Dirofilaria repens microfilariae from a human node fine-needle aspirate: a case report

Abstract

BackgroundHuman dirofilariosis is still a little known infection even in endemic areas. Dirofilariosis is zoonotic infection usually abortive in humans; instead, we report a very rare case (the 4th in the world), the first in Italy, in which at least two infective larvae became mature adults that mated and produced active microfilariae even though they did not reach peripheral blood.Case presentationA 30-year-old Italian woman presented with a transient oedematous swelling on the left abdominal wall with a creeping eruption followed by the occurrence of a subcutaneous nodular painless mass in the iliac region. One month later, a similar temporary swelling appeared on the contralateral inguinal region associated with intermittent joint discomfort in both knees. The patient had recently travelled abroad, therefore many possible diagnoses were to be ruled out. Routine laboratory investigations revealed eosinophilia. An ultrasound examination of the iliac swelling evidenced a well-defined cyst with a big filamentous formation in continuous movement. A fine-needle aspiration of the lesion was performed for parasitological, cytological and histological exams. The prompt microscopic examination of the aspired material showed the presence of numerous microfilariae that were initially morphologically attributed to Mansonella ozzardi. Subsequently, the revision of the Giemsa stained film and molecular analyses of the biological material, allowed to identify Dirofilaria repens as etiological agent of infection.ConclusionsWe report of a case in whom microfilariae were detected in fine-needle aspirate of subcutaneous node, without evidence of microfilaraemia, and the infection failed to become fully patent. Therefore we confirm that complete development and fertilization of D. repens worms in human hosts may occur, at variance with what is commonly believed, that Dirofilaria worms cannot fully develop in humans.Electronic supplementary materialThe online version of this article (doi:10.1186/s12879-016-1582-3) contains supplementary material, which is available to authorized users.

Two cases of subcutaneous dirofilariasis in Barcelona, Spain

“…Fontanelli Sulekova et al 2016). The sample from the patient 2 shared 99% identity with deposited sequences from D. repens.…”

Anthology of Dirofilariasis in Russia (1915–2017)

“…Later, similar results were obtained in Italy. A case was reported in which microfilariae were detected in the fine-needled aspirate of a Dirofilaria subcutaneous node [38]. It was confirmed that complete development and fertilization of D. repens worms in human hosts might occur [38].…”

“…A case was reported in which microfilariae were detected in the fine-needled aspirate of a Dirofilaria subcutaneous node [38]. It was confirmed that complete development and fertilization of D. repens worms in human hosts might occur [38]. In the following years, microfilariae were detected in the blood of a patient [5,39,40], such as in Europe, where 10 cases of D. repens were found in the lung; two similar cases were described in Russia as well [41].…”

Clinical and laboratory features of human dirofilariasis in Russia

“…Several authors have discussed the obligate and facultative relationships between human and the dirofilariasis pathogen Dirofilaria (Nochtiella) repens infection [1] , as well as the role of the human as a potential source of this roundworm infection in nature [1] , [2] . This hypothesis is based on the cases of detection of larvae, adult, and gravid females of D. repens in subcutaneous nodes [3] . Russian literature described the case where D. repens larvae detected in human peripheral blood [2] , [4] .…”