			Home About us Contact

Local Prevalence (local + prevalence)

Distribution by Scientific Domains

Medical Sciences	80%

Selected Abstracts

Spatial variation in population density across the geographical range in helminth parasites of yellow perch Perca flavescens

ECOGRAPHY, Issue 5 2007
Robert Poulin
The abundance of a species is not constant across its geographical range; it has often been assumed to decrease from the centre of a species' range toward its margins. The central assumption of this "favourable centre" model is tested for the first time with parasites, using different species of helminth parasites exploiting fish as definitive hosts. Data on prevalence (percentage of hosts that are infected) and abundance (mean no. parasites per host) were compiled for 8 helminth species occurring in 23 populations of yellow perch Perca flavescens, from continental North America. For each parasite species, correlations were computed between latitude and both local prevalence and abundance values. In addition, the relationships between the relative prevalence or abundance in one locality and the distance between that locality and the one where the maximum value was reported, were assessed separately for each species to determine whether abundance tends to decrease away from the presumed centre of the range, where it peaks. For both the cestode Proteocephalus pearsei and the acanthocephalan Leptorhynchoides thecatus, there was a positive relationship between prevalence or abundance and the latitude of the sampled population. There was also a significant negative relationship between relative prevalence and the distance from the locality showing the maximum value in P. pearsei, but no such pattern was observed for the other 7 parasite species. Since this single significant decrease in prevalence with increasing distance from the peak value may be confounded by a latitudinal gradient, it appears that the distribution of abundance in parasites of perch does not follow the favourable centre model. This means that the environmental variables affecting the density of parasites (host availability, abiotic conditions) do not show pronounced spatial autocorrelation, with nearby sites not necessarily providing more similar conditions for the growth of parasite populations than distant sites. [source]

High Level of Antimicrobial Resistance in French Helicobacter pylori Isolates

HELICOBACTER, Issue 1 2010
Josette Raymond
Abstract Background: Helicobacter pylori is a human pathogen responsible for serious diseases including peptic ulcer disease and gastric cancer. The recommended triple therapy included clarithromycin but increasing resistance has undermined its effectiveness. It is therefore important to be aware of the local prevalence of antimicrobial resistance to adjust treatment strategy. Materials and Methods: Overall, 530 biopsies were collected between 2004 and 2007. The antimicrobial susceptibility of H. pylori was determined by E-test and molecular methods. Results: Among these, 138/530 (26%) strains were resistant to clarithromycin, 324/530 (61%) to metronidazole and 70/530 (13.2%) to ciprofloxacin. Whereas no resistance against amoxicillin and tetracycline was observed, only one strain was resistant to rifampicin. Compared to the patients never treated for H. pylori infection, the prevalence of resistance was significantly higher in patients previously treated (19.1% vs 68% for clarithromycin; 13.2% vs 53.3% for both clarithromycin and metronidazole). The trend analysis revealed an increase of primary resistance to ciprofloxacin between 2004 and 2005 (7.3%) vs 2006,2007 (14.1%) (p = .04) and the secondary resistance reached 22.7% in 2007. Interestingly, 27 biopsies (19.6%) contained a double population of clarithromycin-susceptible and -resistant strains. Conclusions: The reported high prevalence of clarithromycin and multiple resistances of H. pylori suggest that the empiric therapy with clarithromycin should be abandoned as no longer pretreatment susceptibility testing has assessed the susceptibility of the strain. As culture and antibiogram are not routinely performable in most clinical laboratories, the use of molecular test should be developed to allow a wide availability of pretreatment susceptibility testing. [source]

Variation in the TNF Gene Promoter and Risk of Osteolysis After Total Hip Arthroplasty

JOURNAL OF BONE AND MINERAL RESEARCH, Issue 11 2003
FRCS, J Mark Wilkinson PhD
Abstract Genetic factors may influence implant failure caused by osteolysis after THA. In an association study of 481 subjects after THA, we found that carriage of the TNF - 238A allele was associated with an increased incidence of osteolysis versus noncarriage (odds ratio, 1.7) and was independent of other risk factors. Genetic and environmental factors influence implant survival after THA. Introduction: Tumor necrosis factor (TNF) is thought to play a role in osteolysis, the major cause of implant failure after total hip arthroplasty (THA). Natural sequence variations at ,238 and ,308 in the TNF gene promoter are associated with differences in susceptibility to several TNF-mediated diseases. We tested whether these polymorphisms are associated with osteolysis after THA. Materials and Methods: A total of 481 whites (214 with failed versus 267 with intact implants) were recruited 11.7 ± 4 years after cemented THA. Genomic DNA was extracted from peripheral blood and genotyped for the ,238 and ,308 polymorphisms using the Taqman 5, nuclease method. Healthy controls (n = 500) from the background population were also genotyped to establish the local prevalence of these alleles. Results: The carriage of ,238A was 8.8% in the background population and 10.9% in the THA controls (p > 0.05). Carriage of ,238A in the osteolysis group was 17.3% (odds ratio, 1.7; 95% CI, 1.0,2.9). Carriage was highest (20.5%) in patients with more widespread osteolysis (OR, 2.1; 1.2,3.8). The association of ,238A with osteolysis was independent of other risk factors for osteolysis (logistic regression analysis: OR, 1.8; 1.0,3.2). Carriage of ,308A was not associated with osteolysis. Conclusion: Genetic, as well as environmental factors, influence implant failure after THA. Whether the TNF - 238 polymorphism causes a biological change that predisposes to loosening or is in linkage disequilibrium with such a locus is not yet known. [source]

Willingness of dentists in Jordan to treat HIV-infected patients

ORAL DISEASES, Issue 5 2005
M El-Maaytah
Reluctance of dentists to treat human immunodeficiency virus (HIV) positive patients represents a major concern. Many efforts have been extended towards the documentation of the extent of this reluctance and speculation of factors that influence it. Objectives:, Assess the willingness of dentists in Jordan to treat HIV-infected patients. Materials and methods:, Two hundred and forty-two general dental practices were surveyed for their willingness to provide treatment of toothache and routine dental care of an HIV-infected individual. Results:, Only 15% of the dental practices were willing to provide such care. Willingness to provide treatment did not seem to be influenced by financial factors or the local prevalence of HIV disease. Conclusion:, Present data suggest that HIV-infected individuals will have difficulty in obtaining dental health care in Jordan. [source]

Sexually transmitted infections: impact on male fertility

ANDROLOGIA, Issue 2 2008
F. R. Ochsendorf
Summary The impact of sexually transmitted diseases (STD) on male fertility is strongly dependent on the local prevalence of the STDs. In Western countries STD-infections are of minor relevance. In other regions, i.e. Africa or South East Asia, the situation appears to be different. Acute urethritis could not be associated with male infertility. Chronic infections (gonorrhoea) can cause urethral strictures and epididymo-orchitis. Chlamydia trachomatis and Neisseria gonorrhoea can be transmitted to the female partner and cause pelvic inflammatory disease with tubal obstruction. Ureaplasma urealyticum may impair spermatozoa (motility, DNA condensation). Trichomonas vaginalis has, if any, only minor influence on male fertility. The relevance of viral infections (HPV, HSV) for male infertility is not resolved. Any STD increases the chances of transmission of the human immunodeficiency virus (HIV). The HIV infection is associated with infectious semen and the risk of virus transmission. Semen quality deteriorates with the progression of immunodeficiency. Special counselling of serodiscordant couples is needed. STDs should be treated early and adequately to prevent late sequelae for both men and women. [source]