Viruses Of The Pregnant Genital Tract Flashcards
WHat are the 4 mechanisms of reproductive failure caused by viral infection? Egs. of specific viruses?
- replication in foetus -> malformation and death eg. Shmallenburg, BVDV
- damage to placental blood vessels eg. PRRS, arteritis
- Sttress and pyrexia eg. Bluetongue, swine flu
- Combination of the above
Give potential horiozontal and vertical routees of transmission of viruses
> horizontal
- venereal
- spread to gential tract from other sites, esp. respiratory, haemotogenous or ascending
vertical
- transfer to offspring via haematogenous (placenta)
- ascending (genital tract)
- milk
How may virus be shed by carrier animals?
- semen eg. EVA
- respiratory secretions eg. herpes
- faeces eg. BVD
What must be remembered about shedding by carrier animaals
May be intermittent
What do the 3 main equine herpes viruses cause?
- EHV1: abortions, repiratory disease, paralysis
- EHV3: coital exanthema, genital pustules but NOT Abortion
- EHV4: respiratory disease, rarely isolatied abortions
Is EAV notifiable?
Yes
Which EHV is most prevalent in the UK herd?
EHV 1 - 90% crriers
Clinical sings of EHV1?
- Abortion last 3rd of pregnancy
- lung oedema
- multifocal necrosis of the liver, lungs and spleen
- abortion accompanies/shortly after ofetal death (fresh foetus)
HOw may EHV1 be diagnosed?
- PM fetus and placenta
- PCR or virus isolation (rare nowadays)
- microscopy (look for necrosis and viral inclusion bodies etc.)
- EHV1 immunostaining
How may EHV1 be prevented?
Isolate mares in last trimester, ^ biosecuiryt
- Vaccinate all horses (combination vax EHV1 and EHV4)
HOw should EHV be controlled once diagnosed?
- abortion: isolate affected mare
- collect foetus and placenta for Ag testing
- paired serum samples from mare (test rising AB titre) interpretation difficult as could be recrudescence due to stress of abortion or cause of abortion
What causes EVA?
Equine arteritis virus, an arterivirus
What condidiont is EVA similar to in pigs?
PRRS
How does EVA infect the horse?
Respiratory tract or semen
Pathogenesis of EVA?
EAV infects macropphages and endothelia cells and casues arteritis
Clinical signs of EAV abortion?
- variable in mare
- fever
- depression
- conjunctivitis (piink eye)
- abortion
- oedema in legs
How may dx of EVA be determined?
- PM foetus and placenta to detect virus
- virus neutralising Ab levels in mare high at abortion or rising between paired post abortion tutires (seroconversion)
What state may stallions infected with EAV enter? How may this cause problems with diagnosis?
Carrrier state - persistnently infected -> shedding of virus in semen without clinical signs
- can shed intermittently
- persists in accessory glands
When should EAV be suspected ?
Travel history
Can EAV persist in the mare?
No, once infected = immunity for life and clean
WHen is EVA notifiable?
- clinical signs in a stallion
- evidence of EAV infection by semen or blood testing
- clinical signs/lab results indicate EVA in a mare mated/AI within 14d
> used to track down stallion
How is EAV diagnosed?
- aborted foetus or semen samples
- virus isoltion or PCR
Control of EVA?
- movement restrcition
- vaccinate stallions
- ensure antibody negative before vaccination *
WHat type of virus is BVDV?
- Pestivirus (flaviviridae family)
How is BVDV shed?
- respiratory secretions and feaces
- also via semen in AI
WHere does BVDV replicate? How does it affect the foetus?
Respiratory and enteric tract
- haemoatogenous spread to foetus via placenta
WHat is the equivalent of BVDV in sheep?
Border disease virus -> hairy shaker lambs (=PI claves)
WHen can BVDV infect the calf and how does this affect the outcome of disease?
> infection first trimester ( infection second trimester (111-190d)
- aboriton/mummification
- PI possilbe until d140
- congenital deformities esp d125-175 (neuro cerebellar hypoplasia)
infection third trimester >d191
- occasional abortions/stillbirths/weak calves
- predominantly normal calves
How can BVD abortion be dx?
