Onchocerciasis transmission in Ghana: Persistence under different control strategies and the role of the simuliid vectors

Background: The World Health Organization (WHO) aims at eliminating onchocerciasis by 2020 in selected African countries. Current control focuses on community-directed treatment with ivermectin (CDTI). In Ghana, persistent transmission has been reported despite long-term control. We present spatial and temporal patterns of onchocerciasis transmission in relation to ivermectin treatment history. Methodology/Principal Findings: Host-seeking and ovipositing blackflies were collected from seven villages in four regions of Ghana with 3–24 years of CDTI at the time of sampling. A total of 16,443 flies was analysed for infection; 5,812 (35.3%) were dissected for parity (26.9% parous). Heads and thoraces of 12,196 flies were dissected for Onchocerca spp. and DNA from 11,122 abdomens was amplified using Onchocerca primers. A total of 463 larvae (0.03 larvae/fly) from 97 (0.6%) infected and 62 (0.4%) infective flies was recorded; 258 abdomens (2.3%) were positive for Onchocerca DNA. Infections (all were O. volvulus) were more likely to be detected in ovipositing flies. Transmission occurred, mostly in the wet season, at Gyankobaa and Bosomase, with transmission potentials of, respectively, 86 and 422 L3/person/month after 3 and 6 years of CDTI. The numbers of L3/1,000 parous flies at these villages were over 100times the WHO threshold of one L3/1,000 for transmission control. Vector species influenced transmission parameters. At Asubende, the number of L3/1,000 ovipositing flies (1.4, 95% CI = 0–4) also just exceeded the threshold despite extensive vector control and 24 years of ivermectin distribution, but there were no infective larvae in host-seeking flies. Conclusions/Significance: Despite repeated ivermectin treatment, evidence of O. volvulus transmission was documented in all seven villages and above the WHO threshold in two. Vector species influences transmission through biting and parous rates and vector competence, and should be included in transmission models. Oviposition traps could augment vector collector methods for monitoring and surveillance

Pool screen polymerase chain reaction for estimating the prevalence of Onchocerca volvulus infection in Simulium damnosum sensu lato : results of a field trial in an area subject to successful vector control

Detection of infective parasites in the vector population can be an early indicator of recrudescence in areas freed of new cases of onchocerciasis. However, dissection of vector black flies is inefficient in areas subject to effective control. Recently, a polymerase chain reaction (PCR)-based assay has been used to detect a single #Onchocerca volvulus-infected black fly in pools containing large numbers of uninfected flies. This method had not been validated on wild-caught black flies in an area subject to effective vector control. Here, we report a method of restricting the pool screen PCR assay to infectious parasites and the results of a field test in an area subject to long-term vector control. The prevalence of infection determined by dissection did not differ from that determined by pool screen PCR. The results suggest that the PCR assay may be a useful tool for epidemiologic surveillance for #O. volvulus infection. (Résumé d'auteur

Enhancer of zeste 2 polycomb repressive complex 2 subunit polymorphisms in melanoma skin cancer risk

Background: Melanoma is the most deadly skin cancer and its incidence is growing. EZH2, a member of the Polycomb Group (PcGs) proteins family, plays an important biological role in the occurrence and development of melanoma. EZH2 germline genetic polymorphisms have not been yet evaluated in melanoma predisposition. Methods: 330 sporadic Italian melanoma patients and 333 healthy volunteers were genotyped to analyze the association between EZH2 variants rs6950683, rs2302427, rs3757441, rs2072408 and melanoma risk. The functionality of rs6950683 alleles was investigated in keratinocytes (HaCat), melanoma cells (A375) and Human embryonic kidney cells (HEK293), using promoter-reporter assays. Results: Genotype distribution of SNPs showed that rs6950683T and rs3757441C alleles were positively associated with melanoma risk (p=0.003 and 0.004, respectively). Haplotype analysis revealed that TCCA and CCCG haplotypes were associated with a higher risk of melanoma (p=0.02 and 0.04, respectively). Functional assays demonstrated that allele rs6950683T reduce promoter activity in the three cell lines analyzed compared to C allele. Conclusions: rs6950683T and rs3757441C alleles in the EZH2 gene appear positively associated with melanoma risk in the analyzed population. In addition, we demonstrated for the first time the functional role of rs6950683 upstream polymorphism on EZH2 gene expression regulation. Keywords: DNA polymorphisms; functional SNP; haplotypes; predisposition; transient transfection

Hydrogen desorption from ball milled MgH2 catalyzed with Fe

In order to obtain faster hydrogen sorption kinetics, MgH2-Fe nanocomposites were prepared by high-energy ball milling. The MgH2 decomposition was studied in samples obtained by changing in a systematic way both the catalyst amount and the degree of microstructural refinement. To this purpose, blends containing increasing Fe concentration have been ball milled in processing conditions able to impart different amount of structural defects. The resulting samples have been characterized by X-ray diffraction to investigate the microstructural features and the phase composition, while the powder morphology and the degree of catalyst dispersion were analyzed by scanning electron microscopy. Differential scanning calorimetry was carried out to characterize the hydrogen desorption behavior of these nanocomposites. Experimental results clearly show that the characteristics of the desorption process are dominated, among other factors, by the morphology of the catalyst dispersion, which in turns depends on the processing conditions and blend composition. In order to achieve low desorption temperatures the homogeneous catalyst dispersion in micron-size particles throughout the structure is required. This condition can be achieved by suitable tuning of the milling conditions and of the catalyst amount. Copyright EDP Sciences/Società Italiana di Fisica/Springer-Verlag 2005