Nipah Virus Mortality Risk by Age Group
Young adults and middle-aged individuals appear to be at highest mortality risk from Nipah virus infection, though all age groups can be severely affected, with overall case-fatality rates ranging from 40% to 75%. 1, 2, 3
Age Distribution in Nipah Outbreaks
The available evidence from Bangladesh outbreaks (2001-2004) reveals important age-related patterns:
- Two of the four outbreaks principally affected young persons with a median age of 12 years 2
- All age groups were affected across the outbreak series, with 62% of affected persons being male 2
- Among 92 identified patients with Nipah virus infection, 67 (73%) died, indicating uniformly high mortality across age groups 2
Critical Clinical Context
Unlike many viral infections where mortality concentrates in the very young or elderly, Nipah virus demonstrates a different pattern:
- The virus causes severe febrile encephalitis with respiratory syndrome that has a high mortality rate (40-75%) regardless of age 1, 4, 3
- Death occurred a median of 6 days (range 2-36 days) after illness onset among those who died 2
- Clinical features associated with death included temperature >37.8°C, altered mental status, difficulty breathing, and abnormal plantar reflexes—factors not specifically age-dependent 2
Important Caveats
The evidence base for Nipah virus age-specific mortality is limited:
- Most data comes from Bangladesh outbreaks between 2001-2005, which may not represent all transmission patterns 1, 2
- The Malaysian outbreak in 1998-1999 involved different transmission dynamics (pig-to-human versus bat-to-human or person-to-person) 1, 4
- No licensed treatments or vaccines exist, meaning mortality reflects natural disease progression without specific interventions 3, 5
Clinical Implications
The uniformly high case-fatality rate across age groups (40-100% in recognized outbreaks) means that age-based risk stratification is less clinically relevant for Nipah virus than for other respiratory viruses 3, 5. All suspected cases require immediate intensive supportive care regardless of patient age, as the virus affects both the central nervous and respiratory systems with rapid progression 2, 4.