Porcine respiratory disease complex Flashcards
What are the 3 components of the porcine respiratory disease complex?
Bacteria
Viruses
Management and environment (non-infectious causes)
Name some bacteria involved in the porcine respiratory disease complex
M. hyopneumoniae B. bronchiseptica P. multocida A. pleuropneumoniase H. parasuis S. suis
Name some viruses involved in the porcine respiratory disease complex
PRRSV = Porcine reproductive and respiratory syndrome virus SIV = swine influenza virus PRCV = porcine respiratory coronavirus PRV = porcine pseudorabies virus PCV2 = porcine circovirus 2
Which management and environmental conditions contribute to the porcine respiratory disease complex
Overcrowding Ventilation Temperature Mixing different sources Continuous flow Sanitation
What is one of the most common routes of transmission for infectious agents?
Direct pig to pig contact
Describe the role of people in disease transmission
They can transport pathogens on footwear, clothing, hands, etc.
People can carry viruses on their nasal mucosae (nasal carriers) without being infected.
People also determine the movements of domestic animals and products among herds, markets and regions
Why are non-infectious causes (management and environmental factors) significant contributors to respiratory disease?
- Increase transmission and spread of pathogens
- Create unfavourable conditions which result in increased stress for the animal or damage to the respiratory tract
What are the effects of overcrowding and/or improper ventilation?
Can lead to overheating or chilling, increased stress, and increased ammonia and dust levels which have a negative impact on the respiratory tract defences
Describe pig biosecurity measures to help control infectious diseases
- Prohibit unnecessary visitors to the farm.
- Cleanse and disinfect any shared equipment before it enters and after it leaves your premises.
- Make sure that personnel in contact with pigs at different premises take standard precautions, such as cleaning and disinfecting boots and clothing.
- Prevent people with flu-like symptoms coming into contact with pigs.
What are the 3 ways in which the immune system controls pathogens?
Innate immunity
Passive immunity
Adaptive immunity
Describe the window of susceptibilty
As passive immunity decreases and adaptive immunity increases there is a point where the levels of both are low
Describe adaptive immunity
This response system reacts when exposed to pathogens and vaccine antigens, providing long-term protection against future infection by the same invading pathogen. It functions throughout life.
Name the 2 components of adaptive immunity
Cell-mediated immune (CMI) response.
Humoral immune response.
Describe the cell mediated immune response
Produces specific white blood cells (T lymphocytes) that facilitate antibody production and help fight and clear infected cells and protect non-infected cells
Describe the humoral immune response
Produces antibodies that flow through body fluids and mucosal surfaces to help stop infection – mucosal immunity
How does the immune system respond to an infection/vaccination?
- Innate system responds immediately for a short time in generally a non-specific way: phagocytes, cytokines
- Cell-mediated portion of the adaptive response occurs reasonably quickly with the production of white blood cells to kill pathogens and help the humoral response
- After 7-10 days, antibodies from the humoral component of the adaptive immune system begin to appear
When is the PRRS vaccine given to pigs?
- A single dose is given to pigs from 2 weeks of age onwards.
- Finishing pigs: A single vaccination is sufficient for protection until slaughter.
- Breeding pigs: For gilts a (re)vaccination 2-4 weeks before mating is recommended
What may interfere with the response to vaccination?
Maternally derived antibodies
Describe the incubation period of swine influenza virus?
The incubation period of the disease is very short, as little as 12-48 hours and the onset is usually rapid and dramatic.
Describe the symptoms of swine influenza virus in piglets
- It would be unusual to see any signs of swine flu in the sucking pig unless disease entered the herd for the first time
- Colostrum may prevent infection during the sucking period
- Coughing
- Pneumonia
- Fever
Describe the symptoms of swine influenza virus in sows
- High temperatures which cause abortions
- Widespread coughing
- Pneumonia
Describe an outbreak of swine influenza virus in a herd
- When the virus first enters the herd two or three animals may be observed sick for the first two days, followed by:
- A rapid explosive outbreak of inappetence and clinically very ill pigs.
- The effects on the reproductive system follow the sudden onset of a rapid spreading respiratory disease with coughing, pneumonia, fevers and inappetence.
- Acute respiratory distress persists over a period of 7-10 days (depending on the amount of contact between groups of sows).
How can swine influenza virus be introduced to a herd?
- Infected animals including people, pigs and birds.
- Carrier pigs.
- Probably on the wind although this has not been proved.
- Birds particularly waterfowl, are reservoirs of infection.
Which factors contribute to swine influenza virus disease?
- Secondary bacterial infections
- Fluctuating temperatures
- Stress
- Wet bedding and floor surfaces
- Poor nutrition
Describe the reproductive manifestations of a Porcine Circovirus 2 infection
Reproductive failure in breeding herds, predominately associated with increased numbers of mummies and non-viable piglets at parturition
Enzootic pneumonia is caused by?
Mycoplasma hyopneumoniae
How is enzootic pneumonia transmitted?
- Through the movement of the carrier pigs
- By wind-borne infection
Describe the features of Enzootic pneumonia
- long incubation period of two to eight weeks before clinical symptoms are seen.
- The organism dies out quickly outside the pig
- Only has mild effects on the pig
How is Enzootic pneumonia diagnosed?
- Clinical exam PM
- Histology of lesions
- ELISA
- Serum tests for specific antibodies
- Fluorescent antibody tests
- PCR
- Culture and identification of Mycoplasma hyopneumoniae
Increased disease with Enzootic pneumonia is associated with what changes?
- Overcrowding
- Variable temperatures and poor insulation.
- Houses with poor hygiene and high levels of
carbon dioxide and ammonia. - High dust/bacteria levels in the air.
- Pig movement, stress and mixing.
- A shortage of trough space.
- Concurrent disease
- Poor nutrition
Which bacteria Colonised the ciliated epithelium of the respiratory tract?
Bordetella bronchiseptica
What are the effects of Bordetella bronchiseptica infection?
Decreased mucociliary apparatus function and pneumonia
Describe the gross lesions associated with Bordetella bronchiseptica infection?
- Necrohemorrhagic pleuropneumonia in young pigs or a tan, firm bronchopneumonia in older pigs
- Acute form = Cranioventral distribution on the lungs
- The more chronic form seen in nursery and grower pigs is very firm and tan with fibrosis
How is Bordetella bronchiseptica infection diagnosed?
Isolation of the organism from nasal swabs, trachea, or lung
Why is blood seen from the nose of pigs with Bordetella bronchiseptica?
One sight of replication is in the turbinates so blood can be seen to ooze from the nostrils of affected animals
Describe the histological appearance of pigs infected with Bordetella bronchiseptica
Epithelial damage
- Without the functional ciliated epithelium, the mucous layer is static.
- Trapped organisms are not eliminated and instead are allowed to reproduce and dramatically increase the challenge to the pig’s system
- At some point, the challenge may overwhelm the immune defences and result in respiratory disease and/or intoxication
How is Bordetella bronchiseptica prevented?
An avirulent live culture Bordetella bronchiseptica vaccine
How does Bordetella bronchiseptica MAXI/GUARD Nasal Vac work?
Attaches to the ciliated turbinate epithelium and helps stimulate a secretory IgA response.
Nasal Vac occupies Bordetella bronchiseptica (Bb) receptor sites thus effectively blocking attachment of pathogenic Bb.
