Risk Of Reintroduction Research Articles

Reverse zoonotic transmission of human seasonal influenza to a pig herd in Sweden.

In January 2023, a Swedish piglet-producing farm with 2800 sows in production (SIP) was diagnosed with IAV (Influenza A virus) and the isolates were shown to cluster with the human seasonal influenza (2022/2023). In December 2022, employees with flu like symptoms tended to the pigs and a few weeks later, respiratory signs appeared in different age groups; sows in farrowing units were anorectic and pyrectic. Lung and nasal swabs were tested positive for IAV and other respiratory infectious agents. Blanket vaccination against H1N1pdm09 of sows and gilts was initiated but discontinued for sows after 2 treatments. Biosecurity measures aiming to reduce the spread of virus were implemented. However, the compliance to follow the protocol was moderate.Combining immunity and strict sanitary measures is crucial to control virus circulation. As the farmer discontinued sow vaccination and just partly increased biosecurity, this may have contributed to ongoing virus circulation and clinical signs in pigs, even 5 months post-diagnosis. Although H1N1pdm09 already had been found in the herd in 2017, there were no clinical signs or diagnostic results indicating continuous circulation of this or other IAV strains afterwards. However, this cannot be entirely excluded. Swine IAVs pose a risk of reintroduction into the human population, highlighting the importance of vaccination of farm workers against seasonal influenza.

Review of the Highly Pathogenic Avian Influenza in Argentina in 2023: Chronicle of Its Emergence and Control in Poultry.

Highly pathogenic avian influenza (HPAI) is a highly contagious viral disease that represents a significant threat to poultry production worldwide. Variants of the HPAI virus (HPAIV) H5A/Goose/GuangDong/1/96 (H5 Gs/GD/96) lineage have caused five intercontinental epizootic waves, with the most recent, clade 2.3.4.4b, reaching Argentina in February 2023. Initially detected in wild birds, the virus quickly spread to backyard and commercial poultry farms, leading to economic losses, including the loss of influenza-free status (IFS). By March/April 2023 the epidemic had peaked and vaccination was seriously considered. However, the success of strict stamping-out measures dissuaded the National Animal Health Authority (SENASA) from authorizing any vaccine. Suspected cases sharply declined by May, and the last detection in commercial poultry was reported in June. The effective control and potential eradication of HPAIV in Argentina were due to SENASA's early detection and rapid response, supported by private companies, veterinarians, and other stakeholders. Stamping-out measures have been effective for virus elimination and reduced farm-to-farm transmission; however, as the virus of this clade may remain present in wild birds, the risk of reintroduction into poultry production is high. Therefore, maintaining continuous active surveillance will be crucial for promptly detecting any new HPAIV incursion and taking appropriate action to contain virus dissemination.

Delving into the Aftermath of a Disease-Associated Near-Extinction Event: A Five-Year Study of a Serpentovirus (Nidovirus) in a Critically Endangered Turtle Population.

Bellinger River virus (BRV) is a serpentovirus (nidovirus) that was likely responsible for the catastrophic mortality of the Australian freshwater turtle Myuchelys georgesi in February 2015. From November 2015 to November 2020, swabs were collected from turtles during repeated river surveys to estimate the prevalence of BRV RNA, identify risk factors associated with BRV infection, and refine sample collection. BRV RNA prevalence at first capture was significantly higher in M. georgesi (10.8%) than in a coexisting turtle, Emydura macquarii (1.0%). For M. georgesi, various risk factors were identified depending on the analysis method, but a positive BRV result was consistently associated with a larger body size. All turtles were asymptomatic when sampled and conjunctival swabs were inferred to be optimal for ongoing monitoring. Although the absence of disease and recent BRV detections suggests a reduced ongoing threat, the potential for the virus to persist in an endemic focus or resurge in cyclical epidemics cannot be excluded. Therefore, BRV is an ongoing potential threat to the conservation of M. georgesi, and strict adherence to biosecurity principles is essential to minimise the risk of reintroduction or spread of BRV or other pathogens.

