Rising burden of Plasmodium vivax in Mizoram: an emerging threat to malaria elimination in Northeast India

BACKGROUND: India has made tremendous progress in malaria elimination efforts; however, several malaria pockets with high transmission remain that require continuous focus. The Northeast (NE) state of Mizoram, bordering Bangladesh and Myanmar, tops the list for disproportionately contributing to India's malaria burden. Considered a Plasmodium falciparum-endemic region, this study details the shift in malaria epidemiology from P. falciparum to P. vivax in Mizoram, complicating malaria elimination efforts in an already highly vulnerable setting. METHODS: Malaria data for the NE states were obtained from the National Center for Vector Borne Disease Control, while aggregated health center-wise data for Mizoram's Mamit district (2021-2025) were obtained from the Office of the Chief Medical Officer, Mamit district, Mizoram. Spatiotemporal analyses of malaria cases and environmental variables were performed using ArcGIS 10.4 to identify disease trends, clustering, and high-risk areas. RESULTS: In Mizoram, the steep shift in malaria incidence from P. falciparum to P. vivax was noticeable from 2022 onward; from 23% in 2021, P. vivax increased to 47% in 2024 and 42% in 2025. In 2020, Siaha-Mizoram's southern district bordering Myanmar-reported the first increase in P. vivax infections at the state level. In Mizoram's western district of Mamit, P. vivax contributed to 68% of the cases in 2025, and among children < 5 years, 86% of the infections were attributed to P. vivax. While P. falciparum transmission coincided with the monsoon season, P. vivax transmission was perennial. CONCLUSION: The recent surge in Mizoram's P. vivax cases appears to mirror the epidemiological shift from P. falciparum to P. vivax in bordering Myanmar. It is possible P. vivax parasites from Myanmar could have entered Mizoram through the southern districts of Siaha and Lawngtlai. As several studies in the last decade have reported chloroquine-resistant P. vivax infections in Myanmar, it is imperative that therapeutic efficacy studies are urgently carried out in Mizoram to ascertain the status of CQ-resistant parasites.