Viral Respiratory Disease
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Questions and Answers

What is the primary cause of Feline Viral Rhinotracheitis?

  • Feline Immunodeficiency Virus
  • Canine Parvovirus
  • Feline Calicivirus
  • Feline Herpesvirus-1 (correct)

    • Which group of cats is predominantly affected by FHV-1?

  • Cats over five years old
  • Cats without previous vaccinations
  • Kittens under one year of age (correct)
  • Cats that are primarily indoors

    • What is a significant complication of FHV-1 infections in kittens?

  • Ringworm
  • Panleukopenia
  • Leukemia
  • Bronchopneumonia (correct)

    • Which symptom is NOT commonly associated with Feline Viral Rhinotracheitis?

    <p>Diarrhea</p> Signup and view all the answers

    In which form of FHV-1 does the virus reside in sensory neurons without active replication?

    <p>Latent</p> Signup and view all the answers

    What histological feature is indicative of an FHV-1 infection?

    <p>Intranuclear inclusions</p> Signup and view all the answers

    Through which routes can FHV-1 be transmitted?

    <p>Aerosolized droplets and direct contact with secretions</p> Signup and view all the answers

    Which of the following is a potential consequence of FHV-1 infection in pregnant cats?

    <p>Transplacental transmission leading to abortion</p> Signup and view all the answers

    What is a significant risk factor for infection from CHV in puppies?

    <p>Hypothermia</p> Signup and view all the answers

    Which equine herpesvirus is particularly notorious for causing systemic disease?

    <p>EHV-1</p> Signup and view all the answers

    What pathological change does EHV-1 cause in pregnant mares?

    <p>Cell death and placental separation</p> Signup and view all the answers

    What are common clinical signs of EHV-1 infection?

    <p>Fever, anorexia, and nasal discharge</p> Signup and view all the answers

    Which control measure is important to prevent outbreaks of EHV?

    <p>Isolation of affected horses</p> Signup and view all the answers

    What is the primary method through which EHV-1 and EHV-4 are transmitted?

    <p>Genital and respiratory secretions</p> Signup and view all the answers

    EHV-3 is primarily associated with which of the following?

    <p>Venereal infections with genital lesions</p> Signup and view all the answers

    What is a key characteristic of the herpesviruses under the Herpesviridae family?

    <p>Double-stranded DNA genomes</p> Signup and view all the answers

    What complication can arise from EHV-1 following a respiratory infection?

    <p>Viremia leading to encephalomyelitis</p> Signup and view all the answers

    What are the characteristics found in the lesions caused by EHV-1?

    <p>Vasculitis and ischemic necrosis</p> Signup and view all the answers

    Which diagnostic technique is commonly used for detecting EHV-1 in tissues?

    <p>Immunofluorescence and immunohistochemical staining</p> Signup and view all the answers

    What is the consequence of latency in EHV infections?

    <p>Potential for disease episodes later in life</p> Signup and view all the answers

    Why is vaccination crucial for pregnant mares in relation to EHV?

    <p>To protect against systemic disease and abortion</p> Signup and view all the answers

    What is the typical duration of lesions caused by EHV-3?

    <p>14 days</p> Signup and view all the answers

    What is a primary clinical sign of Infectious Laryngotracheitis (ILT)?

    <p>Conjunctivitis</p> Signup and view all the answers

    Which characteristic is NOT associated with the Caliciviridae family of viruses?

    <p>Enveloped structure</p> Signup and view all the answers

    What transmission route is NOT relevant for Infectious Laryngotracheitis?

    <p>Vector-borne transmission</p> Signup and view all the answers

    What can complicate control measures in managing Feline Calicivirus (FCV)?

    <p>High mutation rate leading to various strains</p> Signup and view all the answers

    Which diagnostic technique is NOT commonly used for diagnosing Feline Calicivirus?

    <p>Serological testing</p> Signup and view all the answers

    What is the primary cellular target of Bovine Respiratory Syncytial Virus (BRSV)?

    <p>Ciliated bronchiolar epithelial cells</p> Signup and view all the answers

    Which trait is NOT representative of the Paramyxoviridae family of viruses?

