Three decades of #discovery: An overview of #Hendra virus, the original #Henipavirus

 

Abstract

Hendra virus (HeV) emerged in Australia in 1994, causing a devastating outbreak among horses in Brisbane with spread to humans, resulting in one death. This nonsegmented, negative-stranded RNA virus belongs to the family Paramyxoviridae and represents the first zoonotic paramyxovirus isolated from bats. Flying foxes (genus Pteropus) serve as the natural reservoir, with all four mainland Australian species carrying antibodies with no apparent disease. HeV initiates infection by binding ephrin-B2 receptors on vascular endothelial cells, driving characteristic pathology involving vasculitis, thrombosis, and neurological complications. Horses are amplifying hosts, shedding virus abundantly in respiratory secretions and posing transmission risks to humans during invasive procedures. To date, seven confirmed human infections have been documented, with a 57% fatality rate, presenting as severe respiratory disease or progressive encephalitis. Two genetic variants are now recognized: the original HeV genotype 1 and the emerging HeV genotype 2, identified in limited equine cases. Recent surveillance of bat roosts revealed substantial viral diversity, with peak shedding occurring during winter—coinciding with equine spillover peaks. Prevention integrates multiple strategies: the licensed equine vaccine Equivac which provides One Health protection for both horses and human contacts; biosecurity measures including proper PPE; and habitat restoration to reduce nutritional stress in bat populations. Emerging therapeutics include monoclonal antibodies, with m102.4 showing cross-protective activity against both HeV and the closely related Nipah virus. No licensed human vaccines currently exist, though candidates are in development. Future prevention strategies increasingly recognize the importance of Indigenous-led conservation approaches alongside biomedical interventions. This review will focus on the history of HeV, virus replication and diversity, epidemiology, clinical manifestations, diagnosis, treatment, prevention, as well as ecological and interdisciplinary countermeasures.

Author summary

Hendra virus (HeV) was first detected in 1994, with two outbreaks occurring within 2 months of that year. One was the index outbreak in the Brisbane suburb of Hendra, and the other was retrospectively diagnosed in the following year. This review examines the discoveries that have been made in the 30 years since its discovery.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0014138

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New contagious #skin #disease detected in #horses in #Sweden (State Veterinary Medical Institute, Feb. 11 '26)

 

A horse in Jönköping County and one in Norrbotten County, both of which had blisters and sores on the skin on their legs, were found to be infected with a smallpox virus called equine parapoxvirus or horse parapoxvirus. It is an infection that has not previously been detected in the country.

The equine parapoxvirus was detected in our neighboring country Finland for the first time in 2021. The State Veterinary Institute, SVA, has performed DNA analysis of the virus in the Swedish cases and it turned out to be the same type as in Finland. The virus has caused outbreaks in several Finnish stables with severe skin inflammation on the horses' legs, so-called mug or rasp.

The typical symptom of parapoxvirus is small blisters (pox) that burst into round sores. The virus is transmitted by direct contact but also via equipment, clothing, hands and objects. Sick horses should be kept isolated from other horses. Use disposable gloves and special clothing when handling.   

– This is a new infection that has probably not yet gained a real foothold in Sweden. We have gone back and analyzed previously submitted skin samples from around 80 horses with skin problems in recent years. However, none of these carried parapoxvirus, says Gittan Gröndahl, state veterinarian at SVA.

Humans can also be infected with the horse parapoxvirus and get blisters/pox and sores on the skin. In Finland, a few horse grooms have had problems, but no human cases were reported from the two Swedish stables with sick horses. If someone gets pox or sores after visiting a sick horse, a doctor should be contacted.

– Our assessment is that the risk of further spread of infection is low at present. However, if there are signs of contagious foot and mouth disease, or if there are blisters or typical round wounds in the horse, virus samples should be taken. Keep in mind the risk of infection, and always use disposable gloves when handling wounds in horses, says Gittan Gröndahl.

Samples from suspected cases can be sent for analysis to SVA.

How is equine parapoxvirus transmitted?

· In direct contact between horses

· Indirectly via equipment, clothing, hands and objects

· People can also get blisters (pox) that burst into sores on the skin.

· There is no vaccine.

Think about hygiene

· Use disposable gloves when handling the horse's wounds, even small wounds.

· Wash your hands thoroughly before and after handling wounds.

· Do not share equipment between horses and stables and be careful with hygiene routines

· Contact a doctor if you develop smallpox or sores on skin that has been in contact with a sick horse.

