Topic 56 - Reoviral diseases of poultry Flashcards
causative agent of reoviral disease of poultry:
Orthoreovirus genus, reovirus order
How many protein layers does orthoreovirus have?
2 concentric protein layers, 1 inner capsid and 1 outer capsid
Inner capsid of orthoreovirus
It covers the segmented, double strained RNA genome, which have 10 segments: 3 large, 3 medium and 4 are small. Every segment can translate 1 protein, except the small - can translate 2-3
Outer capsid of orthoreovirus
Contains numerous spurs around the membrane pore
How many species does orthoreovirus have?
10 species
How many serotypes of orthoreovirus?
15
4 mammalian serotypes
11 avian serotypes
Which species are susceptible for mammalian orthoreovirus infection?
cattle, sheep, horse, swine, rabbit, humans
Occurence of mammalian orthoreovirus infection in cattle
Worldwide
how is mammalian orthoreovirus infection in cattle shed?
with faeces and sometimes nasal discharge
transmission route of mammalian orthoreovirus infection in cattle:
per os and air-borne infections
Oro-nasal route
Clincal signs in case of mammalian orthoreovirus infection in cattle:
Mainly seen in calves, because the colostral uptake is not good.
- Mild enteritis
- Respiratory signs
How long can colostral antibodies protect calves in case of mammalian orthoreovirus infection?
5 months
But if colostral uptake is bad, then we can see infections before the 5 months
mammalian orthoreovirus infection in sheep:
In the background of respiratory and enteric diseases of LAMBS
mammalian orthoreovirus infection in horse:
Usually with bacterial co-infections, and we see coughing and nasal discharge
Which bacterual co-infections can we see in horses in case of mammalian orthoreovirus infection
- Streptococcus
- Rhodococci
mammalian orthoreovirus infection in swine:
We see diarrhoea and ecepahlitis
Occurrence of mammalian orthoreovirus infection in swine:
Japan, china and USA (Minnesota and Iowa)
mammalian orthoreovirus infection in rabbit:
We see diarrhoea in young animals
mammalian orthoreovirus infection in humans:
presumably zonoosis!
We see flu-like symptoms: sneezing, coughing
occurrence of Avian orthoreovirus
Worldwide
Susceptibility of Avian orthoreovirus:
Mainly chicken!
But also: turkey, goose, Muscovy duck
Age infected with Avian orthoreovirus:
The virus is age-dependent resistant!
Over 10 weeks of age only infection but no clinical signs
How is Avian orthoreovirus shed?
With faeces and discharges
Which of Avian and mammalian orthoreovirus cause more frequently clinical signs?
Avian orthoreovirus
How long can Avian orthoreovirus survive and in what do the virus survive in?
Survive in the environment.
In 20 degree = 1 year
In 4 degree = 3 years
Transmission route of Avian orthoreovirus:
Per os
Air-borne
Transcutaneous infection, by injuries
How many types does the Avian orthoreovirus have? name them:
2
- Trypsin resistant strain
- Trypsin sensitive strain
Which of the two types of Avian orthoreovirus are more severe?
Trypsin sensitive strain
Transmission route of trypsin resistant strain of Avian orthoreovirus
Per os Infections, causing Diarrhoea
Transmission route of trypsin sensitive strain of Avian orthoreovirus
Air-norne
Transcutaneous
site of replication of Avian orthoreovirus:
Enterocytes and in the bursa fabricii
Pathogenesis of Avian orthoreovirus
After infection, we have the primary replication causing epithel damage and viraemia. The viramiea can cause inflammation of the tendon sheaths and joints.
Avian orthoreovirus infection, what can the inflammation of tendon sheaths and joints cause?
Sometimes the inflammation can cause necrotic and inflammatory foci in the visceral organs (spleen, pancreas and liver)
Isolation of Avian orthoreovirus:
Often we can see several strains from clinically healthy birds
Factors influencing the severity of Avian orthoreovirus-infection:
- Age
- Immunological stage
- Virulence and biotype of the virus strain
- Infection route
- co-infections!!
