VIRAL ENCEPHALITIS

Batman 1 : Shazreen SaznyBatman 2 : Kamariah YusufKursk State Medical University.2nd year 2nd semester.Group 15

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Introduction

• Encephalitis is an acute inflammatory process affecting the brain parenchyma

– Meningoencephalitis

– Encephalomyelitis

– Encephalomyeloradiculitis• Viral infection is the most common and important cause, with

over 100 viruses implicated worldwide

• Incidence of 3.5-7.4 per 100,000 persons per year

• ~20,000 cases reported anually in USA

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Causes

• Viral

• Other microorganisms

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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

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What is 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

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Major Arboviruses that cause encephalitis.

• Flaviviridae– Japanese encephalitis

– St. Louis encephalitis

– West Nile

• Togaviridae– Eastern equine encephalitis

– Western equine encephalitis

• Bunyaviridae– La Crosse encephalitis

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•Flavivirus related to St. Louis encephalitis•Most important cause of arboviralencephalitis 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.

Japanese Encephalitis

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•Flavivirus•Primary host – wild birds•Principal arthropod vector –mosquitoes•Geographic distribution -Africa, Middle East, Western Asia, Europe, Australia, North America, Central America

West Nile Virus

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St. Louis Encephalitis

•Flavivirus•Most common mosquito-transmitted human pathogen in the US•Leading cause of epidemic flaviviral encephalitis

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Eastern Equine Encephalitis

• Togavirus• Caused by a virus

transmitted to humans and horses by the bite of an infected mosquito.

• 200 confirmed cases in the US 1964-present

• Human cases occur relatively infrequently, largely because the primary transmission cycle takes place in swamp areas where populations tend to be limited.

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Western Equine Encephalitis

• Togavirus• Mosquito-borne• 639 confirmed cases

in the US since 1964 • Important cause of

encephalitis in horses and humans in North America, mainly in the Western parts of the US and Canada

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La Crosse Encephalitis

• Bunyavirus• On average 75 cases per

year reported to the CDC• Most cases occur in

children under 16 years old• Zoonotic pathogen that

cycles between the daytime biting treeholemosquito, and vertebrate amplifier hosts (chipmunk, tree squirrel) in deciduous forest habitats

• 1963 – isolated in La Crosse, WI from the brain of a child who died from encephalitis

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Summary – Confirmed and Probable Human Cases in the US

Virus Years Total cases

Eastern Equine 1964-2000 182

Western Equine 1964-2000 649

La Crosse 1964-2000 2,776

St. Louis 1964-2000 4,482

West Nile 1999-present > 9,800

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Other viruses that commonly cause viral encephalitis

Herpes simplex virus type 1 (HSV-1), which is responsible for cold sores

HSV-2, which is responsible for genital herpes

Varicella zoster virus, which causes chicken pox and shingles

Epstein-Barr virus, which causes mononucleosis

Childhood viruses that can cause encephalitis include:

Measles (rubeola)

German measles (rubella)

Mumps

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But, not all cases of encephalitis is caused by virus.

Some others include

BACTERIA

NON INFECTIOUS CAUSES(ALLERGIC REACTIONS OR

TOXIN)FUNGUS

PARASITE

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Sign & symptoms

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90% of people with encephalitis have flu-

like symptoms, (fever, sore throat,

cough, and malaise.)

If the person has meningitis and encephalitis, he or she may have a

headache, stiff neck, vomiting, and be bothered by light

possible hallucinations, agitation, and personality

changes.

Infants may have bulging in the

fontanels or soft spots on the skull.

change in consciousness,

ranging from mild confusion to coma

Have trouble in understanding words.

Coordinating voluntary muscle movements

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Diagnosis

Encephalitis is a serious condition, so you should see a doctor if you or your child start having symptoms. You are usually diagnosed and treated in a hospital at first. After doing

a physical exam, a doctor may take the following steps to diagnose the condition

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• Brain imaging. Brain imaging is often the first test if symptoms and patient history suggest the possibility of encephalitis. The images may reveal swelling of the brain or another condition that may be causing the symptoms, such as a tumor. Technologies may include magnetic resonance imaging (MRI), which can produce detailed cross-sectional and 3-D images of the brain, or computerized tomography (CT), which produces cross-sectional images.

• Electroencephalogram (EEG). Doctor may order an EEG, a test in which a series of electrodes are affixed to the scalp. The EEG records the electrical activity of the brain. Certain abnormal patterns in this activity may be consistent with a diagnosis of encephalitis. EEG may show sharp waves in one or both of temporal lobes.

• Blood and other specimens culture: A minimum of 20 mL of blood in each

of two to three separate cultures per each 24- hour period is necessary for the detection of most bacteremias.

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A lumbar puncture

Or spinal tap, is a procedure to collect cerebrospinal fluid to check for the presence of disease or injury.

A spinal needle is inserted, usually between the 3rd and 4th lumbar vertebrae in the lower spine. Once the needle is properly positioned in the subarachnoid space (the space between the spinal cord and its covering, the meninges), pressures can be measured and fluid can be collected for testing.

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MRI brain (T2W image): right temporal lobe high signal in a patient with herpes encephalitis

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Treatment

Viral encephalitis is a serious medical condition. Although there are no specific medications to treat it, people with symptoms are often given the antiviral medication acyclovir (Zovirax). It works against herpes simplex and varicella-zoster viruses.

Acyclovir (Zovirax) -- treats encephalitis caused by HSV, VZV, and EBVGanciclovir (Cytovene) -- treats encephalitis caused by cytomegalovirus and HSV1Anticonvulsant medications -- prevent and treat seizures that may happen with encephalitis

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Nutrition and Dietary Supplements

• Eat antioxidant foods, including fruits (such as blueberries, cherries, and tomatoes), and vegetables (such as squash and bell peppers).

• Avoid refined foods, such as white breads, pastas, and especially sugar.

• Eat fewer red meats and more lean meats, cold-water fish, tofu (soy, if no allergy), or beans for protein.

• Use healthy oils in foods, such as olive oil or vegetable oil.

• Avoid caffeine, alcohol, and tobacco.

• Drink 6 - 8 glasses of filtered water daily.

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Supplements

• Omega-3 fatty acids, such as fish oil, one to three times daily, to help decrease inflammation and boost the immune system. Fish oil may increase the risk of bleeding, especially if you take blood-thinners such as warfarin (Coumadin), clopidogrel (Plavix), or aspirin.

• Vitamin C, 500 - 1,000 mg 1-3 daily, as an antioxidant and to boost the immune system.

• Probiotic supplement (containing Lactobacillus acidophilus), for digestive and immune system health. If you are taking antibiotics, taking probiotics as well may help you avoid some side effects such as diarrhea.

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Acupuncture

• A study of a small number of people with complications from encephalitis suggests that acupuncture on the scalp may reduce severe complications and symptoms. Some practitioners believe that scalp acupuncture works for people with encephalitis because all meridians converge at the head, and the method can stimulate and regulate qi (energy) throughout the entire body. More research is needed.

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THANK YOU FORTHE

ATTENTION

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