can bird flu affect horses

Since their discovery in the United States in 1963, outbreaks of infection with equine influenza virus (H3N8) have been associated with serious respiratory disease in horses worldwide. Genomic analysis suggests that equine H3 viruses are of an avian lineage, likely originating in wild birds. Equine-like internal genes have been identified in avian influenza viruses isolated from wild birds in the Southern Cone of South America. However, an equine-like H3 hemagglutinin has not been identified. We isolated 6 distinct H3 viruses from wild birds in Chile that have hemagglutinin, nucleoprotein, nonstructural protein 1, and polymerase acidic genes with high nucleotide homology to the 1963 H3N8 equine influenza virus lineage. Despite the nucleotide similarity, viruses from Chile were antigenically more closely related to avian viruses and transmitted effectively in chickens, suggesting adaptation to the avian host. These studies provide the initial demonstration that equine-like H3 hemagglutinin continues to circulate in a wild bird reservoir.

Aquatic birds are the reservoir of influenza A viruses and responsible for the evolution and long-distance spread of the virus (1–3). Occasionally, spillover into domestic poultry or domesticated mammals can result in human infections (2,4,5) and sustained transmission within a new mammalian host, as shown by equine influenza virus (H3N8) (EIV) (3).

The H3N8 EIVs were reported in the southern United States in 1963 during an outbreak in horses imported from Argentina (6,7). This emergence resulted in a pandemic that led to international cocirculation of H7N7 and H3N8 EIVs during the 1960s and 1970s, causing heterosubtypic reassortment that might have contributed to the extinction of H7N7 EIV (8). Today, H3N8 EIVs represent a single genetic lineage capable of inducing serious respiratory disease in susceptible horses.

The origin of the H3N8 lineage is unknown; however, phylogenetic studies and uracil content analysis suggest that these viruses originated in wild birds (9). The H3N8 EIV-like polymerase acidic (PA), nucleoprotein (NP), and nonstructural (NS) genes have been identified in avian influenza viruses (AIV) isolated from South American wild birds since the mid-2000s; the most recent isolation was in Argentina during 2016 (10–12). Time to most recent common ancestor (tMRCA) analysis suggests that these genes likely originated in AIVs during the 1950s (9,12). However, an EIV-like H3 hemagglutinin (HA) has yet to be identified in AIVs from wild birds.

We performed active surveillance of wild birds in Chile and isolated 6 distinct AIVs with HA, NP, NS, and PA genes having high nucleotide homology with the 1963 H3 EIV. The AIVs were isolated from resident waterfowl belonging to the families Anatidae and Rallidae, suggesting that circulation of these viruses might be restricted to nonmigratory species found only in the Southern Cone of South America. Although viruses from Chile had nucleotide similarity with H3 EIVs, they were antigenically like avian influenza viruses and could be transmitted into chickens, suggesting adaptations to the avian host. These studies provided the initial evidence that an H3 EIV-like HA continues to circulate in wild birds.

Although there hasn’t been a similar “shift” in relation to avian influenza viruses, one did occur in the spring of 2009 when an H1N1 virus that contained genes from humans, pigs, emus, and North American swine surfaced to infect people and spread swiftly, resulting in a pandemic. Most people have little to no immunity against the new virus when shifts occur.

This significant alteration in influenza A viruses is referred to as a “antigenic shift.” When a novel influenza A virus subtype that most people are largely or completely immune to infects humans, antigenic shift occurs. An influenza pandemic could happen if this novel influenza A virus sickens people and spreads quickly and persistently from person to person.

Sometimes influenza A viruses that are normally endemic to one species of animal can infect another. For instance, up until 1998, the only viruses that were commonly distributed in the U S. pig population. However, in 1998, human-introduced H3N2 viruses led to a widespread outbreak of disease in the pig population. More recently, wild foxes in the United States have occasionally become infected with H5N1 viruses from birds. S. and in other countries.

Exposure to infected birds’ feces, mucous, or saliva can result in direct infection. Human infections from bird flu are uncommon, but they can occur if enough virus enters a person’s mouth, nose, or eyes through inhalation. Bird flu virus infections may be more common in people who have close or extended unprotected contact (not wearing respiratory and eye protection) with infected birds or in areas contaminated by sick birds or their mucous, saliva, or feces.

While it is uncommon for humans to contract influenza A virus infections directly from animals, outbreaks and occasional human infections brought on by specific avian and swine influenza A viruses have been documented. Last Reviewed: Source:

HA Gene Phylogenetic Nucleotide Analysis

A total of 37,171 fresh fecal samples from wild birds were collected from different wetlands in Chile between 2013 and 2017. H3 subtypes accounted for 5. 8% (n = 8) of the total HA diversity. Six of the H3 viruses, A/cinnamon teal/Chile/{“type”:”entrez-nucleotide”,”attrs”:{“text”:”C19368″,”term_id”:”1631639″}}C19368/2016 (H3N8), A/red-fronted coot/Chile/5/2013 (H3N6), A/yellow-billed pintail/Chile/C2014/2015 (H3N8), A/red-gartered coot/Chile/{“type”:”entrez-nucleotide”,”attrs”:{“text”:”C16030″,”term_id”:”1570737″}}C16030/2016 (H3N4), A/yellow-billed pintail/Chile/{“type”:”entrez-nucleotide”,”attrs”:{“text”:”C30974″,”term_id”:”2362770″}}C30974/2017 (H3N8), and A/yellow-billed pintail/Chile/{“type”:”entrez-nucleotide”,”attrs”:{“text”:”C34473″,”term_id”:”2370614″}}C34473/2017 (H3N8), were isolated from different regions of Chile ( ), had highest nucleotide homology with the HA gene of the 1963 H3N8 EIV lineage, and had lower homology to the H3 of AIVs found in other regions ( ; A The H3 HA sequences were shown by maximum-likelihood trees to form 4 distinct clusters, 3 of which are for viruses with wild bird origin and 1 of which is for the 1963 H3 EIV. The six IAVs for Chile are more phylogenetically related to the 1963 H3N8 EIV than to other avian H3 HAs, forming a sister clade relationship with the 1963 H3 EIV ( ; Appendix Figure 1)

