Nipah Virus Symptoms
Nipah virus infection characteristically presents with fever (occurring in 80% of cases) followed by acute encephalitis with distinctive neurological features including segmental myoclonus, areflexia, and hypotonia—a combination that should raise strong clinical suspicion in endemic areas. 1
Initial Presentation
The disease begins after an incubation period of 4 days to 2 weeks with nonspecific symptoms: 1, 2
- Fever - the most common presenting feature (80% of cases) 1, 3
- Myalgia (muscle pain) - occurs in 47% of patients 3
- Headache - present in 47% of cases 3, 2
- Vomiting - affects 42.6% of patients 3
- Dizziness 2
Neurological Manifestations (Hallmark Features)
The Centers for Disease Control and Prevention identifies acute encephalitis with altered mental status as the hallmark of severe Nipah virus infection, developing over the next few days following initial symptoms: 1
- Altered sensorium/mental status - occurs in 44.1% of cases 3
- Segmental myoclonus - a distinctive movement disorder that, when combined with areflexia and hypotonia, strongly suggests Nipah virus 1, 2
- Areflexia (absent reflexes) - a distinctive physical examination finding 1, 2
- Hypotonia (decreased muscle tone) - another characteristic finding 1, 2
- Dystonia - can develop as the disease progresses 1
- Seizures - occur in 39.2% of cases as a complication 3
- Abnormal pupillary reflexes 2
Respiratory Manifestations
The World Health Organization recognizes that Nipah virus characteristically presents with a combination of encephalitis and respiratory symptoms: 1
- Shortness of breath/acute respiratory distress syndrome - affects 44.1% of patients 3
- Respiratory disorders of varying severity 2
Cardiovascular Findings
Key Clinical Distinction
The presence of segmental myoclonus with areflexia and hypotonia should raise strong suspicion for Nipah virus in endemic areas, as this combination of movement disorders with encephalitis and respiratory symptoms is characteristic of the infection. 1 This distinguishes Nipah from other viral encephalitides that typically do not present with this specific constellation of neurological findings.
Disease Severity
The mortality rate is extremely high at 73.9%, with seizures (39.2%) and altered sensorium (35.7%) being the most common complications. 3 The high case fatality rate underscores the importance of early recognition based on this symptom complex, particularly in endemic regions of South and Southeast Asia. 4, 5