Bed Net Durability Assessments: Exploring a Composite Measure of Net Damage

Background

The durability of Long Lasting Insecticidal Nets (LLINs) in field conditions is of great importance for malaria prevention and control efforts; however, the physical integrity of the net fabric is not well understood making it challenging to determine overall effectiveness of nets as they age. The 2011 World Health Organization Pesticide Evaluation Scheme (WHOPES) guidelines provide a simple, standardized method using a proportional hole index (PHI) for assessing net damage with the intent to provide national malaria control programs with guidelines to assess the useful life of LLINS and estimate the rate of replacement.

Methods

We evaluated the utility of the PHI measure using 409 LLINs collected over three years in Nampula Province, Mozambique following a mass distribution campaign in 2008. For each LLIN the diameter and distance from the bottom of the net were recorded for every hole. Holes were classified into four size categories and a PHI was calculated following WHOPES guidelines. We investigate how the size, shape, and location of holes influence the PHI. The areas of the WHOPES defined categories were compared to circular and elliptical areas based on approximate shape and actual measured axes of each hole and the PHI was compared to cumulative damaged surface area of the LLIN.

Results

The damaged area of small, medium, large, and extra-large holes was overestimated using the WHOPES categories compared to elliptical areas using the actual measured axes. Similar results were found when comparing to circular areas except for extra-large holes which were underestimated. (Wilcoxon signed rank test of differences p< 0.0001 for all sizes). Approximating holes as circular overestimated hole surface area by 1.5 to 2 times or more. There was a significant difference in the mean number of holes < 0.5 cm by brand and there were more holes of all sizes on the bottom of nets than the top. For a range of hypothetical PHI thresholds used to designate a “failed LLIN”, roughly 75 to 80% of failed LLINs were detected by considering large and extra-large holes alone, but sensitivity varied by brand.

Conclusions

Future studies may refine the PHI to better approximate overall damaged surface area. Furthermore, research is needed to identify whether or not appropriate PHI thresholds can be used to deem a net no longer protective. Once a cutoff is selected, simpler methods of determining the effective lifespan of LLINs can help guide replacement strategies for malaria control programs.     

Cost-Effectiveness Analysis of Universal Vaccination of Adults Aged 60 Years with 23-Valent Pneumococcal Polysaccharide Vaccine versus Current Practice in Brazil

Objective

To evaluate the cost-effectiveness of introducing universal vaccination of adults aged 60 years with the 23-valent pneumococcal polysaccharide vaccine (PPV23) into the National Immunization Program (NIP) in Brazil.

Methods

Economic evaluation using a Markov model to compare two strategies: (1) universal vaccination of adults aged 60 years with one dose of PPV23 and 2) current practice (vaccination of institutionalized elderly and elderly with underlying diseases). The perspective was from the health system and society. Temporal horizon was 10 years. Discount rate of 5% was applied to costs and benefits. Clinical syndromes of interest were invasive pneumococcal disease (IPD) including meningitis, sepsis and others and pneumonia. Vaccine efficacy against IPD was obtained from a meta-analysis of randomized control trials and randomized studies, whereas vaccine effectiveness against pneumonia was obtained from cohort studies. Resource utilization and costs were obtained from the Brazilian Health Information Systems. The primary outcome was cost per life year saved (LYS). Univariate and multivariate sensitivity analysis were performed.

Results

The universal vaccination strategy avoided 7,810 hospitalizations and 514 deaths, saving 3,787 years of life and costing a total of USD$31,507,012 and USD$44,548,180, respectively, from the health system and societal perspective. The universal immunization would result in ICERs of USD$1,297 per LYS, from the perspective of the health system, and USD$904 per LYS, from the societal perspective.

Conclusion

The results suggest that universal vaccination of adults aged 60 years with the 23-valent pneumococcal polysaccharide vaccine (PPV23) is a very cost-effective intervention for preventing hospitalization and deaths for IPD and pneumonia is this age group in Brazil.     

Phosphorus-32, a Clinically Available Drug,Inhibits Cancer Growth by Inducing DNA Double-Strand Breakage

Radioisotopes that emit electrons (beta particles), such as radioiodine, can effectively kill target cells, including cancer cells. Aqueous ³²P[PO₄] is a pure beta-emitter that has been used for several decades to treat non-malignant human myeloproliferative diseases. ³²P[PO₄] was directly compared to a more powerful pure beta-emitter, the clinically important ⁹⁰Y isotope. In vitro, ³²P[PO₄] was more effective at killing cells than was the more powerful isotope ⁹⁰Y (P ≤ 0.001) and also caused substantially more double-stranded DNA breaks than did ⁹⁰Y. In vivo, a single low-dose intravenous dose of aqueous elemental ³²P significantly inhibited tumor growth in the syngeneic murine cancer model (P ≤ 0.001). This effect is exerted by direct incorporation into nascent DNA chains, resulting in double-stranded breakage, a unique mechanism not duplicatable by other, more powerful electron-emitting radioisotopes. ³²P[PO₄] should be considered for human clinical trials as a potential novel anti-cancer drug.     

