JEby NTC

Japanese Encephalitis : 

Japanese Encephalitis Dr Naresh T Chauhan Asst Prof Govt Medical College, Bhavnagar.

Introduction : 

Introduction Encephalitis is an acute inflammatory process affecting the brain Viral infection is the most common and important cause, with over 100 viruses implicated worldwide Symptoms Fever Headache Behavioral changes Altered level of consciousness Focal neurologic deficits Seizures Incidence of 3.5-7.4 per 100,000 persons per year

Causes of Viral Encephalitis : 

Causes of Viral Encephalitis Herpes viruses – HSV-1, HSV-2, varicella zoster virus, cytomegalovirus, Epstein-Barr virus, human herpes virus 6 Adenoviruses Influenza A Enteroviruses, poliovirus Measles, mumps, and rubella viruses Rabies Arboviruses – examples: Japanese encephalitis; St. Louis encephalitis virus; West Nile encephalitis virus; Eastern, Western and Venzuelan equine encephalitis virus; tick borne encephalitis virus Bunyaviruses – examples: La Crosse strain of California virus Reoviruses – example: Colorado tick fever virus Arenaviruses – example: lymphocytic choriomeningitis virus

Japanese Encephalitis : 

Japanese Encephalitis Most important cause of arboviral encephalitis worldwide, with over 50,000 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.

What Is An Arbovirus? : 

What Is An Arbovirus? Arboviruses = arthropod-borne viruses Arboviruses are maintained in nature through biological transmission between susceptible vertebrate hosts by blood-feeding arthropods Vertebrate infection occurs when the infected arthropod takes a blood meal

Slide 6: 

http://www.cdc.gov/ncidod/dvbid/arbor/schemat.pdf

Major Arboviruses That Cause Encephalitis : 

Major Arboviruses That Cause Encephalitis Flaviviridae Japanese encephalitis St. Louis encephalitis West Nile Togaviridae Eastern equine encephalitis Western equine encephalitis Bunyaviridae La Crosse encephalitis

Epidemiology : 

Epidemiology Primarily a disease of rural Asia Vector mosquitoes proliferate in close association with birds and pigs Birds and pigs are the major amplifying hosts Culex tritaeniorhynchus the principal vector but many other mosquitoes are competent and can transmit C. pipiens C. quinquefasciatus Species of Aedes, Anopheles

Slide 9: 

http://www.cdc.gov/ncidod/dvbid/arbor/worldist.pdf

Epidemiology : 

Epidemiology July 2005 an outbreak began in northern India and Nepal; by November 10, 2005 Uttar Pradesh and Bihar had 6097 cases, 1400 deaths (23% mortality) Uttar Pradesh Bihar

Incidence and Prevalence : 

Incidence and Prevalence Commonest cause of encephalitis in Asia In hyperendemic areas half of all cases occur in children under 4 years of age, nearly all before age 10 Epidemic and endemic forms

Incidence and Prevalence : 

Incidence and Prevalence Ratio of apparent to inapparent infection ranges from 1:300 to 1:1000 Ratio affected by age, virulence of the strain of virus, cross protective immunity from other Flaviviruses (dengue) Risk to travelers 1 case per 50,000 months of exposure

History of Japanese Encephalitis : 

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 1948 – Japan outbreak 1949 – Korea outbreak 1966 – China outbreak Today – extremely prevalent in South East Asia. 30,000-50,000 cases reported each year.

Flaviviruses : 

Flaviviruses Japanese Encephalitis Virus St. Louis encephalitis virus West Nile Virus

Overview of Flaviviruses : 

Overview of Flaviviruses RNA viruses related to Yellow Fever virus At least 80 different ones, over 40 can infect humans Most are arthropod borne, Ones with the greatest impact on human health Yellow fever virus Dengue fever virus Japanese encephalitis virus West Nile virus St Louis encephalitis virus

Clinical Manifestations : 

Clinical Manifestations Incubation 6-16 days. Spectrum from mild febrile headache to severe encephalitis Headache, fever, nausea, vomiting, drowsiness. Abdominal pain and diarrhea common in children

Initial Signs : 

Initial Signs Headache Malaise Anorexia Nausea and Vomiting Abdominal pain

Developing Signs : 

Developing Signs Altered LOC – mild lethargy to deep coma. AMS – confused, delirious, disoriented. Mental aberrations: hallucinations agitation personality change behavioral disorders occasionally frank psychosis Focal or general seizures in >50% severe cases. Severe focused neurologic deficits.

