First case of <i>Dirofilaria hongkongensis</i> infection in Germany presenting as a breast tumour

Abstract

A 69-year-old Indian born woman residing in Germany for 43 years presented with a palpable and painful induration of her left breast. She noticed the lump after her last short family visit abroad in her home state Kerala, India, 2 months earlier. Her gynaecologist confirmed a mass in the left breast. Mammography revealed an area suspicious for malignancy in segment nine (Figure 1); ultrasound-guided biopsy of the lesion (Figure 2) was performed. Histology did not show signs of malignancy but revealed parts of a ‘worm-like parasite’ suggestive of Wuchereria bancrofti. The patient was referred to our department at St. Marien-Hospital Cologne. No microfilariae were detected microscopically in blood taken at noon and midnight. Anti-filarial antibodies measured by cross-reactive Acanthocheilonema viteae ELISA were highly elevated, Filariasis Test Strip specific for W. bancrofti antigen was negative. Pulmonary CT scan and abdominal ultrasound did not show any pathological findings. Mammography image of the left breast. Ultrasound image of the left breast. The patient received Doxycycline 100 mg bid for suspected lymphatic filariasis and was discharged home. After reassessment of the histological specimen, characteristic features of Dirofilaria repens (Figure 3) were seen. PCR from this specimen supported D. repens infection, while PCR for W. bancrofti and Mansonella spp. were negative. Histology of specimen. At 2- and 4-weeks follow-up after discharge, the patient presented in good clinical condition, the initial symptoms had completely disappeared. Doxycycline was discontinued after a total of 6 weeks of treatment. At the 3- and 4-month follow-ups, the patient remained without any symptoms. Anti-filarial antibodies measured by cross-reactive A. viteae ELISA 3 months after the end of therapy were significantly reduced, indicating treatment success. To determine the origin of the infection, we took increasing cases of Dirofilaria hongkongensis in India into account.1–3 Histomorphologically, D. repens and D. hongkongensis could not be distinguished.1 We therefore used COX 1 and panfilaria 12S rDNA primers3 to amplify the corresponding fragments by PCR. The products were cloned and sequenced. The COX 1 sequence had best hits (percent identity > 98%) to D. hongkongensis. Percent identity to D. repens was < 96%. The 12S rDNA sequence supported the identification as D. hongkongensis with > 99.4% hits to D. hongkongensis. Given that D. hongkongensis also contains Wolbachia endosymbionts, the therapy carried out could be considered effective. In summary, we were able to successfully diagnose and treat the first reported D. hongkongensis infection in Germany—acquired in Kerala, India. D. hongkongensis is a zoonotic parasite of mammals (especially dogs) transmitted by mosquitoes, first described 2012 in Hong Kong4 and on the rise in India.1–3 One imported case from India had been reported in Austria.3 Humans are dead-end hosts. Treatment is usually by surgical removal of the parasite, but doxycycline treatment targeting Wolbachia endosymbionts of filariae is possible5 in cases where surgery generates unnecessary damage. D. hongkongensis is an expanding parasite and should be considered in patients presenting with soft tissue masses after travelling to filarial-endemic areas. I.K., A.H., K.P. and M.P.H. are members of the German Center for Infection Research (DZIF). M.P.H. received funding from the German Center for Infection Research (TTU 09.701). We would like to thank Sabine Nachtsheim, Helene Neufeld and Tilman Aden for their technical assistance. Jakob Schröder: In-patient care, diagnostics and treatment, Conceptualization; Project administration, investigation (literature search), writing original draft, writing review & editing. Camilla Rothe: Supervision, investigation (literature search), writing review & editing. Inge Kroidl: Supervision, investigation (literature search), writing review & editing. Achim Hoerauf: Histological reassessment of specimen, PCR diagnostics, visualization (Figure 3), writing review & editing. Kenneth Pfarr: PCR diagnostics, investigation (literature search), writing review & editing Marc P. Hübner: Histological reassessment of specimen, PCR diagnostics, investigation (literature search), visualization (Figure 3), writing review & editing. Jakob Schroeder (Conceptualization [lead], Project administration [lead], Writing—original draft [lead], Writing—review & editing [lead]), Camilla Rothe (Investigation [supporting], Supervision [lead], Writing—review & editing [supporting]), Achim Hoerauf (Visualization [lead], Writing—review & editing [supporting]), Inge Kroidl (Investigation [supporting], Supervision [supporting], Writing—review & editing [supporting]), Kenneth Pfarr (Investigation [supporting], Writing—review & editing [supporting]), and Marc P. Hübner (Investigation [equal], Visualization [lead], Writing—review & editing [supporting]) Conflict of interest: None declared. Written consent of patient had been obtained.

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