40 Questions
What is the primary mode of transmission of EHV-1?
Direct contact, nasal secretion, reproductive discharge, placenta or aborted fetus
What is the most common syndrome caused by EHV-1?
Abortion
What is the typical duration of viral incubation for EHV-1?
2-10 days
What is the primary diagnostic test for EHV-1?
Fluorescent antibody
What is the most common age group affected by EHV-1?
Mares 3-9 months pregnant
What is the primary treatment for EHV-1 infection?
Supportive nursing and NSAIDs to control malaise and fever
What is the characteristic of EHV-1 infection?
Sudden and deadly
Which of the following is NOT a clinical sign of EHV-1 infection?
Diarrhea
What is the significance of EHV-1 subtype 1?
Causes abortion
What is the primary vector for the bird/rodent-mosquito life cycle of Venezuelan Equine Encephalitis?
Cedecci
What is the characteristic of the epizootic form of Venezuelan Equine Encephalitis?
Mutation to subtype I with a change in mammalian pathogenesis
What is the common name for EHV-1?
Abortion storm virus
Which of the following is NOT a common clinical sign of Equine Encephalomyelitis?
Diarrhea
What is the most efficient vector for the transmission of flaviviruses?
Culex spp.
What is the typical duration between infection and the onset of neurologic signs in Equine Encephalomyelitis?
9-11 days
What is the primary diagnostic test for Equine Encephalomyelitis?
Clinical assessment
What is the characteristic of the CSF examination in Eastern Equine Encephalitis?
Neutrophilic pleocytosis
What is the treatment for muscle tremors and fasciculations in West Nile Virus?
Flunixin meglumine 1.1mg/kg, IV, bid
Which of the following is NOT a flavivirus?
Rabies Virus
What is the geographic distribution of West Nile Virus?
Wide geographic distribution
What is the recommended dose of valacyclovir for treating EHV?
30 mg/kg, PO, tid
What is the primary purpose of doxycycline in EHV treatment?
Anti-inflammatory properties
What is the effect of corticosteroids on the immune system in EHV treatment?
Immune system suppression
What is the primary method of diagnosis for EHV?
PCR and isolation of virus from nasopharyngeal swabs and blood samples
Which of the following is NOT a type of Equine Arboviral Encephalomyelitis?
Rabies
What is the mortality rate of Eastern Equine Encephalomyelitis (EEE)?
50-90%
What is the primary purpose of administering antibiotics to horses with EHV infections?
To prevent secondary bacterial infection
Which virus is primarily transmitted by mosquitoes of the Culex (Melanoconion) spp?
MADV
What is the life cycle of alphaviruses between?
Birds and rodents
What is the prognosis for horses that remain standing after EHV infection?
Good
Which of the following is NOT a transmission method of Equine Arboviral Encephalomyelitis?
Direct horse-to-horse
What is the primary difference between EHV-1 and EHV-4?
EHV-1 causes abortion, while EHV-4 causes respiratory disease
What is the purpose of vaccination in Equine Arboviral Encephalomyelitis prevention?
Prevention of viral infection
Which of the following is a characteristic of EHV-3?
It is a venereal disease
What is the purpose of vaccinating horses at 5, 7, and 9 months of gestation?
To prevent EHV-1 infection
What is the typical age range of horses affected by EHV-4?
Foals to 3 years old
What is the common finding in the complete blood count (CBC) of horses infected with EHV-5?
Neutrophilic leukocytosis
What is the purpose of the virus-specific PCR test in the diagnosis of EHV-5?
To detect the presence of EHV-5
What is the prognosis for survival in horses infected with EHV-5?
Approximately 50%
What is the role of EHV-2 in the development of Rhodococcal infection?
It acts as a forerunner that leads to Rhodococcal infection
Study Notes
Equine Encephalomyelitis
- Equine Encephalomyelitis is a group of diseases caused by viruses transmitted by mosquitoes, including Eastern Equine Encephalitis (EEE), Western Equine Encephalitis (WEE), Venezuelan Equine Encephalitis (VEE), and West Nile Virus (WNV).
Eastern Equine Encephalitis (EEE)
- Mosquito-borne disease with a mortality rate of 50-90%
- Caused by an alphavirus
- Transmitted by mosquitoes, not horse-horse or horse-human
- Sylvatic cycle between passerine birds and Culiseta melanura
Venezuelan Equine Encephalitis (VEE)
- Mosquito-borne disease with a mortality rate of 50-75%
- Caused by an alphavirus
- Has two life cycles: enzootic and epizootic
- Enzootic cycle involves mosquitoes (subgenus Melanoconion/C. spp)
- Epizootic cycle involves several bridge vectors, with horse infection becoming a predominant feature
West Nile Virus (WNV)
- Mosquito-borne disease with a wide geographic distribution
- Caused by a flavivirus
- Has a mortality rate of 35-45%
- Transmitted by mosquitoes, not horse-horse or horse-human
Clinical Signs
- Neurologic signs occur 9-11 days after infection
- Quiet and depressed
- Ataxia, wandering, impaired vision, reduced reflexes, circling, inability to swallow, drooling, fever
- Paralysis usually followed by death 2-3 days after onset of signs
Diagnosis
- Clinical assessment
- CSF examination with neutrophilic pleocytosis (count > 50%)
- IgM capture ELISA (85-90%); neutralizing antibodies (IgG) are the gold standard
- PCR - midbrain and brain stem
Treatment
- Supportive nursing care
- Management of pain and inflammation
- For WNV, flunixin meglumine 1.1mg/kg, IV, bid to prevent muscle tremors and fasciculations
Prevention
- Equine viral diseases vaccination
- Prevent exposure to other horses attending shows or other equine events
Equine Herpes Virus (EHV)
- Species-specific virus with three subfamilies: alpha, beta, and gamma
- 9 documented strains, but only 5 affect domestic horses
- Only EHV1, EHV3, and EHV4 commonly cause diseases in horses
EHV-1 (α)
- Subtype 1 of EHV1
- Causes rhinopneumonitis (respiratory form), abortion, birth of weak foals, peracute vasculitis, and neurological disorders
- Most important viral cause of abortion in horses
- Can be sudden and deadly
- High temperature, "fulminating" respiratory disease
EHV-3 (γ)
- Venereal disease
- Equine Coital Exanthema
- Rare but important
- Self-limiting
- Characteristic lesions on genitalia of stallions and mares
EHV-4 (α)
- Subtype 2 of EHV1
- Respiratory infection only ("Rhino"); rhinopharyngitis and rhinotracheitis
- Non-fatal, rarely results in abortion
- Severe, widespread outbreaks in young horses; foals → 3 years old in training
EHV-2 and EHV-5 (γ)
- "Ubiquitous" but rarely causes disease
- Found in nearly 100% of healthy foals
- Can cause problems in the following diseases:
- EHV2 - Herpetic keratoconjunctivitis in young foals; may act as a forerunner that leads to Rhodococcal infection (through immune suppression)
- EHV5 – equine multinodular pulmonary fibrosis (EMPF); in middle-aged horses
This quiz covers the transmission and life cycle of flaviviruses, including VEE and WNV, and their role in causing encephalitides. It also explores the role of vectors and hosts in the spread of these diseases.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
