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Year : 2015  |  Volume : 58  |  Issue : 3  |  Page : 387-388
Subcutaneous human Dirofilariasis in Vidarbha

Department of Microbiology, Government Medical College, Akola, Maharashtra, India

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Date of Web Publication14-Aug-2015


Zoonotic filariasis due to Dirofilaria repens is prevalent in several regions of the world. Human dirofilariasis due to D. repens has not been widely recognized in India, but few cases reported from some parts of India. Dirofilaria species are commonly encountered in the subcutaneous tissue of dogs, foxes, and cats and it can accidentally infect humans. Here, we report a case of subcutaneous dirofilariasis, presenting as a subcutaneous nodule on the right leg of a 25-year-old female from Vidarbha region.

Keywords: Dirofilariasis, subcutaneous nodules, zoonosis

How to cite this article:
Kombade SP, Mantri R S, Ambhore N A, Karyakarte R P. Subcutaneous human Dirofilariasis in Vidarbha. Indian J Pathol Microbiol 2015;58:387-8

How to cite this URL:
Kombade SP, Mantri R S, Ambhore N A, Karyakarte R P. Subcutaneous human Dirofilariasis in Vidarbha. Indian J Pathol Microbiol [serial online] 2015 [cited 2022 Jan 22];58:387-8. Available from: https://www.ijpmonline.org/text.asp?2015/58/3/387/162923

   Introduction Top

Human dirofilariasis is an accidental infection caused by species of dirofilaria like Dirofilaria repens, D. immitis, D. tenuis and D. ursi. [1] Dirofilariasis is a zoonotic infection which can be found World-Wide. The genus Dirofilaria has two subgenera: Dirofilaria and Nochtiella. Subgenus Nochtiella (e.g. D. repens) is commonly encountered in the subcutaneous tissue of dogs, foxes, and cats and it can accidentally infect humans. [2] While subgenus Dirofilaria (e.g. D. immitis) are typically found in the right ventricle and pulmonary artery of the dogs and cats and it can rarely cause human infections. [2] Culex, Aedes, and Anopheles mosquitoes are vectors for this parasite, which take up the microfilaria while feeding on the blood of an infected host. Microfilaria develops in the malpighian tubules into the third stage larva and then migrates to the proboscis through the body cavity. The transmission takes place when a potential vector bites the dogs or other hosts including humans during a subsequent blood meal. [3]

Human dirofilariasis due to D. repens has not been widely recognized in India. [4] Most of the documented cases of human dirofilariasis recorded in India presented with ocular infections. [3] D. repens is the main causative agent of subcutaneous human dirofilariasis in Asia, including India. [5],[6] We report a rare case of subcutaneous human dirofilariasis.

   Case Report Top

A 25-year-old female presented with a subcutaneous nodule on the right leg just above knee from 3 months. The nodule was initially nontender but gradually patient had discomfort and crawling sensation under the skin. The nodule gradually developed into abscess which bursted spontaneously and revealed a white thread-like worm. The worm was mechanically extracted by the patient and brought to hospital. The patient's blood smear did not show any microfilariae and other investigation like X-ray chest, ultrasonography abdomen and routine laboratory tests were within normal limits.


The worm was thin cylindrical, white, 0.5 mm thick and about 15 cm length [Figure 1]. The anterior end was rounded and of greater diameter than the posterior end. Under the microscope, the outer surface of the nematode's cuticle was found to have fine transverse striations and prominent longitudinal ridges [Figure 2]. Based on size, cuticular morphologic features and internal features, the worm was identified as a D. repens.
Figure 1: Adult worm of D. repens

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Figure 2: Microphotograph showing longitudinal beaded ridges and transverse striations on the cuticle of the worm (×40)