- PM examination on aborted foetus iwth PCR of lymphoid tissue (thymus/spleen)
- Histopath with immunohistochemistry esp. brain tissue
- Foetal serology on free foetal fluids (indicate exposure)
- Maternal serology can be difficult to interpret
Is bluetongue notifiable?
Yes
Is BVDV notifiable?
No, endemic in the UK
How is BVDV prevented/controlled?
- vax dams before pregnancy
- ID and remove PI calved (ag test, followed by 2nd ag or ab test)
> poorly in UK compared to other european countries with eradication prgrammes!
WHat does BHV1 cause?
- IBR
- IPV (infectious pustular vulvovaginitis) and IBP (infectious balanoposthitis) = equivalent to EHV3 coital exanthema in horses
Which aniamls are commonly affected by IPV/IBP?
heifers / young animals
- self limiting disease
Clinical signs of BHV1 infection?
- painful gneital pustules
- swelling
- PU
- aboriton following respiratory infection
How may BHV1 be spread?
- venereal, contact, aerosol
When do BHV-1 abortions gneerally occour? FIndings at PM for dx?
- following respiratory infections
- may be weeeks after infection of dam
- usually 4-8months gestation
> PM - foetal liver and lungs necrosis
- extensive autolysis
Is abortion due to BHV1 common in UK?
NO but common in US and Australia
- different strains with v tropism for repro tract?
Prevention and control of BHV1?
- isolate and test new stock to prevent spread
- Dx: immunofluorescence/immuno-peroxidase on foetal tissues (eg. FAT liver tissue)
- serology diffficult to interpret (recrudescence=cuase/effect?)
- Control: vax v severity and duration clinical signs (DIVA vax best)
- eradication prorammes insome EU countries
What type of virus in SHmallenburg? how is it spread?
- orthobunyavirus (similar to Akabane virus)
- an arbovirus
- spread by midges
What type of disease is shmallenburg?
Neurological!!
- lack of mm innervation -> limb deformitiy
- viras has NEURO tropism
WHen are dams infected with shmallenburg?
early pregnancy
Common findings in shmallenburg foetuses/neonates?
- Arthrogryposis
- Hydrancephaly, cerebellar/cerebral hypoplasia
Dx of shmallenburg?
- PCR brain tissue
- histopath
- foetal serology
- maternal serology for indication
What type of virus is bluetongue?
- Orbivirus
- an arbovirus like shmallenburg (Spread by culicoides midges)
How does bluetongue cause abortion?
- pyrexia of dam
- congential defects due to teratogenic effect (hydrancephaly)
What family of viruses causes PRRS?
Arteriviridae
How is PRRS spread?
- resp tract via aerosol
- genital tract via infected semen
Clinical signs of PRRS?
- respiratory diseasse
- oedema
- subclinical (less virulent strains may be unnoticeable)
- “blue ear disease” due to congestion
- immunosuppression
- late abortions/mummification/premature piglets (arteritis of umbilical vessels and foetus)
How severe is PRRS disease generally in UK?
Mild as it is endemic
How is PRRS dx in abortions?
PCR Lymphoid tissue (thymus, spleen)
WHat is PC2 and what are its effects?
Porcine circovirus - no link with abortion in UK but predisposees other diseases
How may PRRS outbreaks be controlled?
All in all out policy
- quarantine new stock
- separate pregnant sows from rest of herd
- avoid trassnfer of fomites
- screening of semen for AI (PCR)
- vax reduces clinical signs with inactivated vax
-
Why is control of PRRS difficult?
Rapid mutation rate -> many genetic and antigenic variants
- diagnosis and control by vaccine difficult
Give 2 notifiable porcine diseases
- Suid herpesvirus (Aujeskys)
- swine fevers
What does porcine parvovirus cause?
- NOT abortion!!
- SMEDI
How is porcine parvovirus transmitted?
foecal oral
Where does porcine parvovirus replicate?
GIT with NO clinical signs in pigs
WHy is the foetus often affected by porcine parvovirus?
