Viral encephalitis 51..pptx japanese encephalitis

Viral encephalitis is a serious and potentially life-threatening inflammation of the brain caused by a viral infection. Here's an overview:

*Causes:*

1. Herpes simplex virus (HSV) - most common cause
2. Enteroviruses (e.g., poliovirus, coxsackievirus)
3. Arboviruses (e.g., West Nile virus, Japanese encephalitis

1. VIRAL ENCEPHALITIS Leena P S Roll No:51

2. OBJECTIVES Introduction Herpes Viruses Herpes simplex virus Arboviruses Japanese encephalitis virus West Nile virus

3. INTRODUCTION Encephalitis is acute inflammation of the brain parenchyma Caused by invasion of infectious agents –most often viruses ; rarely by parasites or non-infectious causes such as autoimmune encephalitis

4. CLINICAL MANIFESTATIONS Acute febrile illness Confusion Seizures: focal or generalized seizures Neuropsychiatric manifestations such as hallucinations, agitation, personality change, behavioural disorders Focal or diffuse neurological signs(tremor, ataxia, facial weakness) Involvement of hypothalamic-pituitary axis may result in temperature dysregulation, diabetes insipidus

5. LABORATORY DIAGNOSIS CSF analysis: consist of lymphocytic pleocytosis,a mildly elevated protein level, and a normal glucose level

6. HSV ENCEPHALITIS Most common cause of acute sporadic viral encephalitis Frequently involving temporal lobe HSV-1>HSV-2 Children generally get primary HSV infection, acquired exogenously and invades CNS via olfactory bulb Adults get recurrent infections due to reactivation of HSV in trigeminal nerve

7. LABORATORY DIAGNOSIS Polymerase chain reaction (PCR): A test that can detect the herpes simplex virus in CSF Enzyme-linked immunosorbent assay (ELISA) : A test that can detect HSV-1 and HSV-2 antibodies Multiplexed flow immunoassay (MFI) : An automated test that can detect and differentiate between HSV-1 and HSV-2 TREATMENT IV Acyclovir is given for 10 days or until HSV DNA is no longer detected in CSF

8. JAPANESE ENCEPHALITIS Leading cause of vaccine –preventable viral encephalitis in India Enveloped virus containing ssRNA Vector : Transmitted by bite of Culex mosquito
1) C.tritaeniorhynchus (major vector worldwide)
2) C.vishnui (next common vector)

9. Transmission Cycle: JE virus infects several non-human hosts Pigs  Culex Pigs Ardeid birds CulexArdeid birds

10. Animal Hosts: Pigs(amplifier host for JE) Cattles and buffaloes(mosquito attractants) Horses Humans(dead end) Bird Hosts : Ardeid birds(herons, cattle egrets, ducks) Age: Children below 15 years(85%) Elders (10%) Infection is common in rainy season which coincides with maximum mosquito activity

11. CLINICAL MANIFESTATIONS Incubation period: 5-15 days JE typically shows iceberg phenomenon Clinical course: divided into three stages 1) Prodromal stage is a febrile illness;the onset of which may either be abrupt (1-6hrs),acute(6-24hrs),more commonly subacute(2-5days) 2) Acute encephalitis stage: acute onset of fever,disorientation, delirium, seizures 3) Late stage: patient may be recovered fully or retain some neurological deficits permanently

12. LABORATORY DIAGNOSIS IgM antibody capture (MAC) ELISA supplied by NIV,Pune It is a two-step sandwich ELISA ,uses JERA (JE recombinant antigen) to detect JE-specific IgM antibody in serum Molecular methods: RT-PCR, realtime RT-PCR

13. TREATMENT Treatment only by supportive measures; no specific antiviral drugs are available Vaccine prophylaxis for Japanese Encephalitis Live attenuated SA 14-14-2 vaccine: Given in two doses(1 st at 9 completed months-12 months of age and 2 nd at 16-24 months) Inactivated JE vaccine: Two doses;4weeks interval ,for children >3 yrs and adults aged >18 yrs Catch up vaccination: administered to all susceptible children up to 15yrs during disease outbreak

14. WEST NILE ENCEPHALITIS Flavivirus Mainly transmitted by Culex mosquito Zoonotic, maintained in nature by transmission between birds and mosquitoes

15. CLINICAL FEATURES Incubation period: 3-14 days West Nile fever: Common symptoms include fever,headache,tiredness,body aches, nausea, vomiting, sometimes skin rash and swollen lymph glands West Nile encephalitis: may develop rarely

16. DIAGNOSIS IgM antibody capture ELISA detecting IgM antibodies in serum and CSF is available. Viral RNA detection by RT-PCR TREATMENT Only by supportive measures; no specific antiviral drugs are available

17. REFERENCE Essentials Of Medical Microbiology By Apurba S Sastry 4 th Edition