Risk Assessment Of Transmission Research Articles

Dexamethasone does not prevent malignant cell reintroduction in leukemia patients undergoing ovarian transplant: risk assessment of leukemic cell transmission by a xenograft model.

Does dexamethasone (DXM) incubation avoid the reintroduction of leukemic malignant cells after ovarian tissue retransplantation in vivo? DXM incubation prior to retransplantation of ovarian tissue does not prevent reintroduction of leukemic cells. Retransplantation of cryopreserved ovarian cortex from patients diagnosed with acute lymphoblastic leukemia (ALL) involves a risk of reintroducing malignant cells. DXM treatment is effective at inducing leukemic cell death in vitro. This was an experimental study where ovarian cortex fragments from patients with ALL were randomly allocated to incubation with or without DXM (n = 11/group) and grafted to 22 immunodeficient mice for 6months. In a parallel experiment, 22 immunodeficient mice were injected i.p. with varying amounts of RCH-ACV ALL cells (human leukemia cell line) and maintained for 4months. Cryopreserved ovarian fragments from patients with ALL were exposed in vitro to 0.4μM DXM or basal media (control) prior to xenograft into ovariectomized severe combined immunodeficiency (SCID) mice (experiment 1). After 6months of monitoring, leukemia cell contamination was assessed in ovarian grafts and mouse organs by histology, PCR (presence of mouse mtDNA and absence of p53 were together considered a negative result for the presence of human cells) and detection of immunoglobulin monoclonality and specific ALL markers if present in the patient.In experiment 2, a series of 22 immunodeficient female mice was injected with specific doses of the leukemia cell line RCH-ACV (103 - 5 × 106, n = 4/group) to assess the engraftment competence of the SCID model. ALL metastatic cells were detected, by PCR, in five DXM-treated and one control human ovarian tissue graft as well as in a control mouse liver, although malignant cell infiltration was not detected by histology in any sample after 6months. In total, minimal residual disease was present in three DXM-treated and three control mice.RCH-ACV cells were detected in liver and spleen samples after the injection of as little as 103 cells, although only animals receiving 5 × 106 cells developed clinical signs of disease and metastases. This is an experimental study where the malignant potential of leukemic cells contained in human ovarian tissues has been assessed in immunodeficient mice. These results indicate that DXM incubation prior to retransplantation of ovarian tissue does not prevent reintroduction of leukemic cells. Therefore, caution should be taken in retransplanting ovarian tissue from patients with leukemia until safer systems are developed, as leukemic cells present in ovarian grafts were able to survive, proliferate and migrate after cryopreservation and xenograft. Funded by the Regional Valencian Ministry of Education (PROMETEO/2018/137) and by the Spanish Ministry of Economy and Competitiveness (PI16/FIS PI16/01664 and PTQ-16-08222 for S.H. participation). There are no competing interests.

HBV Transmission Risk Assessment in Healthcare Workers, Household and Sexual Contacts of HBV Infected Patients in the Southwest Region of Cameroon.

ObjectivesHepatitis B virus (HBV) is known to be highly transmissible via the body fluids of an infected person. We investigated the transmission risks, awareness, and prevalence among healthcare workers (HCWs), household contacts (HHCs), and sexual partners (SPs) of HBV infected individuals.MethodsWe conducted a cross-sectional study of HCWs, HBV infected individuals as well as their corresponding HHCs and SPs. Data related to some transmission risks and HBV awareness was obtained from each participant using a questionnaire. Blood samples were collected from each participant and tested for hepatitis B surface antigen (HBsAg), hepatitis B e-antigen, and anti-hepatitis B core (anti-HBc). HBV viral load measurement was done for the HBV infected participants.ResultsA total of 596 participants were enrolled (127 HCWs, 128 HHCs, 138 SPs, and 203 HBV infected participants). HHCs (odds ratio (OR): 3.85, confidence interval (CI): 1.89–7.81), and SPs (OR: 3.04, CI: 1.51–6.17) were more associated with HBsAg/anti-HBc positivity compared to HCWs. Age, years spent with HBV infected partner, unprotected sex, and marriage were not identified as risk factors for HBV sexual transmission but cohabiting with an HBV infected SP was significantly (p = 0.005) associated with transmission (OR: 3.56, CI: 1.46–8.72). Female HHCs (OR: 2.48, CI: 1.06–5.80) and SPs (OR: 2.64, CI: 0.95–7.30) were more associated with HBsAg/anti-HBc positivity. The mean viral load (log IU) of HBV infected individuals (3.9±2.0) with HBsAg positive SPs was significantly higher than that of HBV infected individuals (2.8±1.0) with HBsAg negative SPs (p < 0.001).ConclusionsHHCs and SPs of HBV infected patients are more associated with HBV infection compared to HCWs. Horizontal transmission can as well be implicated among SPs since unprotected sex was not identified as a risk factor for transmission, but cohabitation was. Prompt management and preventive measures could be implemented if HHCs and SPs of HBV infected patients are identified, sensitized, and screened.