Anopheles sacharovi in Italy: first record of the historical malaria vector after over 50 years

BackgroundAnopheles sacharovi, a member of the Anopheles maculipennis complex, was a historical malaria vector in Italy, no longer found since the last report at the end of 1960s. In September 2022, within the Surveillance Project for the residual anophelism, a single specimen of An. maculipennis sensu lato collected in Lecce municipality (Apulia region) was molecularly identified as An. sacharovi. This record led to implement a targeted entomological survey in September 2023. MethodsInvestigation was conducted in the areas around the first discovery, focusing on animal farms, riding stables and potential breeding sites. Adult and immature mosquitoes were collected, using active search or traps, in several natural and rural sites. Mosquitoes belonging to An. maculipennis complex were identified morphologically and molecularly by a home-made routine quantitative polymerase chain reaction (qPCR) assay, developed specifically for the rapid identification of An. labranchiae, and, when necessary, by amplification and sequencing of the ITS-2 molecular marker.ResultsOut of the 11 sites investigated, 6 were positive for Anopheles presence. All 20 An. maculipennis s.l. (7 adults, 10 larvae and 3 pupae) collected in the areas were identified as An. sacharovi by ITS-2 sequencing.ConclusionsThe discovery of An. sacharovi, considered to have disappeared from Italy for over 50 years, has a strong health relevance and impact, highlighting an increase in the receptivity of the southern areas. As imported malaria cases in European countries are reported every year, the risk of Plasmodium introduction by gametocyte carriers among travellers from endemic countries should be taken into greater consideration. Our findings allow rethinking and building new models for the prediction and expansion of introduced malaria. Furthermore, to prevent the risk of reintroduction of the disease, the need to strengthen the surveillance of residual anophelism throughout the South should be considered.Graphical

Malaria cases in China acquired through international travel, 2013-2022.

Despite the World Health Organisation certifying China malaria-free in 2021, the risk of local transmission caused by imported malaria cases remains a significant clinical and public health issue. It is necessary to present the changing trends of malaria in China and discuss the role of travel medicine services in consolidating malaria elimination. This study systematically reviewed articles and reports related to human malaria from 2013 to 2022 published in international and Chinese databases. Data on malaria (i.e. number of cases, Plasmodium spp., diagnostic method, country of acquisition, provinces with high risk of re-introduction and transmission) were collected and synthesised, then summarised using descriptive statistics. Overall, 24 758 cases of malaria (>99.5% laboratory confirmed, > 99.2% imported, 0.5% fatal) were reported in China from 2013 to 2022, with a downward trend over the years (4128 cases in 2013 compared to 843 cases in 2022; χ2 trend p-value = 0.005). The last locally acquired case was reported in 2017. P. falciparum (65.5%) was the most common species identified, followed by P. vivax (20.9%) and P. ovale (10.0%). Two Pheidole knowlesi cases were also identified in 2014 and 2017 in returned travellers from Malaysia and Indonesia, respectively. The most common countries of malaria acquisition were Ghana, Angola, and Myanmar. P. vivax was mainly detected in returned travellers from Myanmar, while P. falciparum and P. ovale were detected in travellers from Sub-Saharan Africa. Imported cases were mainly reported in Yunnan, Jiangsu, Sichuan, Guangxi, Shandong, Zhejiang, and Henan provinces, where large numbers of Chinese people travel overseas for work. Returned travellers from malaria-endemic countries pose a significant risk of malaria re-introduction to China. Travel medicine should be strengthened to improve the capacity and accessibility of both pre- and post-travel services, including malaria prophylaxis and prompt diagnosis of illness in returned travellers.

