Tick-borne encephalitis (TBE)

Introduction

-Tick-borne encephalitis (TBE) is a flaviviral infection caused by TBE virus with three subtypes: European, Siberian, and Far Eastern. 

-Flaviviruses are positive-sense, single-stranded RNA, icosahedral capsid, enveloped viruses

-The principal reservoirs and vectors for TBE virus are ticks

-The virus is transmitted to humans by ticks.

-Outbreaks happened after ingestion of unpasteurized milk from infected sheep and goat  

Symptoms & Signs 

-The incubation period is 7–14 days for tick-borne exposures and only 3–4 days for milk ingestion.

-Most cases are subclinical

-The disease is characterized by a biphasic illness.

Fever-myalgia phase: Fever, arthralgia, headaches, nausea

CNS phase: headaches, meningitis, encephalitis, paralysis  

-Post-encephalitic syndrome: headaches, balance disorders, fatigue, hearing defects, attention deficits, depression, learning impairment 

Diagnosis 

Labs: leukocytosis, neutrophilia, hyponatremia 

CSF: pleocytosis 

PCR: Virus detection by RT-PCR in ticks from TBE patients 

ELISA: TBE virus IgM and IgG are detected by ELISA

Treatment 

Treatment is supportive.

Prognosis 

Complete recovery in most cases 

Prevention 

-There is no available TBE vaccine in the United States

-Effective vaccines are available in Europe, Canada and China 

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