    <p>Icosahedral symmetry</p> Signup and view all the answers

    What clinical sign is often observed in high virulence forms of Feline Calicivirus?

    <p>Systemic hemorrhage</p> Signup and view all the answers

    What is the main concern with vaccination against Infectious Laryngotracheitis?

    <p>Reversion to virulence</p> Signup and view all the answers

    Which of the following statements regarding BRSV is correct?

    <p>Syncytial cell formation is a hallmark of infection.</p> Signup and view all the answers

    Which of the following is a notable risk factor for FCV outbreaks?

    <p>High stress and close contact in multi-cat environments</p> Signup and view all the answers

    What aspect of paramyxovirus infectivity is crucial to its pathogenicity?

    <p>Cleavage of the F0 protein</p> Signup and view all the answers

    What is the typical mortality rate range for high virulence Feline Calicivirus?

    <p>30-60%</p> Signup and view all the answers

    What is the primary role of colostrum in calves regarding BRSV outbreaks?

    <p>Offering passive immunity.</p> Signup and view all the answers

    What are common clinical signs associated with Newcastle Disease?

    <p>Respiratory signs and neurological symptoms.</p> Signup and view all the answers

    What factor is critical in preventing Newcastle Disease outbreaks in poultry?

    <p>Biosecurity measures.</p> Signup and view all the answers

    Which type of influenza virus is considered the most significant for veterinary species?

    <p>Type A</p> Signup and view all the answers

    What structure of the influenza virus facilitates the attachment to host cell receptors?

    <p>Hemagglutinin (HA)</p> Signup and view all the answers

    Which strains were primarily responsible for the Great Epizootic of 1872 in equine influenza?

    <p>H3N8 and H7N7</p> Signup and view all the answers

    How is equine influenza mainly transmitted?

    <p>Via aerosolized droplets.</p> Signup and view all the answers

    What is a notable characteristic of Highly Pathogenic Avian Influenza (HPAI) viruses?

    <p>They can lead to neurotropism.</p> Signup and view all the answers

    What clinical sign was observed in dairy cattle infected with HPAI in 2022?

    <p>Decreased milk production.</p> Signup and view all the answers

    What is the primary control strategy for Newcastle Disease?

    <p>Vaccination.</p> Signup and view all the answers

    What is the mode of transmission for Newcastle Disease virus (NDV)?

    <p>Via aerosolized particles and direct contact.</p> Signup and view all the answers

    Which influenza strain was first identified in racing greyhounds in 2004?

    <p>H3N8</p> Signup and view all the answers

    What causes the emergence of new viral combinations and strains in influenza viruses?

    <p>Segmented genome reassortment.</p> Signup and view all the answers

    What role does latency play in herpesvirus infections?

    <p>It leads to persistent infections that can reactivate under stress.</p> Signup and view all the answers

    Which of the following is NOT a virus from the Herpesviridae family?

    <p>Canine Parvovirus</p> Signup and view all the answers

    What is a significant concern regarding vaccination strategies for herpesviruses?

    <p>Vaccination does not prevent infection but can reduce severity.</p> Signup and view all the answers

    What clinical manifestation is associated with Infectious Bovine Rhinotracheitis (IBR)?

    <p>Hemorrhagic ulcers in the nasal cavity.</p> Signup and view all the answers

    What role does biosecurity play in managing BHV-1 infections?

    <p>It helps prevent transmission of the virus between animals.</p> Signup and view all the answers

    What is the primary histopathological finding indicative of BHV-1 infection?

    <p>Intranuclear inclusion bodies in epithelial cells.</p> Signup and view all the answers

    What is a common outcome of caprine herpesvirus-1 (CpHV-1) infection in goats?

    <p>High neonatal mortality without other clinical signs.</p> Signup and view all the answers

    Which of the following best describes how BHV-1 is primarily transmitted?

    <p>Via respiratory droplets and during coitus.</p> Signup and view all the answers

    What is one major challenge in controlling herpesvirus outbreaks in animal populations?

    <p>Latent infections lead to periods of asymptomatic shedding.</p> Signup and view all the answers

    What primary symptom characterizes Canine Herpesvirus (CHV) infection in puppies?

    <p>Fatal generalized hemorrhagic infections.</p> Signup and view all the answers

    Which of the following vaccination strategies is NOT commonly used for BHV-1?

