Occupational risk for Legionella infection among dental healthcare workers: meta-analysis in occupational epidemiology

Objective The occupational risk for Legionella infection among dental healthcare workers (DHCWs) is conjectured because of the risk of routine inhalation of potentially contaminated aerosols produced by the dental instruments. Nevertheless, occupational epidemiology studies are contrasting. This metaanalysis assessed the level of scientific evidence regarding the relative occupational risk for Legionella infection among DHCWs. Methods Literature search was performed without time and language restrictions, using broad data banks (PubMed, Scopus, Web of Science, GOOGLE Scholar) and generic keywords (‘legionella’ AND ‘dent*’). Analytical cross-sectional studies comparing prevalence of high serum Legionella antibody levels in DHCWs and occupationally unexposed individuals were considered. The relative occupational risk was assessed through prevalence ratio (PR) with 95% CI. Between-study heterogeneity was assessed (Cochran’s Q test) and was used to choose the meta-analytic method. Study quality (modified Newcastle-Ottawa Scale) and publication bias (Begg and Mazumdar’s test, Egger and colleagues’ test, trim and fill R0 method) were assessed formally and considered for the sensitivity analysis. Sensitivity analysis to study inclusion, subgroup analyses (dental staff categories; publication year, before vs after 1998, ie, 5 years after the release by the Centers for Disease Control and Prevention of the infection control guidelines in dental healthcare setting) were performed. Results Seven studies were included (2232 DHCWs, 1172 occupationally unexposed individuals). No evidence of publication bias was detected. The pooled PR estimate was statistically non-significant at 95% level (1.7; 95% CI 0.8 to 3.2), study-quality adjustment did not change the PR considerably (PR, 1.5; 95% CI 0.5 to 4.1). PR was statistically significant before 1998 and no longer significant after 1998. Subgroup analysis according to DHCW categories was inconclusive. Conclusions There is no scientific evidence that DHCWs are at high occupational risk. The differences between former and recent studies could be due to different characteristics of municipal water systems and the infection control guideline dissemination

Rethinking dentistry and dental teaching

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Ebola virus infection among western healthcare workers unable to recall the transmission route

Introduction. During the 2014-2016 West-African Ebola virus disease (EVD) outbreak, some HCWs from Western countries became infected despite proper equipment and training on EVD infection prevention and control (IPC) standards. Despite their high awareness toward EVD, some of them could not recall the transmission routes. We explored these incidents by recalling the stories of infected Western HCWs who had no known directly exposures to blood/bodily fluids from EVD patients. Methodology. We carried out conventional and unconventional literature searches through the web using the keyword "Ebola" looking for interviews and reports released by the infected HCWs and/or the healthcare organizations. Results. We identified fourteen HCWs, some infected outside West Africa and some even classified at low EVD risk. None of them recalled accidents, unintentional exposures, or any IPC violation. Infection transmission was thus inexplicable through the acknowledged transmission routes. Conclusions. We formulated two hypotheses: inapparent exposures to blood/bodily fluids or transmission due to asymptomatic/mildly symptomatic carriers. This study is in no way intended to be critical with the healthcare organizations which, thanks to their interventions, put an end to a large EVD outbreak that threatened the regional and world populations

predictors of legionella occurrence in dental unit waterlines of a highly colonized dental hospital