A Study of the Added Value of Xpert MTB/RIF Assay for Assessment of Pulmonary Tuberculosis Transmission Risk

A Study of the Added Value of Xpert MTB/RIF Assay for Assessment of Pulmonary Tuberculosis Transmission Risk

A framework for assessing local transmission risk of imported malaria cases

BackgroundA key issue in achieving and sustaining malaria elimination is the need to prevent local transmission arising from imported cases of malaria. The likelihood of this occurring depends on a range of local factors, and these can be used to allocate resources to contain transmission. Therefore, a risk assessment and management strategy is required to identify risk indexes for malaria transmission when imported cases occur. These risks also need to be quantified and combined to give a weighted risk index score. This can then be used to allocate the resources to each administrative region to prevent transmission according to the degree of risk.MethodsA list of potential risk indexes were generated from a literature review, expert consultation and panel discussion. These were initially classified into 4 first-level indexes including infection source, transmitting conditions, population vulnerability and control capacity. Each of these was then expanded into more detailed second-level indexes. The Delphi method was then used to obtain expert opinion to review and revise these risk indexes over two consecutive rounds to quantify agreement among experts as to their level of importance. Risk indexes were included in the final Transmission Risk Framework if they achieved a weighted importance score ≥ 4. The Analytic Hierarchy Process was then used to calculate the weight allocated to each of the final risk indexes. This was then used to create an assessment framework that can be used to evaluate local transmission risk in different areas.ResultsTwo rounds of Delphi consultation were conducted. Twenty-three experts were used at each round with 100% recovery rate of participant questionnaires. The coordination coefficients (W) for the two rounds of Delphi consultation were 0.341 and 0.423, respectively (P < 0.05). Three first-level indexes and 13 second-level indexes were identified. The Analytic Hierarchy Process was performed to calculate the weight of the indexes. For the first-level indexes, infection source, transmitting conditions, and control capacity, the index weight was 0.5396, 0.2970 and 0.1634 respectively. For the three top second-level indexes, number of imported malaria cases, Anopheles species, and awareness of timely medical visit of patient, the index weight was 0.3382, 0.2475, and 0.1509 respectively.ConclusionsAn indexed system of transmission risk assessment for imported malaria was established using the Delphi method and the Analytic Hierarchy Process. This was assessed to be an objective and practical tool for assessing transmission risk from imported cases of malaria into China.

Risk assessment of schistosomiasis transmission in Chuxiong City of Yunnan Province

To evaluate the potential risk of schistosomiasis transmission so as to provide the evidence for formulating the control strategy. Two villages were selected as the investigated sites in Chuxiong City and the risk of schistosomiasis transmission was evaluated by reviewing the data of schistosomiasis epidemic situation and prevention and control work, and carrying out the field survey for Oncomelania hupensis snail status, wild faeces, and schistosome infection of the population from 2015 to 2017. There was 1.49 hm2 area of snail habitats, with an average density of 0.54 snails/0.1 m2. The occurrence rate of frames with snails was 5.41%. No schistosome-infected snails were found. The positive rate of schistosomiasis serological tests of the residents was 3.36%, but the stool examination positive cases were not found. A total of 58 wild faeces samples were collected but no schistosome infested cases were found. The risk levels of schistosomiasis transmission in both villages were Grade III. Although Chuxiong City has been in a low risk state of schistosomiasis transmission, the density of snails is still high, and there is a risk of infection source importation. In the future, the infection source control and snail control should be strengthened.

Research on Wind Disaster Risk Assessment of Transmission and Distribution Lines

Based on the 10-year wind speed data, geographic data and grid data of Fujian Province, a wind disaster model of transmission and distribution lines including disaster-causing factor, disaster-embedded environment, disaster-bearing body and anti-disaster capability, is established. The geographical information system (GIS) technology is used to vectorize the wind disaster risk index of the transmission and distribution lines, and the distribution map of the wind disaster risk index based on the map of Fujian Province is obtained. The results show that the risk of wind disasters from coastal to inland is gradually decreasing. The risks from Fuzhou to Ningde and Xiamen to Quanzhou are the highest, and the maximum disaster index is 0.69 in Fuzhou.