    <p>DNA vaccines.</p> Signup and view all the answers

    What distinguishes the morbidity rates associated with IBR in high-density cattle operations?

    <p>Morbidity rates can approach 100% in affected cattle.</p> Signup and view all the answers

    What is a potential outcome of Infectious Pustular Vulvovaginitis (IPV) in cattle?

    <p>Subclinical cases that complicate diagnosis.</p> Signup and view all the answers

    What type of lesions are typically observed in fetuses infected with CpHV-1?

    <p>Lesions similar to those seen in neonatal deaths in other species.</p> Signup and view all the answers

    Which of the following viruses is classified as a non-enveloped virus?

    <p>Feline Calicivirus</p> Signup and view all the answers

    What type of viral genome does Bovine RSV possess?

    <p>Single-stranded RNA, negative sense</p> Signup and view all the answers

    Which characteristic is associated with the Orthomyxoviridae family?

    <p>Segmented ssRNA</p> Signup and view all the answers

    What is a key feature of the Newcastle Disease Virus?

    <p>It has a segmented genome.</p> Signup and view all the answers

    Which of the following is a characteristic of viruses in the Herpesviridae family?

    <p>Enveloped, double-stranded DNA</p> Signup and view all the answers

    Study Notes

    Feline Viral Rhinotracheitis (FHV-1)

    • FHV-1, caused by Feline Herpesvirus-1, is a significant upper respiratory disease in cats, particularly affecting kittens under one year old.
    • The incubation period is short, lasting 24-48 hours.
    • Symptoms include sneezing, coughing, nasal and ocular discharge, conjunctivitis, keratitis, frothy salivation, dyspnea, anorexia, weight loss, and fever.
    • Severe cases can lead to corneal ulceration.
    • FHV-1 is the most common cause of feline upper respiratory tract infections.
    • Can cause serious complications like bronchopneumonia.

    Pathogenesis and Disease Forms

    • Four forms of FHV-1 infection exist: acute, chronic, systemic, and latent.
    • The virus infects epithelial cells, causing degeneration and death.
    • It also affects lymphocytes and neuronal cells.
    • Systemic disease is more common in compromised hosts like kittens with insufficient maternal antibodies or geriatric cats with weakened immune systems.

    Latent and Chronic Infections

    • After acute infection resolves, FHV-1 can become latent in sensory neurons without replicating.
    • Reactivation can be triggered by stress, causing mild symptoms like unilateral squint and conjunctivitis.
    • Chronic disease manifests as corneal stromal keratitis and chronic keratoconjunctivitis, with persistent signs that do not fully resolve.

    Transmission and Control of FHV-1

    • Transmitted through aerosolized droplets, direct contact with secretions, and fomites.
    • Can be transmitted transplacentally, potentially causing abortion in pregnant cats.
    • No known non-feline reservoirs for FHV-1.
    • Control measures include disinfection, as the virus survives less than one day outside the host.
    • Vaccination using inactivated, attenuated, or engineered vaccines reduces disease severity and shedding duration, but does not prevent infection.
    • High prevalence of latent infections complicates control efforts.

    Herpesviridae Family

    • Includes viruses causing significant diseases in various domestic animals.
    • Species-specific envelope glycoproteins are present.
    • Poor environmental survival, requiring close contact for transmission, especially in high-density settings.
    • Divided into subfamilies: alpha, beta, and gammaherpesviridae, each with unique replication and latency characteristics.

    Latency and Reactivation

    • Latent infections lead to periodic shedding triggered by stress or immune compromise.
    • Alphaherpesviruses typically establish latency in sensory ganglia, while betaherpesviruses may remain latent in secretory glands and lymphoid tissues.

    Clinical Implications of Herpesviridae

    • Infections can cause severe disease in young, immune-compromised, and elderly animals.
    • Examples include Infectious Bovine Rhinotracheitis (IBR), presenting with fever, nasal discharge, and respiratory distress.