Introduction. Legionella is frequently detected in Dental Unit Waterlines (DUWLs). Although such a high occurrence is not necessarily associated with high risk for Legionnaire's disease among patients and staff, it is prudent to monitor DUWLs for Legionella periodically. Since this procedure is long and expensive, surrogate markers are frequently used. Aim. To investigate whether surrogate markers are predictive of Legionella detection in DUWLs in a highly colonized dental hospital. Material and methods. DUWLs from a dental hospital where legionellae were detected intermittently throughout a period of ten years was considered. The investigated predictors were total viable flora (TVF) at 37°C and at 22°C, Pseudomonas (legionellae competitor) occurrence and season. Multivariate analysis was made and, using the best fitting logistic regression model, the probability to detect legionellae in water from DUWLs was estimated. Results. Legionellae were detected in 52% water samples collected in summertime and never detected in wintertime at levels ranging between 0 and 200 colony forming units(CFU)/L. The odds ratio of legionellae occurrence were 25.0 for Pseudomonas undetected vs. detected, 108.3 for summertime vs. wintertime, 2.2-2.3 for TVF levels at 37°C and 22°C >200 CFU/mL vs. ≤200 CFU/mL. A 29% probability to detect legionellae from DUWLs, where Pseudomonas was undetected, TVF levels were >200 CFU/mL and in summertime, was estimated. Conclusion. Despite legionellae were ubiquitous in the dental hospital during the study period, in the most favourable conditions for Legionella growth (lack of competitor, high biofilm and hot weather), legio nellae were detected in almost one third of DUWLs

effect of cleaning and disinfection on naturally contaminated clinical contact surfaces

Introduction. Data regarding methicillin-resistant Staphylococcus aureus, Legionella pneumophila, Hepatitis B virus suggest that the environment plays an important role in infection transmission in dental healthcare settings. The Centres for Disease Control and Prevention suggest covering clinical contact surfaces with disposal barriers or disinfecting them between patients. Both methods have drawbacks; preliminary data suggest that cleaning could be an alternative. Aim. To investigate microbial contamination on dental chairs after dental therapy with turbine and decontamination power of disinfection and cleaning. Material and methods. We assessed microbial contamination of a dental chair, used by paediatric patients receiving conservative/ endodontic therapy and located in an annex isolated from the rest of the dental office. Contact plates containing Nutrient Agar were used to assess microbial load, immediately before and after treatment, and following one of two decontamination protocols. Protocol-1 comprised cleaning (sodium lauryl sulphate- based soap) followed by disinfection (hypochlorite solution); and protocol-2 was soap-based cleaning only. Contamination levels were classified as no growth; scanty (<2.5 CFU/ cm2); light (2.5-12 CFU/cm2); moderate (12-40 CFU/cm2); or heavy growth (40-100 CFU/cm2). Results. Contamination ranged between moderate and heavy growth for 93.3% samples after dental therapy before decontamination. Scanty growth was obtained from 93.3% samples and 96.7% samples after protocol 1 and protocol-2, respectively. Initial level of contamination had no significant effect on the final level and the decontamination power of the two protocols was not significantly different either. Conclusion. Dental therapy produced high levels of microbial contamination which justified the use of adequate disinfection and/or cleaning. Cleaning alone was sufficient to decontaminate the surface of the dental chair, while disinfection offered no additional effect

Prevalence of reactive tuberculin skin test in dental healthcare workers and students

Introduction. The risk for active tuberculosis (TB) infection among dental healthcare workers (DHCWs) is controversial. Specifically, TB incidence is generally low among general dental practitioners, but it is higher than in the general population among hospital/prison dentists, DHCWs who work in endemic areas, students during clinical training with direct patient contact. Aim. To investigate prevalence of reactive tuberculin skin test (TST) among dental students and DHCWs in an Italian dental university hospital. Material and methods. DHCWs (n=76), dental (n=92) and dental hygienist (n=13) students, administrative staff (n=15, reference group), who were not previously vaccinated against TB, provided their consent to undergo the Mantoux test, the standard recommended TST. Unadjusted and adjusted odds ratios (ORs) of reactive TST for working categories and for years of practice in the dental hospital were assessed through logistic regression analysis. Results. Prevalence of reactive TST estimates were 0.0%, 17% (95% confidence interval, 95CI, 11-26%), 20% (95CI, 12-30%) and 7% (95CI, 1-30%) among dental hygienist students, dental students, dental healthcare workers and administrative staff, respectively. The adjusted ORs for working categories were non-significant, but they were significant at 95% level for the years of exposure (OR, 1.09 for each year of practice at the hospital; 95CI, 1.01-1.19). Conclusion. High prevalence values could be due to cross immunization from non-tubercular mycobacteria, frequently found in dental unit waterlines, or boosting from repeated TST occasions. However, these data suggest that the risk for TST conversion is associated with the years of practice in dental hospitals

