What are the signs of encephalitis in humans after a tick bite and when do the first symptoms appear? - briefly
Encephalitis following a tick bite commonly produces fever, intense headache, neck stiffness, confusion, seizures or reduced consciousness, frequently with nausea or vomiting. Symptoms usually emerge within one to three weeks after exposure, though early neurological signs may appear within a few days.
What are the signs of encephalitis in humans after a tick bite and when do the first symptoms appear? - in detail
Tick‑borne encephalitis (TBE) develops after a bite from an infected Ixodes tick. The incubation period typically ranges from 4 to 28 days, most cases presenting between 7 and 14 days post‑exposure. The disease progresses through a biphasic course in the majority of patients.
During the first, nonspecific phase, patients experience flu‑like manifestations. Common findings include:
- Sudden fever (often > 38.5 °C)
- Headache, usually frontal or occipital
- Generalized malaise and fatigue
- Myalgia and arthralgia
- Nausea, vomiting, or abdominal discomfort
These symptoms usually last 2 – 5 days and may resolve spontaneously before the second phase begins.
The second, neurological phase is characterized by meningo‑encephalitic signs. Typical presentations are:
- High‑grade fever persisting or recurring
- Severe headache with neck stiffness (meningeal irritation)
- Photophobia and phonophobia
- Altered mental status: confusion, disorientation, or somnolence
- Cognitive deficits: impaired concentration, memory loss
- Focal neurological deficits: paresis, ataxia, dysarthria, or cranial nerve palsies
- Seizures, which may be generalized or focal
- Tremor, involuntary movements, or extrapyramidal signs
In some patients, the disease advances to a paralytic form, marked by flaccid weakness of limbs, often resembling Guillain‑Barré syndrome, or to a chronic encephalitic state with persistent neurocognitive impairment.
Laboratory evaluation supports the clinical picture. Cerebrospinal fluid analysis reveals pleocytosis (predominantly lymphocytes), elevated protein, and normal or slightly reduced glucose. Serologic testing for TBE‑specific IgM and IgG antibodies confirms infection; polymerase chain reaction may detect viral RNA in early stages.
Early recognition of the prodromal flu‑like phase, followed by prompt identification of meningeal and encephalitic signs, is essential for timely supportive care and prevention of severe sequelae.