P755 Long-term need for restart of biologics after withdrawal in patients with Inflammatory Bowel Disease in mucosal healing

Abstract Background In patients with inflammatory bowel disease (IBD) on biologic therapy, once remission has been achieved, withdrawal is a frequent issue in clinical practice that generates uncertainty in aspects such as the reduction of adverse effects and costs, but also the risk of recurrence of activity and the need to restart treatment. The aim of this study was to determine the rate of long-term reintroduction of biologics after withdrawal due to mucosal healing (MH) in IBD, the response to reintroduction and the associated factors. Methods Observational, descriptive, single-centre, retrospective, descriptive study of 178 cases in 164 patients diagnosed with ulcerative colitis (UC) or Crohn's disease (CD) who were withdrawn from anti-tumor necrosis factor (anti- TNF) therapy once MH had been demonstrated, between July 2009 and February 2022. Demographic and phenotypic characteristics of IBD, characteristics of biologic and immunosuppressive therapy, analytical and endoscopic/histological variables at the time of withdrawal were collected. We analysed the risk of restarting biologics due to clinical relapse and response to reintroduction of treatment. We evaluated possible factors related to the risk of restarting treatment and response to treatment. Results We included 178 cases. 123 CD and 55 UC. Most had received infliximab (62.9%) and the main indication was corticodependence (68%). Median follow-up was 78 months (IQR 59-95). Clinical relapse occurred in 69% of cases and 61.2% required reintroduction of biologics, with the probability of retreatment at 1, 3, 5 and 7 years being 19.4%, 50%, 60% and 63.4%, respectively (Figure 1). The response to reintroduction was 86.2%. Only 1.68% required surgery during follow-up. Univariate analysis showed higher risk of re-introduction at younger age at diagnosis (23 vs 30 vs 30, p 0.022) and at withdrawal (32 vs 40, p 0.019) and longer follow-up time after withdrawal (82 vs 71, p 0.026). Multivariate analysis also identified the indication for corticodependence (p 0.046). Conclusion The risk of relapse and re-starting treatment is high in the long term after withdrawal of biologic therapy for MH in IBD. Younger age at diagnosis and withdrawal, indication for corticodependence and long-term follow-up are risk factors for poor outcome. Reintroduction of treatment is very effective with low complication rates.

Malaria Stratification Mapping in Thailand to Support Prevention of Reestablishment.

Thailand aims to eliminate malaria by 2026, with 46 of the country's 77 provinces already verified as malaria free. However, these provinces remain susceptible to the reestablishment of indigenous transmission that would threaten the national goal. Thus, the country is prioritizing national and subnational prevention of reestablishment (POR) planning while considering the spatial heterogeneity of the remaining malaria caseload. To support POR efforts, a novel nonmodeling method produced a malaria stratification map at the tambon (subdistrict) level, incorporating malaria case data, demographic data, and environmental factors. The stratification analysis categorized 7,425 tambons into the following four risk strata: Local Transmission (2.9%), At Risk for Transmission (3.1%), High Risk for Reintroduction (2.9%), and Low Risk for Reintroduction (91.1%). The stratification map will support the national program to target malaria interventions in remaining hotspots and mitigate the risk of transmission in malaria-free areas.

Treated municipal wastewater as a source of high-risk and emerging multidrug-resistant clones of E. coli and other Enterobacterales producing extended-spectrum β-lactamases

Extended-spectrum β-lactamase (ESBL)-producing Enterobacterales are a major public health problem, and wastewater from municipal wastewater treatment plants (WWTPs) is a potential means of spreading them into the environment and community. Our objective was to isolate ESBL-producing E. coli and other Enterobacterales from wastewater after treatment at Croatia's largest WWTP and to characterize these isolates by phenotypic and genotypic testing. Of the 200 bacterial isolates, 140 were confirmed as Enterobacterales by MALDI-TOF MS, with Escherichia coli and Klebsiella spp. predominating (69% and 7%, respectively). All 140 enterobacterial isolates were multidrug-resistant (MDR) and produced ESBLs. The most prevalent ESBL genes among the isolates tested were blaCTX-M-15 (60%), blaTEM-116 (44%), and blaCTX-M-3 (13%). Most isolates (94%) carried more than one ESBL gene in addition to blaCTX-M. Genes encoding plasmid-mediated AmpC, most notably blaEBC, were detected in 22% of isolates, whereas genes encoding carbapenemases (blaOXA-48, blaNDM-1, blaVIM-1) were less represented (10%). In E. coli, 9 different sequence types (ST) were found, with the emerging high-risk clones ST361 (serotype A-O9:H30) and pandemic ST131 (serotype B2–O25:H4) predominating (32% and 15%, respectively). Other high-risk E. coli clones included ST405 (3%), ST410 (3%), CC10 (3%), ST10 (3%), and ST38 (2%), and emerging clones included ST1193 (2%) and ST635 (2%). Whole-genome sequencing of three representative E. coli from two dominant clone groups (ST361 and ST131) and one extensively drug-resistant K. oxytoca revealed the presence of multiple plasmids and resistance genes to several other antibiotic classes, as well as association of the blaCTX-M-15 gene with transposons and insertion sequences. Our findings indicate that treated municipal wastewater contributes to the spread of emerging and pandemic MDR E. coli clones and other enterobacterial strains of clinical importance into the aquatic environment, with the risk of reintroduction into humans.

