Lecture 10 - Aujeszky's disease, Japanese encephalitis Flashcards
ADV stands for?
and give two alternative names
Aujeszky disease virus
Pseudorabies
Mad itch
AUJESZKY’S DISEASE is a contagious disease of
pigs,
caused by herpesvirus, characterized by CNS signs and high mortality in young animals, and respiratory illness in older pigs.
AUJESZKY’S DISEASE is a contagious disease of pigs, caused by herpesvirus, characterized by
CNS signs and high mortality in young animals,
and respiratory illness in older pigs.
Causative agent of Aujeszky’s disease (ADV).
Aujeszly’s disease virus which belongs to:
Genus Varicellovirus,
family Herpesviridae
ADV type of virus?
DNA virus
only 1 serotype
Host range of ADV.
mammals but clinical cases affect pigs.
Pigs are Natural hosts and the only animals to become latent carriers.
Distribution of ADV.
Europe, Southeast Asia,
Central and South America-
Eradicated in some countries (e.g. New Zealand).
Morbidity of ADV.
Morbidity <100%
Mortality of ADV.
Mortality: increases the younger the piglet.
1-2% grower and finisher pigs
5-10% weaner pigs
50% in nursery pigs
<100% piglets less than one week old
Excretion of ADV.
tonsillar epithelium,
milk, urine and vaginal and preputial secretions
Transmission of ADV.
Direct transmission
Aerosols
Fomites
In utero
Route: respiratory and oral
IP of ADV.
suckling pigs 2-4 days,
weaned and adults 3-6 days
Clinical signs of ADV in piglets less than 1 week old.
Fever, listlessness and anorexia then tremors, paddling, seizures or other symptoms of CNS involvement.
“Dog-like” sitting position (due to hindleg paralysis).
May die within hours,
usually in 24-46 hours – high mortality in newborn piglets.
Clinical signs of ADV in weaners.
Mainly respiratory illness: fever, anorexia, weight loss, coughing, sneezing, conjunctivitis and dyspnea.
May be complicated by secondary bacterial infections.
Recovery 5-10 days.
Clinical signs of ADV in adult pigs.
Infection usually mild or inapparent with respiratory symptoms.
Clinical signs of ADV in cattle & sheep.
Almost always fatal within few days
Intense pruritis, CNS signs
Post mortem lesions of ADV.
Lesions often subtle or absent.
Serous or fibroneurotic rhinitis.
Pulmonary edema, congestion, consolidation.
LNs – congested and hemorrhagic
Necrotic foci in other organs
Suspect ADV when…?
high mortality and CNS signs in young piglets,
and lower mortality and respiratory signs in older animals.
Material for diagnosis of ADV. (3)
Nasal swabs
Oropharyngeal fluid, biopsies of the tonsils
Brain and tonsils
Lab analyses for diagnosis of ADV. (3)
Virus isolation
Detection of viral DNA or antigens by immunofluorescence, immunoperoxidase, virus neutralization assays or PCR.
Serology – virus neutralization, latex agglutination, ELISA.
Treatment of ADV.
no treatment, viral
Prevention & control of ADV.
Quarantine & disinfection
Vaccination protects pigs from clinical signs and decrease viral shedding, but does not provide sterile immunity or prevent latent infections.
Eradication strategies for ADV. (3)
Test and remove
Offspring segregation
Depopulation
JEV stands for?
Japanese encephalitis virus
Give 4 alt. names for JEV.
Japanese encephalitis virus alt. names:
Japanese B Encephalitis
Mosquito-born Encephalitis
Brain Fever
Summer Encephalitis
JAPANESE ENCEPHALITIS is a disease caused by
a mosquito-borne flavivirus associated with reproductive losses in pigs and encephalitis in horses and people.
despite being vector-borne is still contagious!!
JAPANESE ENCEPHALITIS is a disease caused by a mosquito-borne flavivirus associated with (2)
reproductive losses in pigs and
encephalitis in horses and people.
Causative agent of JEV.
And which family/genus?
Japanese encephalitis virus belonging to
Genus Flavivirus,
family Flaviviridae
JEV viral type?
serotypes?
RNA virus
One serotype
Stability of JEV. (3)
Virus very labile and does not survive well in the environment.
