Viral infections of the genital tract Flashcards
Where do viruses often spread to the genital tract haematogenously or ascendingly from?
upper respiratory tract
Broadly, how may viruses cause reproductive failure? 4
Viral replication in foetal tissues leading to malformation or death.
Damage to placental BVs —> interrupted blood supply to foetus
Stress and pyrexia due to viral infection
Combination of above
What does EHV-1 cause? 4
Abortions (last 3rd pregnancy), accompanies or shortly follows foetal death
respiratory disease - lung oedema
paralysis
Multifocal necrosis - liver, lungs, spleen
What does EHV-3 cause? 2
genital pustules (exanthema, more externally visible) but not abortion, hyperplastic lymphoid nodules, usually a transient virus
What does EHV-4 cause?
respiratory disease, very rarely isolated abortions
What are the 2 main viruses affecting horse genital tracts?
EHV
EAV = Equine Arteritis Virus - NOTIFIABLE - last case 2012
How to diagnose EHV-1 abortion.
PME - foetus and placenta
PCR or virus isolation
Microscopic examination of tissue sections - EHV-1 immunostaining
What is a sign of interpartum death?
meconium around the anus
How can EHV be prevented?
Isolate pregnant mares in last trimester
Vaccinate all horses on premises - combination vaccines (EHV-1 and 4)
How can EHV be controlled?
Isolate mare in case of abortion
Collect foetus and placenta - Ag test
Paired serum samples (mare) - test for rising Ab titre but difficult in cases of vaccination and/or recrudescence due to stress of abortion)
How does EAV enter the horse? 2
respiratory tract or semen
What does EAV infect? 2
macrophages and endothelial cells and causes arteritis
How do you diagnose EAV? 4
CLINICAL SIGNS - variable, fever, depression, conjunctivitis/pink eye, abortion, BUT may be subclinical
PME - foetus and placenta for PCR
PAIRED SERUM - mare, virus neutralising Ab titres
TRAVEL HISTORY?
How are stallions affected by EAV?
persistently infected, shed virus in semen without clinical signs.
The virus persists in the accessory glands. Does not persisit in the mare.
When is EAV notifiable?
If clinical signs are observed in a stallion or evidence for EAV infection is present by semen or blood testing.
Clinical signs or laboratory results indicate EVA in a mare mated or AI’d within past 14 days.
How can EAV be controlled? 3
PME - foetus or semen - virus isolation or PCR
Movement restrictions
Stallion vaccination (confirm Ab negative prior to doing this)
What is the equivalent of BVDV in sheep?
Border disease virus/ Hairy shaker lambs
How is BVDV shed? 3
respiratory secretions, (faeces, semen)
Where does BVDV replicate?
respiratory and enteric tract
haematogenous spread to foeuts via placenta
Outline the different phases of BVDV infection
FIRST TRIMESTER (0-110): no foetal immunocompetenece, embryonic/foetal death –> resportion, abortion, mummification, PI calf/Hairy shaker lamb
SECOND TRIMESTER (111-190): abortions mummification, PIs usually only until day 140, congenital deformities (especially days 125-175) - e.g. cerebellar hypoplasia
THIRD TRIMESTER (after day 191): occsasional abortions/stillbirths/ weak calves, predominantly ‘normal’ calves
How can BVD be diagnosed? 4
PME - foetus, PCR of lymphoid tissue
Histopathology + immunohistochemistry (esp brain tissue)
Foetal serology - free foetal fluids, indicates exposure
Maternal serology - difficult to interpret sometimes.
How can BVDV be prevented/controlled?
Vaccinate dams before pregnancy
Identify and removed PI animals (Ag test + second Ag test or Ab test)
Various EU coutries have eradication programs
What can BHV-1 cause? 2
IBR
IPV or IBP
How can BHV be spread? 3
venereal, contact or aerosol