SARS-CoV-2 Neutralizing Antibodies in Free-Ranging Fallow Deer (Dama dama) and Red Deer (Cervus elaphus) in Suburban and Rural Areas in Spain

Effective control of zoonotic infectious diseases requires identifying the animal species involved in the infectious cycle as transmitters or reservoirs where the pathogen could persist and evolve, increasing the risk of reintroduction of new variants in humans and animals. Multiple surveillance studies have detected the presence of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) or specific antibodies in free-ranging white-tailed deer (Odocoileus virginianus) in North America, being the wild mammal species with the most reported cases of SARS-CoV-2 infection. However, so far, all attempts to detect the infection in European cervids have been unsuccessful. In this study, we demonstrated the presence of specific antibodies against SARS-CoV-2 in European fallow deer (Dama dama) and red deer (Cervus elaphus) in Spain. However, all samples of European roe deer (Capreolus capreolus), taxonomically related to the American white-tailed deer, were seronegative for the virus. We tested 215 serum samples from roe deer (n = 116), red deer (n = 63), and fallow deer (n = 36) collected in eight provinces of central-southern Spain between 2017 and 2022. We first screened sera by a surrogate virus neutralization test (sVNT) ELISA based on the binding of the receptor-binding domain of SARS-CoV-2 to the angiotensin-converting enzyme 2 (ACE2) receptor and then confirmed positive samples by a conventional virus neutralization test (cVNT) against the Alpha, Delta, and Omicron variants. Four fallow deer and two red deer samples were seropositive in both neutralization assays. Four samples of fallow deer and one of red deer, collected in a suburban park near Madrid in February 2022, had antibodies against the Alpha, Delta, and Omicron variants, while a seropositive sample of red deer, collected in a rural area in February 2021, was specific for the Delta variant. All samples collected before the start of the pandemic in Spain were seronegative for sVNT, which also indicates that there are not cross-reactive antibodies potentially elicited by other viruses antigenically related to SARS-CoV-2. The results indicate probable human-to-deer transmission of SARS-CoV-2, but do not clarify whether there was subsequent spread within herds.

Health Economic Analysis of Antiviral Drugs in the Global Polio Eradication Endgame.

