactamase-encoding genes of the CTX-M-1 (50.7%), CTX-M-9 (41.5%), TEM (59.9%), and SHV (2.8%) groups were detected singly or in combination. The percentages of single ESBL isolates harboring CTX-M-1 or -9 plus TEM groups were 35.2% and 16.2%, respectively. B1 was the most prevalent phylogroup in ESBL isolates from pork (44.7%), poultry (55.9%), and shrimp (72.7%). B2 was the least prevalent (4.2% and 4.8% for pork and poultry isolates, respectively). The prevalence of multidrug resistance (MDR; resistance to ≥ 3 antimicrobial groups) in ESBL-producing E. coli isolated from food was 85.9%. DISCUSSION AND CONCLUSIONS: This is the first report of the characteristics of ESBL-producing E. coli in retail foods in a local city in Vietnam. Our findings indicate that retail foods are contaminated with ESBL-producing E. coli, of which many were MDR. Further monitoring and public health efforts targeting food administration are needed to control the spread of ESBL-producing bacteria in communities.
Subject(s)
Escherichia coli/isolation & purification , Genes, Bacterial , Meat/microbiology , Poultry/microbiology , Seafood/microbiology , Animals , Chickens , DNA, Bacterial/genetics , Drug Resistance, Multiple, Bacterial , Escherichia coli/drug effects , Escherichia coli/genetics , Food Contamination , Food Microbiology , Phylogeny , Swine , VietnamABSTRACT
Although EPI have been implemented successfully during some years from 1989 to 2000, but from 1998 to 2000 measles outbreak had been occurred in Khanh Hoa province with following characteristics: Almost of cases were children with whom had not been injected measles vaccine only 9.9% of cases had been vaccinated. There was no difference in gender, a majority of cases were in age groups of 1-4 and 5-9. Erythema symptom was occurred in 80% of cases. Serological and isolated results of virus showed that, there were no significant different among gender, age group and injecting vaccine
