An epidemiological overview of the equine influenza epidemic in Great Britain during 2019

Protective efficacy of a bivalent equine influenza H3N8 virus-like particle vaccine in horses

Equine influenza (EI) is a highly contagious acute respiratory disease of wild and domesticated horses, donkeys, mules, and other Equidae. EI is caused by the Equine Influenza virus (EIV), is endemic in many countries and outbreaks still have a severe impact on the equine industry globally. Conventional EI vaccines are widely used, but a need exists for a platform that facilitates prompt manufacturing of a highly immunogenic, antigenically matched, updated vaccine product. Here we developed a plant-produced bivalent EI virus-like particle (VLP) vaccine candidate which lacks the viral genome and are therefore non-infectious. We conducted a pilot safety/dose response study of a plant produced bivalent VLP vaccine expressing the HA proteins of Florida clade (FC) 1 and FC2 EIV in 1:1 ratio. Groups of three EIV seronegative horses were vaccinated using four antigen levels (0 sham control, 250, 500, 1000 HAU/dose component). Two doses of vaccines were administered one month apart, and horses were observed for adverse reactions, which were minimal. Sera were collected for hemagglutination inhibition (HI) testing using FC1 and FC2 viruses. One month after the second dose, all horses were challenged with the aerosolized FC1 virus. Horses were observed daily for clinical signs, and nasopharyngeal swabs were collected to quantify viral RNA using qPCR and infectious virus by titration in embryonated hens' eggs. Results showed that all vaccinated groups seroconverted prior to challenge. Post-challenge, both clinical scores and virus shedding were much reduced in all vaccinates compared to the sham-vaccinated controls. We conclude that the VLP vaccines were safe and effective in this natural host challenge model. A safe, efficacious, new-generation bivalent EI VLP vaccine produced in plants, which can promptly and regularly be antigenically matched to ensure optimal protection, will pave the way to highly competitive commercially viable vaccine products for all economic environments globally.

Predictors and barriers for biosecurity uptake and risk understanding among Ontario horse owners

Objective

This study aimed to describe implementation of biosecurity practices by Ontario horse owners and investigate whether biosecurity implementation was associated with horse-owner demographic characteristics and personality traits.

Procedure

A cross-sectional questionnaire was administered to a convenience sample of horse owners in Ontario to collect data on demographics, personality traits, risk comprehension, and biosecurity practices. Hierarchical cluster analysis was used to identify clusters of participants with shared personality traits, and univariable associations between clusters and demographic and biosecurity variables were examined.

Results

A total of 271 participants were included in the analysis. Participants were primarily female (86%), from 25 to 44 y old (57%), and engaged in leisure riding (64%). Facility-level biosecurity plans were reported to be in place by 59% of participants, with 47% indicating that vaccinations were required within those plans. Other biosecurity practices were reported to be used less often by participants; for example, boot washing (31%) and disinfecting hands (27%). Two clusters of participants were identified according to similarities in personality traits: Cluster 1, which was characterized by high extraversion scores; and Cluster 2, which was characterized by high neuroticism scores. Cluster 1 participants were more involved in competitions, sought information from other horse owners, and received disease outbreak news from veterinarians. Cluster 2 participants exhibited higher variability in biosecurity practices implemented.

Conclusion

Biosecurity is variably implemented on Ontario equine facilities, which warrants the need for ongoing efforts to increase uptake at high-risk facilities. Recommendations include fostering collaboration, providing tailored support and resources, and improving communication channels.

Clinical relevance

Demographic, personality, and other lifestyle traits influence horse owners' biosecurity behaviors. Equine veterinarians may benefit from considering these factors to ensure effective communication and implementation of biosecurity plans at equine facilities.

Detection of equine influenza virus gene in the air around infected horses

Equine influenza virus (EIV) can be transmitted by inhalation of aerosolized droplets, direct contact, and contaminated fomites. However, to our knowledge, there are no reports of the recovery of EIV from the air surrounding infected horses. Here, we evaluated whether EIV can be recovered from the air in the stalls of experimentally infected horses by using an air sampler. Furthermore, we examined whether rapid molecular test kits with reaction times of less than 30 min can detect EIV from air samples for potential field application. Two horses kept in individual stalls were experimentally infected with EIV. Air samples were collected daily by using an air sampler until 13 days post-inoculation (dpi). Viral genes were detected in 26 out of 28 air samples from both horses at 1-13 dpi by real-time RT-PCR. A rapid molecular test kit based on real-time RT-PCR detected viral genes in 23 air samples from one horse at 1-9 and 12 dpi, and from the other at 1-13 dpi. These findings confirm that horses infected with EIV shed the virus into the air. Air sampling is safe for humans and horses and avoids the potential for injury when nasopharyngeal swabs need to be collected from untrained or aggressive horses. EIV RNA was detected in the air samples by using real-time RT-PCR or the rapid molecular test kit before the horses showed clinical signs. Thus, air samplers can detect EIV RNA as early as possible through routine testing in locations such as quarantine facilities.

