FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W3090972979> ?p ?o ?g. }

• W3090972979 endingPage "14" @default.
• W3090972979 startingPage "9" @default.
• W3090972979 abstract "As the world continues to battle the COVID-19 pandemic and the pig farming sector is concerned with the relentless geographical spread of African Swine Fever, another serious veterinary epizootic, which has gone largely unnoticed by the general media, emerged in the early months of 2020. African horse sickness (AHS), perhaps the most feared equine infectious disease, appeared in South-East Asia and threatens the equine industry worldwide. Indeed, on 17 March 2020, the Thai veterinary authorities communicated to the OIE (World Organisation for Animal Health) a confirmed case of African horse sickness (AHS) in Pak Chong, Nakhon Ratchasima, Thailand.1, 2 The outbreak is thought to have started a few days earlier in February. Since then, despite the implementation of a range of control measures (including control of animal movements, use of insect netting, and vaccination with the live attenuated vaccine), the disease spread to other dispersed locations in the country. A total of 15 different outbreaks have been recorded so far, resulting in more than 500 horse deaths, bringing the mortality rates above 90%. This is the first ever outbreak of AHS in Thailand and the first occurrence of AHS in Asia in some 60 years. In the absence of AHS occurring in neighbouring countries in decades, the emergence of AHS thousands of miles away from endemic regions for the disease, it is likely that the Thai outbreak has its origins in the importation of AHS-infected animals. Thailand is a non-endemic country for AHS and consequently its whole equine population is immunologically naive to the virus and therefore highly susceptible to the severe clinical manifestations of the disease. The hot and humid climate of Thailand, with the absence of cold winters that would interrupt the activity of Culicoides spp biting midges, the hematophagous insects that transmit African horse sickness virus (AHSV), make the continuous transmission of the disease in the region and its spread to other parts of Asia highly plausible. Some of these recent outbreaks occurred in provinces of Thailand that share borders with Myanmar, Cambodia, Malaysia and Laos, and if they are not brought under control, they will threaten the livelihoods of a large proportion of the human population of these countries, already battered by the effects of the COVID-19 pandemic. Indeed, local Thai ponies play an important role in the agricultural systems in these communities, and given the high mortality rates and effects of AHS on international trade of horses, this outbreak can also have a devastating impact on the thriving thoroughbred industry of mainland China and Hong-Kong. The evolution of historic outbreaks of AHS outside the African continent indicates that international and local veterinary bodies should monitor the Thailand epizootic very carefully. The Iberian Peninsula epizootic of 1987 – 19933, 4 amply illustrates the need for caution. It started in central Spain in 1987 and then spread to the South of the country the following seasons. Despite all possible control measures that were put in place, both in Spain and neighbouring Portugal, the virus spread to Portugal in 1989.5 It was only after vigorous and comprehensive control measures, which included widespread vaccination, control of animal movements, insect control and rigorous sero-surveillance, that this outbreak was finally eradicated. It is likely, that the mild and short winters in the South of the Iberian Peninsula contributed to the presence of AHS in that part of the world for consecutive seasons. AHS is a lethal disease that can spread rapidly within an equine population, has a high negative economic impact in countries where it occurs and affects dramatically international trade of horses. For all these reasons AHS is one of the listed diseases of the OIE (World Organisation for Animal Health)6 and is the only equine infectious disease for which the OIE issues an official recognition of disease freedom for a country or parts thereof (OIE, Terrestrial Animal Health Code).7 The loss of the AHS-freedom status is already affecting Thailand and the same will happen to neighbouring countries should AHS spread in the region. As a consequence, horse exports will be severely restricted, for example horse exports to the EU will be banned for 2 years.8 In addition, regaining OIE AHS-freedom status and restoration of equine trade with the rest of the world will require sound active and passive disease surveillance strategies, using appropriate and validated diagnostic methods. This is a task that requires efficient coordination of the veterinary services and authorities both at national and international levels. The logical diversion of national funding efforts to combat the current COVID-19 pandemic will undoubtedly play a detrimental role in the capacity to curtail the expansion of AHS in the region. Vaccination is an essential pillar of any AHS control programme and it needs to be implemented in conjunction with other control measures such as rapid accurate diagnosis, disease surveillance, prevention of insect biting and control of the movement of horses