    Infectious Bovine Rhinotracheitis (IBR) and Infectious Pustular Vulvovaginitis (IPV)

    • Hyperemic Nasal Mucosa: Lesions in nasal cavity, including focal necrosis with purulent inflammation, leading to large, shallow, hemorrhagic ulcers covered by a cream-colored pseudo-membrane.
    • Conjunctivitis: Often presents with profuse lacrimation, which may be the only observable sign.
    • Morbidity Rates: Up to 100% morbidity in affected populations, particularly in high-density cattle operations.
    • Gastroenteritis in Neonates: Neonatal calves can experience gastroenteritis, resulting in high mortality rates.
    • Bovine Respiratory Disease Complex (BRDC): IBR contributes to BRDC, leading to severe pneumonia due to secondary bacterial infections.
    • Subclinical Cases: Many cases of IPV are subclinical, making diagnosis challenging.

    Pathogenesis and Pathology of BHV-1

    • Bovine Herpesvirus 1 (BHV-1) is a significant pathogen, implicated in various conditions including abortion, balanoposthitis in bulls, and acute death in calves due to ADR.
    • Light microscopy reveals intranuclear inclusion bodies in epithelial cells, indicative of viral infection and necrosis.
    • The disease is characterized by intense inflammatory responses within necrotic mucosa, leading to the formation of pseudomembranes.
    • BHV-1 establishes latency in the sciatic and trigeminal ganglia, complicating control measures and leading to potential reactivation.
    • Transmission routes include respiratory droplets and coitus, highlighting the importance of biosecurity.

    Diagnosis and Control Measures

    • Diagnosis of BHV-1 can be achieved through PCR, electron microscopy, immunofluorescence, and rapid enzyme immunoassays.
    • Syncytia and eosinophilic intranuclear inclusions are critical for confirming infection.
    • Both inactivated and live-attenuated vaccines are commonly used; however, vaccination does not prevent infection but reduces disease severity.
    • Some European countries are attempting eradication through testing, quarantine, and removal of infected animals, a strategy not widely adopted in the US.
    • Immunization before transport is believed to enhance antibody titers and reduce transmission risks.
    • The use of whole virus vaccines is limited due to concerns about safety and efficacy.

    Caprine Herpesvirus-1 (CpHV-1) and Canine Herpesvirus (CHV)

    • CpHV-1 causes severe respiratory disease and gastrointestinal issues in kids, mirroring IPV in cattle.
    • Can lead to abortion storms in goats, often without other clinical signs.
    • Fetuses infected with CpHV-1 exhibit lesions similar to those seen in canine and equine neonatal deaths, indicating a shared pathogenesis.
    • CpHV-1 is also associated with vulvovaginitis in goats.
    • The disease can lead to significant economic losses in goat farming due to high mortality and reproductive failures.
    • Vaccination and biosecurity measures are essential to control the spread of CpHV-1.
    • CHV causes fatal generalized hemorrhagic infections in puppies under 4 weeks, leading to systemic infections and necrosis in multiple organs.
    • Transmitted during parturition or oronasally from other infected animals.
    • Infected puppies may exhibit painful crying, abdominal pain, and dyspnea.
    • Adult dogs serve as reservoirs for CHV, necessitating vaccination of breeding animals to protect vulnerable puppies.
    • The virus thrives at temperatures around 33°C, making hypothermia a significant risk factor for infection in puppies.
    • Isolation of affected litters and disinfection of environments are critical control measures.

    Equine Herpesvirus (EHV)

    • EHV-1 and EHV-4 are the primary causes of equine abortion, with EHV-1 causing systemic disease.
    • Infected mares may abort without prior signs.
    • EHV-1 causes cell death and placental separation in the gravid uterus.
    • While the mare may not exhibit severe illness, the fetus can suffer significant necrosis.
    • Following respiratory infection, viremia can occur, leading to serious systemic complications, including encephalomyelitis.
    • Previous infection does not necessarily lead to long-term fertility issues, although latency and potential reactivation are concerns.
    • Vaccination strategies are crucial for preventing outbreaks and protecting pregnant mares from EHV-1.