Polio antiviral drugs (PAVDs) may provide a critical tool in the eradication endgame by stopping poliovirus infections in immunodeficient individuals who may not clear the virus without therapeutic intervention. Although prolonged/chronic poliovirus excreters are rare, they represent a source of poliovirus reintroduction into the general population. Prior studies that assumed the successful cessation of all oral poliovirus vaccine (OPV) use estimated the potential upper bound of the incremental net benefits (INBs) of resource investments in research and development of PAVDs. However, delays in polio eradication, OPV cessation, and the development of PAVDs necessitate an updated economic analysis to reevaluate the costs and benefits of further investments in PAVDs. Using a global integrated model of polio transmission, immunity, vaccine dynamics, risks, and economics, we explore the risks of reintroduction of polio transmission due to immunodeficiency-related vaccine-derived poliovirus (iVDPV) excreters and reevaluate the upper bound of the INBs of PAVDs. Under the current conditions, for which the use of OPV will likely continue for the foreseeable future, even with successful eradication of type 1 wild poliovirus by the end of 2023 and continued use of Sabin OPV for outbreak response, we estimate an upper bound INB of 60 million US$2019. With >100 million US$2019 already invested in PAVD development and with the introduction of novel OPVs that are less likely to revert to neurovirulence, our analysis suggests the expected INBs of PAVDs would not offset their costs. While PAVDs could play an important role in the polio endgame, their expected economic benefits drop with ongoing OPV use and poliovirus transmissions. However, stakeholders may pursue the development of PAVDs as a desired product regardless of their economic benefits.HighlightsWhile polio antiviral drugs could play an important role in the polio endgame, their expected economic benefits continue to drop with delays in polio eradication and the continued use of oral poliovirus vaccines.The incremental net benefits of investments in polio antiviral drug development and screening for immunodeficiency-related circulating polioviruses are small.Limited global resources are better spent on increasing global population immunity to polioviruses to stop and prevent poliovirus transmission.

Prevalence of poliovirus neutralizing antibodies in Italian population: A systematic review and meta-analysis

IntroductionThe introduction of anti-poliomyelitis vaccines has driven progress toward the global eradication of wild polioviruses, a millennium goal of the World Health Organization. With the vaccination campaigns carried out since 1964, in 2002 Italy was certified polio-free, considering that no cases had been recorded since 1983. Nevertheless, it is crucial to guarantee high level of immunization coverage also in low-endemicity countries, considering that sporadic polio cases can be recorded. To evaluate the presence of susceptible subjects in the population, seroepidemiological studies are key actions. MethodsWe conducted a systematic review of the relevant literature to evaluate the prevalence of anti-PV neutralizing antibodies in Italian population. Seven studies, selected among scientific articles available in MEDLINE/PubMed, ISI Web of Knowledge and Scopus and published from January 1, 2012, to November 15, 2022, were included. ResultsThe pooled prevalence of subjects without PV1 neutralizing antibodies was 6.4% (95%CI = 0.5–16.9), for PV2 it was 5.3% (95%CI = 0.4–14.2), and for PV3 it was 13.0% (95%CI = 4.0–25.7; I2 = 98.5%). Levels of neutralizing antibodies appears to decrease with increasing age; this decline is a proxy for the real risk factor, which is the time since the last vaccine dose. ConclusionsPublic health institutions must be aware of the risk of reintroduction of wild PV in polio-free countries and therefore they must keep high level of immunization in population and reinforce the active surveillance systems.

A U.S. Isolate of Theileria orientalis Ikeda Is Not Transstadially Transmitted to Cattle by Rhipicephalus microplus.

Theileria orientalis Ikeda has caused an epidemic of bovine anemia and abortion across several U.S. states. This apicomplexan hemoparasite is transmitted by Haemaphysalis longicornis ticks; however, it is unknown if other North American ticks are competent vectors. Since the disease movement is largely determined by the host tick range(s), the prediction of the T. orientalis spread among U.S. cattle populations requires determination of additional competent tick vectors. Although Rhipicephalus microplus has mostly been eradicated from the U.S., outbreaks in populations occur frequently, and the U.S. remains at risk for reintroduction. Since R. microplus is a vector of Theileria equi and T. orientalis DNA has been detected in R. microplus, the goal of this study was to determine whether R. microplus is a competent vector of T. orientalis. Larval R. microplus were applied to a splenectomized, T. orientalis Ikeda-infected calf for parasite acquisition, removed as molted adults, and applied to two T. orientalis naïve, splenectomized calves for transmission. After 60 days, the naïve calves remained negative for T. orientalis by PCR and cytology. Additionally, T. orientalis was not detected in the salivary glands or larval progeny of acquisition-fed adults. These data suggest that R. microplus is not a competent vector of the U.S. T. orientalis Ikeda isolate.

The risk of reintroduction of measles in Mexico.

The risk of reintroduction of measles in Mexico.

Vaccination against poliomyelitis in Brazil from 2011 to 2021: successes, setbacks, and challenges ahead.