Sensitive to UV
Inactivated in pH 1-3
Main host range of JEV. (4)
horses (primary affected domestic animals but a dead-end host), donkeys
pigs (amplifiers)
humans (dead-end host)
birds: herons and egrets (reservoirs)
Can also infect: cattle, sheep, goats, dogs, cats, chicken, ducks, wild mammals, reptiles and amphibians but is SUBclinical in these.
Distribution of JEV
endemic in Asia: Japan, India
has jumped to Australia too
Morbidity of JEV in
horses
swine
humans
horses < 2%
swine < 100%
humans 5-35%
Mortality of JEV in
horses
swine
humans
horses 5-40%
swine death is rare
humans 5-35%
Excretion of JEV.
swine: oronasal secretions (between 2 and 8 days post infection), urine, sperm
dead-end hosts do not transmit of course.
Transmission of JEV.
By mosquito vectors via bite
But also,
Direct contact – droplets
Indirect contact via insects moving it.
Iatrogenic
Routes:
respiratory (inhalation)
in utero (not common)
cutaneous
JEV: Natural infection contributes to long lasting immunity in
adult pigs and surviving piglets
IP of JEV
In horses: 4-14 days, mostly subclinical though.
In pigs: 3-4 days
In humans: 5-15 days
3 forms of JEV
transitory form
lethargic form
hyperrexcitable form
Describe the Transitory form of JEV in horses.
Fever (2-4 days), anorexia
Impaired locomotion, congested or jaundiced mucosa
Recovery 2–3 days
Describe the lethargic form of JEV in horses.
Febrile periods, stupor, bruxism and chewing motions, difficulty in swallowing, incoordination, evidence of neck rigidity, impaired vision, paresis and paralysis.
Petecchiation of mucosa
Recovery within a week
Describe the hyperexcitable form of JEV in horses.
Pyrexia, profuse sweating and muscle tremors,
aimless wandering, aggression, loss of vision, collapse, coma and death.
Clinical signs of JEV in Swine.
Mild febrile disease or subclinical disease in non-pregnant females.
Reproductive disease ((50-70%) abortion, stillbirths etc.)
Congenital: tremors, convulsions, death soon after birth.
Suckling piglets and weaners: wasting, depression or hindlimb paralysis may be seen in suckling piglets and weaner pigs.
Boars: infertility and edematous, congested testicles.
Clinical signs of JEV in humans.
Less than 1% of people develop neurologic illness.
Fever, headache, vomiting.
Mental status changes, neurologic symptoms, weakness, movement disorders, sensitivity to light, neck stiffness.
Seizures are common, especially among children
20% – 30% among patients with encephalitis die
30%-50% of survivors continue to have neurologic, cognitive, or psychiatric symptoms
Abortions
Post mortem lesions of JEV in pigs.
Subcutaneous edema, and hemorrhages, hydrocephalus, encephalitis, cerebellar hypoplasia
Congestion in the lung, liver, heart, spleen and lymph nodes
Multifocal hepatic and splenic necrosis
Post mortem lesions of JEV in horses.
Nonspecific lesions of CNS that are usually only microscopic NOT macro:
diffuse non-suppurative encephalomyelitis with apparent perivascular cuffing
phagocytic destruction of nerve cells, perivascular cuffing
focal gliosis
blood vessels appear dilated with numerous mononuclear cells
Material for diagnosis of JEV. (4)
Brain, spinal cord, tonsils, oral fluid
CSF, Blood
Aborted fetuses, placenta
Thoracic fluid from aborted fetuses up to 70 days of age.
Lab analyses for diagnosis of JEV. (3)
Virus isolation
Detection of viral DNA or antigens by RT-PCR, virus neutralization assays, Ag-ELISA.
Serology: hemagglutination inhibition, ELISA.
Tx for JEV.
none, viral
Prevention & control of JEV. (5)
Housing animals in-doors
Vector control: removal of stagnant water.
Separate raising of swine near horses.
Quarantine.
Vaccination.
Vaccination against JEV.
Immunization of swine because they are JE virus amplifiers to reduce amplification, ensure healthy litters and decrease likelihood of aspermia.
Horses, humans:
- Live modified
- Inactivated
- genotype mutation renders some vax nonefficacious
