Dengue Literature Review

Dengue Neurological Complications

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Dengue Neurological Complications

Overview

Dengue virus can cause a range of neurological complications through three distinct pathways: (1) systemic or metabolic disturbances causing encephalopathy; (2) direct CNS invasion causing encephalitis, particularly by DENV-2 and DENV-3; and (3) autoimmunity-mediated complications, including Guillain–Barré syndrome (GBS) and acute disseminated encephalomyelitis (ADEM/autoimmune encephalomyelitis). Of these, ADEM is the most robustly documented at the population level, occurring within the first month of dengue illness.

Key Points from Literature

Neuropathogenesis: Three Pathways

From Guzman2016 - Dengue Infection and Shih2023 - Autoimmune Disease Risk After Dengue:

  1. Encephalopathy — altered consciousness from cerebral oedema (systemic vascular leakage), hepatic encephalopathy from dengue hepatitis, or metabolic disturbance; does not require direct CNS viral invasion.
  2. Encephalitis — direct DENV CNS invasion with viral detection in CSF; especially associated with DENV-2 and DENV-3; rarer than encephalopathy; can present as dengue encephalitis with fever, seizures, and CSF pleocytosis.
  3. Autoimmune-mediated — post-infectious syndromes in which molecular mimicry or non-specific activation of autoreactive T-cell clones against myelin or other self-antigens drives CNS or peripheral nervous system pathology; includes ADEM and GBS.

Autoimmune Encephalomyelitis (ADEM)

The most epidemiologically confirmed neurological complication of dengue. From Shih2023 - Autoimmune Disease Risk After Dengue:

  • In a population-based cohort of 63,814 lab-confirmed dengue patients, ADEM incidence was 1.53 per 10,000 person-years (dengue) vs. 0.54 (controls); aHR 2.72 (95% CI 1.84–4.02), P < 0.0001.
  • 16 dengue patients (0.025%) vs. 0 controls developed ADEM in the first month after symptom onset (HR >9999); risk was not significantly elevated thereafter.
  • Risk elevated in both sexes: males aHR 32 (P = 0.0010), females aHR 3.44 (P = 0.0001).
  • Reported onset of neurological symptoms in dengue-associated ADEM ranges from day 3 to day 19 after initial dengue symptoms, consistent with a post-infectious autoimmune mechanism.
  • ADEM is also known as postinfectious encephalomyelitis; the mechanism is a transient autoimmune response directed at myelin or other self-antigens — possibly via molecular mimicry or non-specific activation of autoreactive T-cell clones (see Infection-Triggered Autoimmunity).
  • Prior hospital-based meta-analysis estimated 0.4% of dengue patients develop ADEM — approximately 16× higher than the population-based estimate, reflecting the bias of hospital-only ascertainment toward severe presentations.
  • Other single-stranded RNA flaviviruses (West Nile virus, Zika, Chikungunya) are similarly reported to trigger autoimmune encephalomyelitis.

Guillain–Barré Syndrome (GBS)

  • Dengue is reported in case series as a trigger for GBS (post-infectious demyelinating polyneuropathy); multiple case reports have been described (see Guzman2016 - Dengue Infection).
  • However, in the Shih2023 population-based cohort study, the association was NOT statistically significant after correction for multiple testing (aHR 1.29; 95% CI 0.61–2.72; P = 0.5106).
  • Whether the case-report signal represents a true biological association at low incidence, or chance co-occurrence, remains uncertain. The incidence is too low for adequate power even in this large cohort (only 10 GBS cases in the dengue group).

Dengue-Associated Seizures

Velazqueza2017 - SLE vs Dengue Case Series documents a 3-year-old female patient who presented with fever and convulsive crisis as the initial manifestation of confirmed dengue infection, alongside thrombocytopenia, facial oedema, and proteinuria (nephrotic syndrome). She deteriorated and required ICU admission. The case is complicated by a subsequent SLE diagnosis 2 months later — the acute-phase seizures could represent dengue encephalopathy (metabolic/systemic pathway from thrombocytopenia, hypoalbuminaemia, and plasma leakage), direct CNS dengue involvement, or early CNS lupus. The temporal association with confirmed acute dengue at presentation places this case in the dengue neurological spectrum, though definitive mechanism attribution is not possible. This case illustrates the diagnostic challenge in dengue-endemic settings when SLE and dengue co-occur.