Assessment of West nile virus transmission risk from a weather-dependent epidemiological model and a global sensitivity analysis framework

West Nile virus (WNV) transmission risk is strongly related to weather conditions due to the sensitivity of the mosquitoes to climatic factors. We assess the WNV transmission risk of humans to seasonal weather conditions and the relative effects of parameters affecting the transmission dynamics. The assessment involves a known epidemiological model we extend to account for temperature and precipitation and a global uncertainty and sensitivity analysis framework. We focus on three relevant quantities, the basic reproduction number (R0), the minimum infection rate (MIR), and the number of infected individuals. The highest-priority weather-related WNV transmission risks can be attributed to the birth and death rate of mosquitoes, the biting rate of mosquitoes to birds, and the probability of transmission from birds to mosquitoes. Global sensitivity analysis indicates that these parameters make up a big part of the explained variance in R0 and MIR. The analysis allows for a dynamic assessment over time capturing the period parameters are more relevant than others.Global uncertainty and sensitivity analysis of WNV transmission risk to humans enable insights into the relative importance of individual parameters of the transmission cycle of the virus facilitating the understanding of the dynamics and the implementation of tailored control strategies.

Spatial distribution of Haemaphysalis species ticks and human Kyasanur Forest Disease cases along the Western Ghats of India, 2017-2018.

Kyasanur Forest Disease (KFD) is a viral haemorrhagic fever, transmitted to humans and other hosts by a tick vector of genus Haemaphysalis. It affects 400-500 people annually in the Western Ghats region of India through spring to summer season. To understand the species composition, distribution, and abundance of Haemaphysalis ticks in endemic taluks (sub-districts) of India, a surveillance for ticks was conducted between October 2017 and January 2018. In total 105 sites were selected based on grid sampling from five taluks representing five KFD endemic states in south India. A sum of 8373 ticks were collected by using standard flagging method. The study showed a wide distribution of host seeking tick species among the selected taluks, wherein Haemaphysalis spinigera was predominant in 3/5 taluks, Haemaphysalis bispinosa in 1/5 taluks, and both the species in 1/5 taluks. Further, the H. spinigera abundance was categorised and compared with the incidence of human cases during the same season. The grids with very high and high H. spinigera abundance had 70% of the 205 human cases reported. This method of tick surveillance could be efficiently used as a standard model for KFD transmission risk assessment and prediction of impending outbreaks.

From H5N1 to HxNy: An epidemiologic overview of human infections with avian influenza in the Western Pacific Region, 2003–2017

Since the first confirmed human infection with avian influenza A(H5N1) virus was reported in Hong Kong Special Administrative Region in 1997, sporadic zoonotic avian influenza viruses causing illness in humans have been identified globally, with the WHO Western Pacific Region as one of the hotspots. From November 2003, when a resurgence of H5N1 virus activity in humans and animals occurred, through September 2017, 1,838 human infections with avian influenza viruses in the region were reported to WHO. Viruses infecting humans were A(H5N1), A(H5N6), A(H6N1), A(H7N9), A(H9N2) and A(H10N8). The vast majority of infections were with H7N9 (n=1,562) and H5N1 (n=238) viruses, and most (n=1583, 86%) were reported from December through April. In poultry and wild birds, H5N1 and H5N6 subtypes were the most widely distributed, with outbreaks reported from ten and eight countries and areas, respectively. Regional analyses of human infections with avian influenza subtypes revealed distinct patterns and variations in epidemiology across countries, age, and time. Such epidemiologic patterns may not be apparent from aggregated global summaries or isolated country reports; regional assessment can offer additional insight that can inform risk assessment and response efforts. As infected animals and contaminated environments are the primary source of human infections, regional analyses that bring together surveillance data from human and animal health sectors are an important basis for exposure and transmission risk assessment and public health action. A One Health approach combining sustained event-based surveillance with enhanced collaboration between the human, animal (domestic and wildlife), and environmental sectors will provide a basis to inform joint risk assessment and coordinated response capacities

Hepatitis E virus: a nationwide study for risk assessment of foodborne transmission

Hepatitis E virus: a nationwide study for risk assessment of foodborne transmission

Risk factors spatial-temporal detection for dengue fever in Guangzhou.

