Inf. diseases II - Swine diseases (resp.) Flashcards
PRCV
PORCINE RESPIRATORY CORONAVIROSIS
PORCINE RESPIRATORY CORONAVIROSIS (PRC) is very contagious disease of
weaner pigs that is characterized by coughing, sneezing and mild respiratory infection.
PORCINE RESPIRATORY CORONAVIROSIS (PRC) is very contagious disease of weaner pigs that is characterized by
coughing, sneezing and mild respiratory infection.
Describe the causative agent of PRCV
porcine respiratory corona virus
RNA
G.Alphacoronavirus
F.Coronaviridae
Variant of TGEV so infection with PRCV makes pigs immune to TGEV.
Serotypes of of PRCV
Many serotypes with different virulence.
Most of the serotypes do not cause illness.
Only the most virulent serotype causes mild respiratory disease.
PRCV survival in environment
Virus can survive in the environment for long time
Enzootic in swine herds worldwide.
Infection is subclinical in many infected herds.
Target demographic of PRCV
Infects piglets of all ages.
Clinical illness in 1-6 month-old pigs.
Infection occurs mostly right after weaning.
Morbidity of PRCV
low
Enzootic in swine herds worldwide
Infection is subclinical in many infected herds
Transmission of PRCV
Excretion: respiratory, feces
Excretion up to 2 weeks after infection.
Mostly respiratory excretion.
Airborne respiratory transmission
Direct contact
Route: respiratory
Clinical signs of PRCV
Mild fever
Dyspnea, polypnea, anorexia – variable degrees.
Co-infection with other respiratory pathogens. If mono-infection, the suckling piglets may have a cough for a short period – may go unnoticed.
Adult mostly subclinical with no clinical signs.
Post mortem signs of PRCV. (2)
Bronchointerstitial pneumonia (5-60%).
(Cranial and middle lung lobe have thick consistence, dark red to purple color.)
If secondary bacterial infections – lesions are more severe.
Material for diagnosis of PRCV. (2)
nasal swabs
lungs
Lab analyses for diagnosis of PRCV. (3)
RT-PCR and highly specific competitive ELISA are the only diagnostic measures that can differentiate PRCV and TGEV!
Virus isolation
Prevention & control of PRCV. (3)
Not a big problem for general herd health – no prevention measures in place.
No vaccines.
NB! Infection with PRCV make the pigs immune to TGEV!
Alt. name for mycoplasmal pneumonia
Enzootic pneumonia
However, note, some sources try to differentiate these two into 2 separate diseases.
Some say Mycoplasmal pneumonia describes only the effects of the mycoplasma and when there is secondary infection involved as well, it would be called enzootic pneumonia.
mycoplasmal pneumonia or Enzootic pneumonia is a chronic respiratory disease of pigs, caused by
Mycoplasma hyopneumoniae, characterized by sporadic disease of coughing and decrease in growth rate.
mycoplasmal pneumonia or Enzootic pneumonia is a chronic respiratory disease of pigs, caused by Mycoplasma hyopneumoniae, characterized by
sporadic disease of coughing and decrease in growth rate.
Causative agent of MP
MP = Mycoplasma pneumonia
Mycoplasma hyopneumoniae, gram neg. bacterium.
Primary agent – “opens the door” for other agents. Secondary agent: Pasteurella multocida.
Can also be other, e.g. Haemophilus parasuis, Actinobacillus pleuropneumoniae
Where is MP found?
mycoplasmal pneumonia found worldwide
also in estonia
When does MP typically occur?
Seasonal – higher occurrence rate from November to March
Morbidity of MP
Morbidity decreases with increasing age
Finishing pigs and adults may recover completely
Herd morbidity <93%
Transmission of MP
Excretion: respiratory
Coughing and sneezing: spread is 5-6m
Spread to neighboring farms with aerosols within 3,2 km radius
Aerogenic
Direct contact
Route: respiratory
IP of MP
IP: 10-16 days
Mostly chronic, rarely acute outbreaks
Clinical signs of acute MP
Mostly chronic, rarely acute outbreaks.
Signs of acute:
Acute respiratory distress, acute pneumonia
Dehydration
Fever
Morbidity <100%
High mortality in all age groups
Clinical signs of chronic MP
In endemic herds Young piglets are usually infected at 3-10 weeks of age, clinical signs seen in suckling piglets.
Dry cough (7-8 coughs in one episode)
Worsens while moving (e.g. during feeding)
Difficulties to breath
Uneven growth rate, loss of appetite
Post mortem signs of MP. (4)
Lung lesions, Catarrhal pneumonia
Bronchial LNs – enlarged, edematous
With secondary infections:
Pleuritis and pericarditis
Hepatization and congestion with a suppurative bronchopneumonia
the most common respiratory infection in pigs:
Enzootic pneumonia (aka mycoplasmal pneumonia) with or without secondary bacterial invasion, is the most common respiratory infection in pigs!
Material for diagnosis of MP. (3)
Blood
Colostrum
Lung tissue
Lab analyses for diagnosis of MP. (2)
Serology (ELISA) – antibodies from sera and colostrum.
Detecting organism – lung tissue culture, immunofluorescence, PCR, antigen-ELISA.