How does encephalitic tick affect a human? - briefly
An infected tick can introduce encephalitic viruses that provoke brain inflammation, producing fever, headache, neurological deficits, and, in severe cases, life‑threatening encephalitis.
How does encephalitic tick affect a human? - in detail
Encephalitic ticks transmit viruses that invade the central nervous system after a bite. The pathogen, most commonly a Tick‑borne Encephalitis (TBE) virus or Powassan virus, enters the bloodstream during feeding and reaches the brain within days to weeks, depending on the viral strain and host immunity.
Transmission and incubation
- Tick attaches for several hours, secreting saliva that suppresses local immune response.
- Virus particles are released into the host’s dermal capillaries.
- Incubation period ranges from 5 days to 4 weeks; shorter intervals often correlate with higher viral loads.
Early systemic phase
- Fever, malaise, headache, and myalgia appear.
- Laboratory findings may show mild leukocytosis and elevated C‑reactive protein.
- Symptoms usually resolve spontaneously, but a proportion of patients progress to neuroinvasion.
Neurological phase
- Acute encephalitis manifests as high fever, altered mental status, seizures, and focal neurological deficits.
- Meningitis signs include neck stiffness and photophobia.
- Cerebellar involvement leads to ataxia and dysarthria.
- In severe cases, acute flaccid paralysis or coma develops.
Diagnostic approach
- Serological testing for virus‑specific IgM and IgG in serum and cerebrospinal fluid.
- Polymerase chain reaction (PCR) detects viral RNA in blood or CSF during early infection.
- Magnetic resonance imaging often reveals hyperintense lesions in basal ganglia, thalamus, or brainstem.
Therapeutic management
- No specific antiviral approved; treatment is supportive.
- Antipyretics control fever; intravenous fluids maintain hydration.
- Anticonvulsants manage seizures; corticosteroids may reduce cerebral edema in selected cases.
- Intensive care provides airway protection and monitoring of intracranial pressure when necessary.
Prognosis
- Mortality rates vary: 1–2 % for TBE, up to 10 % for Powassan virus.
- Long‑term sequelae include persistent cognitive deficits, gait disturbances, and chronic fatigue in 30–50 % of survivors.
- Early recognition and prompt supportive care improve outcomes.
Prevention
- Personal protection: long clothing, tick‑repellent (DEET or permethrin), daily body checks after outdoor activity.
- Landscape management reduces tick habitat.
- Vaccination against TBE virus is available in endemic regions and provides high efficacy when administered in a three‑dose schedule.
Understanding the pathogen’s life cycle, the timing of clinical phases, and evidence‑based supportive measures is essential for reducing morbidity and mortality associated with tick‑borne encephalitic infections.