    Equine Rhinotracheitis/Rhinopneumonitis

    • EHV-1 infects lymphocytes and monocytes/macrophages, which transport the virus to the CNS, leading to infection of endothelial cells.
    • Encephalomyelitis results from lesions caused by viral replication in endothelial cells lining arterioles in the brain and spinal cord.
    • Clinical signs of encephalomyelitis can range from mild ataxia to severe limb paralysis and even death.
    • Focal lesions are characterized by vasculitis, thrombosis, and ischemic necrosis of adjacent neural tissue.
    • Hemorrhagic areas are typically randomly distributed within the affected regions of the brain and spinal cord.
    • Intranuclear inclusion bodies are found in various organs including the lung, liver, spleen, and adrenal glands.

    Clinical Signs and Diagnosis

    • EHV-1 and EHV-4 are closely related, with a recombinant antigen based on glycoprotein G used to distinguish between them.
    • Common clinical signs include fever, anorexia, and nasal discharge that progresses from serous to mucopurulent.
    • Diagnosis can be indirect through the pathology of aborted fetuses.
    • Immunofluorescence and immunohistochemical staining are key techniques for virus detection in tissues.
    • Rising antibody titers in affected mares can indicate infection.

    Transmission and Control Measures

    • Transmitted through genital and respiratory secretions, primarily via droplet transmission.
    • Recrudescence of latent virus can lead to disease episodes later in life.
    • Control measures include isolating pregnant mares based on foaling dates and avoiding the introduction of new mares into established groups.
    • Vaccination options include live-attenuated and inactivated vaccines for EHV-1.
    • Isolation of infected horses is critical to prevent the spread of EHV-1.

    Equine Coital Exanthema (EHV-3)

    • A venereal disease analogous to human herpes simplex virus, presenting with acute pustular and ulcerative lesions in genital areas.
    • Lesions can also appear on the penis, prepuce, and occasionally on the lips and upper respiratory tract.
    • The disease typically resolves within 14 days, but healed horses may have depigmented spots indicating they are carriers.
    • EHV-3 is not associated with abortion or infertility.

    Virus Characteristics and Transmission

    • EHV-3 is not cross-reactive with other equid herpesviruses in serological tests.
    • Transmission occurs through direct contact, aerosol, and during breeding, with potential for subclinical respiratory infections in yearlings.
    • Latency can occur, but the specific anatomical site for latency has not been established.

    Control Measures

    • Breeding should be restricted until lesions have healed to prevent further transmission of EHV-3.
    • Awareness of the disease's symptoms and potential for reactivation is crucial for managing horse populations.

    Introduction to Viral Respiratory Diseases

    • Identify the structural components of a virus, including nucleic acid type and envelope presence.
    • Differentiate viruses based on structural components, such as size, shape, and genetic material.
    • Illustrate archetype virus life histories, detailing replication and transmission processes.
    • Explain how structural differences between viruses influence their life histories and pathogenicity.

    Viral Families and Their Characteristics - Herpesviridae

    • Enveloped viruses with double-stranded DNA (dsDNA) genomes ranging from 125-300 kb.
    • Three subfamilies: alpha, beta, and gamma, each with distinct pathogenic profiles.
    • Can establish latent infections, complicating eradication efforts.
    • Poor environmental survival, necessitating close contact for transmission.

    Infectious Laryngotracheitis (ILT)

    • Clinical signs include conjunctivitis, dyspnea, and bloody expectorant, with mortality rates ranging from 20% to 70%.
    • Transmission occurs via inhalation, ingestion, or conjunctival inoculation, primarily from carrier birds.
    • The virus replicates in the tracheal epithelium, leading to severe respiratory symptoms.
    • Vaccination can lead to reversion to virulence, complicating control measures.

    Caliciviridae Family

    • Non-enveloped viruses with single-stranded RNA (+ssRNA) genomes approximately 8 kb in size.
    • Icosahedral symmetry and a diameter of 27-40 nm, contributing to their stability in the environment.
    • High antigenic variation, particularly in the P2 subdomain, affecting host range and tissue specificity.
    • Replication occurs in cells deficient in STAT1 and interferon receptor genes, enhancing viral propagation.

    Feline Calicivirus

    • Low virulence forms present in young cats (10 weeks to 3 years) with symptoms like conjunctivitis and oral ulcers.
    • High virulence form, known as Virulent Systemic FCV, emerged in 1998 with a mortality rate of 30-60%.
    • Vaccinated cats may experience worse outcomes due to exacerbated disease from pre-existing immunity.
    • Pathogenesis involves targeting epithelial cells, particularly in the oral and respiratory tracts, leading to ulceration and necrosis.

