Topic 55 - Diseases of farm animals caused by reoviruses and rotaviruses Flashcards
Name two subfamilies of reoviridae:
- Sedoreoviridae family
- Spinareoviridae family
Name two genuses under sedoreoviridae of veterinary impact:
- Orbivirus
- Rotavirus
Name a genus under spinareoviridae which is of veterinary impact:
- Orthoreovirus
Name diseases under orbivirus genus:
- African horse sickness
- Equine encephalosis
- Bluetongue
Name diseases under rotavirus genus:
rotavirus A
Name disease under orthoreovirus:
- Avian orthoreovirus
- Mammalian orthoreoviruses
What type of virus is reovirus?
RNA
but the virus is segmented
How many segments does reoviruses have?
10-12 segments
What can happen to the segments of reoviruses?
The genetic properties of the virus can change if two viruses replicate and mixes the segments
Why can reoviruses be problematic for vaccine developers?
Segments + RNA viruses are very variable. They have a lot of species, several serotypes.
Are reoviruses enveloped or non-enveloped?
non-enveloped
Resistance of reoviruses:
Depends on the genus
Resistance of orbivirus genus:
Weak resistance
They need insects to transmit the virus from one animal to another. The virus will be killed in the stomach, so the insect will infect via the blood
Resistance of Orthoreovirus:
Good resistance. The faeces provides extra protection for the virus, so disinfectants are not enough
The virus can survive in the stomach, so oral infection can happen
Resistance for rotaviruses:
Good resistance. The faeces provides extra protection for the virus, so disinfectants are not enough
The virus can survive in the stomach, so oral infection can happen
Can cause enteric disease because they can be present in the enteric environment, in the GI tract
Isolation of orthoreoviruses:
easier
Isolation of orbi- and rotaviruses:
We use embryonic eggs. We inoculate the virus into the vessels of the embrynic egg
Host range of reoviruses
Euryxen
Can infect several species
Host range restrictions of reoviruses:
Humans cannot infect animals, and animals cannot infect humans
Vectors of orbivirus:
Mosquitos = biological vectors
What is a biological vector?
The virus can replicate inside the body of the mosquito
Is reovirus a zoontic disease?
It cannot be excluded as zoonotic disease, but the virus have specific strains for humans and specific strains for animals
Causative agent of rotavirus:
How many species does rotavirus have?
What are their names?
9 species, named from A-J
Which of the 9 species of rotavirus are most important for veterinarians?
A, B and C
Species susceptible for Rotavirus, type A:
Most mammals and birds, 90% of human cases
Species susceptible for Rotavirus, type B:
Human
Swine
Cattle
Sheep
Rat
Species susceptible for Rotavirus, type C:
Swine
Rarely humans
How many genome segments does rotavirus have?
11
Are rotaviruses resistant?
yes
How long does rotavirus survive, and in what do they survive?
for months in the environment
How is rotavirus shed?
With faeces
Occurence of rotaviruses:
Worldwide
It is a frequent cause of problems in humans and animals
Route of transmission for rotaviruses:
Faecal-oral route
Does rotaviruses have germinative infection?
no, but the surface of the eggs may be infected.
Cleaning + disinfection of the eggs is important
Pathogenesis of rotaviruses
After infection there is a multiplication in the enterocytes mainly in the middle and distal regions of the small intestines. It will cause epithelial damage, villus atrophy, osmotic diarrhoea and exsiccosis
How is rotaviruses shed?
shedding in the faeces in high titres
What can cause even more severe clinical signs of rotaviruses?
Simultaneous infection
Name some infections that can happen simultaneous with rotavirus:
- Parvo
- Corona
- Astroviruses
- E.coli
- Cryptosporidia
Clinical signs of rotavirus:
- Sudden massive diarrhoea
- Loss of appetite, due to abdominal pain
- Weakening
- Retarded body weight gain
Which age is most susceptible of rotaviruses?
1 (2) weeks of age
Older animals are also susceptible to infection, but due to some biochemical situations in the enteric tracts, the young animals are more susceptible to infection and also the enteric flora in a few-day old animals are not optimal
Incubation period of rotavirus:
24-48 hours
Morality rate of rotavirus:
low
If there are other infections present, the outcome can be fatal
When can we see recovery after infection with rotavirus?
End of the 2nd week
Clinical signs in older animals in case of rotavirus:
More severe, and there is immunosuppression in the background
Why can we see recovery in case of rotaviruses?
Because the basal cells and crypt is not affected, the epithelial cells can be reproduced leading to recovery.
If the villus is damaged, we see more severe infections
Why can we see villus atrophy in case of rotavirus?
The basal cells are not affected, but the epithelial cells covering the villus are affected byt the virus = villus atrophy
Pathological lesions in case of rotaviruses:
- Undigested, liquid content in the intestines
- Enlarged intestines
Histopathological lesions in case of rotaviruses:
- Inflammation in the enteric mucosa
- Villus atrophy and blunting
How to diagnose rotavirus:
By age affected and clincal signs we have a good suspicion, but we also do virus detection
Which laboratory methods to detect the rotavirus can be done?
RT-PCR is 1st choice
We can do AgELISE to check the variability of the virus
Treatment of rotaviruses:
- AB against bacterial co-infections
Prevention of rotaviruses:
- Sufficient colostrum uptake
- Sufficient vaccination of the mother (to produce good colostrum)
- Hygiene
Vaccine type for rotavirus:
inactivated, usually polyvalent vaccines
When and how often do we vaccinate for rotavirus?
Pregnant cows twice in the 3rd trimester, and then repeatedly vaccinations is the key
Name a human pathogen disease, caused by reovirs:
Seadornavirus-associated diseases, which are sub-named after the place they are found
How many segment does seadornavirus-associated disease have?
12
Which vector does seadornavirus-associated disease have?
mosquito - culicidae
Pathogenesis of seadornavirus-associated disease:
In humans, but also found in animals
Clinical signs of seadornavirus-associated disease:
influenza-like illness
- Fever
- Muscle pain
- Joint pain
A consequence of seadornavirus-associated disease:
Encephalitis
