Viruses of the genital tract + pregnant uterus Flashcards
Tranmission
horizontal + vertical
reproductive failure - causes
Viral replication in foetal tissues leading to
malformation or death
Damage to placental blood vessels leading to
interrupted blood supply to the foetus
Stress and pyrexia due to viral infection
combination of the above
equine herpes virus
EHV-1: abortions, respiratory disease, paralysis
EHV-3: causes genital pustules but not abortion
EHV-4: respiratory disease, very rarely isolated abortions
EHV-1
Abortion typically in last third of pregnancy
Lung oedema
Multifocal necrosis in liver, lungs and spleen
Abortion accompanies or occurs shortly after foetal
death
EHV-1 - diagnosis
Post mortem examination of fetus + placenta
Polymerase chain reaction (PCR) or virus isolation
Microscopic examination of tissue sections
EHV-1 immunostaining
EHV - prevention
Isolation of pregnant mares during last trimester
(disinfection of boots etc.)
Vaccination of all horses on the premises
Combination vaccines EHV-1 and EHV-4
EHV - control
In case of abortion isolate affected mare
Collect foetus and placenta for testing (antigen test) Paired serum samples from mare to test for rising
antibody titre (but interpretation difficult if mare
vaccinated against infection and also recrudescence due to stress of abortion can occur)
equine arteritis virus (EAV)
Arterivirus (Family Arteriviridae) Causes equine viral arteritis (EVA) Notifiable disease Last case in UK in 2012 Entry via respiratory tract or semen Infects macrophages and endothelial cells and causes arteritis
EAV abortion diagnosis
Clinical signs in mare: variable - fever, depression, conjunctivitis (‘pink eye’), abortion
Post mortem exam of aborted foetus and placenta – may detect virus
Virus-neutralising antibody levels in mare high at abortion or rising between paired post abortion titres
stallions persistently infected + shed in semen without clinical signs
investigate in travel Hx
EAV - problems in diagnosis
May be subclinical
Stallions can shed virus in semen intermittently or
persistently without showing clinical signs
Virus persists in accessory glands
Is not considered to persist in the mare
EAV - diagnosis + control
Diagnosis on aborted foetus or on semen samples
using virus isolation or PCR
Movement restrictions
Vaccination of stallions (confirm that he is antibody
negative before vaccination)
bovine viral diarrhoea (BVDV)
Pestivirus (Family Flaviviridae)
Shed in respiratory secretions and faeces
Transmission also via semen during AI
Virus replication in respiratory and enteric tract
Haematogenous spread to foetus via placenta
(equivalent in sheep is Border disease virus – hairy
shaker lambs)
BVDV - timing of infection
First trimester of pregnancy (0-110 days) prior to
immunocompetence - Embryonic/ foetal death – resorption/ abortion/mummification, Persistent infection (PI calf)
Second trimester (111-190 days) - Abortions/mummification, PIs usually only until ~ day 140, Congenital deformities (esp day 125-175)
Third trimester after day 191 - occasional abortions/ stillbirths/ weak calves, Predominately “normal” calf
BVDV - abortion diagnosis
Post mortem examination on aborted foetus with
PCR of lymphoid tissue (thymus/ spleen)
Histopathology with immunohistochemistry (esp.
brain tissue)
Foetal serology on free foetal fluids for indication of
exposure
Maternal serology (but can be difficult to interpret)
BVDV - prevention + control
BVDV is endemic in the UK
Vaccination of dams before pregnancy
Identify and remove persistently infected animals
(antigen test followed by second antigen test or antibody test)
Various European countries have eradication programs
bovine herpesvirus 1 (BHV-1)
causes - IBR (infectious bovine rhinotracheitis) and
IPV (infectious pustular vulvovaginitis) or IBP
(infectious balanoposthitis)
Transfer venereal, contact or via aerosol
IPV/IBP
Painful genital lesions (pustules/ulcers)
Swelling
Frequent urination
Tend to be self-limiting
BHV-1 - abortions
Following respiratory infections (mostly)
Abortion may occur weeks after infection of dam
Usually 4-8 months of gestation
Necrosis in foetal liver and lung
Frequently extensive autolysis
uncommon in the UK but more common in the US
BHV-1 - diagnosis, prevention + control
Latent herpesvirus can become reactivated due to stress
Isolate + test new stock to prevent spread to herd
Diagnosis: immunofluorescence/ immuno-peroxidase on foetal tissues
Serological testing difficult to interpret
Vaccination reduces severity and duration of clinical disease (DIVA vaccines)
Eradication programs in various European countries
schmallenberg virus
Orthobunyavirus (similar to Akabane virus) + Arbovirus
Infection of dam during early pregnancy
Virus has neurotropism
affected foetuses/ neonates - Arthrogryposis, Hydranencephaly; cerebellar/ cerebral hypoplasia