between geographical regions. The latter, normally results in the implementation of regionalisation policies and the geographical demarcation of ‘AHS-free’, ‘Protection’, ‘Surveillance’ and ‘Infected’ Zones, following the general principles established by the OIE Terrestrial Code.9 The application of these OIE guidelines have been translated into different pieces of legislation in the EU.10 the UK11 and the Republic of South Africa. Now, these policies and regionalisation strategy are being adopted in Thailand. However, monitoring the spread of the disease and regulating the movement of horses between regions of different disease status is labour-intensive and very demanding for veterinary authorities since it often involves, amongst other measures, strict checks of the infectious status of individual horses prior to movement, and the application of protracted quarantine procedures. These procedures will become even more complicated when systematic vaccination of the horse population is performed. Indeed, the only two types of vaccines that have ever been used in the field to combat AHS are: a) the whole virus attenuated AHSV vaccine (LAV), in use today; and b) the whole virus inactivated vaccine, used on a very limited scale in Iran in the 1960s and in Spain during the last year of the outbreak in 1993.3 Both types of vaccine induce an antibody response to all virus antigens and therefore it is not possible to differentiate naturally infected from vaccinated animals. Systematic vaccination of an entire horse population with these vaccines would provide protection but at the same time would result in high levels of seroprevalence. Therefore, demonstrating AHS disease freedom and/or monitoring the spread of the disease on the basis of serological data would be very complicated. The use of RT-PCR testing for monitoring the spread of infection, aiming at detecting recent infections within a population vaccinated with the attenuated vaccine, would also be challenging since RT-PCR tests can detect viral RNA in the blood of vaccinated animals for up to 100 days post vaccination. Interpretation of RT-PCR test results in horse populations vaccinated with the inactivated vaccine would be easier but these vaccines are not available yet and their protective efficacy against AHSV serotype 1, responsible for the current outbreak, is yet to be demonstrated. Systematic use of vaccination of a horse population is therefore incompatible with the AHS disease-freedom status. This is reflected in the Article 12.1.2 of the OIE Terrestrial code, which states that ‘...A country or zone may be considered free from AHS when infection with AHSV is notifiable in the whole country, systematic vaccination is prohibited, importation of equids and their semen, oocytes or embryos are carried out in accordance with this chapter, and either:.........’.9 Therefore, the main dilemma veterinary authorities are confronted with during an AHS epizootic occurring in a non-endemic country, such as Thailand and other countries in the region, is whether to vaccinate or not the horse population or parts thereof. If vaccination is finally mandated, then further considerations need to be taken into account such as: a) when to vaccinate; b) in which parts of the country is the vaccine going to be used and what animals would be vaccinated (all equids? or only certain species or breeds?); c) how surveillance is going to be performed; and d) what is the strategy to eradicate the disease, i.e. when to stop vaccinations and how to regain the AHS-freedom status. With regards to the current outbreak, these dilemmas are not only for Thailand to consider, but also for neighbouring countries that are threatened by the spread of AHS in their territories and are monitoring this outbreak. It is being reported that Cambodia and China are already testing horses for AHS.12 The pre-emptive use of current licensed vaccines in Thailand's neighbouring countries will inevitably result in loss of the AHS-freedom status and will result in economic losses due to trade restrictions. Surveillance of disease and infection using diagnostic tests validated according to international standards recommended by the OIE will play an essential role in the control of the current outbreak. Rapid accurate diagnostic tests play a critical role in disease control and surveillance, health certification and international trade of horses. The last two decades have witnessed the development of both RT-PCR and serological AHS diagnostics. Also, significant advances have been made towards the harmonisation and standardisation of diagnostic procedures. The coordinated efforts of the main AHS stakeholders (research scientists, official diagnostic laboratories, the International equine Industry and the OIE) culminated in the demonstration that the most commonly used RT-PCR and ELISA diagnostic tests perform according to the stringent criteria specified in the OIE Diagnostic Manual.13-16 Management of the current outbreak in Thailand requires the implementation of the measures mentioned previously with special emphasis on surveillance, which has to be tailored to the specific epidemiological context of this particular outbreak. With the availability of only one type of vaccine (LAV) and the risks associated with the pre-emptive use of