Dengue fever (DF) has been a growing public-health concern in China since its emergence in Guangdong Province in 1978. Of all the regions that have experienced dengue outbreaks in mainland China, the city of Guangzhou is the most affected. This study aims to investigate the potential risk factors for dengue virus (DENV) transmission in Guangzhou, China, from 2006 to 2014. The impact of risk factors on DENV transmission was qualified by the q-values calculated using a novel spatial-temporal method, the GeoDetector model. Both climatic and socioeconomic factors were considered. The impacts on DF incidence of each single factor and the interaction of two factors were analysed. The results show that the number of days with rainfall of the month before last has the highest determinant power, with a q-value of 0.898 (P < 0.01); the q-values of the other factors related to temperature and precipitation were around 0.38-0.50. Integrating a Pearson correlation analysis, nonlinear associations were found between the DF incidence in Guangzhou and the climatic factors considered. The coupled impact of the different variables considered was enhanced compared with their individual effects. In addition, an increased number of tourists in the city were associated with a high incidence of DF. This study demonstrates that the number of rain days in a month has great influence on the DF incidence of the month after next; the temperature and precipitation have nonlinear impacts on the DF incidence in Guangzhou; both the domestic and overseas tourists coming to the city increase the risk of DENV transmission. These findings are useful in the risk assessment of DENV transmission, to predict DF outbreaks and to implement preventive DF reduction strategies.

Strategy for prevention and control of imported infectious disease

The process of globalization increases the risk of global transmission of infectious diseases, resulting in pressure for country's prevention and control of imported infectious disease. Based on the risk assessment of disease importation and local transmission, a strategy that conducting importation prevention and routine prevention and control before the importation of disease and taking emergency control measures after the importation of disease was developed. In addition, it is important to take part in global infectious disease response action, aid the countries with outbreak or epidemic to actively decrease the risk of disease importation.

Assessment of HIV transfusion transmission risk in South Africa: a 10-year analysis following implementation of individual donation nucleic acid amplification technology testing and donor demographics eligibility changes.

In 1998 we estimated that 34/million infectious window period donations were entering the blood supply at the South African National Blood Service. Selective use of donations based on donor race-ethnicity reduced this risk to 26/million donations but was deemed unethical. Consequently, in 2005 South African National Blood Service eliminated race-ethnicity-based collection policies and implemented individual-donation nucleic acid testing (ID-NAT). We describe the change in donor base demographics, human immunodeficiency virus (HIV) detection rates, and transfusion-transmissible HIV risk. In ten years 7.7 million donations were tested for anti-HIV and HIV RNA. Number of donations, HIV prevalence, ID-NAT yield rate, serology yield rate and residual transfusion-transmissible HIV risk were analyzed by donor type, race-ethnicity, age, and sex. Multiple regression analysis was performed to investigate the determinants of HIV-positive and nucleic acid testing yield donations. The combined strategy of increasing donations from black donors and implementing ID-NAT increased the proportion of donations from black donors from 6% in 2005 to 30% in 2015 (p < 0.00001), and reduced the transfusion-transmissible risk from 24 to 13 per million transfusions. ID-NAT interdicted 481 (1:16,100) seronegative window period donations, while one transfusion-transmissible case (0.13 per million) was documented. Race-ethnicity and donor type were highly significant predictors of HIV positivity, with adjusted odds ratio for first-time donors of 12.5 (95% confidence interval, 11.9-13.1) and for black race-ethnicity of 31.1 (95% confidence interval, 28.9-33.4). The proportion of serology yields among HIV-infected donors increased from 0.27% to 2.4%. ID-NAT enabled the South African National Blood Service to increase the number of donations from black donors fivefold while enhancing the safety of the blood supply.

Occurrence and subtype distribution of Blastocystis sp. in humans, dogs and cats sharing household in northern Spain and assessment of zoonotic transmission risk

