Equine Temperate Diseases Flashcards
is equine viral arteritis notifiable
yes
what is equine viral arteritis associated with
resp disease
abortion
perinatal mortality
what is equine viral arteritis characterized by
panvasculitits
what is the main source of equine viral arteritis
semen
resp secretions
fetus/placenta/amniotic fluid
what is the incubation period of equine viral arteritis
3-14d
what are the do the severity of clinical signs of EVA depend on
EVA isolate
Immune status
Age
what are the principle syndromes of EVA
Respiratory disease (‘mild influenza’)
Pyrexia and mild nasal discharge
Conjunctivitis (‘pink eye’), rhinitis
Limb/scrotal/mammary/ventral/peri-orbital edema
Abortion in up to 50% infected mares
Neonatal mortality (respiratory distress)
what are the reservoir for infections in EVA and how
carrier stallions
continuous viral replication in epithelium of accessory sex gland
how is EVA transmitted to mares via carrier stallions
Natural breeding
AI (virus survives freezing)
does EVA effect fertility of mares and stallions
no long term effects
how is EVA diagnosed
Clinical signs
History
Seroconversion
Virus isolation/detection
Detection of carrier stallions:
- Serology
- Virus detection/isolation
- Test breeding seronegative mares
Hard evaluation co-ordinated by APHA
how is EVA prevented and controlled
Establish disease status of breeding stock
- Serology of all horses prior to breeding use
- Virus detection/isolation
Breed to seronegative stallions
Vaccination
- Stallions and teasers
- Record in passport
Test prior to import/export
Isolate new arrivals (21 days)
Under EU law importation of shedder stallions or semen is NOT permitted
what is equine infectious anemia (EIA) also known as
swamp fever
what is the agent that causes equine infectious anemia
lentivirus (Retrovirus)
integrates genetic material into the host genome which allows viral replication and persistence for lfie
how do animals become asymptomatic carriers of EIAV
viral replication associated with viral mutations
heterogenous population and antigenic variation
aids immune avoidance and persistence
is EIAV notifiable
yes
how is EIAV transmitted
Biting flies (mechanical vector)
Iatrogenic
Transplacental
Colostral, venereal
Needles, stomach tubes, etc (veterinarians)
Frozen plasma
when is the highest risk for EIAV
when infected blood is from horse/donkey/mule with acute clinical disease
Greatest risk when vector density high
can subclinical EIAV carriers spread it
no unlikely
what are the acute clinical signs of EIAV
Pyrexia
Petechiation
Limb adema
Inappetance
Hemolysis and severe anemia
what is chronic presentation of EIAV
Cyclical lethargy
Weight loss
Anemia
Chronic debilitating disease
what is the incubation period of EIAV
1-3 weeks to months (14-42d)
are EIAV chronic carriers asymptomatic or symptomatic
relatively symptom free
how does EIAV cause hemolysis
Immune mediated and non-immune mediated
- Not always present, but seen in debilitated
what is the evidence of hemolysis in EIAV
icterus and high bilirubin
positive coombs results
what is the clinicopathology of EIAV
hemolysis
concurrent thrombocytopenia
lymphocytosis, monocytosis
how is EIAV diagnosed
Serological tests:
- Most horses seroconvert within 45 days
- Positive on Coggins test (AGID)
- Incubation of up to 157d reported in Ireland outbreak
EIA ELISA more sensitive and rapid to complete
what is the infectious agent of african horse sickness
orbivirus
9 serotypes
is african horse sickness notifiable
yes
OIE list A
where is african horse sickness endemic
sub-saharan africa
what is the vector of african horse sickness
culicoides
what is the pathogenesis of african horse sickness
infection –> regional lymph nodes –> primary viremia –> target organs –> secondary viremia
causes microvascular endothelial cell injury
infection and activation of monocyte – macrophages (pulmonary intravascular macrophages)
capillary leakage, edema, hemorrhage, inflammation, DIC
what are the clinical signs of african horse sickness in the incubation period
5-7d (2-10d)
fever
anorexia
edema
hemorrhage
sudden death
what is the mortality of acute ‘dunkop’ pulmonary form of african horse sickness
>95%
what is the mortality of the subacute ‘dikkop’ cardiac form