schamallenberg - diagnosis
PCR (brain tissue)
Histopatholgy
Foetal serology
Maternal serology for indication
bluetongue
Orbivirus Arbovirus (midges- culicoides) Abortions (also due to pyrexia in dam) Congenital defects due to teratogenic effect: hydranencephaly Notifiable
porcine reproductive + respiratory syndrome (PRRS)
Family Arteriviridae
Infection of respiratory tract via aerosol or genital tract via virus infected semen
Respiratory disease + oedema or subclinical
Less virulent strains may not cause obvious clinical signs
immunosuppression
Abortions/ mummification/ premature piglets
PRRS diagnosis in abortions
PCR of lymphoid tissue (e.g. spleen)
PRRS - prevention + control
PRRS is endemic in UK
SPF, all in – all out or quarantine of new stock
Separate pregnant sows from rest of herd and avoid
transfer of fomites
Screening of semen for AI by PCR
Vaccination (reduces clinical signs) with inactivated
vaccine
rapidly mutates - circulation of many genetic + antigenic variants
diagnosis and control by vaccination difficult
porcine parvovirus
Stillbirths, mummification,embryonic death + infertility (SMEDI)
Abortion uncommon
Transmission: faecal oral
Replicates in GIT without clinical signs
transplacental infection of foetus (rapidly dividing cells)
Early embryonic death (< 30 days) leads to resorption (infertility)
Infection at later stages causes death of foetus with
mummification
Death at late stages leads to stillbirths
If infected >70 days, foetal death less frequent due to immune response
porcine parvovirus - diagnosis, prevention + control
PCR on liver (or heart) tissue if CRL is < 70 days (not immunocompetent) or foetal fluid serology in older foetuses.
Diagnosis by immunofluorescence on frozen foetal liver (viral antigen FAT)
Virus isolation (expensive and doesn’t always work – viable virus and fresh tissue)
Vaccination
swine influenza
Type A Influenza virus (H1N1, H3N2)
Predominately respiratory signs
Pyrexia >41°C
Abortions predominately due to disease in sows
Transplacental infections considered rare
Diagnosis - PCR/ (virus isolation) in acutely infected animals
Paired serology
porcine circovirus-2
Abortions, mummification, stillbirths – not confirmed
in UK
birth of weak piglets, congenital tremor – not confirmed in UK
Post-weaning multisystemic wasting syndrome (PMWS)
Porcine dermatitis and nephropathy syndrome (PDNS)
PCV-2 associated disease
Probably multifactorial aetiology (other viruses and bacteria) and/ or predisposes to other diseases e.g. PRRS but also able to cause disease by itself
porcine circovirus-2 - diagnosis, prevention + control
Histopathology (heart), IHC – not PCR!
SPF, all in- all out
Optimised management conditions
Vaccination
aujeszky’s disease (pseudorabies)
Family Herpesviridae Notifiable Entry via respiratory tract CNS signs and high mortality in piglets In pregnant sows: haematogenous spread to foetus Abortions/stillbirths Eradicated from UK infectious to cats + dogs - fatal
classical swine fever
Pestivirus in family Flaviviridae Notifiable: Last outbreak in UK in 2000 High mortality Diarrhoea Haemorrhages in skin and other organs such as kidneys Abortion, mummification, stillbirths
African swine fever
Family Asfaviridae Notifiable So far never occurred in the UK Clinical signs very similar to classical swine fever including reproductive failure
viruses of the reproductive tract of the dog
Canine herpesvirus (CHV)
Infection of pups during birth (via birth canal) or shortly after birth (contact) can lead to systemic
herpesvirus infection
immature immune system + poor regulation of body temperature allows infection to establish
Organ necrosis and death
Diagnosis by gross + histopathological findings
Vaccine now available for pregnant bitches
viruses causing reproductive failure in cats
Feline Leukaemia virus - Can cross placenta and lead to reproductive failure (resorption of foetuses or abortion)
• Diagnosis: antigen test (queen) or
immunofluorescence/ PCR on aborted foetuses
• Prevention: vaccination
Feline parvovirus (feline panleucopenia virus) - Can lead to reproductive failure or cerebellar hypoplasia
• Prevention: vaccination
detection of virus
Samples from foetal organs or whole foetus as well as placenta
Virus isolation, PCR or antigen detection
Problems: if samples are not fresh - viruses lose infectivity, nucleic acids and proteins degrade
detection of antibodies
Antibody detection in foetal fluids: indicates infection of foetus
only useful once foetus is immunocompetent
Serology of the dam showing rising antibody titres
Problems: Possible delay between - infection of dam and infection of foetus + Infection of foetus and reproductive failure becoming apparent
Seroconversion may therefore have occurred earlier and will not be detected
