Sri Lanka is currently experiencing a large Chikungunya outbreak after 16 years and the current virus was of the Indian Ocean Lineage (IOL) with several unique mutations, Sri Jayewardenepura University’s Immunology and Molecular Medicine Department Head Prof. Neelika Malavige said in a post on X.
She said a team of researchers carried out whole genomic sequencing of the currently circulating Chikungunya virus (CHIKV) strain and found that it was of the Indian ocean lineage (IOL), similar to the currently circulating CHIKV strains in South Asia. The findings of this research can be found in a paper titled “The re-emergence of Chikungunya in Sri Lanka: A genomic investigation,” published on medRxiv.
While the E:226V mutation, which has been associated with Aedes albopictus transmission efficiency, was absent in all 2025 CHIKV viral sequences, they carried the E1:K211E and E2: V264A mutations, which result in enhanced viral fitness within the Aedes aegpti mosquito. The mutations nsP1:I167V, nsP2:I171V, nsP2:T224I, nsP3:A382I and nsp4: were detected in the non-structural protein, with the Sri Lankan 2025 CHIKV strains showing unique mutations within nsP3:T224I and nsP4: S90A,” the paper said.
“As some of these novel mutations have not been characterized previously, it is important to find out how they affect fitness within mosquitoes, viral replication and immune evasion,” she said in a post on X.
Sri Lanka experienced the first outbreak of CHIKV between the years 2006 to 2008, which led to 37,667 clinically suspected infections. Although CHIKV had caused outbreaks in the region, including in India from 1960s onwards, surveys have shown that CHIKV is unlikely to have circulated in Sri Lankans prior to 2006, the researchers claim.
After the outbreak waned in 2008, CHIKV cases were not reported in Sri Lanka for the next decade. However, febrile surveillance during years 2017 to 2018, has shown that in some regions in Sri Lanka, around 1% of febrile patients were infected with CHIKV, indicating that the virus had been circulating in Sri Lanka despite not causing outbreaks.
“After 16 years around the end of 2024, patients presenting with a Chikungunya-like illness was reported in Colombo, which was later confirmed as CHIKV cases. Since then, the reported CHIKV cases have rapidly increased and now Sri Lanka is experiencing a large outbreak. Due to a lack of widespread access to CHIKV diagnostics and a concurrent dengue outbreak, the true estimates of cases from this outbreak are unknown. The genomic sequence of the currently circulating CHIKV strain is needed to guide decisions around diagnostics and outbreak,” the researchers said.
(dailynews.lk)
(This story, originally published by dailynews.lk has not been edited by SLM staff)