Rapidly dividing cellls
What does infection at different stages of pregnancy by porcine parvovirus cause?
- early embreyonic death ( resorption (infertility)
- infection at later stages -> mummification or stilbirth
- infection >70d foetal death less frequent due to immune response
Diagnosis of Parvovirus porcine?
- PCR liver or heart tissue if CRL (crown rump length) <70d (ie. not immunocompetent)
- foetal fluid serology in older foetuses
- immunofluorescence on frozen foetal livet (viral ag FAT)
- virus isolation (expensive, doesnt always work)
How may porcine parvovirus be prevented/controlled?
- vaccination
- keeping herd endemically infected (want to see some mummificationsso you know the herd is still immune)
What is the swine influenze pathogen?
Type A influenze virus (H1N1, H3N2)
What type of disease is swine influenza predominantly?
Respiratory, causes pyrexia->
How does swine influenza cause aboritons?
Pyrexia in sow
- transplacental infections rare
How may swine influenze be diagnosed?
- PCR (virus isolation) in acutely affected animals
- paired serology
What does PCV2 cause and is it common in the UK?
- abortions, mummification and stillbirthd, weak piglets and congenital tremor
- not ever confirmed in UK
- post-weaning multisystemic wasting syndrome (PMWS)
- porcine dermitis and nephropathy syndrome (PDNS)
Is theres PCV2 vax?
Yes
WHat is AUjesky’s disease also known as?
Pseudorabies
WHat virus causes Aujesky’s disease?
Herpesviridae
Is Aujesky’s disease common?
No notifiable disease
How does Aujesky’s disease enter the body?
Respiratory tract
CLinical signs of Aujesky’s disease?
CNS signs, high mortality in piglets
- pregnant sows: haematogneous spread to foets -> abortion.stillbirth
What type of pathogencauses classical swine fever?
- pestivirus (flaviviridae)
Is classical swine fever common?
No, notifiable
Clinical signs of classical swine fever
- high mortality
- D+
- ameorrrhages in skin and other orgnas esp kidneys
- abortion, mummification,stillbirthd, congenital tremors (~=hairy shakerr lamb)
Which species may AUjesky’s disease also affect? CLinical signs?
Dogs that eat the piglets -> lung oedem AND DEATH
Has African swine fever ever occourred in the UK?
- No
- notifiable
Clinical isgns of African swine fever?
- very similar to classical swine fever including repro failure
When does canine herpesvirus (CHV) infect dogs?
during birth via birth canal or shortly after birth (contact) -> systemic herpesvirus infection
What syndrome is canine herpes virus associated with? Why does it infect these dogs? Tx?
Fading puppy syndrome (puppies start screaming then die)
- due to immature immune system and poor regulation of body temperature
Increase body temperrature to Tx
What is the pathogenesis of canine herpesvirus?
- organ necrosis, death
- haemorrhages esp. kidneys
Dx of canine herpesvirus?
Gross and histpath findings (intranuclear inclusion bodies)
Prevention of canine herpesvirus?
- vax for pregnant bitches
Which 2 viruses cause reproductive fialure in the cat? dx? tx/prevention?
> feline leukaemia virus
- crosses placenta
- reproductive failure and resorption/abortion
-dx: ag test (queen) imunofluorescence/PCR on aborted foetuses
- prevention: vax
feline parvovirus (feline panleucopenia virus)
- repro failure (early)
- cerebellar hypoplasia (later)
- prevention: vax
What tropism does parvovirus show?
rapidly dividing cells
How is virus detected generally? When may problems with smaples arise?
- virus isolation, PCR or Ag detection
- problems isf samples not fresh (ciruses lose infectivity, nucleic acids and proteins degrade)
How may antibodies be used to detect infection? Problems?
- Ab detection in foetal fluids (only once foetus is immunocompetent)
- Serology of dam showing ^ Ab titre
> problems - possible delay between infection of dam and ifnection of foetus
- possible delay between infection of foetus and reproductive failure becoming apparent
-> seroconversion may thereofre have occoured earlier and will not be detected
