What are the clinical manifestations, diagnosis, treatment, and prevention strategies for a patient potentially exposed to or infected with the Nipah virus, particularly in relation to symptoms such as fever, headache, and respiratory issues?

Nipah Virus: Comprehensive Presentation Guide

Overview and Epidemiology

Nipah virus is a deadly zoonotic paramyxovirus with a 73.9% mortality rate that causes severe encephalitis and respiratory disease, transmitted primarily through contaminated date palm sap and direct human contact. 1, 2

• The virus was first identified in Malaysia in 1998 and has since caused 25 outbreaks in South Asia, resulting in 429 cases and 307 deaths. 1, 3
• Geographic distribution includes the Indian subcontinent, Bangladesh, Indonesia, Southeast Asia, Pakistan, southern China, northern Australia, and the Philippines. 4
• Fruit bats of the genus Pteropus serve as the natural reservoir, with five of 14 Malaysian bat species identified as carriers. 5, 4

Transmission Pathways

Person-to-person transmission occurs in approximately 50% of recognized cases, making this a critical public health threat. 6, 2

• Primary transmission routes include consumption of raw date palm sap contaminated by bat saliva or urine. 2, 4
• Secondary transmission occurs through direct contact with infected patients' saliva, with physical contact identified as the strongest risk factor. 2, 4
• Intermediate transmission can occur through infected domestic animals (cattle, pigs, goats) that consumed bat-contaminated food. 2
• Nosocomial transmission is well-documented, requiring strict infection control measures. 4

Clinical Presentation

The hallmark presentation is acute encephalitis with altered mental status developing after an initial febrile phase, accompanied by distinctive movement disorders including segmental myoclonus with areflexia and hypotonia. 6, 7

Initial Symptoms (Incubation: 4 days to 2 weeks)

• Fever occurs in 80% of cases and is the most common presenting feature. 7, 1
• Myalgia (47%), headache (47%), and vomiting (42.6%) are frequent early symptoms. 1
• Dizziness and nonspecific flu-like symptoms may precede neurological involvement. 4

Neurological Manifestations

• Altered sensorium develops in 44.1% of cases as encephalitis progresses. 1
• Segmental myoclonus with characteristic 1:1 relationship to EEG periodic complexes indicates severe CNS involvement. 6
• Areflexia and hypotonia are distinctive physical examination findings that should raise strong suspicion in endemic areas. 6, 7
• Dystonia can develop as the disease progresses. 6, 7
• Seizures occur in 39.2% of cases and may progress to status epilepticus. 6, 1
• Abnormal pupillary reflexes may be present. 4

Respiratory Manifestations

• Shortness of breath or acute respiratory distress syndrome develops in 44.1% of cases. 1
• Pneumonitis is a common feature requiring aggressive respiratory support. 8
• Tachycardia and hypertension may accompany respiratory distress. 4

Laboratory Findings

• Thrombocytopenia, leukopenia, and transaminitis may be present but are not universal. 5
• Virus levels in serum remain low, but detection in cerebrospinal fluid is comparatively high. 4

Diagnostic Approach

RT-PCR is the most commonly used diagnostic test (45.5% of cases) and should be performed on blood, CSF, throat swabs, and urine during the acute phase. 1, 5

• Serum neutralization test (SNT) is the gold standard for diagnosis. 4
• ELISA can be used for antibody detection during the convalescent phase if SNT cannot be performed. 5, 4
• Herpes simplex PCR must be performed on all CSF specimens to rule out treatable causes of encephalitis. 6
• Continuous EEG monitoring is required to detect subclinical seizure activity and characteristic periodic complexes. 6
• Contact the CDC Special Pathogens Branch for guidance on case management and diagnostic testing. 8

Treatment and Management

The primary treatment is intensive supportive care with aggressive respiratory support, as there are no FDA-approved antiviral therapies, though ribavirin can be considered as an investigational agent (C-III recommendation from the Infectious Diseases Society of America). 8, 6, 5