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   Discussion Top

Zoonotic filariasis due to D. repens is prevalent in several regions of the world, mainly reported from Europe, Africa and Asia. [7] The first documented report of human dirofilariasis dates back to the report of Addario from Italy in 1885. [2] The first reported case of human ocular dirofilariasis in India occurred in Kerala in 1976 and subcutaneous dirofilariasis caused by D. repens was recorded in 2004 in the same region. [5]

Most of the dirofilariasis cases are asymptomatic. The symptomatic ones typically manifests as either subcutaneous nodules or lung parenchymal disease. Patients usually present with single migratory nodule which may or may not be tender. [5] In our case study, patient had nontender subcutaneous nodules. Surgical removal of the worm from biopsy is the treatment of choice. [7] The clinical implication of human dirofilariasis is that, these subcutaneous lesions may be initially misidentified as malignant tumours, requiring invasive investigation and surgery before the correct diagnosis is made. [8]

Exact identification of the species may be possible after studying the fully matured worm. D. repens has a cuticle of 20 µm thickness, transverse striations, and large numbers of external longitudinal ridges. D. immitis can be differentiated from D. repens by the absence of longitudinal ridges and transverse striations. [5],[6] In order to confirm the diagnosis of D. repens infection, DNA extraction followed by panfilarial PCR may be performed. [6] In developing countries like India, owing to the infection with D. repens has been increasing in India and other parts of the world. [9] Human cases of dirofilariasis are mostly under reported and under diagnosed probably because of the varied clinical presentations and organ affected. Dirofilariasis should be considered in the differential diagnosis of a single migratory or nonmigratory subcutaneous swelling, though not a known endemic area of Dirofilariasis.

   References Top

Pampiglione S, Canestri Trotti G, Rivasi F. Human dirofilariasis due to Dirofilaria (Nochtiella) repens: A review of world literature. Parassitologia 1995;37:149-93.  Back to cited text no. 1
Khyriem AB, Lynrah KG, Lyngdoh WV, Banik A. Subcutaneous dirofilariasis. Indian J Med Microbiol 2013;31:403-5.  Back to cited text no. 2
[PUBMED]  Medknow Journal  
Permi HS, Veena S, Prasad HK, Kumar YS, Mohan R, Shetty KJ. Subcutaneous human Dirofilariasis due to Dirofilaria repens: Report of two cases. J Glob Infect Dis 2011;3:199-201.  Back to cited text no. 3
Sabu L, Devada K, Subramanian H. Dirofilariosis in dogs and humans in Kerala. Indian J Med Res 2005;121:691-3.  Back to cited text no. 4
Padmaja P, Kangalakshmi S, Samuel R, Kuruvilla PJ, Mathai E. Subcutaneous Dirofilariasis in southern India: A case report. Ann Trop Med Parasitol 2005;99:437-40.  Back to cited text no. 5
Sathyan P, Manikandan P, Bhaskar M, Padma S, Singh G, Appalaraju B. Subtenons infection by Dirofilaria repens. Indian J Med Microbiol 2006;24:61-2.  Back to cited text no. 6
[PUBMED]  Medknow Journal  
Karyakarte RP, Damle AS. Metazoa-Tissue nematodes: Dirofilaria. In: Medical Parasitology. 3 rd ed. Kolkatta: Books and Allied (P) Ltd.; 2008. p. 210-11.  Back to cited text no. 7
D′Souza R, Jakribettu RP, Sudharsana SH, Aithala SP. Subcutaneous nodule: A case of Dirofilaria. Int J Appl Basic Med Res 2013;3:64-5.  Back to cited text no. 8
Damle AS, Iravane Bajaj JA, Khaparkhuntikar MN, Maher GT, Patil RV. Microfilaria in human subcutaneous Dirofilariasis: a case report. J Clin Diagn Res 2014;8:113-4.  Back to cited text no. 9

Correspondence Address:
Akola Sarika Prabhakar Kombade
Department of Microbiology, Government Medical College, Akola, Collector Office Road, Akola - 444 001, Maharashtra
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0377-4929.162923

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  [Figure 1], [Figure 2]

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