Source: 

Link: https://www.sva.se/aktuellt/nyhetsarkiv/webbnyheter/ny-smittsam-hudsjukdom-paavisad-hos-haestar-i-sverige/

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First serological #evidence of equine #coronavirus and #SARS-CoV-2 in #horses in North #Africa

 

Abstract

Viral diseases cause significant economic losses within the equine population. Horses are susceptible to equine coronavirus (ECoV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), although only ECoV has been associated to clinical disease. The aim of this study was to investigate, for the first time in Algeria, the seroprevalence of ECoV and SARS-CoV-2 antibodies and the prevalence of ECoV infection in horses. In 2022, a total of 299 serum samples was collected from horses aged 1 to 27 years. Serological analysis for the presence of ECoV and SARS-CoV-2 was performed using a validated in-house and a commercially available ELISA, respectively. In addition, fecal samples of these animals were tested for the presence of ECoV RNA by RT-qPCR. SARS-CoV-2-ELISA positive sera with high S/P ratios and negative samples close to the doubtful threshold were retested using a virus neutralization test (VNT). The seroprevalence of ECoV and SARS-CoV-2 in the tested horses was 63.5% (190/299) and 4.3% (13/299), respectively. Among CoVs-seropositive horses, six were seropositive for both ECoV and SARS-CoV-2, thus 6/10 sera were VNT positive, including two ELISA-negative samples for SARS-CoV-2. ECoV seroprevalence varied according to age, breed and sex. None of the fecal samples tested positive for ECoV. Antibodies against SARS-CoV-2 were confirmed by VNT in six samples (2%). One SARS-CoV-2-positive serum tested by ELISA and confirmed through VNT was cytotoxic for VERO cells. This study is the first to report the circulation of ECoV and SARS-CoV-2 in the Algerian horse population. Further studies are necessary to isolate and obtain molecular characterisation of ECoV and SARS-CoV-2 from horses in Algeria.

Source: Veterinary Research Communications, https://link.springer.com/article/10.1007/s11259-025-10928-0

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Re-Emergence of #Usutu Virus and Spreading of #WestNile Virus #Neuroinvasive Infections During the 2024 Transmission Season in #Croatia

Abstract

Neuroinvasive arboviruses such as tick-borne encephalitis virus (TBEV), West Nile virus (WNV), Usutu virus (USUV), and Toscana virus (TOSV) have (re-)emerged with increasing incidence and geographic range. We analyzed the epidemiology of arboviral infections in Croatia during the 2024 transmission season. A total of 154 patients with neuroinvasive diseases (NID), 1596 horses, 69 dead birds, and 7726 mosquitoes were tested. Viral RNA was detected using RT-qPCR. IgM/IgG-specific antibodies were detected using commercial ELISA or IFA, with confirmation of cross-reactive samples by virus neutralization test. RT-qPCR-positive samples were Sanger sequenced. Arboviral etiology was confirmed in 33/21.42% of patients with NID. WNV was most frequently detected (17/11.03%), followed by TBEV (10/6.49%), USUV (5/3.24%), and TOSV (1/0.64%). WNV infections were reported in regions previously known as endemic, while in one continental county, WNV was recorded for the first time. USUV infections re-emerged after a six-year absence. In addition to human cases, acute WNV infections were recorded in 11/395 (2.78%) of horses and two dead crows. WNV IgG seropositivity was detected in 276/1168 (23.63%) and TBEV IgG seropositivity in 68/428 (15.88%) horses. None of the tested mosquito pools were positive for WNV and USUV RNA. Phylogenetic analysis showed the circulation of WNV lineage 2 and Usutu Europe 2 lineage. Climate conditions in 2024 in Croatia were classified as extremely warm, which could, at least in part, impact the quite intense arboviral season. The spreading of flaviviruses in Croatia highlights the need for continuous surveillance in humans, animals, and vectors (“One Health”).