Diseases caused by Avian orthoreovirus:
- Tenosynovitis and arthritis
- Helicopter disease
- PEMS = Poult Enteritis and Mortality Syndrome
- Immunosuppression
Clinical signs of Tenosynovitis and arthritis:
- Lameness
- Swollen knee, mostly metatarsal joints
- arthritis
- Haemorrhages under the skin
- swollen thoracic bursa
- rupture of the Gastrocnemius tendon, due to which we see deformed toe
Age susceptibility of Tenosynovitis and arthritis:
4-8 week old broilers
Morbidity of Tenosynovitis and arthritis:
5-50%
Mortality of Tenosynovitis and arthritis:
2-10%
Recover time of Tenosynovitis and arthritis
Within 4-6 days
In milder cases
Pathological lesions in case of Tenosynovitis and arthritis:
- Arthritis in the knee and metatarsal joint
- Deformed toes
- Haemorrhages
- Erosions in the synovial cartilage
- Rupture of the M. Gastrocnemius
- Villus proliferation
- Ankylosis can also be found
Laboratory methods to diagnose Tenosynovitis and arthritis:
Virus isolation with embryonated eggs and chicken liver
Chicken liver: can check the cytoplasmic effect
We do RT-PCR, ELISA
Why do we do PCR in case of Tenosynovitis and arthritis?
Because the Tenosynovitis and arthritis is contaminated with bacterial infections, we have to detect the reovirus in the background (PCR) and sometimes we find the adenovirus instead (same clinical signs)
Prevention methods against Tenosynovitis and arthritis:
- Avoid early infection with good hygiene
- Immunisation with vaccine
What type of vaccine is used against Tenosynovitis and arthritis?
We vaccinate against reovirus, using a ATTENUATED or INACTIVATED vaccine, or even a combined vaccine can be used
In case of Tenosynovitis and arthritis, how long does yolk immunity last?
5-7 weeks
Which age do we vaccinate against Tenosynovitis and arthritis, with the attenuated strain?
at the age of 5-7 weeks, and then a repetition on week 11
Which age do we vaccinate against Tenosynovitis and arthritis, with the inactivated strain?
Before laying season, 18-22 week of age
Sometimes the reovirus can cause a “generalised form”, which chickens are susceptible and what can we see?
Mainly found in immunosuppressed chickens
We see:
necrosis, inflammation and degenerative processes i the visceral organs, and we see a enlarged+haemorrhagic kidney
Prevention methods for generalised form of reovirus:
- Technology
- Hygiene
- Vaccinations
Other forms of avian orthoreoviruses:
- Runting-Stunting-Syndrome (RSS)
- Poult Enteritis and Mortality Syndrome (PEMS)
Turkey orthoreovirus, what is it, and what does it cause?
It is a multifactoria disease
Causes:
1. Tenosynovitis
2. PEMS (Poult Enteritis and Mortality Syndrome)
Turkey orthoreovirus, causing tenosynovitis, what can we see?
- Inflammation of the joints
Pathological lesions of tenosynovitis caused by Turkey orthoreovirus
The gastrocnemius and the flexor tendons of the toes are mostly affected
Turkey orthoreovirus, causing PEMS, what can we see?
- Diarrhoea
- reduced food intake
Pathological lesions of PEMS caused by Turkey orthoreovirus
- tissue lesions
- inflammation in the liver, spleen and bursa fabricii
Orthoreovirus of waterfowl, how many virus types can we see? name them
2
- Classical
- New typed
Susceptible species of classical Orthoreovirus of waterfowl:
musck duck
goose
Susceptible species of new typed Orthoreovirus of waterfowl:
musck duck
goose
duck
mallard
What can we see in case of Orthoreovirus of waterfowl?
- Tenosynovitis
- Arthritis
- Diarrhoea
Pathological lesions in case of Orthoreovirus of waterfowl infection:
- Liver and spleen is enlarged
- necrotic foci in liver and spleen
- kidney enlarged with haemoerrhages
- Pericarditis
- Tenosynovitis
Other species that can be infected with orthoreoviruses:
- Pheasant
- Grey partridge
- Ostriches
- Crow
- American woodcock
- Parrots
- Canadian tit
Susceptible species of reptile reovirus:
- lizard
- snakes
- turles
clinical signs in case of reovirus in reptiles:
often subclinical, but sometimes we see RESPIRATORY SIGNS and co-infections with bacterial adenoviral and paramyxoviral infections