Prevalence and Clinical Spectrum (Farias2024)

Farias2024 - Dengue Mimickers synthesises prevalence data from clinical dengue literature (narrative review, Brazil):

  • Encephalopathy/encephalitis: 0.5–6.2% of dengue patients (wide range reflects case ascertainment differences — hospital-based studies capture higher rates)
  • Haemorrhagic stroke: 0.06–0.26% of hospitalised dengue patients; typically presents ~1 week after fever; symptom cluster: moderate-to-severe headache, vomiting, abrupt hemiparesis, unconsciousness
  • Headache present in >97% of all dengue patients — primary headache disorders (migraine, tension-type) can therefore be mistaken for dengue in endemic settings
  • EEG findings in encephalitis: burst suppression, electrographic seizures, focal patterns, epilepsy partialis continua
  • MRI: diffuse cerebral oedema or normal — no specific MRI signature for dengue encephalitis; ADEM, Japanese B encephalitis, Chikungunya are MRI-based differential diagnoses
  • Post-infectious immune-mediated syndromes listed: mononeuropathies, GBS, brachial neuritis, transverse myelitis, ADEM, acute cerebellitis, opsoclonus-myoclonus syndrome, optic neuritis, parkinsonism
  • Dengue myositis: cytokine-mediated muscle cell injury → rhabdomyolysis → AKI; hypokalemia can cause acute flaccid quadriplegia without cranial nerve palsy or sphincteric impairment

Other Neurological Manifestations

From Guzman2016 - Dengue Infection:

  • Transitory Parkinsonism: rare, reversible parkinsonian features in the post-acute phase; mechanism unknown.
  • Dengue-related maculopathy: visual disturbance (blurring, scotoma) during or after dengue; associated with retinal haemorrhage and foveal oedema; may persist.
  • Dengue encephalopathy: altered consciousness from systemic causes; more common than encephalitis; does not require viral CNS invasion.

Retinal Vasculitis

Palacios2016 - Autoimmunity in Dengue Literature Review cites Chang et al. (2007, Singapore) documenting retinal vasculitis as a dengue complication in young women: dengue virus infection provoked antibody production and immune complex deposition, leading to retinal vasculitis. The mechanism is immune complex–mediated, not direct viral invasion — distinguishing it from dengue-related maculopathy, which involves direct haemorrhagic/oedematous changes. Retinal vasculitis is therefore categorised alongside the autoimmunity-mediated complications (pathway 3) rather than direct viral encephalitis (pathway 2), and the case series also implicates Singapore as a setting where this complication has been reported.

Note: The original Chang 2007 paper is not in this wiki; the connection is documented via Palacios2016’s citation.

Serotype-Specific CNS Tropism

DENV-2 and DENV-3 are specifically implicated in direct CNS invasion leading to encephalitis (see Shih2023 - Autoimmune Disease Risk After Dengue, Guzman2016 - Dengue Infection). The mechanism likely involves differences in neurotropism encoded in NS proteins — consistent with the pattern that NS protein variation underlies differences in dengue tissue tropism and epidemic potential across serotypes.

Contradictions & Debates

  • The discrepancy between the 0.025% ADEM rate in Shih2023 and the 0.4% in prior meta-analysis is explained by case ascertainment: hospital-based studies capture only severe presentations, while this population-based study includes all outpatient and inpatient dengue. The true incidence in hospitalised dengue patients is expected to be higher than 0.025%.
  • GBS is biologically plausible as a dengue complication (molecular mimicry; see Infection-Triggered Autoimmunity; canonical example with C. jejuni), but the Shih2023 population-level analysis found no significant association. This may reflect insufficient statistical power (10 events) rather than absence of a true effect.
  • Data on serotype distribution was not available in Shih2023, preventing a definitive test of whether ADEM risk varies by serotype (e.g., DENV-2/3 > DENV-1/4).

Sources

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