Diagnosis of Encephalitis
The diagnosis of encephalitis can be challenging because the symptoms often resemble other conditions such as meningitis, stroke, or severe flu. However, accurate and early diagnosis is critical, as encephalitis can progress quickly and cause permanent brain damage or death if not treated promptly.
Doctors begin by reviewing the patient’s symptoms, medical history, and possible exposures. They will ask about recent infections, vaccination status, travel history, insect bites, and whether the person has a weakened immune system. In South Africa, TB, HIV, and vector-borne illnesses are also considered when diagnosing encephalitis.
Physical and Neurological Examination
A detailed examination checks for signs of brain inflammation. This may include:
Level of consciousness
Reflexes and coordination
Muscle strength and tone
Eye movements and speech
Any change in mental state, seizures, or confusion suggests possible brain involvement.
Tests to Confirm Diagnosis
Lumbar puncture (spinal tap) – This is one of the most important tests. A small sample of cerebrospinal fluid (CSF) is taken from the spine and analysed for:
White blood cell count (indicating infection or inflammation)
Glucose and protein levels
Presence of viruses or bacteria using PCR or cultures
Tuberculosis testing in TB-prone regions
Blood tests – Used to detect infections, autoimmune markers, or inflammation. In HIV-positive individuals, opportunistic infections like CMV or toxoplasmosis may be checked.
Brain imaging (CT or MRI) – These scans help identify inflammation, swelling, bleeding, or masses in the brain. MRI is especially helpful in viral encephalitis cases.
Electroencephalogram (EEG) – Records electrical activity in the brain. It may show patterns suggestive of encephalitis, particularly in those with seizures or altered consciousness.
Viral and bacterial PCR testing – Detects genetic material of pathogens such as herpes simplex virus (HSV), enteroviruses, or TB. This allows for targeted treatment.
HIV testing – In South Africa, many patients with encephalitis also undergo routine HIV screening to identify immunosuppression and guide care.
Diagnosis of Encephalitis
Diagnosis can take time, particularly when the cause is unknown or the patient is severely ill. However, treatment is often started before test results return if clinical suspicion is high.
The diagnosis of encephalitis relies on a combination of tests, imaging, and clinical judgement. Early recognition and hospital-based investigation are essential for protecting brain function and improving outcomes.
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