2. INTRODUCTION
Acute encephalitis is a group of similar neurologic manifestation caused by
several different viruses, bacteria, fungus, parasites, spirochetes ,
chemicals/toxins.
WHO introduced the term AES(Acute Encephalitis Syndrome) in order to
get more number of cases.
3. DEFINTION
ETIOLOGY
EPIDEMIOLOGY
CLINICAL FEATURES
DIAGNOSIS
MANAGEMENT
PREVENTION AND CONTROL
4. DEFINITION
Encephalitis : Acute, diffuse, inflammatory process affecting brain
parenchyma – Most commonly viral
Encephalopathy : Clinical syndrome of altered mental status, manifesting
as reduced consciousness or altered behaviour – Many causes, incl. viral
encephalitis
Acute Encephalitis Syndrome : Defined as a person of any age, at any
time of year with the acute onset of fever and a change in mental
status(confusion, disorientation, coma, or inability to talk) and/ or new
onset of seizures ( excluding simple febrile sz.)
5. AES is a spectrum of diseases with equal contribution of JE and non JE
etiology.
Till date, Japanese encephalitis is the leading cause of AES all over India,
both in pediatric and adult population.
6.
7. EPIDEMIOLOGY OF JE
Agent
Geographical Distribution
Hosts
Transmission
Morbidity and Mortality
8. Definition: JE is an inapparent to acute arboviral infection of horses, pigs
and humans. It’s a zoonotic disease i.e. infecting mainly animals and
incidentally man.
9. AGENT
Flavivirus related to St. Louis encephalitis
Most important cause of arboviral encephalitis worldwide, with over
45,000 cases reported annually
Transmitted by culex mosquito, which breeds in rice fields
Mosquitoes become infected by feeding on domestic pigs and wild birds
infected with Japanese encephalitis virus. Infected mosquitoes transmit
virus to humans and animals during the feeding process.
10. History of Japanese Encephalitis
1800s – recognized in Japan
1924 – Japan epidemic. 6125 cases, 3797 deaths
1935 – virus isolated in brain of Japanese patient who died of encephalitis
1938 – virus isolated from Culex mosquitoes in Japan
Today – extremely prevalent in South East Asia. 30,000-50,000 cases
reported each year.
11. FOUR GENOTYPES OF JE
Genotype 3 is mostly found in panindia
Genotype 1 is found in UP and west Bengal
Genotypes 2 and 4 rarely found in India
The JE virus is mainly isolated in ardied birds (cattle egrets and pond
herons) – natural reservoirs
The JE virus multiply in the body of some animals particularly pigs –
amplifying host
16. PATHOGENESIS
Virus enters the body through the bite of the insect vector – mosquito
After multiplication in local and regional lymph nodes,viremia of varying
duration ensues
Virus is transported to target organ (brain) via blood
Virus proliferate and damage the neuronal tissue, thereby elicits nervous
manifestations
17. CLINICAL FEATURES
Incubation Period - 5 to 15 days
Only 1 in 300 to 1 in 1000 infections develop into encephalitis, rest
asymptomatic
Course of disease- 3 stages
Prodromal stage
Acute encephalitic stage
Late stage and sequelae
21. LATE STAGE
Aphasis or Dysarthria
Ocular palsies
Pyrimidal and extra pyramidal signs in the form of hemiplegia,
quadriplegia, dystonia , choreoathetosis and coarse tremors.
24. Morbidity/Mortality
Swine
– High mortality in piglets – Death rare in adult pigs
Equine
– Morbidity: 2%, during an outbreak – Mortality: 5%
Humans
– Mortality: 5-35% – Serious neurologic sequelae: 33-50%
25. 30-50% of the people that survive the infection develop paralysis, brain
damage, or other serious permanent sequelae
Average period between the onset of illness & death is about 9 days
In utero infection possible: Abortion of fetus
26. DIFFERENTIATION OF JE AND NON JE,
AES
Acute fever with altered sensorium persisting for more than 2 hours with
focal seizures of any part of body, suggestive of encephalitis
Rash with fever excludes encephalitis
AES with symmetrical neurological signs likely to be cerebral malaria
32. EEG
EEG usually shows abnormal spikes in acute encephalitis.
Spikes in temporal lobe region suggestive of HSV Encephalitis
33. CSF STUDY
High CSF pressure
Increased WBC count ( usually < 250/cu mm ;predominantly lymphocytes)
Elevated protein concentration (usually < 150 mg/dl)
Normal glucose concentration
Specific diagnostic tests – PCR tests for viruses, culture for bacteria, fungi
and mycobacteria, serology for arboviruses.
34. SEROLOGY
Detection of virus specific IgM antibody – provide definitive diagnosis
IgM antibody is present only for 1 to 3 months and hence denote acute
encephalitis
35. TREATMENT OF AES
A broad spectrum antibiotic such as ceftriaxone – can be stopped when
investigations does not reveal bacterial meningitis
Acyclovir must be started in all cases of sporadic viral encephalitis – should
be stopped when an alternate diagnosis has been made or HSV PCR is
negative
36.
37. PREVENTION AND CONTROL OF AES
Surveillance for cases of AES
Vector control
Reduction in man vector contact
Vaccination
38. JE VACCINATION – TWO TYPES
Inacivated vaccine derived from vero cell prepared from an Indian strain of
JE virus (JENVAC)
Very safe and effective
2 doses given 1 month apart
39. The recently introduced Chinese live attenuated SA 14 14 2 JE vaccine
Now available in routine immunization in children under universal
immunization program in 181 endemic districts of India since 2011
NVBDCP has identified 20 hyperendemic districts in assam, UP and west
Bengal for introduction of adult JE vaccination (>15 to 65 yrs)
Till now, 8 districts have been covered by adult vaccination programme
In 3rd july 2014, the GOI had announced the introduction the single dose
of JE vaccine for adults in endemic districts
40. RECENT TRENDS OF AES IN INDIA
In recent years, investigations into large outbreaks of AES have been
negative for JEV
Instead outbreaks were found to be due to a rhabdovirus (Chandipura
virus) or water borne entero viruses
Factor might account for Entero viruses replacing JEV as the major cause of
AES is JE vaccination campaigns launched in endemic districts
41. A multisector approach involving health, water resources, sanitation and
rural development departments is needed for designing and implementing
novel preventive strategies that would focus on containment of water
borne entero viruses and vectors for chandipura virus
We also need to move from JE surveillance to surveillance for the entire
spectrum of AES