Blastocystis sp. is probably the most common enteric parasite in humans globally. Although the role of Blastocystis in human disease is still controversial, epidemiological and experimental evidence suggests that pathogenicity may be associated with certain subtypes of the protist. Since the life cycle of Blastocystis is maintained through still elusive pathways, companion animals have attracted the attention of researchers as potential reservoirs of human infections. In order to evaluate the risk of zoonotic transmission of Blastocystis, we investigated the occurrence and molecular diversity of this microorganism in human, canine and feline populations sharing temporal and spatial settings in the province of Álava, northern Spain. A total of 268 (including 179 human, 55 canine and 34 feline) faecal specimens were obtained from 63 family households during February-December 2014. Detection of Blastocystis was achieved by PCR amplification and sequencing of small subunit rRNA genes. Blastocystis was found in 35.2% (95% CI: 0.29%-0.42%) of the human stool samples analysed, but not in any of the canine or feline faecal specimens investigated. Out of the 63 PCR-positive human samples, 84.1% (53/63) were successfully subtyped, allowing the identification of the subtypes ST2 (62.3%), ST3 (17.0%), ST1 (13.2%) and ST4 (7.5%). No mixed subtype infections were identified. Blastocystis carriage was independent of the gender and region of origin of the affected individuals, but children in the age groups of >5-10years and >10-15years were significantly more affected by the protist. None of the risk factors considered (water-use practices, contact with livestock, contact with individual undergoing diarrhoeal episodes) were associated with increased prevalence of Blastocystis. Our data demonstrate that pet dogs and cats play a negligible role as natural reservoirs of human Blastocystis infection in this geographic region, although the applicability of these results should be corroborated in future molecular epidemiological studies.

Assessment of schistosomiasis transmission risk after flood damage in Wuhan City

To assess the schistosomiasis transmission risk after flood damage in Wuhan City. Schistosomiasis epidemic villages in Wuhan City were selected by using probability proportional to size sampling (PPS). The field investigations of Oncomelania hupensis snails, the activity of people and cattle on marshland, water infectivity of schistosome, reservoir host infection and wild feces contamination were conducted. I-III levels of risk environments were assessed and treated with appropriate measures. A total of 90 schistosomiasis epidemic villages and 170 environments were monitored. Totally 9 811 snails were dissected but no Schistosoma japonicum infected snails were found. There were significant decreases in the density of snails and the survival rate of living snails after the flood (χ2 = 102.517, t = 4.724, both P < 0.01). Totally 289 pieces of wild feces were captured, and no eggs of S. japonicum were detected. A total of 11 surveillance and forecast sites were detected on water systems, and 221 sentinel mice were placed. After breeding, 219 sentinel mice survived (99.10%), and no schistosome infection was detected. In addition, 1 720 mouse traps were placed in 3 survey sites, and 66 Apodemus agrarius were captured, and no schistosome-infected ones were found. All of the environments were assessed as Grade III. Meanwhile, 5 key schistosomiasis control areas were determined, and no emergency happened after the implementation of comprehensive control interventions. The risk of schistosomiasis transmission remains low in Wuhan City after the flood, but the potential epidemic risk cannot be ignored.

Experimental risk assessment for chikungunya virus transmission based on vector competence, distribution and temperature suitability in Europe, 2018.

BackgroundOver the last decade, the abundant distribution of the Asian tiger mosquito Aedes albopictus in southern Europe and the import of chikungunya virus (CHIKV) by infected travellers has resulted in at least five local outbreaks of chikungunya fever in France and Italy. Considering the ongoing spread of Ae. albopictus to central Europe, we performed an analysis of the Europe-wide spatial risk of CHIKV transmission under different temperature conditions. Methods: Ae. albopictus specimens from Germany and Italy were orally infected with CHIKV from an outbreak in France and kept for two weeks at 18 °C, 21 °C or 24 °C. A salivation assay was conducted to detect infectious CHIKV. Results: Analyses of mosquito saliva for infectious virus particles demonstrated transmission rates (TRs) of > 35%. Highest TRs of 50% for the mosquito population from Germany were detected at 18 °C, while the Italian population had highest TRs of 63% at 18 °C and 21 °C, respectively. Temperature data indicated a potential risk of CHIKV transmission for extended durations, i.e. sufficiently long time periods allowing extrinsic incubation of the virus. This was shown for areas already colonised by Ae. albopictus, as well as for large parts of central Europe that are not colonised. Conclusion: The current risk of CHIKV transmission in Europe is not primarily restricted by temperature, which allows extrinsic incubation of the virus, but rather by the vector distribution. Accordingly, all European countries with established populations of Ae. albopictus should implement respective entomological surveillance and monitoring systems, as basis for suitable control measures.

