Human infection by Dirofilaria repens in Sri Lanka: A retrospective audit of cases reported by the Department of Parasitology, University of Colombo from 2007 to 2023

Sri Lanka is endemic for human dirofilariasis, a mosquito-borne zoonotic filarial disease. This study is an audit of microscopically confirmed Dirofilaria repens cases at the Department of Parasitology, Faculty of Medicine, University of Colombo, from 2007 to 2023. Data collected from patients was descriptively analysed for age, sex, residential district, and anatomical location of lesions. In total, 92 cases were confirmed with D. repens. Patients’ ages varied from 8 months to 80 years (mean=27.6, n=92). The highest number of patients was in the 0-9 years age category (n=32/92, 34.8%). The majority infected were males (n=49/92, 53.3%). The highest number of samples was submitted from the Colombo district. (n=64/92,69.6%). Ocular dirofilariasis was reported in 60.9% (n=56/92), with females significantly affected more than males (χ²=8.335,df=1;p=0.004). Subcutaneous dirofilariasis was reported in 39.1% (n=36/92), significantly more affecting the age category <20 years (χ²=9.808,df=2;p=0.007). Human dirofilariasis causes morbidity, particularly in children, and should be included in the differential diagnosis of patients with ocular and subcutaneous lesions in Sri Lanka.