How does a bite from an encephalitis‑carrying tick manifest? - briefly
Initial signs are fever, headache, and fatigue. Within days, neurological manifestations such as neck stiffness, confusion, or seizures may appear.
How does a bite from an encephalitis‑carrying tick manifest? - in detail
A bite from a tick that harbors a virus capable of causing encephalitis initiates a sequence of clinical events that can be divided into three phases: early local reaction, systemic febrile illness, and neurological involvement.
The initial site often shows a painless erythematous macule or papule. In some cases, a small vesicle or ulcer may develop, but the lesion rarely produces significant itching or swelling. The tick’s saliva contains anticoagulants and immunomodulatory proteins, which can mask the severity of the local response.
Within 3‑7 days after exposure, a non‑specific febrile phase may appear. Typical features include:
- Fever ranging from 38 °C to 40 °C
- Headache, often described as dull or throbbing
- Malaise and fatigue
- Myalgia, especially in the limbs
- Nausea or loss of appetite
These symptoms are indistinguishable from many viral infections and may resolve spontaneously in a few days. Approximately 30 % of patients progress to the second, neurologic phase after a brief asymptomatic interval.
Neurological manifestations emerge 5‑14 days post‑bite and are characterized by:
- High‑grade fever persisting beyond 48 hours
- Neck stiffness and photophobia indicating meningeal irritation
- Altered mental status: confusion, disorientation, or agitation
- Focal deficits: tremor, ataxia, or weakness of one limb
- Cranial nerve palsies, most commonly facial nerve involvement
- Seizures in severe cases
- Paraparesis or quadriparesis if spinal cord inflammation occurs
Laboratory findings typically reveal pleocytosis in cerebrospinal fluid, elevated protein, and sometimes a mild lymphocytic predominance. Serologic testing for specific IgM antibodies confirms the viral etiology, while polymerase chain reaction may detect viral RNA in blood or CSF during the early neurologic stage.
Prompt recognition of these patterns is essential for initiating supportive care, monitoring respiratory function, and, where available, administering antiviral therapy or immunoglobulin preparations to reduce morbidity.