What is the fatality rate of chikungunya?

Fatality Rate of Chikungunya

The overall mortality rate of chikungunya is approximately 0.3% (95% CI: 0.1-0.7%), though this increases dramatically to 10% among patients who develop neurological complications such as encephalitis or encephalopathy. 1, 2

Overall Mortality Rates

• The pooled mortality rate across multiple studies is 0.3%, making chikungunya rarely fatal in the general population 2
• The death rate is not particularly high under typical circumstances, though excess mortality has been documented during large outbreaks 3
• Most chikungunya infections are self-limiting, with the acute phase lasting 7-10 days 2, 4

High-Risk Populations with Elevated Mortality

Neurological Complications

• Patients who develop CNS involvement (encephalitis or encephalopathy) face a 10% case fatality rate, representing a 33-fold increase compared to uncomplicated cases 1
• During the 2005-2006 La Réunion outbreak, 57 of 300,000 cases developed neurological complications, with 10% mortality in this subgroup 1
• Neurological disease is more severe in adults compared to infants, though both age groups are vulnerable 1

Age-Specific Risks

• Elderly patients and newborns are particularly vulnerable to severe and potentially fatal outcomes 1
• Neonates with perinatal transmission during maternal viremia at delivery face high morbidity, with encephalopathy being a major complication 1

Time-Dependent Mortality Risk

• The risk of death is highest within the first 7 days after symptom onset (IRR 8.40-8.75), declining to near-baseline by 85-168 days 5
• Within 28 days of symptom onset, mortality risk remains elevated at approximately 2-4 times baseline 5
• The increased mortality risk persists for up to 84 days after symptom onset 5

Cause-Specific Mortality

Chikungunya increases the risk of death from specific cardiovascular and metabolic causes within the first month:

• Diabetes-related deaths: IRR 3.75-8.43 within 28 days 5
• Ischemic heart disease deaths: IRR 2.38-3.67 within 28 days 5
• Cerebrovascular disease deaths: IRR 1.80-2.73 within 28 days 5

Regional and Reporting Considerations

• The corrected lethality rate (5.7 per 1,000 cases) is 6.8 times higher than initially reported, indicating substantial underreporting of chikungunya-related deaths 6
• In Brazil's 2016-2017 outbreaks, only 24.4% of deaths in patients with chikungunya mentioned the disease on death certificates 6
• The highest corrected lethality rates occur in patients aged ≥80 years (75.4 per 1,000), 65-79 years (20.7 per 1,000), and infants <1 year (8.6 per 1,000) 6

Long-Term Outcomes and Quality of Life

Among survivors of neurological complications, only 40% of adults achieve apparent full recovery three years post-infection 1

• Among infants with neurological involvement, 1 in 13 developed cerebral palsy and 4 had low developmental quotients at follow-up 1
• Chronic symptoms persist in 44% of cases (95% CI: 31-57%), primarily debilitating arthralgia that can last months to years 2

Critical Clinical Pitfalls

• Chikungunya mortality is significantly underestimated when relying solely on surveillance data, as many deaths occur from complications rather than direct viral effects 6
• Deaths occurring in the acute (38.1%) and post-acute (29.6%) phases may not be attributed to chikungunya on death certificates 6
• Unlike dengue, chikungunya does not typically cause warning signs requiring hospitalization in pregnant women, though neonatal outcomes can be severe with peripartum transmission 1, 7