Source: Viruses, https://www.mdpi.com/1999-4915/17/6/846

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Multiple introductions of #equine #influenza virus into the #UK resulted in widespread #outbreaks and #lineage #replacement

Abstract

Influenza A viruses (IAVs) are prime examples of emerging viruses in humans and animals. IAV circulation in domestic animals poses a pandemic risk as it provides new opportunities for zoonotic infections. The recent emergence of H5N1 IAV in cows and subsequent spread over multiple states within the USA, together with reports of spillover infections in humans, cats and mice highlight this issue. The horse is a domestic animal in which an avian-origin IAV lineage has been circulating for >60 years. In 2018/19, a Florida Clade 1 (FC1) virus triggered one of the largest epizootics recorded in the UK, which led to the replacement of the Equine Influenza Virus (EIV) Florida Clade 2 (FC2) lineage that had been circulating in the country since 2003. We integrated geographical, epidemiological, and virus genetic data to determine the virological and ecological factors leading to this epizootic. By combining newly-sequenced EIV complete genomes derived from UK outbreaks with existing genomic and epidemiological information, we reconstructed the nationwide viral spread and analysed the global evolution of EIV. We show that there was a single EIV FC1 introduction from the USA into Europe, and multiple independent virus introductions from Europe to the UK. At the UK level, three English regions (East, West Midlands, and North-West) were the main sources of virus during the epizootic, and the number of affected premises together with the number of horses in the local area were found as key predictors of viral spread within the country. At the global level, phylogeographic analysis evidenced a source-sink model for intercontinental EIV migration, with a source population evolving in the USA and directly or indirectly seeding viral lineages into sink populations in other continents. Our results provide insight on the underlying factors that influence IAV spread in domestic animals.

Author summary

Influenza causes significant disease burden in animals, including wild birds, sea lions, pigs, horses, dogs, and more recently, cows. Outbreaks and epizootics of influenza in agricultural species are a threat to food security and the economy whereas in wild animals they could affect biodiversity and conservation efforts. Given the zoonotic nature of influenza viruses and the high levels of contact between domestic animals and humans, animal influenza is also a public health concern. Here, we combined geographical, epidemiological, and virus sequence data to determine key factors that led to one of the largest epizootics of equine influenza in the United Kingdom in decades. We show that an American equine influenza virus lineage was introduced into Europe and replaced the virus lineage that had been circulating in the United Kingdom for nearly 20 years. We also analysed a global dataset of virus genomes and propose a model of equine influenza virus intercontinental migration, in which USA is the main source of viruses to other countries. Our results provide important information concerning the basic principles of influenza virus circulation in animal populations. This is central to devise effective measures of disease control that would increase animal health while reducing zoonotic risk.

Source: PLoS Pathogens, https://journals.plos.org/plospathogens/article?id=10.1371/journal.ppat.1013227

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Did #horses act as intermediate #hosts that facilitated the emergence of 1918 #pandemic #influenza?

Abstract

The ecological factors that led to the 1918 influenza pandemic remain unknown. We hypothesise that horses acted as intermediate hosts spreading a pre-pandemic avian-origin virus before 1918. This is supported by reports describing a large epizootic of unusually severe equine influenza beginning in 1915. Furthermore, the high horse demand during WWI resulted in one of the biggest equine mobilisations in North America between 1914 and 1918. This extensive movement of horses provided abundant opportunities for virus reassortment between pre-pandemic avian and human influenza viruses. Archived equine tissues or serum samples will be needed to test this hypothesis.

Source: Journal of Infectious Diseases, https://academic.oup.com/jid/advance-article-abstract/doi/10.1093/infdis/jiaf197/8115353?redirectedFrom=fulltext&login=false

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#Japan - Equine #influenza virus (Inf. with) - Immediate notification

 <Outbreaks 1-3> In early April, Livestock Hygiene Service Centres (LHSCs) in Kumamoto Prefecture received notifications from farmers with animals presenting clinical signs and collected samples. On 8 April, the LHSCs confirmed positive for Equine Influenza by RT-PCR. Genotyping is currently underway.

Source: WOAH, https://wahis.woah.org/#/in-review/6420

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Evidence of #Influenza A(#H5N1) #Spillover #Infections in #Horses, #Mongolia

Abstract

Recent outbreaks of influenza A(H5N1) have affected many mammal species. We report serologic evidence of H5N1 virus infection in horses in Mongolia. Because H3N8 equine influenza virus is endemic in many countries, horses should be monitored to prevent reassortment between equine and avian influenza viruses with unknown consequences.

Source: Emerging Infectious Diseases Journal, https://wwwnc.cdc.gov/eid/article/31/1/24-1266_article

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#Sudan - #Equine #influenza virus (Inf. with) - Immediate notification

Virus untyped. Unspecified domestic equidae species in South Darfur.

Source: WOAH, https://wahis.woah.org/#/in-review/6097

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