Recognition of Neisseria meningitidis by the Long Pentraxin PTX3 and Its Role as an Endogenous Adjuvant

Long pentraxin 3 (PTX3) is a non-redundant component of the humoral arm of innate immunity. The present study was designed to investigate the interaction of PTX3 with Neisseria meningitidis. PTX3 bound acapsular meningococcus, Neisseria-derived outer membrane vesicles (OMV) and 3 selected meningococcal antigens (GNA0667, GNA1030 and GNA2091). PTX3-recognized microbial moieties are conserved structures which fulfil essential microbial functions. Ptx3-deficient mice had a lower antibody response in vaccination protocols with OMV and co-administration of PTX3 increased the antibody response, particularly in Ptx3-deficient mice. Administration of PTX3 reduced the bacterial load in infant rats challenged with Neisseria meningitidis. These results suggest that PTX3 recognizes a set of conserved structures from Neisseria meningitidis and acts as an amplifier/endogenous adjuvant of responses to this bacterium.     

Perceived Impact of Dental Pain on the Quality of Life of Preschool Children and Their Families

The aim of the present study was to evaluate the perceived impact of dental caries and dental pain on oral health-related quality of life (OHRQoL) among preschool children and their families. A cross-sectional study was conduct with 843 preschool children in Campina Grande, Brazil. Parents/caregivers answered a questionnaire on socio-demographic information, their child’s general/oral health and history of dental pain. The Brazilian version of the Early Childhood Oral Health Impact Scale was administered to determine the perceived impact of caries and dental pain on OHRQoL. The children underwent an oral examination. Logistic regression for complex sample was used to determine associations between the dependent and independent variables (OR: Odds ratio, α = 5%). The independents variables that had a p-value <0.20 in the bivariate analysis were selected for the multivariate model. The prevalence of dental caries and dental pain was 66.3% and 9.4%, respectively. Order of birth of the child, being the middle child (OR: 10.107, 95%CI: 2.008-50.869) and youngest child (OR: 3.276, 95%CI: 1.048-10.284) and dental pain (OR: 84.477, 95%CI: 33.076-215.759) were significant predictors of the perceived impact on OHRQOL for children. Poor perception of oral health was significant predictor of the perceived impact on OHRQOL for family (OR=7.397, 95%CI: 2.190-24.987). Dental caries was not associated with a perceived impact on the ORHQoL of either the children or their families. However, order of child birth and dental pain were indicators of impact of OHRQoL on preschool children and poor perception of oral health was indicators of impact on families.     

Hospital Admission following Acute Kidney Injury in Kidney Transplant Recipients Is Associated with a Negative Impact on Graft Function after 1-Year

The incidence and outcomes of acute kidney injury (AKI) in kidney transplantation are poorly known. Retrospective cohort analysis was performed on the data of all patients (≥3 months after transplantation and ≥16 years of age) admitted to the hospital due to medical or surgical complications from 2007 to 2010. We analyzed 458 kidney transplant recipients, 55.2% men, median age 49 (IQR, 36–58) years, median of 12.5 (IQR, 3–35) months after kidney transplantation; admitted to the hospital due to medical or surgical complications. Most of the patients received a kidney from a deceased donor (62.2%), the primary cause for hospital admission was infection (60.7%) and 57 (12.4%) individuals were diagnosed with acute rejection (AR). The incidence of AKI was 82.3%: 31.9% stage 1, 29.3% stage 2 and 21.2% stage 3. Intensive care unit (ICU) admission (OR 8.90, 95% CI: 1.77–44.56 p = 0.008), infection (OR 5.73, 95% CI: 2.61–12.56, p<0.001) and the use of contrast media (OR 9.34, 95% CI: 2.04–42.70, p = 0.004) were the independent risk factors for AKI development. The mortality rate was 2.1% and all patients who died were diagnosed with AKI. Even after the exclusion of AR cases, at the end of 12 months, the individuals with AKI exhibited higher percent changes in creatinine values when compared with individuals without AKI (9.1% vs. -4.3%; p<0.001). According to KDIGO system, we found a high incidence of AKI among the complications of renal transplantation. As in other scenarios, AKI was associated with renal function loss at 1-year after the hospital discharge.     

Barn Owl Productivity Response to Variability of Vole Populations

We studied the response of the barn owl annual productivity to the common vole population numbers and variability to test the effects of environmental stochasticity on their life histories. Current theory predicts that temporal environmental variability can affect long-term nonlinear responses (e.g., production of young) both positively and negatively, depending on the shape of the relationship between the response and environmental variables. At the level of the Czech Republic, we examined the shape of the relationship between the annual sum of fledglings (annual productivity) and vole numbers in both non-detrended and detrended data. At the districts’ level, we explored whether the degree of synchrony (measured by the correlation coefficient) and the strength of the productivity response increase (measured by the regression coefficient) in areas with higher vole population variability measured by the s-index. We found that the owls’ annual productivity increased linearly with vole numbers in the Czech Republic. Furthermore, based on district data, we also found that synchrony between dynamics in owls’ reproductive output and vole numbers increased with vole population variability. However, the strength of the response was not affected by the vole population variability. Additionally, we have shown that detrending remarkably increases the Taylor’s exponent b relating variance to mean in vole time series, thereby reversing the relationship between the coefficient of variation and the mean. This shift was not responsible for the increased synchrony with vole population variability. Instead, we suggest that higher synchrony could result from high food specialization of owls on the common vole in areas with highly fluctuating vole populations.