msp1, msp2, and glurp genotyping to differentiate Plasmodium falciparum recrudescence from reinfections during prevention of reestablishment phase, Sri Lanka, 2014-2019.

BACKGROUND: Sri Lanka after eliminating malaria in 2012, is in the prevention of re-establishment (POR) phase. Being a tropical country with high malariogenic potential, maintaining vigilance is important. All malaria cases are investigated epidemiologically and followed up by integrated drug efficacy surveillance (iDES). Occasionally, that alone is not adequate to differentiate Plasmodium falciparum reinfections from recrudescences. This study evaluated the World Health Organization and Medicines for Malaria Venture (MMV) recommended genotyping protocol for the merozoite surface proteins (msp1, msp2) and the glutamate-rich protein (glurp) to discriminate P. falciparum recrudescence from reinfection in POR phase. METHODS: All P. falciparum patients detected from April 2014 to December 2019 were included in this study. Patients were treated and followed up by iDES up to 28 days and were advised to get tested if they develop fever at any time over the following year. Basic socio-demographic information including history of travel was obtained. Details of the malariogenic potential and reactive entomological and parasitological surveillance carried out by the Anti Malaria Campaign to exclude the possibility of local transmission were also collected. The msp1, msp2, and glurp genotyping was performed for initial and any recurrent infections. Classification of recurrent infections as recrudescence or reinfection was done based on epidemiological findings and was compared with the genotyping outcome. RESULTS: Among 106 P. falciparum patients, six had recurrent infections. All the initial infections were imported, with a history of travel to malaria endemic countries. In all instances, the reactive entomological and parasitological surveillance had no evidence for local transmission. Five recurrences occurred within 28 days of follow-up and were classified as recrudescence. They have not travelled to malaria endemic countries between the initial and recurrent infections. The other had a recurrent infection after 105 days. It was assumed a reinfection, as he had travelled to the same malaria endemic country in between the two malaria attacks. Genotyping confirmed the recrudescence and the reinfection. CONCLUSIONS: The msp1, msp2 and glurp genotyping method accurately differentiated reinfections from recrudescence. Since reinfection without a history of travel to a malaria endemic country would mean local transmission, combining genotyping outcome with epidemiological findings will assist classifying malaria cases without any ambiguity.

Identifying the strains of dengue circulating in the western province of Sri Lanka during 2019-2022.

A study conducted from July 2019 to May 2022 at several hospitals in the Western Province, Sri Lanka, focused on dengue virus strains during the COVID-19 pandemic. Among 417 febrile patients, 47% were PCR-positive for dengue. Serotyping revealed DENV-1 (12.8%), DENV-2 (46.4%), DENV-3 (37.2%), and DENV-4 (3.6%). Sequencing identified two genotypically distinct variants of DENV-3 and two genotypically distinct variants of DENV-1, while DENV-2 showed a single genotype cluster. Notably, the study found concurrent circulation of two DENV-3 and two DENV-1 genotypes, along with DENV-2, during the pandemic in the area. This data suggests the presence of multiple dengue strains, including several DENV-1 and DENV-3 variants, without major epidemic outbreaks reported in the Western Province. Continuous monitoring and research are essential to understand the dynamics of these dengue strains in the context of the COVID-19 pandemic.