vaccination in AHS-free areas, detection of AHS cases and monitoring the spread of disease, using the laboratory tests mentioned above, is going to play an absolutely critical role in controlling this outbreak. However, the use of RT-PCR for surveillance will be hampered by the high sensitivity of test, capable of detecting traces of viral RNA in blood for long periods of time after infection,17 and the impossibility of discerning whether a positive result is the consequence of vaccination or infection. Furthermore, viral RNA can be detected in blood of AHS convalescent animals that are no longer infectious and makes it more difficult to discern whether an active virus infection is circulating within a population. The complications of using RT-PCR for surveillance in vaccinated populations are well-known.18 The use of serology for surveillance is of high value as it would provide complementary information to the RT-PCR data and permits testing a large number of samples. However, serological data would only indicate whether AHS has been previously circulating in a horse population, unless serum samples are periodically collected from such population and the levels of antibodies are quantifiable by the serological test. In the latter case, a seroconversion (normally defined as four-fold increase in antibody titre) detected between two serum samples collected from the same animal within a period of 2 or more weeks, would indicate that an active infection occurred between the sample collection timepoints. However, of the AHS serological tests recommended by the OIE,13 only the SNT is suitable for quantifying serum antibody titres. However, the SNT is very laborious, slow, highly dependent of well-trained laboratory personnel, difficult to standardise and requires the use of high containment laboratories (up to Biosafety Level 3). Considering that vaccination is currently being used in Thailand, the strategy for disease surveillance is going to play a vital role in controlling this outbreak but adaptation of existing tests to the current epidemiological context would be necessary for improved control. All of the above indicates that an AHS DIVA vaccine would reduce costs of control policies when an outbreak occurs, improve safety of horse movements within endemic countries and finally would facilitate international trade of horses in both directions (from Thailand to the rest of the world and vice versa). Due to the drawbacks of the LAV (especially, the risk of reversion to virulence and genome segment re-assortment between vaccine and field virus), AHS research has consistently focused on finding alternative vaccine strategies that are safer and more efficacious. Over the last three decades, a broad range of vaccine platforms for AHS have been explored, ranging from protein sub-unit vaccines, to genetically modified AHSV and viral vector vaccines (reviewed by Dennis et al.19). None have yet reached the market. The reasons for this are multiple, and include amongst others, the size of the equine vaccine market, high costs of vaccine development (need for high containment animal facilities), ethical constraints (use of horses for research) and costs of manufacturing. Despite this, some of these DIVA strategies are close to entering the clinical development phase. Indeed, these new vaccines use selected viral protective antigen(s) enabling the development of complementary diagnostic tests based on the antigen and gene segments that are not included in the vaccine. The DISA (Disabled Infectious Single Animal),20 DISC (Disabled Infectious Single Cycle),21 VLP (virus-like particle)22-24 approaches are all attractive options for further research and are theoretically DIVA compatible. Their disadvantage for DIVA is that on top of developing the vaccine, investment is needed to develop and validate the DIVA accompanying test. In the case of DISC and DISA approaches, the licensing pathway for these biologically-active genetically-modified AHS virus vaccines, seems more cumbersome than for other alternative technologies. Other DIVA compatible vaccine strategies, however, have a long-track record of safety and efficacy, and can be used already in conjunction with differential diagnostic tests currently in use. Indeed, vaccines that are based only on AHSV-VP2 and/or VP5, the main targets of virus neutralising antibodies, are already DIVA compatible when used with AHSV-VP7-based diagnostic tests. These are routinely used in AHS-diagnostic laboratories. Furthermore, both RT-PCR tests based on the VP7 gene, and VP7-based ELISA procedures are recommended by the OIE13 and some of these specific tests have been very rigorously tested and reached Stage III of the OIE validation pathway,14-16 In terms of efficacy, baculovirus expressed VP2/VP5 sub-unit vaccines have been demonstrated to induce virus neutralising antibodies and protection in laboratory rodents and also in horses,25, 26 It is believed that they did not reach the market due to the high costs of manufacturing in an industrial setting. However, recent studies demonstrated that vaccine production yields can be improved significantly and that at least in the mouse model, protection can be achieved with just one vaccine dose.27 Canarypox-based vaccines expressing AHSV-VP2/ VP5 have also shown promising results