Abstract
BACKGROUND: Malaria remains a critical public health challenge in southeastern Bangladesh, particularly in Cox's Bazar, where the mass displacement of over one million Rohingya refugees since 2017 has heightened transmission risks. The interplay of ecological fragility, overcrowded living conditions, and climatic variability underscores the need for a deeper understanding of malaria epidemiology in this high-risk setting. METHODS: A 4-year repeated cross-sectional study was conducted (2021-2024) in Camp No. 26, Teknaf, Cox's Bazar. A total of 582 participants were enrolled, comprising 486 individuals from the malaria-endemic refugee camp and 96 healthy controls from a nonendemic region. All were screened for Plasmodium falciparum and Plasmodium vivax using rapid diagnostic tests (RDTs), with microscopy performed to confirm all RDT-positive cases and a subset of RDT-negative samples. Meteorological data (temperature, rainfall, and humidity) were obtained from regional weather stations. Serological profiling assessed total anti-Plasmodium antibodies, while hematological parameters including hemoglobin concentration, RBC and platelet counts, and ESR were measured. Correlation and regression analyses were employed to identify climatic predictors of malaria incidence and their associations with immunohematological changes. RESULTS: Out of 582 individuals, 345 malaria cases were confirmed. Peak transmission occurred during the monsoon season (June-September), particularly in August. P. falciparum infections showed earlier and sharper peaks compared to P. vivax. Relative humidity demonstrated the strongest correlation with incidence (r = 0.724-0.77), followed by rainfall and temperature. Antibody titers were significantly higher in P. falciparum-positive individuals. Infected participants exhibited anemia, thrombocytopenia, and elevated ESR, with more pronounced alterations in P. falciparum cases. CONCLUSION: This study highlights the seasonal and species-specific nature of malaria transmission in Rohingya refugee camps, driven predominantly by climatic variables, particularly humidity. The observed serological and hematological alterations underscore their potential as biomarkers for surveillance. These findings advocate for climate-sensitive, species-specific malaria control strategies tailored to displaced populations.