The reappearance of Chikungunya virus in Bangladesh, 2024

Objectives

We investigated a new outbreak of Chikungunya virus (CHIKV) in Dhaka and nearby areas of Bangladesh in 2024, examining its epidemiology, clinical features, and genomic characteristics.

Methods

The Institute of Epidemiology, Disease Control and Research enrolled suspected Chikungunya cases from October 19 to December 31, 2024. Reverse transcription polymerase chain reaction was performed, and positive cases were followed up via telephone between days 21 and 28. The E1 gene of 12 samples was sequenced.

Results

Of 394 enrolled patients, 138 (35%) were CHIKV-positive, mostly male (64.5%) and over 30 years old (83.3%), with 98.6% residing in Dhaka. Common symptoms included fever (100%), arthralgia (97.8%), myalgia (83.2%), and headache (65.0%). While no fatalities were recorded, 14.5% required hospitalization with an average stay of 5.9 days, and patients lost an average of 10.5 workdays. At 28 days, 81% of 58 follow-up patients had persistent symptoms. Both hospitalization and persistent symptoms were associated with having >4 symptoms initially (incidence risk ratio: 1.14; 95% confidence interval: 1.02-1.27 and 1.19; 95% confidence interval: 1.01-1.39, respectively). Sequence analysis identified an E1-K211E substitution, with phylogenetics revealing a distinct East-Central-South-African (ECSA) sub-lineage compared to 2017 strains.

Conclusions

CHIKV is likely to re-emerge in Bangladesh amid the ongoing dengue outbreak, posing a risk of a major outbreak soon. Strengthening efforts to control Aedes mosquitoes is essential.