    Pathogenesis and Clinical Implications

    • The primary reservoir for ILTV is carrier birds, shedding the virus in oronasal secretions.
    • Transmission routes include inhalation, ingestion, and conjunctival inoculation, leading to respiratory disease.
    • The virus replicates in the tracheal epithelium, causing laryngotracheitis and severe clinical signs.
    • Management strategies must consider the potential for vaccination to revert to virulence.
    • FCV primarily infects epithelial cells, leading to oral ulcerations and mild upper respiratory infections.
    • The virus can also target endothelial cells, resulting in hemorrhage and systemic illness in high virulence cases.
    • Viral protein P2 interacts with tight junctions, facilitating cell entry and subsequent necrosis/apoptosis.
    • High genetic variability allows for reinfection with new variants, complicating control efforts.

    Feline Calicivirus

    • Primarily affects the respiratory system of cats, leading to symptoms such as oral ulcers, nasal discharge, and conjunctivitis.
    • The virus can cause edema, necrosis, erosion, ulceration, and sloughing of footpads, indicating severe systemic involvement.
    • FCV is known for its ability to mutate, leading to various strains that can cause different clinical presentations.
    • The disease is often exacerbated in multi-cat environments, such as shelters, where stress and close contact facilitate transmission.

    Diagnosis and Transmission

    • Diagnosis of FCV involves isolation of the virus from secretions, with techniques such as RT-PCR and immunofluorescence being commonly used.
    • The virus is transmitted through direct contact, fomites, and aerosolized droplets, making it highly contagious in crowded settings.
    • Clinically, the focus is on symptomatic treatment rather than exhaustive diagnostic procedures, especially in acute cases.

    Control Measures

    • Vaccination is a key control strategy, with modified live vaccines being more effective in reducing signs and viral shedding.
    • Quarantine measures and management practices are essential in preventing outbreaks, particularly in shelters.
    • Disinfection protocols, such as using a 10% bleach solution, are critical in controlling the spread of FCV.

    Paramyxoviridae Family

    • Includes several significant viruses affecting various animal species, characterized by their -ssRNA genome and pleomorphic virions.
    • Closely related to Rhabdoviridae and Filoviridae, sharing deep phylogenetic relationships based on gene order and expression.
    • Many paramyxoviruses are enzootic within specific host species but can cross over to others, highlighting the risk of zoonotic transmission.

    Pathogenesis and Infectivity

    • The cleavage of the F0 protein is crucial for the infectivity of paramyxoviruses.
    • Receptors for these viruses vary, with some utilizing sialic acids and others, like henipaviruses, using ephrin B2 and B3 proteins.

    Emerging Viruses and Concerns

    • New paramyxoviruses are continually being discovered, indicating a growing diversity within the family and potential for cross-species emergence.
    • The henipavirus genus, particularly those associated with bats, poses significant public health concerns due to their high mortality rates in humans.
    • Continuous surveillance and research are necessary to monitor these emerging threats.

    Bovine Respiratory Syncytial Virus (BRSV)

    • A major cause of respiratory disease in cattle, particularly affecting young and recently weaned animals.
    • Clinical signs include fever, respiratory distress, and pneumonia, often without significant oculonasal discharge.
    • The virus can lead to severe outbreaks, especially in winter months, and is a key contributor to Bovine Respiratory Disease Complex (BRDC).

    Pathogenesis and Cellular Targets

    • BRSV primarily targets ciliated bronchiolar epithelial cells, leading to cell death and impaired ciliary clearance, making the animal more susceptible to secondary infections.
    • The disease features syncytial cell formation, a hallmark of BRSV infection, which can be observed histologically.

    Bovine Respiratory Syncytial Virus (BRSV)

    • BRSV is transmitted through aerosols and direct contact.
    • Subclinical infections are common, making control challenging.
    • Vaccination is crucial, but immunity is often partial and short-lived, requiring booster doses.
    • Colostrum provides passive immunity to calves, aiding in BRSV outbreak management.

