Independently learned diseases Flashcards
Equine encephalomyelitis is
a zoonotic viral disease affecting Equidae, caused by an Alphavirus, characterized by characterized by fever, anorexia, and severe depression.
Equine encephalomyelitis agent
Eastern, Western and Venezuelan equine encephalomyelitis viruses.
(EEE, WEE and VEE)
Genus Alphavirus, Family Togaviridae.
RNA virus
Host range of Equine Encephalomyelitis
Affects primarily horses.
Principal reservoir hosts are birds.
NB zoonosis! Humans are dead-end host.
Equine Encephalomyelitis Distribution:
present in the Americas
Equine Encephalomyelitis Morbidity:
EEE: high morbidity, 90-95%
WEE: low morbidity
VEE: variable
Equine Encephalomyelitis Mortality:
EEE: often fatal
WEE: approx. 30% mortality
VEE: mortality 20-80%
Which Equine Encephalomyelitis variant is the “worst”?
EEE: high morbidity, 90-95% and
often fatal
Equine Encephalomyelitis Transmission
vector-borne (mosquitos)
IP of Equine Encephalomyelitis
EEE, 4-14 days;
WEE, 1-5 days;
VEE: 2-5 days.
Equine Encephalomyelitis forms of disease
asymptomatic or subclinical, mild, acute, severe
Clinical signs of Equine Encephalomyelitis
fever, anorexia, and severe depression.
In severe cases, it can progress to hyperexcitability, blindness, ataxia, severe mental depression, recumbency, convulsions, and death.
Most infections in birds are nonclinical.
Human symptoms: febrile illness and, in some cases, more severe neurological symptoms.
Post-mortem lesions of equine Encephalomyelitis
Brain congestion, edema and/or hemorrhages
Meningeal inflammation
Neuronal damage
Perivascular cuffing around brain blood vessels
Material for diagnosis of
equine Encephalomyelitis
blood, brain tissue, CSF
Lab analyses for diagnosis of equine Encephalomyelitis
viral identification
serology
Epizootic Hemorrhagic Disease is
an acute, infectious viral disease of wild ruminants, caused by Epizootic hemorrhagic disease virus (EHDV), characterized by widespread hemorrhage and oral ulceration.
Agent for Epizootic hemorrhagic disease virus (EHDV)
Family & genus
Epizootic hemorrhagic disease virus
Family Reoviridae, Genus Orbivirus
RNA virus
serovars of EHDV
Epizootic hemorrhagic disease virus (EHDV)
8+ serotypes plus Ibaraki virus
EHDV demonstrates immunological cross reactivity with the Bluetongue virus group.
EHDV stability
inactivated by high temperatures, acidic and alkaline pH, and common disinfectants.
Resistant to UV light.
Host range of Epizootic Hemorrhagic Disease
can infect most wild and domestic ruminants.
Particularly white-tailed deer in North America.
Can cause clinical disease in cattle (Ibaraki virus form).
Distribution of EHD
most prominent in North America, Mediterranean countries.
Morbidity of EHD
Morbidity and mortality may be as high as 90% in white tailed deer; however, severity varies depending on the year and geographical location.
Mortality of EHD
Morbidity and mortality may be as high as 90% in white tailed deer; however, severity varies depending on the year and geographical location.
Transmission of EHDV
vector-borne, Culicoides spp.
In temperate regions infection is most common in the late summer and autumn during peak vector population, while infection occurs throughout the year in tropical regions.
IP of EHDV
estimated at 2–10 days.
Forms of dz in EHD
Forms of disease: peracute, acute, chronic & Ibaraki disease in cattle.
Clinical signs of EHD
Peracute – severe edema of head, neck, lungs
Acute – widespread hemorrhages and edema
Chronic – sloughing of hoof walls; rumen erosions, ulcers
Ibaraki – muscle degeneration, emaciation, erosions/ulceration
Post mortem lesions of EHD
Widespread hemorrhages
Edema particularly evident in the lungs and the serous membranes lining the body cavities.
Ulcerations and erosions may be present in the oral mucosa, including the tongue, gums, and palate.
Swollen, congested LNs.
The spleen may be enlarged, congested, and show hemorrhagic areas.
The heart may show lesions, including congestion and hemorrhages.
