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?

Diarrhea Signup and view all the answers

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

Latent Signup and view all the answers

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

Intranuclear inclusions Signup and view all the answers

Through which routes can FHV-1 be transmitted?

Aerosolized droplets and direct contact with secretions Signup and view all the answers

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

Transplacental transmission leading to abortion Signup and view all the answers

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

Hypothermia Signup and view all the answers

Which equine herpesvirus is particularly notorious for causing systemic disease?

EHV-1 Signup and view all the answers

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

Cell death and placental separation Signup and view all the answers

What are common clinical signs of EHV-1 infection?

Fever, anorexia, and nasal discharge Signup and view all the answers

Which control measure is important to prevent outbreaks of EHV?

Isolation of affected horses Signup and view all the answers

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

Genital and respiratory secretions Signup and view all the answers

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

Venereal infections with genital lesions Signup and view all the answers

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

Double-stranded DNA genomes Signup and view all the answers

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

Viremia leading to encephalomyelitis Signup and view all the answers

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

Vasculitis and ischemic necrosis Signup and view all the answers

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

Immunofluorescence and immunohistochemical staining Signup and view all the answers

What is the consequence of latency in EHV infections?

Potential for disease episodes later in life Signup and view all the answers

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

To protect against systemic disease and abortion Signup and view all the answers

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

14 days Signup and view all the answers

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

Conjunctivitis Signup and view all the answers

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

Enveloped structure Signup and view all the answers

What transmission route is NOT relevant for Infectious Laryngotracheitis?

Vector-borne transmission Signup and view all the answers

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

High mutation rate leading to various strains Signup and view all the answers

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

Serological testing Signup and view all the answers

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

Ciliated bronchiolar epithelial cells Signup and view all the answers

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

Icosahedral symmetry Signup and view all the answers

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

Systemic hemorrhage Signup and view all the answers

What is the main concern with vaccination against Infectious Laryngotracheitis?

Reversion to virulence Signup and view all the answers

Which of the following statements regarding BRSV is correct?

Syncytial cell formation is a hallmark of infection. Signup and view all the answers

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

High stress and close contact in multi-cat environments Signup and view all the answers

What aspect of paramyxovirus infectivity is crucial to its pathogenicity?

Cleavage of the F0 protein Signup and view all the answers

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

30-60% Signup and view all the answers

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

Offering passive immunity. Signup and view all the answers

What are common clinical signs associated with Newcastle Disease?

Respiratory signs and neurological symptoms. Signup and view all the answers

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

Biosecurity measures. Signup and view all the answers

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

Type A Signup and view all the answers

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

Hemagglutinin (HA) Signup and view all the answers

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

H3N8 and H7N7 Signup and view all the answers

How is equine influenza mainly transmitted?

Via aerosolized droplets. Signup and view all the answers

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

They can lead to neurotropism. Signup and view all the answers

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

Decreased milk production. Signup and view all the answers

What is the primary control strategy for Newcastle Disease?

Vaccination. Signup and view all the answers

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

Via aerosolized particles and direct contact. Signup and view all the answers

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

H3N8 Signup and view all the answers

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

Segmented genome reassortment. Signup and view all the answers

What role does latency play in herpesvirus infections?

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

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

Canine Parvovirus Signup and view all the answers

What is a significant concern regarding vaccination strategies for herpesviruses?

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

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

Hemorrhagic ulcers in the nasal cavity. Signup and view all the answers

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

It helps prevent transmission of the virus between animals. Signup and view all the answers

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

Intranuclear inclusion bodies in epithelial cells. Signup and view all the answers

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

High neonatal mortality without other clinical signs. Signup and view all the answers

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

Via respiratory droplets and during coitus. Signup and view all the answers

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

Latent infections lead to periods of asymptomatic shedding. Signup and view all the answers

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

Fatal generalized hemorrhagic infections. Signup and view all the answers

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

DNA vaccines. Signup and view all the answers

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

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

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

Subclinical cases that complicate diagnosis. Signup and view all the answers

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

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

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

Feline Calicivirus Signup and view all the answers

What type of viral genome does Bovine RSV possess?

Single-stranded RNA, negative sense Signup and view all the answers

Which characteristic is associated with the Orthomyxoviridae family?

Segmented ssRNA Signup and view all the answers

What is a key feature of the Newcastle Disease Virus?

It has a segmented genome. Signup and view all the answers

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

Enveloped, double-stranded DNA 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.