Multi Criteria Decision Model for Risk Assessment of Transmission and Distribution Assets

This article describes how in order to prioritize the risks for a large number of assets, various criteria are used for ranking the asset risk. Since the criteria used for developing the risk rank is a mixture of quantitative and qualitative, a method was required to handle both the quantitative and qualitative criteria with varying scales that can be used for the electrical industry's assets. This article proposes a hybrid multi-criteria decision model (MCDM) that combines both weighted sum model (WSM) and analytical hierarchy process (AHP). The hybrid model is then applied to the strategic asset management plan for the electric power industry for ranking the assets risk. In this application, a large number of criteria reflecting asset conditions with their numerical values are available for which WSM method worked quite efficiently. The AHP method was applied to the criteria where qualitative criteria were available. Both methods were then synthesized, and the proposed hybrid method was formulated which resulted in a computationally efficient outcome with robust mathematical framework. The results show that the proposed method exhibited optimal results for the electric industry's asset where qualitative criteria are for AHP method was limited to 3 to 5. In the case of WSM, a larger number of quantitative criteria could be accommodated although for the application only six criteria were utilized.

Mapping the transmission risk of Zika virus using machine learning models

Zika virus, which has been linked to severe congenital abnormalities, is exacerbating global public health problems with its rapid transnational expansion fueled by increased global travel and trade. Suitability mapping of the transmission risk of Zika virus is essential for drafting public health plans and disease control strategies, which are especially important in areas where medical resources are relatively scarce. Predicting the risk of Zika virus outbreak has been studied in recent years, but the published literature rarely includes multiple model comparisons or predictive uncertainty analysis. Here, three relatively popular machine learning models including backward propagation neural network (BPNN), gradient boosting machine (GBM) and random forest (RF) were adopted to map the probability of Zika epidemic outbreak at the global level, pairing high-dimensional multidisciplinary covariate layers with comprehensive location data on recorded Zika virus infection in humans. The results show that the predicted high-risk areas for Zika transmission are concentrated in four regions: Southeastern North America, Eastern South America, Central Africa and Eastern Asia. To evaluate the performance of machine learning models, the 50 modeling processes were conducted based on a training dataset. The BPNN model obtained the highest predictive accuracy with a 10-fold cross-validation area under the curve (AUC) of 0.966 [95% confidence interval (CI) 0.965-0.967], followed by the GBM model (10-fold cross-validation AUC = 0.964[0.963-0.965]) and the RF model (10-fold cross-validation AUC = 0.963[0.962-0.964]). Based on training samples, compared with the BPNN-based model, we find that significant differences (p = 0.0258* and p = 0.0001***, respectively) are observed for prediction accuracies achieved by the GBM and RF models. Importantly, the prediction uncertainty introduced by the selection of absence data was quantified and could provide more accurate fundamental and scientific information for further study on disease transmission prediction and risk assessment.

Risk Assessment of Bulgarian Electricity Network under Natural Disasters

The electricity transmission and distribution networks are heavily affected from natural disasters. Electricity networks can also incur multiple or multi-risks, including their conjoint and cascading effects, or systemic risks. The aim this paper is to propose an approach for risk assessment of Bulgarian electricity transmission and distribution network under natural disasters. The proposed approach for risk assessment is based on guidelines and techniques of risk management standards ISO 31000:2009 and EN 31010:2010. Here, the risk assessment is the overall process of risk identification, risk analysis and risk evaluation. The risk assessment results can support the all key stakeholders to take more informed decision about effective protection of the electricity networks from natural disasters.

Polio vaccines and biorisk management of polioviruses

Japan is the first country where inactivated polio vaccines derived from Sabin attenuated strains, which are used to manufacture oral polio vaccines, were introduced in routine immunization program. The Sabin-derived inactivated vaccine has been developed based on the fact that Sabin strains are less neurovirulent and manufactured at safer productionfacilities than wild polioviruses. It is also convincing that Sabin strains are more safely used for evaluating the efficacy of inactivated vaccines in rat immunogenicity tests. However, in the current situation where polioviruses are close to being eradicated, the facilities that manufacture vaccines and/or conduct quality control of them are needed to meet the biorisk management requirements established by WHO, which are based on the Polio Eradication & Endgame Strategic Plan 2013-2018. At present, type 2 polioviruses including Sabin 2 strain should be contained in the facilities which meet the WHO biorisk management requirements. The respective facilities are expected to give full consideration based on a careful risk assessment of viral transmission not only to personnel, but also to the environment and the community around the facilities, and the establishment of biorisk management will be needed. Thus, the facilities handling and storing infectious polioviruses must be certified as poliovirus-essential facilities following the WHO biorisk management requirements.