The drop in childhood vaccination coverage (VC), including poliomyelitis, has become a health concern. The objective was to analyze the temporal trend of coverage of the three doses of the polio vaccine in the first 12 months of life between 2011 and 2021, in addition to mapping vaccination coverage in Brazil, including the COVID-19 pandemic period. An ecological study was carried out using interrupted time series (STI) techniques and spatial analysis, with data from the National Immunization Program Information System. The VC trend was adjusted by the Newey-West variance estimator according to the federated units and the Brazilian Deprivation Index. The VC distribution was estimated by Bayesian models and the spatial clusters by the global and local Moran index, identifying areas of lower coverage in the health regions. There was a reduction in the VC over the period in all regions, being more pronounced in the North and Northeast regions and during the Covid-19 pandemic. The biggest drops were identified in states and health regions with greater social vulnerability after 2019. The drop in VC shows that the risk of reintroduction of the wild virus is imminent and the challenges need to be faced with the strengthening of the Brazilian Health System (SUS).

Vacinação contra poliomielite no Brasil de 2011 a 2021: sucessos, reveses e desafios futuros

Abstract The drop in childhood vaccination coverage (VC), including poliomyelitis, has become a health concern. The objective was to analyze the temporal trend of coverage of the three doses of the polio vaccine in the first 12 months of life between 2011 and 2021, in addition to mapping vaccination coverage in Brazil, including the COVID-19 pandemic period. An ecological study was carried out using interrupted time series (STI) techniques and spatial analysis, with data from the National Immunization Program Information System. The VC trend was adjusted by the Newey-West variance estimator according to the federated units and the Brazilian Deprivation Index. The VC distribution was estimated by Bayesian models and the spatial clusters by the global and local Moran index, identifying areas of lower coverage in the health regions. There was a reduction in the VC over the period in all regions, being more pronounced in the North and Northeast regions and during the Covid-19 pandemic. The biggest drops were identified in states and health regions with greater social vulnerability after 2019. The drop in VC shows that the risk of reintroduction of the wild virus is imminent and the challenges need to be faced with the strengthening of the Brazilian Health System (SUS).

Two Nigerian States (Plateau and Nasarawa) Have Eliminated Transmission of Human Onchocerciasis-A Report of Post-ivermectin Mass Drug Administration Surveillance.

Transmission of Onchocerca volvulus (causing "river blindness") was interrupted in two states of Nigeria (Plateau and Nasarawa) in 2017 in accordance with 2016 WHO guidelines. Ivermectin mass drug administration was halted in January 2018, and posttreatment surveillance activities were conducted over a 3-year period. Vector Simulium damnosum s.l. flies were collected during the 2019 (39 sites) and 2020 (42 sites) transmission seasons. Head pools were tested by polymerase chain reaction for the presence of third-stage O. volvulus larvae; 15,585 flies were all negative, demonstrating an infective rate of <1/2,000 with 95% confidence. In 2021, the Nigerian Federal Ministry of Health declared the two-state area as having eliminated transmission. Plateau and Nasarawa states are the first of 30 endemic states in Nigeria to have met the WHO criteria for onchocerciasis elimination. Post-elimination surveillance will need to continue given the risk of reintroduction of transmission from neighboring states.

Актуальные проблемы сохранения балобана в республике Казахстан

Актуальные проблемы сохранения балобана в республике Казахстан

Protease-Independent Production of Poliovirus Virus-like Particles in Pichia pastoris: Implications for Efficient Vaccine Development and Insights into Capsid Assembly.