Clinical Manifestations : 

Clinical Manifestations Death in 5-40% Children under 10 more likely to die or have residual neurological defects Poor prognosis associated with Respiratory dysfunction Babinsky’s sign Frequent or prolonged seizures Prolonged fever Albuminuria High viral replication in the brain

Neurologic Signs : 

Neurologic Signs Most Common Aphasia Ataxia Hemiparesis with hyperactive tendon reflexes Involuntary movements Cranial nerve deficits (ocular palsies, facial weakness)

Neuropsychiatric Sequelae : 

Neuropsychiatric Sequelae Occur in 45-70% of survivors, particularly severe in children Parkinsonism Seizures Paralysis Mental retardation Psychiatric disorders

Other Causes of Encephalopathy : 

Other Causes of Encephalopathy Anoxic/Ischemic conditions Metabolic disorders Nutritional deficiency Toxic (Accidental & Intentional) Systemic infections Critical illness Malignant hypertension Mitochondrial cytopathy (Reye’s and MELAS syndromes) Hashimoto’s encephalopathy Traumatic brain injury Epileptic (non-convulsive status) CJD (Mad Cow)

Differential Diagnosis : 

Differential Diagnosis Distinguish Etiology Bacterial infection and other infectious conditions Parameningeal infections or partially treated bacterial meningitis Nonviral infectious meningitides where cultures may be negative (e.g., fungal, tuberculous, parasitic, or syphilitic disease) Meningitis secondary to noninfectious inflammatory diseases MRI Can exclude subdural bleeds, tumor, and sinus thrombosis Biopsy

Standard Case definition : 

Standard Case definition Suspect (History) A person of any age at any time of year with acute onset of fever and change in mental status AND/OR new onset of seizures (Exclude SFS) Probable (History and clinical Exa) A suspect case that occurs in close geographical and temporal relationship to a laboratory confirmed case of JE, in the context of an outbreak Confirmed (laboratory Test) Presence of JE virus specific Ig-M antibodies

Laboratory Diagnosis : 

Laboratory Diagnosis Diagnosis is usually based on CSF Normal glucose Absence of bacteria on culture. Viruses occasionally isolated directly from CSF IgM-capture ELISA Polymerase Chain Reaction techniques Detect specific viral DNA in CSF

Treatment : 

Treatment When HSE cannot be ruled out, Acyclovir must be started promptly (before the patient lapses into coma) and continued at least 10 days for maximal therapeutic benefit. Rocky Mountain spotted fever should also be considered, and empiric treatment with Doxycycline is indicated.

Dexamethasone : 

Dexamethasone Synthetic adrenocortical steroid Potent anti-inflammatory effects Dexamethasone injection is generally administered initially via IV then IM Side effects: convulsions; increased ICP after treatment; vertigo; headache; psychic disturbances

Prevention : 

Prevention Personal protective measures and mosquito elimination are the most important travellers going to endemic areas may consider vaccination

Prevent mosquito breeding : 

Keep all drains free from blockage Cover tightly all water containers, wells and water storage tanks Top up all defective ground surfaces to prevent the accumulation of stagnant water Prevent mosquito breeding

Prevent mosquito breeding : 

Put all used cans and bottles into covered dustbins Change water for plants at least once a week, leaving no water in the saucers underneath flower pots Prevent mosquito breeding

Prevention of Mosquito Bites : 

Prevention of Mosquito Bites Avoid going to rural area during dusk and dawn when the mosquitoes are most active Wear light-colored, long-sleeved clothing and trousers Apply DEET-containing mosquito-repellents over exposed parts of the body and clothes every 4 to 6 hours For DEET products used by children, its concentration should be less than 10%

Prevention of Mosquito Bites : 

Prevention of Mosquito Bites hang mosquito screens around your bed, use insecticides or coil incenses to repel mosquitoes Place of accommodation should have air-conditioners or mosquito nets; or Install mosquito nets to doors and windows so that mosquitoes can’t get in

Vaccination : 

Vaccination Appears to be 91% effective There is no JE-specific therapy other than supportive care Live-attenuated vaccine developed and tested in China Appears to be safe and effective Vero cell-derived inactivated vaccines have been developed in China

Vaccines for JE virus : 

Vaccines for JE virus Inactivated vaccine grown in primary hamster kidney cells Live attenuated vaccine (SA14-14-2) grown in hamster kidney cells Licensed as JE-VAXR Three subcutaneous injections over a month with a booster at 3 years 91% efficacy in a large field trial in Thailand

Community-Wide Efforts : 

Community-Wide Efforts Clean Up Breeding Grounds Ensure Safe Blood Supply Mosquito Control Programs Controversial Surveillance

See Doctor Immediately : 

See Doctor Immediately Having been bitten by a mosquito and displaying symptoms of JE afterwards Falling ill, especially having a fever within one month after you have returned from abroad Tell your doctor where you have been

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THANKS