Equine Influenza: Epidemiology, Pathogenesis, and Strategies for Prevention and Control

Equine influenza (EI) is a highly contagious respiratory disease caused by the equine influenza virus (EIV), posing a significant threat to equine populations worldwide. EIV exhibits considerable antigenic variability due to its segmented genome, complicating long-term disease control efforts. Although infections are rarely fatal, EIV's high transmissibility results in widespread outbreaks, leading to substantial morbidity and considerable economic impacts on veterinary care, quarantine, and equestrian activities. The H3N8 subtype has undergone significant antigenic evolution, resulting in the emergence of distinct lineages, including Eurasian and American, with the Florida sublineage being particularly prevalent. Continuous genetic surveillance and regular updates to vaccine formulations are necessary to address antigenic drift and maintain vaccination efficacy. Additionally, rare cross-species transmissions have raised concerns regarding the zoonotic potential of EIV. This review provides a comprehensive overview of the epidemiology, pathogenesis, and prevention of EI, emphasizing vaccination strategies and addressing the socio-economic consequences of the disease in regions where the equine industry is vital.

Respiratory viruses affecting health and performance in equine athletes

Some respiratory viruses can affect equine athletes, with acute respiratory clinical signs leading to a reduced ability to perform. The direct association between equine respiratory viruses and athletic performance is unclear in subclinically affected horses. This narrative review summarises the current evidence on respiratory viruses most commonly detected in performing horses, including equine herpesviruses, equine influenza virus, equine rhinitis viruses, equine arteritis virus, and equine adenovirus 1. It covers their virology, clinical manifestations, epidemiology, pathogenesis, diagnosis, and control measures, with a focus on their impact on performance. Molecular diagnostics on nasopharyngeal swabs are the preferred method for detecting equine respiratory viruses nowadays. Studies highlighted in this review reveal a high prevalence of equine herpesviruses -particularly gammaherpesviruses- in the airways of both healthy and diseased horses. In contrast, equine rhinitis A virus, equine arteritis virus, and equine adenovirus 1 are the least common viruses. Transportation contributes to spreading equine infectious diseases across countries and can temporarily weaken the immune system, increasing the risk of respiratory viral infections and reactivation of latent equine herpesviruses. Moreover, respiratory viral infections are frequently observed in young horses starting their training. Although there is limited evidence on the specific impact of equine respiratory viruses on performance, this review emphasises that vaccination and care management are essential strategies for limiting the spread and severity of outbreaks in sport horses.

'I want to be the sort of owner that he wants me to be': Rationales for biosecurity implementation among British horse owners

BACKGROUND

Horse owners play a critical role in mitigating the risk of pathogen spread between horses. However, little is known about how they view biosecurity and whether they experience barriers to the uptake of preventive measures.

OBJECTIVES

To explore horse owners' attitudes, perceptions, and experiences of biosecurity and identify how these factors shape horse owners' decisions for biosecurity implementation.

STUDY DESIGN

Qualitative study using semi-structured interviews.

METHODS

Interviews were conducted with 23 horse owners across Great Britain. Participants were purposively selected to include those in different geographic regions, with different management arrangements, and varied length of horse ownership experience. Interviews were audio-recorded, transcribed verbatim, and analysed using a critical realist thematic analysis.

RESULTS

Participants felt a moral obligation to prioritise their horse's happiness, which became a challenge when certain biosecurity measures (e.g., quarantine) were perceived as compromising their horse's happiness or comfort (Theme 1). A lack of biosecurity was the social norm among shared yards and competition venues (Theme 2), which made it difficult for participants to implement biosecurity measures effectively on their own. Combined with the sense of moral obligation participants felt towards their horse, this meant that participants had to 'care double' (i.e., be more vigilant than they would otherwise) to compensate for collective inaction (Theme 3).

MAIN LIMITATIONS

Participants may have been more interested in and/or knowledgeable about biosecurity than the general horse owning population.

CONCLUSIONS

The findings highlight several challenges that could be addressed to improve biosecurity implementation among horse owners. Efforts to encourage improved uptake of biosecurity measures should focus on communicating how reducing the risk of disease aligns with horse care. Further research on social norms in the horse industry is needed, in addition to identifying strategies to encourage a collective adoption of biosecurity measures.

Spatiotemporal pattern and suitable areas analysis of equine influenza in global scale (2005-2022)

Equine influenza (EI) is a severe infectious disease that causes huge economic losses to the horse industry. Spatial epidemiology technology can explore the spatiotemporal distribution characteristics and occurrence risks of infectious diseases, it has played an important role in the prevention and control of major infectious diseases in humans and animals. For the first time, this study conducted a systematic analysis of the spatiotemporal distribution of EI using SaTScan software and investigated the important environmental variables and suitable areas for EI occurrence using the Maxent model. A total of 517 occurrences of EI from 2005 to 2022 were evaluated, and 14 significant spatiotemporal clusters were identified. Furthermore, a Maxent model was successfully established with high prediction accuracy (AUC = 0.920 ± 0.008). The results indicated that annual average ultraviolet radiation, horse density, and precipitation of the coldest quarter were the three most important environmental variables affecting EI occurrence. The suitable areas for EI occurrence are widely distributed across all continents, especially in Asia (India, Mongolia, and China) and the Americas (Brazil, Uruguay, USA, and Mexico). In the future, these suitable areas will expand and move eastward. The largest expansion is predicted under SSP126 scenarios, while the opposite trend will be observed under SSP585 scenarios. This study presents the spatial epidemiological characteristics of EI for the first time. The results could provide valuable scientific insights that can effectively inform prevention and control strategies in regions at risk of EI worldwide.