in horses, at least with AHSV serotype 4, demonstrating both cellular and humoral protective immune responses could be induced.28, 29 Likewise, AHSV-VP2 vaccines based on recombinant modified Vaccinia Ankara virus (MVA) were shown to be protective in small animal models and in horses and it was shown that the main protective mechanism was mediated by virus neutralising antibodies.30-35 Furthermore, the potential to use this strategy as a polyvalent approach was also demonstrated.36 With regards to safety, in contrast with attenuated vaccines, the risk of developing an active AHSV infection in horses vaccinated with baculovirus-expressed VP2/VP5 sub-unit, Canarypox VP2/VP5 or MVA-VP2 vaccines is effectively nil. This is because these vaccines are based on non-replicative AHSV viral antigens. There are a large number of vaccines based on these technology platforms that have been developed and commercialised to prevent human and veterinary diseases. A few examples of these studies include vaccines preventing equine influenza, West Nile, human papillomavirus, MERS, Ebola, human influenza.28, 29, 37-42 Therefore, claims that these technologies are not safe or not suitable for manufacturing AHS vaccines22 are not supported by scientific evidence. Thus, all three vaccine technology platforms are suitable for industrial production, have an excellent track record of safety and have proven efficacy in the field. Any of these three vaccine platforms represent a realistic prospect for development and commercialisation of a safe, efficacious and DIVA compatible AHS vaccine. They also present the advantage that they are compatible with one another since they are based on the same protective antigens (i.e. AHSV-VP2). AHS is a truly devastating disease from both an animal welfare perspective and in respect of the economic damage that it causes. The virus is endemic to Sub-Saharan Africa but historically has emerged periodically in Southern Europe, North Africa, the Arabian Peninsula, the Middle East, Iran and India. Today it is causing a serious outbreak in Thailand, threatening the whole region. The European experience with bluetongue, a disease of ruminants that has become endemic in this continent and is caused by a virus closely related to AHSV and transmitted by the same insect vectors, is a serious reminder of what could potentially occur with AHS in South-East Asia. The spread of AHS and possible endemicity of AHSV in Asia is particularly worrying due to the lack of safe and effective vaccines able to control the disease without expensive and time-consuming additional disease management measures. The control of the current outbreak in Thailand and limitation of its wider spread in Asia will be challenging. The use of the polyvalent live attenuated vaccine, which contains in its formulation attenuated viruses of several AHSV serotypes other than AHSV type 1, will require careful design of disease surveillance protocols. Besides the implementation of vaccination with the live attenuated vaccine, the International Horse Sports Confederation (IHSC) is focusing its support on the development of polyvalent whole virus inactivated vaccines,43 which may prove sub-optimal due to the limited DIVA capability and unknown protective efficacy for AHSV-1. Therefore, at present, immediate control measures of AHS in Thailand need to focus strongly on disease surveillance, control of animal movements and re-adjusting of regionalisation policies, whilst improvements in diagnostics that facilitate surveillance procedures are developed. The Thailand outbreak of AHS is highlighting the problems that are associated with the use of whole virus attenuated vaccines in a non-endemic context and the lack of alternative safe and effective vaccines with DIVA capacity. At the time of finishing writing this article, a total of 15 outbreaks have been reported from Thailand44 and another outbreak of AHS has been reported in Malaysia, near the border with Thailand,45 which reflects the seriousness of the present situation. It will be crucial to determine the serotype and nucleotide sequence of this virus in order to elucidate the origins of this new outbreak. Dr Castillo-Olivares was partly funded by the Horizon 2020 Project PALEBLU (Grant Number: H2020-SFS-2016-2017; ID: 727393-2)" @default.
• W3090972979 created "2020-10-08" @default.
• W3090972979 creator A5006473769 @default.
• W3090972979 date "2020-10-02" @default.
• W3090972979 modified "2023-10-04" @default.
• W3090972979 title "African horse sickness in Thailand: Challenges of controlling an outbreak by vaccination" @default.
• W3090972979 cites W1493336413 @default.
• W3090972979 cites W1967312424 @default.
• W3090972979 cites W1996236104 @default.
• W3090972979 cites W1996483589 @default.
• W3090972979 cites W2017258610 @default.
• W3090972979 cites W2018657005 @default.
• W3090972979 cites W2024830567 @default.
• W3090972979 cites W2032700186 @default.
• W3090972979 cites W2040794215 @default.
• W3090972979 cites W2086671573 @default.
• W3090972979 cites W2095354600 @default.
• W3090972979 cites W2109052217 @default.
• W3090972979 cites W2112808191 @default.
• W3090972979 cites W2114217495 @default.
• W3090972979 cites W2218941270 @default.
• W3090972979 cites W2413374157 @default.
• W3090972979 cites W2504828590 @default.