    Newcastle Disease (ND)

    • ND presents with respiratory signs, conjunctivitis, and neurological symptoms.
    • Mortality rates can range from 0-100%.
    • Caused by Avian Paramyxovirus Type 1, with pathogenic strains posing a significant threat in poultry.
    • ND can affect humans, highlighting its zoonotic potential.
    • The virus spreads rapidly within flocks, replicating in the upper respiratory tract and causing severe respiratory distress.
    • Transmission occurs through aerosolized particles and direct contact, emphasizing the importance of biosecurity measures for poultry management.
    • Vaccination is the main control strategy, with various vaccine strains available for poultry protection.
    • Biosecurity measures, including isolation of infected birds and strict hygiene protocols, are essential in preventing outbreaks.

    Influenza Viruses

    • Belongs to the Orthomyxoviridae family, characterized by segmented genomes.
    • Influenza A is the most significant type for veterinary species.
    • The segmented genome allows for reassortment, leading to new viral combinations and strains.
    • Influenza viruses are enveloped, single-stranded RNA viruses with a negative sense.
    • Hemagglutinin (HA) and Neuraminidase (NA) are crucial surface glycoproteins, facilitating viral entry and exit from host cells.
    • There are four main types of influenza viruses: A, B, C, and D.
    • Influenza A viruses are further classified into subtypes based on their HA and NA proteins.

    Equine Influenza

    • The Great Epizootic of 1872 was a significant outbreak of equine influenza, primarily caused by the H7N7 and H3N8 strains.
    • H3N8 has become more prevalent and has undergone mutations, some contributing to canine influenza.
    • Clinical signs in adult horses are typically mild, but foals may experience severe symptoms, including pneumonia and conjunctivitis.
    • Transmission occurs through aerosolized droplets, wind, and fomites, with migratory waterfowl serving as reservoirs.
    • Control measures include movement restrictions, thorough disinfection, and vaccination, though clinical signs are not definitive for diagnosis.
    • Vaccination is not routinely recommended for canine influenza but may be considered in high-density populations or during outbreaks.

    Highly Pathogenic Avian Influenza (HPAI)

    • HPAI viruses are categorized into low and highly pathogenic strains.
    • H5N1 is a notable example that entered the U.S. in 2021.
    • HPAI can affect a wide range of hosts, including mammals, and is characterized by neurotropism.
    • Control measures for HPAI include testing, movement restrictions, and vaccination development.
    • HPAI was detected in dairy cattle in 2022, affecting 10-20% of herds.
    • Clinical signs in cattle include decreased milk production and mild respiratory symptoms.
    • Transmission routes include fomites, aerosol droplets, and contaminated milk, which can be neutralized by pasteurization.
    • The presence of multiple receptor types in cattle suggests a potential for infection by various influenza strains.

    Herpesviridae

    • Enveloped DNA viruses
    • Double-stranded DNA genome
    • 3 subfamilies: Alpha, Beta, and Gamma

    Caliciviridae

    • Non-enveloped RNA viruses
    • Single-stranded, positive-sense RNA genome
    • Icosahedral symmetry

    Paramyxoviridae

    • Enveloped RNA viruses
    • Single-stranded, negative-sense RNA genome
    • Pleomorphic shape
    • Linear genome 13-19 kb long

    Orthomyxoviridae

    • Enveloped RNA viruses
    • Segmented single-stranded RNA genome
    • Important for Influenza viruses
    • Surface glycoproteins: Hemagglutinin and Neuraminidase

    Feline Calicivirus

    • Single-stranded, positive-sense RNA genome
    • 7.7 kb long
    • Non-enveloped

    Bovine Respiratory Syncytial Virus (BRSV)

    • Single-stranded, negative-sense RNA genome
    • Low antigenic variation
    • Member of the Paramyxoviridae Family

    Newcastle Disease Virus (NDV)

    • Avian paramyxovirus
    • Enveloped, single-stranded, negative-sense RNA genome
    • Pleomorphic
    • Can affect humans

    Feline Herpesvirus 1 (FHV-1)

    • Double-stranded DNA virus
    • Member of the Herpesviridae family

    Influenza Virus

    • Enveloped RNA virus
    • Segmented genome
    • Important surface glycoproteins (Hemagglutinin and Neuraminidase)

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