3. Japanese Encephalitis Flashcards
Enveloped
single-stranded RNA
with a cubic nucleocapsid
flavivirus
(3) structural proteins of Flavivirus
[ CME ]
C - capsid protein
M - matrix protein
E - envelope protein
the receptor binding protein
envelope protein (E)
Zoonotic mosquito
borne flavivirus (family Flaviviridae)
The first case documented in 1871 in Japan.
Japanese Encephalitis
JE is closely related with what disease?
West Nile virus
JE (epidemiology)
Clinical case (each year):
Deaths (each year):
# Countries:
Clinical case (each year): 68,000
Deaths (each year): 13,600 - 20,400
# Countries: 25
Is JE identified in the Philippines?
Yes
What region is JE predominant in the Philippines?
Northern Region (I, II, etc)
JE has been part of the list of notifiable diseases under the Philippine Integrated Disease Surveillance and Response (PIDSR) surveillance since _______
2009
Peak of JE cases
a. months
b. season
a. July - October
b. wet season
Vector of JE
Culex gelid
Culex tritaeniorhynchus
Where is JE predominant? Give the type of place
agricultural areas
- rice paddies
- farms
urban areas (sometimes)
The natural maintenance
reservoir for JE virus
birds of family Ardeidae
Has high viral load of JE but no clinical signs
Ardeidae birds
Act as important amplifiers of the virus producing high viraemia that infect mosquito vectors
Pigs
Pigs has high viremia that lasts for __-__ days.
2-4 days
____________ are the primary affected domestic animals of JE
although other equids (donkeys) are also susceptible
Horses
Other “subclinically infected” animals which likely do not contribute to spread include: (10)
cattle
sheep
goats
dogs
cats
chickens
ducks
wild mammals
reptiles
amphibians
Season when JE is predominant in Northern temperate areas
Late summer / Early autumn
In SPRING season, Ardeid birds migrate between ____ & ___, introducing JE virus
rural & urban
Season when JE is predominant in Southern tropical areas
Year-round
In southern tropical areas, JE is a continual cycle between (3)
- birds
- swine
- mosquitoes
Incubation period of JE
4-15 days
(ave: 6-8 days)
Severe disease of JE (signs)
rapid onset of high fever,
headache,
neck stiffness,
disorientation,
coma,
seizures,
spastic paralysis,
ultimately death
(2) Dominant initial symptoms in children (JE)
- gastrointestinal pain
- vomiting
Of those who survive, 20% - 30% suffer (3)
- permanent intellectual
- behavioral or neurological sequelae
( e.g. paralysis,
recurrent seizures or
the inability to speak)
Defined as a person of any age, at any time of year with the acute onset of fever and at least one of
- change in mental status
- new onset of seizures
Acute Encephalitis Syndrome (AES)
defined as case that meets the clinical case definition for AES
AES (suspected JE) case
an AES case with JEV-specific IgM antibody in a sample of CSF or serum detected by IgM-capture ELISA
Laboratory-confirmed JE
seizure that occurs in a child aged 6 months to less than 6 years old, whose only finding is fever and a single generalized convulsion lasting less than 15 mins, and who recovers consciousness within 60 min of seizure
simple febrile seizure
The JE virus was found to be the causative agent in 7 - 18% of ___ & encephalitis cases in PH
clinical meningitis
JE virus was found to be the causative agent in 16-40% of ____ ____
clinical encephalitis
Majority of JE cases occurred in children ____ age.
below 15 years of age
Individuals ____ comprised 15% of cases
older than 18 years
Infection with JEV before _____ days of gestation can cause:
abortion,
fetal mummification or
stillbirth,
or the birth of weak piglets
60-70 days
___ ___ ___ most often demonstrate neurologic signs of “tremors” and “convulsions” and may die soon after birth
live born piglets
Mortality in non
immune, infected piglets can approach
100%
Natural infection of JE results in ______
long lasting immunity
mortality rate in adult swine
near ZERO
Three (3) syndromic manifestations of JE
[ TLH ]
- Transitory type syndrome
- Lethargic type syndrome
- Hyperexcitable type syndrome
Syndromic manifestation:
moderate fever
lasting 2-4 days accompanied by:
- inappetence,
- impaired locomotion,
- congested
- jaundiced mucosa
most commonly with swift recovery of 2-3 days
Transitory type syndrome
Syndromic manifestation:
variable febrile periods (as high as 41 C), with a
- pronounced stupor,
- bruxism
- chewing motions,
- difficulty in swallowing,
- petechiation of mucosa,
- advanced incoordination,
- evidence of neck rigidity,
- impaired vision,
- paresis andralysis
recovery usually occurs within about a week
Lethargic type syndrome
high fevers (41 C or higher) accompanied by:
- profuse sweating
- muscle tremors
- aimless wandering
- behavioral changes
manifested by:
- aggression
- loss of vision
- collapse
- coma
- death
neurologic sequelae may result
Hyperexcitable type syndrome
What type of clinico-pathological feature is most common in JE
Subclinical disease
mortality rate of JE in horses
5-15% (up to 30%)
Morbidity rates reported from field cases vary from
less than 1% to 1.4 %
Identification of JE agents (4)
[ BSCB ]
- Brain
- Spinal cord
- Cerebrospinal fluid (CSF)
- Blood**
this is obtained from
aborted fetuses up to 70 days of age
thoracic fluid
where to store JE tissue from recently dead animals
10% formalin
Diagnosis of JE
- Virus isolation in laboratory animals
- Virus isolation in cell culture
- Real time RT-PCR***
- Antigen detection
- Serology
Recommended diagnosis of JE in humans
JE virus-specific IgM capture ELISA on CSF/serum
JE virus specific IgM can be measured (after onset of symptoms) in the:
CSF: ___ days
serum: ___ days
CSF: 4 days
serum: 7 days
Test that can be performed to confirm the presence of JE virus specific neutralizing antibodies and discriminate between cross-reacting antibodies from closely related flaviviruses (such as dengue and West Nile viruses).
Plaque reduction neutralization tests
Prevention and control of JE (4)
- PPE against mosquito bites
- Vaccine
- Mosquito vector control
- Surveillance
Types of vaccine for JE (4)
- modified live
- inactivated
- live attenuated
- live recombinant (chimeric)
vaccine produced in hamster or swine kidney tissue culture or hamster lung (HmLu) cell line
modified live vaccine
vaccine prepared in mouse brain, chick embryo or cell lines,
(e.g. Vero cells)
inactivated vaccine
