Comparative epidemiology of poliovirus transmission

Global epidemiology of vaccine-derived poliovirus 2016-2021: A descriptive analysis and retrospective case-control study

BACKGROUND

Vaccine derived poliovirus (VDPV) remains a major barrier to polio eradication, and recent growing emergences are concerning. This paper presents the global epidemiology of circulating VDPV (cVDPV) by exploring associations between demographic and socioeconomic factors with its recent rise.

METHODS

Data on reported cVDPV cases and isolates between January 1 2016 and June 30 2021 were compiled from EPIWATCH, an open-source observatory for outbreak scanning and analysis, the World Health Organisation (WHO) and ProMed, and analysed descriptively. Reports containing cVDPV case information were included while duplicates and defective links were excluded. Data collection occurred from April 5 2021 to July 16 2021. To identify factors associated with cVDPV, a retrospective case-control study comparing socioeconomic profiles of countries which reported cVDPV with those that did not was undertaken with weighted logistic regression analysis.

FINDINGS

cVDPV caused by serotype 2 poliovirus was the predominant strain (95%) of 1818 total human cVDPV cases reported. Of 40 countries reporting cVDPV cases or isolates, 22 (55%) had polio vaccination coverages below 80%. Low vaccination coverage (Adjusted OR = 83·41, 95% CI: [5·01, 1387·71], p = 0·0020) was found to be associated with increased odds of reporting cVDPV after adjusting for confounding effects of GDP per capita, female adult literacy rates, maternal mortality rate, and Global Peace Index.

INTERPRETATION

Our findings reinforce the importance of maintaining high levels of vaccination, as risk of re-emergence rises when immunity wanes. Interventions to increase vaccination and standards of living in developing countries, coupled with robust surveillance are required if humanity hopes to eradicate polio in the near future.

FUNDING

This research was supported by the MRFF 2021 Frontier Health and Medical Research Grant (ID RFRHPI000280), Department of Health, the Australian Government.

Analysis and prediction of hand, foot and mouth disease incidence in China using Random Forest and XGBoost

Hand, foot and mouth disease (HFMD) is an increasingly serious public health problem, and it has caused an outbreak in China every year since 2008. Predicting the incidence of HFMD and analyzing its influential factors are of great significance to its prevention. Now, machine learning has shown advantages in infectious disease models, but there are few studies on HFMD incidence based on machine learning that cover all the provinces in mainland China. In this study, we proposed two different machine learning algorithms, Random Forest and eXtreme Gradient Boosting (XGBoost), to perform our analysis and prediction. We first used Random Forest to examine the association between HFMD incidence and potential influential factors for 31 provinces in mainland China. Next, we established Random Forest and XGBoost prediction models using meteorological and social factors as the predictors. Finally, we applied our prediction models in four different regions of mainland China and evaluated the performance of them. Our results show that: 1) Meteorological factors and social factors jointly affect the incidence of HFMD in mainland China. Average temperature and population density are the two most significant influential factors; 2) Population flux has different delayed effect in affecting HFMD incidence in different regions. From a national perspective, the model using population flux data delayed for one month has better prediction performance; 3) The prediction capability of XGBoost model was better than that of Random Forest model from the overall perspective. XGBoost model is more suitable for predicting the incidence of HFMD in mainland China.

Gold-Oligonucleotide Nanoconstructs Engineered to Detect Conserved Enteroviral Nucleic Acid Sequences

Enteroviruses are ubiquitous mammalian pathogens that can produce mild to life-threatening disease. We developed a multimodal, rapid, accurate and economical point-of-care biosensor that can detect nucleic acid sequences conserved amongst 96% of all known enteroviruses. The biosensor harnesses the physicochemical properties of gold nanoparticles and oligonucleotides to provide colourimetric, spectroscopic and lateral flow-based identification of an exclusive enteroviral nucleic acid sequence (23 bases), which was identified through in silico screening. Oligonucleotides were designed to demonstrate specific complementarity towards the target enteroviral nucleic acid to produce aggregated gold–oligonucleotide nanoconstructs. The conserved target enteroviral nucleic acid sequence (≥1 × 10⁻⁷ M, ≥1.4 × 10⁻¹⁴ g/mL) initiates gold–oligonucleotide nanoconstruct disaggregation and a signal transduction mechanism, producing a colourimetric and spectroscopic blueshift (544 nm (purple) > 524 nm (red)). Furthermore, lateral-flow assays that utilise gold–oligonucleotide nanoconstructs were unaffected by contaminating human genomic DNA, demonstrated rapid detection of conserved target enteroviral nucleic acid sequence (<60 s), and could be interpreted with a bespoke software and hardware electronic interface. We anticipate that our methodology will translate in silico screening of nucleic acid databases to a tangible enteroviral desktop detector, which could be readily translated to related organisms. This will pave the way forward in the clinical evaluation of disease and complement existing strategies to overcome antimicrobial resistance.

Quality evaluation of molecular diagnostic tests for astrovirus, sapovirus and poliovirus: A multicenter study

BACKGROUND

Astrovirus (AstV), Sapovirus (SaV) and Poliovirus (PV) are important pathogens that cause infections in children under five years of age. It is a very important task to systematically monitor and evaluate the diagnostic performance of these viruses in clinical laboratories.

METHODS

In our study, we performed a multicenter evaluation study among 21 laboratories across China using simulated stool samples spiked with self-designed AstV, SaV and PV pseudoviral particles.

RESULTS

The testing capability of 80.0% (16/20, AstV), 52.6% (10/19, SaV), and 25.0% (2/8, PV) of the participating laboratories were found to be "competent" in reporting correct results for all samples. The main type of errors were false negatives. None of the laboratories identified the subtypes of AstV and SaV, and six laboratories specifically identified the subtypes of PV. Lacking of well-trained personnel and adequate funding were the main challenges. From the questionnaire results, 55.6% laboratories (10/18) believe that training personnel could improve the laboratory testing performance.

CONCLUSIONS

The laboratories showed a competent diagnostic performance for AstV, but inferior diagnostic performances for SaV and PV. Sensitivity of detection and the ability for virus typing should be improved clinically. Professional and standardized personnel training is urgently needed to further improve laboratory performance.

Review of poliovirus modeling performed from 2000 to 2019 to support global polio eradication

INTRODUCTION

Over the last 20 years (2000-2019) the partners of the Global Polio Eradication Initiative (GPEI) invested in the development and application of mathematical models of poliovirus transmission as well as economics, policy, and risk analyses of polio endgame risk management options, including policies related to poliovirus vaccine use during the polio endgame.

AREAS COVERED

This review provides a historical record of the polio studies published by the three modeling groups that primarily performed the bulk of this work. This review also systematically evaluates the polio transmission and health economic modeling papers published in English in peer-reviewed journals from 2000 to 2019, highlights differences in approaches and methods, shows the geographic coverage of the transmission modeling performed, identified common themes, and discusses instances of similar or conflicting insights or recommendations.

EXPERT OPINION

Polio modeling performed during the last 20 years substantially impacted polio vaccine choices, immunization policies, and the polio eradication pathway. As the polio endgame continues, national preferences for polio vaccine formulations and immunization strategies will likely continue to change. Future modeling will likely provide important insights about their cost-effectiveness and their relative benefits with respect to controlling polio and potentially achieving and maintaining eradication.