Respiratory Management Protocol

• Start with standard oxygen therapy via nasal cannula or mask, titrating to maintain SpO2 >90-96%. 8
• Consider high-flow nasal oxygen (HFNO) or non-invasive ventilation (NIV) with close monitoring only in carefully selected patients with mild respiratory distress, and only in an ICU setting with strict airborne precautions. 6
• Proceed to endotracheal intubation and invasive mechanical ventilation within 1-2 hours if no improvement occurs—do not delay intubation by attempting prolonged trials of NIV or HFNO, as this increases mortality and puts staff at risk during emergency intubation. 8, 6
• Use lung-protective ventilation strategies with tidal volumes of 4-6 mL/kg predicted body weight and plateau pressures <30 cmH2O if ARDS develops. 8

Neurological Management

• Aggressive anticonvulsant therapy is required for myoclonic seizures and status epilepticus. 6
• Manage increased intracranial pressure with standard critical care protocols. 8
• Continuous EEG monitoring is mandatory to detect subclinical seizure activity. 6

Investigational Antiviral Therapy

• Ribavirin can be considered for Nipah virus encephalitis, though evidence for efficacy is limited (C-III recommendation). 8, 6, 5
• m102.4 monoclonal antibody and favipiravir are the only other antivirals with some activity against Nipah virus, but are not widely available. 5

Critical Care Monitoring

• Continuously monitor vital signs including heart rate, respiratory rate, blood pressure, and pulse oximetry. 8, 6
• Assess neurological status frequently, watching for declining consciousness, seizures, or focal neurological deficits. 8
• Monitor water-electrolyte balance, acid-base balance, and organ function continuously. 6
• Watch for complications including ARDS, septic shock, stress ulcers, and deep vein thrombosis. 6

Nutritional and Psychological Support

• Provide high-protein, high-vitamin, carbohydrate-containing diets for patients who can tolerate oral intake. 6
• For critically ill patients, provide enteral nutrition as soon as possible; if not feasible, initiate parenteral nutrition promptly. 6
• Provide psychological support using techniques like mindfulness-based stress reduction to relieve anxiety and panic. 6

Infection Control Measures

Healthcare workers must use airborne precautions with N-95 respirators, gowns, aprons, and face shields when caring for suspected or confirmed cases, as person-to-person transmission occurs in approximately 50% of cases. 6, 5

• Admit patients to negative pressure isolation rooms; if unavailable, use single rooms. 9
• Maintain a list of all staff who have contact with the patient. 9
• All staff should monitor for symptoms for 10 days following exposure and should not come to work if they develop fever. 9
• Restrict visitors to next of kin/legal guardian only. 9
• Standard precautions, hand hygiene, and personal protective equipment are the cornerstone of infection prevention. 5

Prognosis and Long-Term Outcomes

The mortality rate is 73.9%, and survivors may experience long-term neurological sequelae or relapsing encephalitis. 8, 1

• Myoclonic jerks with characteristic 1:1 relationship to EEG periodic complexes indicate severe CNS involvement and poor prognosis. 6
• Do not discharge patients without comprehensive follow-up plans, as neurological sequelae may emerge later. 6
• Early diagnosis and treatment are crucial to prevent life-threatening consequences. 1

Prevention Strategies

Prevention focuses on decreasing bat access to date palm sap and reducing exposure to infected patients' saliva. 2

• Avoid consumption of raw date palm sap in endemic areas. 2
• Implement barriers to prevent bat contamination of food sources. 2
• Educate communities about transmission risks from infected domestic animals. 2
• Currently, only one equine vaccine is licensed; no human vaccine is available. 4

Critical Pitfalls to Avoid

• Do not delay intubation with prolonged NIV trials—this worsens outcomes and creates emergency intubation situations that endanger staff. 8, 6
• Do not assume fever alone indicates malaria or other common infections in endemic areas—maintain high suspicion for Nipah when encephalitis or respiratory symptoms develop. 1
• Do not underestimate transmission risk—approximately 50% of cases result from person-to-person spread. 6, 2
• Do not discharge without definite diagnosis and comprehensive follow-up, as relapsing encephalitis can occur. 6