A 3-year-old, 4.5 kg spayed female cat (domestic shorthair), living in Yangsan, Korea, had been vomiting irregularly for several days with anorexia and lethargy, without showing any signs of diarrhea. The cat was a stray cat, and after being adopted by the current owner, the cat was reared indoors for more than half a year. Additionally, the cat was regularly treated with preventive medicine (Advocate for cat; Bayer, Seoul, Korea) to prevent endo- and ecto-parasites. Initially, the sick cat was diagnosed with inflammatory bowel disease based on the history, clinical symptoms, and ultrasonography (data not shown). For the treatment, peroral prednisolone (Solondo Tab. 5 mg; Yuhan, Seoul, Korea) (1 mg/kg) was prescribed twice a day for three months. Although the symptoms improved with treatment, the cat did not appear to be completely cured. One day after the treatment, the cat vomited, and two long proglottids of tapeworms, approximately 30 cm each, were recovered without a scolex (Fig. 1A).

For the diagnosis, fecal floatation tests were performed using a saturated sodium nitrate solution (specific gravity 1.33). Based on the fecal examination and gross morphological characteristics of the worms, the parasite was identified as Spirometra sp. (Fig. 1A–C). In the fecal floatation test, no other parasite eggs were identified. For exact species identification, based on morphological and molecular methods, the recovered proglottids of worms were kept in 70% ethyl alcohol and were submitted to the College of Veterinary Medicine, Chungbuk National University, Cheongju, Korea.

Broadline spot-on solution (Boehringer Ingelheim; Seoul, Korea) containing praziquantel was applied twice a month according to the manufacturer’s instructions. One month after the last application, a fecal examination was performed; however, Spirometra eggs were still observed. Before additional treatment, complete blood count was evaluated using Exigo eos (Boule Diagnostics AB, Spånga, Sweden), and certain hematological values, including mean corpuscular volume, mean corpuscular hemoglobin, and platelets, showed abnormalities (Supplementary Table S1). Thereafter, praziquantel (Distocide^® Tab.; Shinpoong Pharm, Seoul, Korea) was administered orally at 35 mg/kg twice, once every two weeks. One month after the last administration, no eggs were observed from the feces and additional fecal examination was performed more than two months later, verifying the completion of treatment.

A 3-year-old, 3 kg female cat (domestic shorthair), living in Daegu, Korea, had been vomiting, and proglottids of a tapeworm, approximately 15 cm long, were recovered. Before vomiting, the cat showed symptoms such as anorexia and lethargy without diarrhea. This cat was a stray cat and had been adopted by the current owner and was reared indoors. After adoption, vaccination was not administered. For the diagnosis, a fecal floatation test was performed, and Spirometra eggs were identified. Praziquantel (DS Anthelmine Puppy Tab.; Daesung Microbiological Labs., Uiwang, Korea) (12.5 mg) was administered four times daily. Following the treatment, no additional proglottids of Spirometra were recovered either through vomiting or feces. Subsequently, anorexia and lethargy disappeared. However, an additional fecal flotation test was not performed owing to the owner’s refusal.

For exact species identification, proglottids of adult worms were kept in 70% ethyl alcohol and were submitted to the College of Veterinary Medicine, Chungbuk National University, Cheongju, Korea.

Species identification was performed using both morphological and molecular examinations. The size of the proglottid from Case 1 was 5.69 mm (width, standard deviation 0.30) ×0.68 mm (length, standard deviation 0.05) and the proglottid from Case 2 was sized 5.88 mm (width, standard deviation 0.21)×1.26 mm (length, standard deviation 0.13). For each sample, at least 10 gravid proglottids were measured. For morphological analysis, the proglottids of adult worms were stained with acetocarmine, and the morphological characteristics confirmed the parasite belonging to Spirometra sp. Additionally, molecular techniques were applied to target cox1 gene analysis. In brief, genomic DNA of adult worms was extracted from the proglottids using the QIAamp^® DNA Mini Kit (Qiagen, Hilden, Germany) according to the manufacturer’s instructions. The complete sequence of the Spirometra cox1 gene was amplified by PCR using the AccuPower HotStart PCR Premix kit (Bioneer, Daejeon, Korea), as previously described [12]. The amplified PCR products were sent to Macrogen (Daejeon, Korea) for sequencing, and two additional internal primers were used (forward: GTT TAC CTC GGC GTG TTT GT; reverse: ATC ACC ACC ACC CAA AGG AT).

Using direct sequencing, two complete Spirometra sp. cox1 sequences (1,566-bp) were obtained. Based on the phylogenetic analysis, both Spirometra sp. belonged to Type I (Fig. 2), as suggested by Yamasaki et al. [11]. The phylogenetic tree was constructed using MEGA based on the Maximum Likelihood method with 500 bootstrap replications. Nucleotide analysis showed that the sequences in this study shared 99.7% identity with each other, and BLASTn revealed a high genetic identity of 99.7% and 99.4%, respectively, to S. decipiens (MT122766) from the USA. The sequences identified in this study were submitted to the GenBank database MW031094-MW031095.