Dirofilariosis, cutaneous

Infestation transmitted by mosquitoes (especially Culex, Aedes, Anopheles species) with the dog skin worm Dirofilario repens. The nematodes primarily prefer dogs. Only rarely are humans affected.

Dirofilaria repens and immitis (dog skin worm)

Infections with Dirofilario repens are endemic in many countries in Africa and Asia. In Europe, the parasites are found throughout the Mediterranean region, protugal, the Canary Islands, the Balkans, and often also in Hungary and Ukraine. In Germany infections with Dirofilaria are very rare. Most cases are imported.

When a mosquito bites, the worm larvae enter the host (carnivores) and develop there in the subcutaneous tissue (D.repens) or lungs (D.immitis) into adult worms of considerable size (up to 20cm). The female adult worms produce larvae, so-called microfilariae, which enter the bloodstream. They are then transferred to a new host by mosquitoes.

The human being is a false host in this chain of infection. In humans, the worm can develop but cannot reproduce. Microfilariae are not produced in humans. Normally, the worm dies spontaneously a few months after infection.

Uncharacteristic lump in the skin. Diagnosis is generally made by biopsy.

Excision of the subcutaneous mass. Anthelmintic therapy is not necessary.

The 52-year-old patient from Ukraine, living in Germany, was last in his original home country 3 months ago and presented with a swelling of the right cheek that had been present (noticed) for 2 weeks and was only slightly painful. A few weeks ago, the patient had noticed once fever with chills and severe joint pain. These had improved under Ibuprofen.

Sonographically, a slightly calcified mass with a diameter of 1.5 cm and low echoes was visible.

Laboratory: eosinophilia of 8.5%, IgE normal; CRP slightly elevated. Other laboratory parameters were within the normal range. No filarial antibodies were detectable.

Therapy: Excision of the lump in healthy patients

Histology: Detection of female nematodes in the stage of inflammatory degeneration.

Course: Uncomplicated healing. No systemic therapy

1. Sassnau R et al.(2014) Climate suitability for the transmission of Dirofilaria immitis and D. repens in Germany. Vet parasitol 205:239-245
2. Tappe D et al.(2014) A case of autochthonous human Dirofilaria infection, Germany, March 2014 Euro Surveill 19:2-4.