A quicksand called health literacy

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The face of Ebola: changing frequency of haemorrhage in the West African compared with Eastern-Central African outbreaks

BACKGROUND: The West-African (WA) Zaire Ebolavirus disease (EVD) outbreak was characterized by an exceptionally high number of cases and deaths as compared with the Eastern-Central African (ECA) outbreaks. Despite the Zaire Ebolavirus being the most lethal for humans, case-fatality rate, close to 80 % in ECA outbreaks, almost halved to 47 % in Guinea-Liberia-Sierra Leone (WA). Such an improvement was due to the remarkable implementation of international humanitarian aids. Some studies also suggested that the long human-to-human transmission cycle occurred in WA, gave rise to human adaptation and consequent immune escape. Haemorrhage, the main feature in seriously infected EVD patients, is due to the immune system that triggers the infected endothelial cells which expose the spike-like glycoprotein (GP) of the virion on their surface. If the human adaptation hypothesis holds true, the proportion of EVD patients with haemorrhage in the WA outbreak should be lower than in the ECA outbreaks due to immune escape. Therefore, the aim of this meta-analysis was to compare the relative frequencies of three typical haemorrhagic symptoms (conjunctival -CB, nasal -NB, gingival -GB- bleedings) in the ECA and WA outbreaks. METHODS: Literature searches were performed through PubMed and Scopus using generic keywords; surveys including at least ten patients reporting CB, NB, GB relative frequencies were extracted and split into ECA and WA. The meta-analytical methods chosen were based on the levels of between-study heterogeneity and publication bias. Pooled CB, NB, GB relative frequencies in ECA and WA were estimated and compared. Subgroup analysis including only studies on Zaire Ebolavirus also was performed. RESULTS: Fifteen studies (10 ECA, 5 WA) were located with 4,867 (CB), 3,859 (NB), 4,278 (GB) EVD patients overall. GB pooled relative frequency was 45.3 % (95 % confidence interval -95 CI, 34.7-56.1 %) and 18.0 % (95 CI, 6.0-34.5 %), in ECA and WA; NB was 10.6 % (95 CI, 5.7-16.8 %) and 1.3 % (1.0-1.8 %); GB was 24.2 % (95 CI, 11.9-39.2 %) and 1.9 % (95 CI, 1.4-2.4 %). Subgroup analysis confirmed these results. CONCLUSIONS: During the WA outbreak the relative frequency of GB decreased by two thirds, while NB and GB almost disappeared, suggesting that the Zaire Ebolavirus human adaptation hypothesis is plausible

Effects of basic traditional Chinese diet on body mass index, lean body mass, and eating and hunger behaviours in overweight or obese individuals

Abstract Objective To compare the effects of a basic traditional Chinese diet with a Western standard diet on body mass index (BMI), lean body mass (LBD), and eating and hunger behaviours. Methods A sample of 284 patients were randomized into 2 groups: group A (n = 142) followed a basic traditional Chinese diet (BCTD) and group B (n = 142) followed a Western standard diet (WSD). Both diets were set at approximately 1200 calories. The patients enrolled were compared before treatment and 6 weeks after treatment, and then follow-ups were made at 1 year and 5 years. Results In the BCTD group, BMI decreased by 0.46 kg/m2 and LBM by 0.25 kg, versus respectively 0.28 kg/m2 and 0.41 kg in the WSD group. Findings of eating self-assessment, hunger measurement and psychophysical indices of health were also in favour of the BCTD. Conclusion Outcomes show that the BCTD has a better effect on BMI and LBM, as well as over the medium/long term, and provides stronger psychophysical support to obese patients