Distinct Haematological Signatures in Active and Chronic Lymphatic Filariasis: Evidence of Lymphocytosis in Chronic Disease and Eosinophilia in Active Infection

Abstract

Background: Lymphatic filariasis (LF) is a debilitating neglected tropical disease that continues to impose significant health and socioeconomic burdens in endemic communities. Although the clinical manifestations of LF are well recognized, the haematological alterations associated with disease progression from active infection to chronic lymphatic pathology remain inadequately characterized. Understanding these changes may provide accessible biomarkers for disease staging and clinical assessment. Objective: This study aimed to compare the haematological profiles of active and chronic lymphatic filariasis and identify characteristic immune-cell signatures associated with different stages of infection. Methods: A cross-sectional observational study was conducted among six confirmed lymphatic filariasis patients from a rural endemic population, including five chronic cases and one active case. Clinical evaluation was performed alongside routine haematological investigations comprising haemoglobin estimation, total and differential leukocyte counts, platelet count, and Erythrocyte Sedimentation Rate (ESR). Comparative assessment was undertaken to evaluate stage-specific variations in haematological parameters. Results: Chronic lymphatic filariasis was the predominant presentation and was associated with persistent lower limb involvement, elevated ESR, and marked lymphocyte predominance. In contrast, the active infection case demonstrated significant eosinophilia accompanied by an increased inflammatory response. While eosinophilia is classically linked to helminthic infections, its limited presence in chronic cases and the emergence of lymphocytosis suggest a transition from acute antiparasitic responses to sustained immune activation and chronic inflammation. Elevated ESR was observed across both disease stages, indicating persistent inflammatory activity. Conclusion: Distinct haematological signatures were observed between active and chronic lymphatic filariasis, with eosinophilia characterizing active infection and lymphocytosis predominating in chronic disease. These preliminary findings highlight the potential utility of routine haematological parameters as simple, cost-effective indicators of disease stage and host immune response, warranting validation through larger multicentric studies.

Keywords: Lymphatic filariasis; Chronic filariasis; Active filariasis; Lymphocytosis; Eosinophilia; Rural health.