Viruses affecting the respiratory system in both veterinary and medical contexts share common characteristics, such as their ability to cause infections of the airways, leading to symptoms like coughing, sneezing, fever, and difficulty breathing. However, the specific viruses, clinical signs, and disease management approaches can differ based on the species.
A. Veterinary Respiratory Viruses
1. Avian Influenza Virus (AIV)
- Family: Orthomyxoviridae
- Genus: Influenzavirus A
- Host: Poultry (chickens, ducks, turkeys) and wild birds
- Transmission: Direct contact with infected birds, contaminated surfaces, aerosols
- Pathogenesis: The virus infects respiratory epithelial cells, leading to inflammation and tissue damage. It can also spread systemically, causing severe systemic disease in highly pathogenic strains.
- Clinical Signs: Respiratory distress, nasal discharge, coughing, reduced egg production, swollen sinuses, sudden death in severe cases
- Prevention: Biosecurity measures, vaccination, culling infected birds
2. Bovine Respiratory Syncytial Virus (BRSV)
- Family: Paramyxoviridae
- Genus: Pneumovirus
- Host: Cattle, particularly young calves
- Transmission: Aerosols, close contact
- Pathogenesis: The virus damages the respiratory epithelium, leading to bronchitis and pneumonia. Secondary bacterial infections often occur due to compromised defenses.
- Clinical Signs: Coughing, nasal discharge, fever, difficulty breathing, depression, secondary bacterial infections
- Prevention: Vaccination, management practices to reduce stress and crowding
3. Equine Influenza Virus
- Family: Orthomyxoviridae
- Genus: Influenzavirus A
- Host: Horses
- Transmission: Aerosolized droplets, close contact
- Pathogenesis: The virus infects the respiratory epithelium, causing inflammation and damage, which may lead to secondary bacterial infections.
- Clinical Signs: Fever, nasal discharge, coughing, lethargy, loss of appetite
- Prevention: Vaccination, quarantine of infected animals, good hygiene
4. Porcine Reproductive and Respiratory Syndrome Virus (PRRSV)
- Family: Arteriviridae
- Genus: Arterivirus
- Host: Pigs
- Transmission: Direct contact, aerosols, contaminated equipment
- Pathogenesis: The virus targets macrophages in the lungs, leading to impaired immune response and increased susceptibility to secondary infections.
- Clinical Signs: Respiratory issues (coughing, difficulty breathing), reproductive problems (abortions, stillbirths)
- Prevention: Biosecurity, vaccination, herd management strategies
5. Canine Parainfluenza Virus
- Family: Paramyxoviridae
- Genus: Respirovirus
- Host: Dogs
- Transmission: Aerosols, direct contact
- Pathogenesis: The virus infects the respiratory epithelium, leading to inflammation and a predisposition to secondary bacterial infections.
- Clinical Signs: Coughing, nasal discharge, lethargy, fever
- Prevention: Vaccination, avoiding crowded areas like kennels
6. Feline Calicivirus (FCV)
- Family: Caliciviridae
- Genus: Vesivirus
- Host: Cats
- Transmission: Direct contact, contaminated objects, aerosols
- Pathogenesis: The virus infects the upper respiratory tract, leading to inflammation and ulceration, especially in the oral cavity.
- Clinical Signs: Upper respiratory signs (sneezing, nasal congestion), conjunctivitis, oral ulcers
- Prevention: Vaccination, good hygiene practices
B. Medical (Human) Respiratory Viruses
1. Influenza Virus (A, B, C)
- Family: Orthomyxoviridae
- Genus: Influenzavirus A, B, C
- Host: Humans, birds, pigs
- Transmission: Aerosols, droplets, contaminated surfaces
- Pathogenesis: The virus infects respiratory epithelial cells, causing cell death and inflammation, leading to respiratory symptoms and secondary infections.
- Clinical Signs: Fever, cough, sore throat, muscle aches, fatigue; severe cases can lead to pneumonia
- Prevention: Annual vaccination, hygiene practices, antiviral medications
2. Respiratory Syncytial Virus (RSV)
- Family: Paramyxoviridae
- Genus: Pneumovirus
- Host: Humans (particularly infants and the elderly)
- Transmission: Aerosols, direct contact with secretions
- Pathogenesis: The virus causes cell fusion (syncytia) in respiratory epithelial cells, leading to airway obstruction and inflammation.
- Clinical Signs: Common cold-like symptoms, severe respiratory distress in infants, bronchiolitis, pneumonia
- Prevention: Hygiene practices, monoclonal antibody treatment for high-risk infants
3. Coronavirus (including SARS-CoV-2)
- Family: Coronaviridae
- Genus: Betacoronavirus
- Host: Humans, various animals (bats, camels)
- Transmission: Aerosolized droplets, direct contact
- Pathogenesis: The virus infects respiratory epithelial cells, leading to inflammation, lung injury, and systemic effects in severe cases.
- Clinical Signs: Fever, cough, shortness of breath; severe cases may progress to pneumonia and ARDS
- Prevention: Vaccination, social distancing, hygiene practices
4. Human Parainfluenza Virus (HPIV)
- Family: Paramyxoviridae
- Genus: Respirovirus and Rubulavirus
- Host: Humans
- Transmission: Aerosols, droplets, contaminated surfaces
- Pathogenesis: The virus infects the respiratory tract, leading to inflammation and swelling of the airways, particularly in children.
- Clinical Signs: Croup, bronchitis, common cold symptoms in children and immunocompromised individuals
- Prevention: Hygiene practices, supportive care
5. Adenovirus
- Family: Adenoviridae
- Genus: Mastadenovirus
- Host: Humans
- Transmission: Aerosols, direct contact, fecal-oral route
- Pathogenesis: The virus infects epithelial cells of the respiratory tract, leading to inflammation and tissue damage.
- Clinical Signs: Mild cold-like symptoms, pharyngitis, bronchitis, conjunctivitis, pneumonia
- Prevention: Hygiene practices, adenovirus vaccine for military personnel
6. Rhinovirus
- Family: Picornaviridae
- Genus: Enterovirus
- Host: Humans
- Transmission: Aerosols, direct contact with contaminated surfaces
- Pathogenesis: The virus primarily infects nasal epithelial cells, leading to inflammation and mucosal swelling.
- Clinical Signs: Common cold symptoms such as sneezing, runny nose, mild cough
- Prevention: Hygiene practices