First Reported Circulation of Equine Influenza H3N8 Florida Clade 1 Virus in Horses in Italy

BACKGROUND

Equine influenza (EI) is a highly contagious viral disease of equids characterized by pyrexia and respiratory signs. Like other influenza A viruses, antigenic drift or shift could lead to a vaccine-induced immunity breakdown if vaccine strains are not updated. The aim of this study was to genetically characterize EIV strains circulating in Italy, detected in PCR-positive samples collected from suspected cases, especially in the absence of formal active surveillance.

METHODS

Between February and April 2019, blood samples and nasal swabs collected from each of the 20 symptomatic horses from North and Central Italy were submitted to the National Reference Centre for Equine Diseases in Italy to confirm preliminary analysis performed by other laboratories.

RESULTS

None of the sera analysed using haemagglutination inhibition and single radial haemolysis presented a predominant serological reactivity pattern for any antigen employed. All nasal swabs were positive with IAV RRT-PCR. Only one strain, isolated in an embryonated chicken egg from a sample collected from a horse of a stable located in Brescia, Lombardy, was identified as H3N8 Florida lineage clade 1 (FC1). In the constructed phylogenetic trees, this strain is located within the FC1, together with the virus isolated in France in 2018 (MK501761).

CONCLUSIONS

This study reports the first detection of H3N8 FC1 in Italy, highlighting the importance of monitoring circulating EIV strains to verify the vaccine composition appropriateness for maximum efficacy.

Equine influenza outbreak in Eastern of Algeria in 2021: The first introduction of Florida Clade 1 to Maghreb area

We have performed an equine influenza (EI) serological study of the equine population in Algeria by testing 298 serum samples collected between February and August 2021 from 5 provinces. The results were obtained performing an NP-ELISA. Our results revealed that 49.3% (147/298) samples positive for antibodies to EI (H3N8). During this study and after a gap of one decade an outbreak of EI was reported in Algeria in the first week of March 2021. The disease was confirmed by virus detection from the nasal swabs (n = 39) by qRT-PCR and by identifying 5 EI seroconversion. The virus sequences were identified as H3N8 by sequencing the haemagglutinin (HA) and neuraminidase (NA) genes. Alignment of HA1 amino acid sequence confirmed that viruses belong to Clade 1 of the Florida sublineage in the American lineage. This study indicate the first detection of FC1 strain of EIV in Maghreb area.

Cross-Sectional Survey of Horse Owners to Assess Their Knowledge and Use of Biosecurity Practices for Equine Infectious Diseases in the United States

Horses are transported in the United States more than any other livestock species and co-mingle at various events; therefore, they are considered to be at an increased risk for infectious disease transmission. The fragmented movement of horses combined with numerous sites of co-mingling makes tracing the potential spread of a disease outbreak a necessary part of an infection control plan, both locally and nationally. The cross-movement of personnel with horses and the persistence of endemic diseases make biosecurity implementation an ongoing challenge. Although many of the risks for infection are known, there is limited documentation about the usefulness of prospective control measures. The objective of this survey was to determine horse owners' understanding and knowledge of biosecurity practices for preventing infectious diseases in the United States. Questions covered owner demographic information, including horse use which was divided into 10 categories as follows: Pleasure/Trail Riding, Lessons/School, Western Show, English Show, Breeding, Farm/Ranch, Retired, Racing, Driving and Other. The survey was distributed by sending requests to a list of horse owner organizations, which then sent emails to their members. The email request described the survey and provided a website link to start the survey. A total of 2413 responses were collected. Analysis of the results included cross-tabulation to identify significant differences in biosecurity knowledge and awareness by horse use. Significant differences by horse use were identified for vaccination, biosecurity planning, use of isolation, disease risk, monitoring for diseases, co-mingling of horses, sanitation, medical decision making and health record requirements for horse events. In summary, the results suggest that most owners are not highly concerned about the risk of disease or the use of biosecurity. There are several biosecurity applications and techniques which can be increased and will benefit horse health and welfare. These include reliance on temperature monitoring, isolation of new horses at facilities, risks of horse mingling, entry requirements such as vaccination and health certificates at events, and an emphasis on having biosecurity plans for facilities and events where horses co-mingle. The information from this study will be used to create tools and information that horse owners and veterinarians can use to implement appropriate biosecurity practices for different types of horse uses and events.