Treatment algorithm

Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups: see disclaimer

ACUTE

symptomatic patients

1st line – supportive care

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ACUTE
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symptomatic patients
1st line – 

supportive care

There is no specific antiviral treatment available, and management involves supportive care for symptomatic patients, as well as close monitoring for the development of complications.[41]​ Asymptomatic patients do not require treatment.

Patients with febrile illness require supportive care, which includes ample oral fluid intake (i.e., enough fluids to be passing clear urine) and use of analgesics and/or antipyretics (e.g., paracetamol).

In the absence of neuroinvasive symptoms, febrile illness usually resolves in 1 to 2 weeks.[4]

Primary options

paracetamol: children: consult product literature for guidance on dose; adults: 500-1000 mg orally every 4-6 hours when required, maximum 4000 mg/day

Plus – oral or intravenous fluids + anti-emetic

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ACUTE
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symptomatic patients
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with vomiting and diarrhoea
Plus – 

oral or intravenous fluids + anti-emetic

Treatment recommended for ALL patients in selected patient group

Nausea, vomiting, and diarrhoea may occur in symptomatic patients.

If there is severe dehydration due to vomiting and diarrhoea, admit the patient to hospital, if possible, and administer oral or intravenous fluids (crystalloids such as normal saline or Ringer's lactate solution) along with an anti-emetic (e.g., ondansetron).

Initial administration of a single oral dose of ondansetron may obviate the need for intravenous fluids or hospitalisation in children.[56]

Other anti-emetics are not recommended due to lack of benefit and risk of adverse effects.

Primary options

ondansetron: children ≥8 kg body weight (intravenous): 0.15 mg/kg intravenously as a single dose, maximum 4 mg/dose; children 8-15 kg body weight (oral): 2 mg orally as a single dose; children 16-30 kg body weight (oral): 4 mg orally as a single dose; children >30 kg body weight (oral): 8 mg orally as a single dose; adults: 8 mg intravenously/orally every 8 hours when required

Plus – hospitalisation + further supportive care

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ACUTE
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symptomatic patients
|
with neurological symptoms
Plus – 

hospitalisation + further supportive care

Treatment recommended for ALL patients in selected patient group

Admit the patient to hospital, if possible, if they are exhibiting neurological symptoms (e.g., irritability, drowsiness, altered mental status, disorientation, ataxia, seizures, paresis, cranial nerve palsies, focal weakness, meningismus).

Admission to the intensive care unit may be required.

Patients with severe meningeal symptoms may require analgesia for headaches, as well as an anti-emetic and rehydration for associated nausea and vomiting.[41]

Closely monitor patients for the development of seizures, cerebral oedema, and intracranial hypertension.[41]

Closely monitor the patient’s airway.[41]​ Secure the airway by intubation if the patient has altered mental status (e.g., obtundation), and initiate mechanical ventilation.

Perform a cranial nerve examination, fundoscopic examination, and head computed tomography (CT) or brain magnetic resonance imaging (MRI) scan to evaluate for cerebral oedema and elevated intracranial pressure. If intracranial pressure is elevated, consider head elevation, hyperventilation, and intravenous mannitol to reduce pressure.[57] In such instances, the placement of an external ventricular device is recommended. 

Primary options

mannitol: children and adults: 0.25 g/kg intravenously as a single dose, may repeat every 6-8 hours if necessary

Plus – anticonvulsant

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ACUTE
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symptomatic patients
|
with neurological symptoms
Plus – 

anticonvulsant

Treatment recommended for ALL patients in selected patient group

Evaluate patients with neurological involvement for seizures, and administer anticonvulsants if there is seizure activity or a history of seizures.

Benzodiazepines are preferred for the initial management of seizures, with lorazepam being most effective due to its long half-life.

Phenytoin is recommended if a second drug is needed to terminate seizures. In pregnant women, phenytoin is only used in life-threatening infection, because it is teratogenic.

Primary options

lorazepam: children: 0.05 to 0.1 mg/kg (maximum 4 mg/dose) intravenously as a single dose, may repeat dose once after 10-15 minutes if necessary; adults: 4 mg intravenously as a single dose, may repeat dose once after 10-15 minutes if necessary

Secondary options

phenytoin: children and adults: 15-20 mg/kg intravenously as a single dose, followed by 10 mg/kg as a single dose after 20 minutes if necessary

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Plus – empirical antiviral therapy

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ACUTE
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symptomatic patients
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with neurological symptoms
Plus – 

empirical antiviral therapy

Treatment recommended for ALL patients in selected patient group

Start treatment with empirical intravenous aciclovir, to cover for possible herpes simplex virus infection, in: patients with cerebrospinal fluid or imaging findings suggesting viral encephalitis; or if these results will not be available within 6 hours; or if the patient is deteriorating.[54]

Primary options

aciclovir: children: consult specialist for guidance on dose; adults: 10 mg/kg intravenously every 8 hours

Plus – empirical antibiotic therapy

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ACUTE
|
symptomatic patients
|
with neurological symptoms
Plus – 

empirical antibiotic therapy

Treatment recommended for ALL patients in selected patient group

If meningitis or meningoencephalitis is suspected, droplet precautions may be necessary in hospitalised patients until bacterial infections are excluded (follow your local protocols).

Start treatment with empirical antibiotic therapy and continue until bacterial encephalitis has been ruled out.[53]

Consult local protocols for choice of appropriate broad-spectrum antibiotics.

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Please note that formulations/routes and doses may differ between drug names and brands, drug formularies, or locations. Treatment recommendations are specific to patient groups. See disclaimer

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