The tMRCA between the 1963 H3 EIV and the H3 AIVs from Chile, as well as between the H3 sequences from avian species that are not from Chile and the EIV H3, was estimated using Bayesian molecular clock analysis (,, panel A) As of 201954%, the tMRCA of the 201963% EIV% H3% is 201954% (95% credible interval 201948% E2%80% 931959). The H3%20HA%20tMRCA%20is%201916%20(95%%credible%20interval%201883%E2%80%931941) and the H3%20HA%20EIV%201963%20is%201916%20. Conversely, the tMRCA of the avian H3%HAs is not from Chile, and the H3/1963%H3N8%20EIV from Chile is 201845% (2095% credible interval 201795% E2%80%931882). A comprehensive HA divergence time tree is supplied by us (Appendix Figure 2).

Gene segment Equine-like, no. positive/no. tested† GTR relaxed GTR strict HKY relaxed HKY strict
HA 6/8 1916 (1883–1941) 1918 (1909–1927) 1917 (1886–1939) 1918 (1909–1927)
PA 19/26 1948 (1938–1956) 1946 (1941–1950) 1948 (1935–1957) 1946 (1941–1950)
NP 24/29 1947 (1936–1955) 1945 (1940–1950) 1947 (1936–1955) 1945 (1939–1949)
NS1 11/27 NA NA NA NA

Sample Collection, Screening, and Sequencing

Fresh feces from birds were collected from the environment during 2013–2017 at different wetlands across the central region of Chile. These samples were collected by using sterile flocked swabs (Copan Italia S.P.A., and stored in 1-mL universal transport media tubes (Copan Italia S.P.A). They were then transported at 4°C to the Faculty of Veterinary Science of the University of Chile (Santiago, Chile) and stored at ?80°C until analysis.

At St., quantitative reverse transcription PCR and RNA extraction were carried out. Jude Children’s Research Hospital (Memphis, TN, USA) as described (13). To sum up, the Mag Max-96 IA/ND Viral RNA Isolation Kit (Life Technologies, was used to extract RNA from 50 ?L of swab specimen. thermofisher. com) on a ThermoFisher Scientific Kingfisher Flex Magnetic Particle Processor thermofisher. com). Using a CFX96 Real-Time PCR System, 4x TaqMan Fast Virus Master Mix (ThermoFisher Scientific), primers, and probes specific to the influenza A matrix gene, quantitative reverse transcription PCR was carried out (14) samples where the cycle threshold is set As previously mentioned (15), an attempt was made to isolate viruses from 9-day-old specific pathogen-free (SPF) embryonated chicken eggs.

Genetic barcoding was used to determine the host species using primers that amplified the cytochrome oxidase I gene as previously mentioned (16). The two methods used for sequencing were deep sequencing on an Illumina MiSeq System ( or Sanger sequencing with universal oligonucleotide primer sets as described (17). illumina. com) as described (18). Sequences were assembled using the web application CLC Genomic Workbench Version 9. cabgrid. res. in/biocomp/CLCBio/clc-bio. html). The Chilean H3 sequences utilized in this investigation have been added to GenBank (accession nos. {“type”:”entrez-nucleotide”,”attrs”:{“text”:”KX101146″,”term_id”:”1032810572″}}KX101146, {“type”:”entrez-nucleotide”,”attrs”:{“text”:”KY644162″,”term_id”:”1158623320″}}KY644162, {“type”:”entrez-nucleotide”,”attrs”:{“text”:”MH675632″,”term_id”:”1450486427″}}MH675632, {“type”:”entrez-nucleotide”,”attrs”:{“text”:”MH499154″,”term_id”:”1433050245″}}MH499154, {“type”:”entrez-nucleotide”,”attrs”:{“text”:”MK163999″,”term_id”:”1512469978″}}MK163999, and {“type”:”entrez-nucleotide”,”attrs”:{“text”:”MK164010″,”term_id”:”1512470003″}}MK164010).


Can horses get the flu from humans?

This isn’t a case of the virus being on their hands and passed through contact, but humans that are infected and shedding it in their own nasal secretions to infect horses.

What are the symptoms of a virus in a horse?

The viral infection can cause fever, depression, and oedema (swelling) especially of the limbs and inflammation around the eyes. The virus may cause abortion in pregnant mares and severe respiratory disease and death in young foals.

Does bird flu affect other animals?

Bird flu viruses have in the past been known to sometimes infect mammals that eat (presumably infected) birds or poultry, including but not limited to wild animals, such as seals, bears, foxes, skunks; farmed mink; stray or domestic animals, such as cats and dogs; and zoo animals, such as tigers and leopards.

How long does it take for a horse to recover from the flu?

The clinical signs generally abate within a few days, but complications due to secondary infections are common. While most animals recover in two weeks, the cough may continue longer and it may take as much as six months for some horses to regain their full ability.