• W3090972979 cites W2603856916 @default.
• W3090972979 cites W2606227898 @default.
• W3090972979 cites W2650297127 @default.
• W3090972979 cites W2729486657 @default.
• W3090972979 cites W2793851714 @default.
• W3090972979 cites W2802983646 @default.
• W3090972979 cites W2885511870 @default.
• W3090972979 cites W2895841945 @default.
• W3090972979 cites W2930141921 @default.
• W3090972979 cites W2972884925 @default.
• W3090972979 cites W2992922205 @default.
• W3090972979 cites W3016653642 @default.
• W3090972979 doi "https://doi.org/10.1111/evj.13353" @default.
• W3090972979 hasPubMedCentralId "https://www.ncbi.nlm.nih.gov/pmc/articles/7821295" @default.
• W3090972979 hasPubMedId "https://pubmed.ncbi.nlm.nih.gov/33007121" @default.
• W3090972979 hasPublicationYear "2020" @default.
• W3090972979 type Work @default.
• W3090972979 sameAs 3090972979 @default.
• W3090972979 citedByCount "19" @default.
• W3090972979 countsByYear W30909729792021 @default.
• W3090972979 countsByYear W30909729792022 @default.
• W3090972979 countsByYear W30909729792023 @default.
• W3090972979 crossrefType "journal-article" @default.
• W3090972979 hasAuthorship W3090972979A5006473769 @default.
• W3090972979 hasBestOaLocation W30909729791 @default.
• W3090972979 hasConcept C116675565 @default.
• W3090972979 hasConcept C144024400 @default.
• W3090972979 hasConcept C151730666 @default.
• W3090972979 hasConcept C159047783 @default.
• W3090972979 hasConcept C205649164 @default.
• W3090972979 hasConcept C22070199 @default.
• W3090972979 hasConcept C2776796636 @default.
• W3090972979 hasConcept C2778022620 @default.
• W3090972979 hasConcept C2780762169 @default.
• W3090972979 hasConcept C42972112 @default.
• W3090972979 hasConcept C45355965 @default.
• W3090972979 hasConcept C71924100 @default.
• W3090972979 hasConcept C86803240 @default.
• W3090972979 hasConcept C99454951 @default.
• W3090972979 hasConceptScore W3090972979C116675565 @default.
• W3090972979 hasConceptScore W3090972979C144024400 @default.
• W3090972979 hasConceptScore W3090972979C151730666 @default.
• W3090972979 hasConceptScore W3090972979C159047783 @default.
• W3090972979 hasConceptScore W3090972979C205649164 @default.
• W3090972979 hasConceptScore W3090972979C22070199 @default.
• W3090972979 hasConceptScore W3090972979C2776796636 @default.
• W3090972979 hasConceptScore W3090972979C2778022620 @default.
• W3090972979 hasConceptScore W3090972979C2780762169 @default.
• W3090972979 hasConceptScore W3090972979C42972112 @default.
• W3090972979 hasConceptScore W3090972979C45355965 @default.
• W3090972979 hasConceptScore W3090972979C71924100 @default.
• W3090972979 hasConceptScore W3090972979C86803240 @default.
• W3090972979 hasConceptScore W3090972979C99454951 @default.
• W3090972979 hasIssue "1" @default.
• W3090972979 hasLocation W30909729791 @default.
• W3090972979 hasLocation W30909729792 @default.
• W3090972979 hasOpenAccess W3090972979 @default.
• W3090972979 hasPrimaryLocation W30909729791 @default.
• W3090972979 hasRelatedWork W1739995691 @default.
• W3090972979 hasRelatedWork W2125589035 @default.
• W3090972979 hasRelatedWork W2409955079 @default.
• W3090972979 hasRelatedWork W2412817614 @default.
• W3090972979 hasRelatedWork W2465173536 @default.
• W3090972979 hasRelatedWork W2613304624 @default.
• W3090972979 hasRelatedWork W3025837618 @default.
• W3090972979 hasRelatedWork W37813243 @default.
• W3090972979 hasRelatedWork W2185710539 @default.
• W3090972979 hasRelatedWork W3044554241 @default.
• W3090972979 hasVolume "53" @default.
• W3090972979 isParatext "false" @default.
• W3090972979 isRetracted "false" @default.
• W3090972979 magId "3090972979" @default.
• W3090972979 workType "article" @default.