Symptoms of Nipah Virus Infection in Toddlers
Nipah virus infection in toddlers presents with fever, headache, altered mental status, vomiting, and dizziness, often accompanied by distinctive neurological signs including myoclonus, hypotonia, areflexia, and rapid progression to encephalitis with brain stem involvement. 1
Initial Presenting Features
The early symptoms that should raise suspicion for Nipah virus infection include:
- Fever - Present in the vast majority of cases as an initial symptom 1, 2
- Headache - A prominent early complaint 1, 2
- Vomiting - Common gastrointestinal manifestation 1, 2
- Dizziness - Frequently reported in the prodromal phase 1, 2
- Altered mental status - Ranging from drowsiness to confusion 1
Distinctive Neurological Signs
Nipah virus causes characteristic neurological manifestations that distinguish it from other encephalitides:
- Myoclonus - Segmental myoclonic jerks are a distinctive feature 1, 2
- Dystonia - Abnormal muscle tone and posturing 1
- Areflexia - Absent or diminished reflexes 1, 2
- Hypotonia - Decreased muscle tone, particularly notable in young children 1, 2
- Reduced level of consciousness - Occurs in approximately 55% of patients, indicating severe brain stem involvement 2
- Seizures - Can occur as part of the encephalitic syndrome 1
Brain Stem and Autonomic Features
The virus has a predilection for the brain stem and upper cervical spinal cord, producing:
- Abnormal doll's-eye reflex - A poor prognostic sign indicating severe brain stem dysfunction 2
- Cranial nerve defects - Due to brain stem involvement 1
- Hypertension - Autonomic dysfunction manifestation 2
- Tachycardia - Another autonomic sign associated with poor prognosis 2
Respiratory Manifestations
Unlike some other encephalitides, Nipah virus can cause concurrent respiratory disease:
- Pneumonitis - Respiratory tract involvement is documented 1
- Respiratory symptoms - May accompany or precede neurological features 3, 4
Neuroimaging Findings
MRI characteristics that support the diagnosis include:
- Discrete focal lesions throughout the brain 1
- Predominant involvement of subcortical and deep white matter of cerebral hemispheres 1
- Brain stem lesions - Reflecting the clinical brain stem syndrome 1
Critical Clinical Pitfalls
The most dangerous error is failing to consider Nipah virus in endemic areas (South Asia, particularly Bangladesh and India) when a toddler presents with encephalitis following exposure to bats, contaminated food (especially date palm sap), sick animals (particularly pigs), or infected humans. 1, 3, 4
Key points to avoid missing the diagnosis:
- Geographic context is essential - Nipah should be on the differential for any encephalitis case in South Asia 1
- Exposure history is critical - Ask specifically about bat exposure, consumption of raw date palm sap, contact with pigs or sick individuals 3, 4, 5
- Human-to-human transmission occurs - Unlike the Malaysian outbreak (primarily pig-to-human), Bangladesh and India outbreaks show person-to-person spread 3, 4
- The combination of encephalitis with distinctive myoclonus, areflexia, and hypotonia should trigger consideration of Nipah virus 1, 2
Rapid Progression and Prognosis
- Mortality rate is high (approximately 32% in documented outbreaks) with rapid deterioration 2
- Neurologic relapse can occur after initially mild disease 2
- Tachycardia and abnormal doll's-eye reflex are associated with poor outcomes 2
- Death typically results from severe brain stem involvement 2
Diagnostic Approach in Suspected Cases
When Nipah is suspected based on clinical features and epidemiology:
- Serologic testing from serum and CSF 1
- CSF culture (though sensitivity may be limited) 1
- Contact Special Pathogens Branch at CDC for guidance on testing and biosafety 1
- PCR, immunohistochemistry, and virus isolation require BSL4 laboratory facilities 1