The Diversity of Human Dirofilariasis in Western Sri Lanka

Abstract

Background. Human dirofilariasis is an emerging zoonosis in many countries. Dirofilariasis caused by Dirofilaria repens may present with diverse clinical manifestations in humans due to aberrant localization of worm lesions causing diagnostic dilemmas. The aim of this retrospective study was to describe and update the demography and clinical spectrum of human dirofilariasis in western Sri Lanka. Nematode or nematode fragments isolated from excision biopsies that were confirmed as D. repens at the Department of Parasitology, Faculty of Medicine, University of Kelaniya, Sri Lanka, between 2012 and 2018 were included. Data on age, gender, and clinical details were obtained from case files. Identity of worms was established by morphometry and cuticle characteristics on wet-mount preparation. Specimens from unusual case presentations were further analyzed by PCR with specific primers for internal transcribed spacer region 2 (ITS2) of the ribosomal DNA. Results. Sixteen nematode specimens isolated from subconjunctiva (n=2), subcutaneous (n=13) and intramuscular (n=1) locations were identified as D. repens by morphometry (average length 11.5 cm) and the characteristic longitudinal striations on cuticle visualized by microscopy. The age distribution of cases ranged from 1 to 65 years with a mean of 21.5. Females were more frequently affected (n=10, 62.5%) and worm locations were commonest in the orbital region (5/16) and scrotum (3/16). Imaging techniques were of use in detecting infections in deeper tissue levels. PCR analysis of DNA extracted from a worm in an intramuscular granuloma of the temporal region elicited the expected band at 484bp for D. repens. Conclusions. Human dirofilariasis is on an upward trend in incidence. Imaging techniques were of use in clinical diagnosis and molecular speciation in establishing the species identity in unusual case presentations. We suggest a more conservative approach in the management of human dirofilariasis and recommend a one health approach for control.

Human dirofilariosis in Austria: the past, the present, the future

“…One possible explanation might lie within population-specific or national differences in daily activities and habits, including outdoor and international travel activities or clothing preferences, or the discrepancies might merely be caused by the small size of our study population and the possibility of missed cases due to the lack of a central reporting system. Dirofilariosis in minors in Austria was rare, which is similar to the numbers reported in other countries, wih the exception of Sri Lanka, where more than one third of human dirofilariosis cases were found among children and adolescents [ 2 , 57 , 58 ]. Consistent with previous reports [ 2 , 32 ], the most frequent affected localization in our study population was the upper half of the body, particularly the head.…”

Molecular Characterization of Culturable Aerobic Bacteria in the Midgut of Field‐Caught Culex tritaeniorhynchus, Culex gelidus, and Mansonia annulifera Mosquitoes in the Gampaha District of Sri Lanka

“…However, the occurrence of zoonotic brugian filariasis raises an issue as mass treatment of the human population with antifilarial drugs would not eliminate the reservoir of infection nor the vector population. Human dirofilariasis is another zoonotic filarial infection, commonly encountered in the country [ 31 – 33 ].…”

Omental dirofilariasis caused by <em>Dirofilaria repens</em>; visceralisation in a patient with diabetes mellitus

“…3 Sri Lanka, with its first case reported in 1962, is documented to have the second-highest prevalence of subcutaneous and ocular dirofilariasis cases caused by D. repens between 1995-2000. 4 Several intra-oral cases were reported as well. 4 Hitherto, visceral manifestations due to Dirofilaria spp.…”

“…4 Several intra-oral cases were reported as well. 4 Hitherto, visceral manifestations due to Dirofilaria spp. have not been reported from Sri Lanka.…”