The production of enterovirus virus-like particles (VLPs) that lack the viral genome have great potential as vaccines for a number of diseases, such as poliomyelitis and hand, foot, and mouth disease. These VLPs can mimic empty capsids, which are antigenically indistinguishable from mature virions, produced naturally during viral infection. Both in infection and in vitro, capsids and VLPs are generated by the cleavage of the P1 precursor protein by a viral protease. Here, using a stabilized poliovirus 1 (PV-1) P1 sequence as an exemplar, we show the production of PV-1 VLPs in Pichia pastoris in the absence of the potentially cytotoxic protease, 3CD, instead using the porcine teschovirus 2A (P2A) peptide sequence to terminate translation between individual capsid proteins. We compare this to protease-dependent production of PV-1 VLPs. Analysis of all permutations of the order of the capsid protein sequences revealed that only VP3 could be tagged with P2A and maintain native antigenicity. Transmission electron microscopy of these VLPs reveals the classic picornaviral icosahedral structure. Furthermore, these particles were thermostable above 37°C, demonstrating their potential as next generation vaccine candidates for PV. Finally, we believe the demonstration that native antigenic VLPs can be produced using protease-independent methods opens the possibility for future enteroviral vaccines to take advantage of recent vaccine technological advances, such as adenovirus-vectored vaccines and mRNA vaccines, circumventing the potential problems of cytotoxicity associated with 3CD, allowing for the production of immunogenic enterovirus VLPs in vivo. IMPORTANCE The widespread use of vaccines has dramatically reduced global incidence of poliovirus infections over a period of several decades and now the wild-type virus is only endemic in Pakistan and Afghanistan. However, current vaccines require the culture of large quantities of replication-competent virus for their manufacture, thus presenting a potential risk of reintroduction into the environment. It is now widely accepted that vaccination will need to be extended posteradication into the foreseeable future to prevent the potentially catastrophic reintroduction of poliovirus into an immunologically naive population. It is, therefore, imperative that novel vaccines are developed which are not dependent on the growth of live virus for their manufacture. We have expressed stabilized virus-like particles in yeast, from constructs that do not require coexpression of the protease. This is an important step in the development of environmentally safe and commercially viable vaccines against polio, which also provides some intriguing insights into the viral assembly process.

Malaria Vector Surveillance and Control in an Elimination Setting in South Africa.

South Africa's malaria elimination plans are aligned to the World Health Organization's aim for a malaria-free world and include specific objectives within a specified time frame. These are proving difficult to achieve owing to the sporadic nature of locally acquired malaria in some affected districts, while other districts that were endemic for the disease are either malaria-free or very close to that goal. The WHO also specifies that continued measures to prevent the re-establishment of transmission are required in areas where elimination has been achieved. These measures include routine malaria vector surveillance in endemic districts that are free of malaria to assess receptivity and risk of reintroduction, which may prove difficult to justify in the face of competing public health priorities and limited resources. These issues are discussed here within the framework of vector surveillance and control and include recommendations on how they can be addressed going forward.

Investigation of airport sewage to detect importation of poliovirus, Poland, 2017 to 2020

BackgroundPolioviruses are human pathogens which may easily be imported via travellers from endemic areas and countries where oral polio vaccine (OPV) is still routinely used to polio-free countries. Risk of reintroduction strictly depends on polio immunisation coverage. Sustaining a polio-free status requires strategies that allow rapid detection and control of potential poliovirus reintroductions.AimThe aim of this study was to apply environmental surveillance at an international airport in Poland to estimate the probability of poliovirus importation via air transport.MethodsBetween 2017 and 2020, we collected 142 sewage samples at Warsaw Airport. After sewage concentration, virus was isolated in susceptible cell cultures. Poliovirus isolates were characterised by intratypic differentiation and sequencing.ResultsSeven samples were positive for polioviruses. All isolates were characterised as Sabin-like polioviruses type 3 (SL-3). No wild or vaccine-derived polioviruses were found. The number of mutations accumulated in most isolates suggested a limited circulation in humans. Only one SL-3 isolate contained seven mutations, which is compatible with more than half a year of circulation.ConclusionSince OPV was withdrawn from the immunisation schedule in Poland in 2016, detection of SL-3 in airport sewage may indicate the events of importation from a region where OPV is still in use. Our study shows that environmental surveillance, including airport sewage investigation, has the capacity to detect emerging polioviruses and monitor potential exposure to poliovirus importation. Poliovirus detection in sewage samples indicates the need for sustaining a high level of polio immunisation coverage in the population.