Case Report: Successful Treatment of a Patient with Microfilaremic Dirofilariasis Using Doxycycline

Abstract

We report the case of a 56-year-old woman with microfilaremic dirofilariasis due to Dirofilaria repens, which is a very rare condition in humans. Of note, just one of six large-volume blood samples of this patient was positive for microfilariae. Polymerase chain reaction (PCR) and sequencing of the parasite gene determined the geographic origin of the causative helminth. The patient was treated successfully with doxycycline. This drug was chosen because of the patient's reluctance to the use of ivermectin and to provide an anthelmintic effect by targeting the bacterial endosymbiont Wolbachia present in most filarial species.

Figure 1.

Cross section through a nematode found in an excised subcutaneous mass from the patient’s neck. The internal structures of the helminth are partly necrotic. The external ridges seen on the cuticle of the nematode are typical for Dirofilaria repens. This figure appears in color at www.ajtmh.org.