3. Japanese Encephalitis Flashcards by isay mango

Enveloped
single-stranded RNA
with a cubic nucleocapsid

flavivirus

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(3) structural proteins of Flavivirus

[ CME ]

C - capsid protein
M - matrix protein
E - envelope protein

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the receptor binding protein

envelope protein (E)

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Zoonotic mosquito
borne flavivirus (family Flaviviridae)

The first case documented in 1871 in Japan.

Japanese Encephalitis

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JE is closely related with what disease?

West Nile virus

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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

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Is JE identified in the Philippines?

Yes

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What region is JE predominant in the Philippines?

Northern Region (I, II, etc)

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JE has been part of the list of notifiable diseases under the Philippine Integrated Disease Surveillance and Response (PIDSR) surveillance since _______

2009

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Peak of JE cases
a. months
b. season

a. July - October
b. wet season

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Vector of JE

Culex gelid
Culex tritaeniorhynchus

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Where is JE predominant? Give the type of place

agricultural areas
- rice paddies
- farms

urban areas (sometimes)

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The natural maintenance
reservoir for JE virus

birds of family Ardeidae

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Has high viral load of JE but no clinical signs

Ardeidae birds

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Act as important amplifiers of the virus producing high viraemia that infect mosquito vectors

Pigs

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Pigs has high viremia that lasts for __-__ days.

2-4 days

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____________ are the primary affected domestic animals of JE

although other equids (donkeys) are also susceptible

Horses

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Other “subclinically infected” animals which likely do not contribute to spread include: (10)

cattle
sheep
goats
dogs
cats
chickens
ducks
wild mammals
reptiles
amphibians

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Season when JE is predominant in Northern temperate areas

Late summer / Early autumn

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In SPRING season, Ardeid birds migrate between ____ & ___, introducing JE virus

rural & urban

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Season when JE is predominant in Southern tropical areas

Year-round

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In southern tropical areas, JE is a continual cycle between (3)

birds
swine
mosquitoes

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Incubation period of JE

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4-15 days
(ave: 6-8 days)

Severe disease of JE (signs)

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rapid onset of high fever,
headache,
neck stiffness,
disorientation,
coma,
seizures,
spastic paralysis,
ultimately death

(2) Dominant initial symptoms in children (JE)

1. gastrointestinal pain 2. vomiting

Of those who survive, 20% - 30% suffer (3)

1. permanent intellectual 2. 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 ]

1. Transitory type syndrome 2. Lethargic type syndrome 3. 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 ]

1. Brain 2. Spinal cord 3. Cerebrospinal fluid (CSF) 4. 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

1. Virus isolation in laboratory animals 2. Virus isolation in cell culture 3. Real time RT-PCR*** 4. Antigen detection 5. 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)

1. PPE against mosquito bites 2. Vaccine 3. Mosquito vector control 4. Surveillance

Types of vaccine for JE (4)

1. modified live 2. inactivated 3. live attenuated 4. 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

3. Japanese Encephalitis Flashcards

(57 cards)