50%
what does the dunkop pulmonary form of african horse sickness cause
peracute respiratory distress and death
pulmonary edema
what does the cardiac form of african horse sickness (dikkop) cause
supraorbital edema and head swelling
how is african horse sickness diagnosed
clinical signs/PM
virus isolation
serology
real time reverse transcription quantitative PCR (RT-PCR) (whole blood or tissue sample)
what is the risk of AHSV to the UK
potential culicoides vector in UK and ROI
unlikely to become resident unless climate change
into through international horse movement or wind-borne spread of vector
what would be the likely sequelae of a AHSV outbreak in the UK
Interaction of AHVLA with local bodies
- EU notification with trade restrictions
Restricted to insect proof stabling at outbreak site
- Vector control
Immediate slaughter of infected cases
20km control zone around outbreak
Surrounded by 100km protection zone
Testing programme and vector surveillance
New vaccine development may promote ring vaccination if multiple cases
how is AHSV prevented
Prevent/minimize exposure to vector, using multiple techniques
Vaccination programme
Risk of reversion to wild type in use of attenuated vaccines, with infection of susceptible individuals; generic recombination
Recombinant modified Vaccinia Ankara virus expressing different viral proteins has been developed; may offer better prospect in non-endemic regions
how could AHSV exposure to the vector be prevented/minimized
Stabling at peak times of midge activity
Vector proof stabling and traps at entrance to stables
Repellents, midge proof sheets
what is the vaccination protocol of AHSV
Live attenuated polyvalent vaccine strains depends on multiple doses, such that animals may become immune to all strains only by age of 4 years
Monovalent vaccines used in disease outbreak situations when strain is isolated
what is the agent that causes dourine
trypanosoma brucei equiperdum
is dourine notifiable
yes
how is dourine transmitted
venereal tranissmion
possible biting fly spread
how is dourine diagnosed
complement fixation test (CFT) and immunofluorescence antibody test (IFAT)
what are the clinical signs of dourine
swelling of urogenital tract
abortion
infertility
wasting
ataxia
how is dourine treated and controlled
No effective treatment reported
Culling of infected animals in countries where this is notifiable
Infection makes breeding programmes very difficult in countries where there is no screening
No vaccine available
Cross-reaction of all lab rests between this trypanosome and those spread by tsetse fly and other biting flies
what are the clinical signs of equine trypanosomoniasis
Weight loss
Inappetence
Pyrexia
Progressive anemia
Variable edema
Metabolic acidosis
Collapse
Peripheral parasitemia
Hindlimb UMN signs first (8/8)
- Weakness, truncal sway
- Low head carriage
- Some with F/L proprioceptive lesions
- Occasional urogenital swelling
- Later stages changes in mentation
- Progressive weakness, collapse
- Inability to rise
what causes the chronic progression of multifocal neurological signs in equine trypanosomoniasis
infiltration of blood-brain barrier with all subspecies of T brucei
how is equine trypanosomoniasis treated
Isometamidium is treatment of choice
Low therapeutic index
Routine health screening for PCV/TSP and parasite burden required throughout the year
Prophylactic intervention
how is equine trypanosomosis controlled
Minimize exposure to biting flies, including tsetse flies
Local repellents
how is the UK equine industry protected from infectious diseases
Veterinary vigilance for unusual field clinical cases key
- Prompt reporting and isolation
- Dourine, EIA, EVA, WNV, AHSV
Particular care with imported horses, those travelling on 10day health certificate and those moving from within EU
Increased vigilance for incorrect/absent passports
Vaccination could be considered for WNV in at risk horses
Continuous updating and attention to disease outbreak status
Recognition that early detection and testing massively beneficial in reducing spread
Continued monitoring
- Sentinel birds (WNV)
- Resident Culicoides species (AHSV)
- Endemic tick population (Piroplasmosis)
