〔Med. Entomol. Zool. Vol. 67 No. 4 p. 233‒235 2016〕 233 DOI: 10.7601/mez.67.233 Finding of the human ea Pulex irritans (Siphonaptera: Pulicidae) in Hokkaido, Japan with human dermatitis caused by this ea Kenichi Takahashi*, 1), Mamoru Takahashi2) and Koukichi Hamasaka3) * Corresponding author: [email protected] 1) Graduate School of Dairy Science, Rakuno Gakuen University, 582 Bunkyoudai-Midorimachi, Ebetsu, Hokkaido 069‒8501, Japan 2) Department of Anesthesiology, Saitama Medical University, Moroyama-machi, Iruma-gun, Saitama 350‒0495, Japan 3) Hamasaka Dermatology Clinic, 7‒1‒10, Nishimachikita, Nishiku, Sapporo, Hokkaido 063‒0061, Japan (Received: 3 October 2016; Accepted: 3 November 2016) Abstract: A female resident of Hokkaido visited a dermatology clinic after developing dermatitis on her both legs. A flea collected in the patient’s home was identified as the human flea, Pulex irritans Linnaeus, 1758. All circumstantial evidence indicates flea bites as the cause of the dermatitis. Key words: Pulex irritans, human dermatitis, Hokkaido, Japan steroids. At the initial visit, it was suggested to the Introduction patient that there might be insects present in the The human flea, Pulex irritans Linnaeus, 1758, dwelling. Three days after visit, the patient collected is distributed throughout the world and has been a flea in her room and brought it to the clinic for recorded in a wide range of mammal hosts including identification. Since then, a pest control technician humans, domestic dogs, cats, pigs, badgers (Meles visited and visually inspected the presence of fleas meles) and foxes (Vulpes vulpes) (Hopkins and on the same day, but no more fleas were found in her Rothschild, 1953; Sakaguti, 1962). This species is also room. Following treatment and removal of the flea, the medically important as a possible vector of flea-borne dermatitis improved without recurrence of symptoms diseases such as plague, murine typhus, tularemia and and only the pigmented lesions of her skin were tapeworm (Bitam et al., 2010; Eisen and Gage, 2012). observed on October 3, 2015. In Japan, the human flea was widespread and Morphological Characteristics common until the 1970s, and was frequently reported of the Specimen from humans and their immediate environment, domestic dogs, livestock and wild mammals (Fujisaki, The collected insect was an adult female flea (Fig. 1952; Sakaguti, 1962; Iwashige and Kitamura, 1979). 1), and was identified asP. irritans, one of seven Soon after, records became increasingly rare and̶to species of the genus Pulex (Wagner, 1933; Hopkins and the authors’ knowledge̶the last reported detection Rothschild, 1953; Barrera, 1955; Smit, 1958; Tipton was from 1983 (Okabe et al., 1983). and Méndez, 1966; Lewis and Grimaldi, 1997), based Here we report a recent detection of the human flea on the following morphological criteria: (1) frontal in Hokkaido, Japan, and a case of human dermatitis margin smoothly rounded and frontal tubercle absent likely caused by this flea. (Fig. 2), (2) single ocular seta below eye and only one strong seta on occiput (Fig. 2), (3) genal and pronotal Case Report combs absent (Fig. 2), (4) a row of 11 small spiniform The patient was a 51-year-old woman who lived setae apicoventrally on hind coxa (Fig. 3), (5) pleural on the fourth floor of a five-story condominium in rod of mesopleurum absent, (6) seventh abdominal Sapporo, Hokkaido, Japan. She kept no pet animals. sternite with short lobe and narrow sinus below, and From the beginning of August, 2015, itchy eruptions (7) head of spermatheca sub-globular, its tail longer started to appear on both legs. As there was no than head (Fig. 4). symptomatic improvement, she visited one of the Discussion author’s clinic on August 29, 2015. A total of 47 mostly tense blisters of 2‒3 cm in diameter and some reddish Records of the human flea, P. irritans, which had eruptions were observed on both lower extremities been common before, ceased in the 1980s in Japan (left side 11, right side 36). The patient was treated for unclear reasons (Fujisaki, 1952; Sakaguti, 1962; with oral steroids, oral anti-histamines and topical Iwashige and Kitamura, 1979; Okabe et al., 1983; 234 Med. Entomol. Zool. Fig. 1. A female of P. irritans. Fig. 4. Spermatheca. (Yamauchi, 2005) have also been sporadically reported. The present study revealed the dermatitis of a resident of Hokkaido caused by the human flea. The patient had travelled to France immediately before the onset of symptoms (from July 26th to August 3rd, 2015), but no pruritic rash during the travel period. It is not clear if the flea had been accidentally brought from the visited region (e.g., inside luggage), or whether it invaded the home of the patient (which is near a forested area) from the environment. The fact that flea bites ceased after the removal of a single flea does not indicate the presence of a flea population in the vicinity and suggested the importation of the flea. The recent presence of P. irritans in France is well established, where it has been detected on goats (Christodoulopoulos, 2003) and Fig. 2. Head and prothorax with a single ocular seta (A) dogs (Gilles et al., 2008). In addition, there are various below the eye and only one strong seta (B) in occiput. recent reports of human flea infestation of pet animals, livestock and wildlife in other countries of Europe (Christodoulopoulos and Theodoropoulos, 2003; Sréter et al., 2003; Beck et al., 2006; Bond et al., 2007; Domínguez et al., 2011; Gracia et al., 2013) as well as infestation of humans in an UK hospital (Thomas et al., 2000). The human flea is one of the causative species of flea-borne diseases (Bitam, 2010; Eisen and Gage, 2012), and has been considered as a possible or probable vector for plague in endemic areas of the world (Denis et al., 1999; Laudisoit et al., 2007; Leulmi et al., 2014; Ratovonjato et al., 2014). Moreover, several Rickettsia and Bartonella spp. have been Fig. 3. Small spiniform setae on the hind coxa. detected in the human flea (Rolain et al., 2005; Sackal et al., 2008; Jiang et al., 2013). The present finding Kano and Shinonaga, 1997; Ohtaki et al., 1999; Ohno, demonstrates either the persistence of this species in 2007). Since then, the presence of the human flea in Japan, or the possibility of accidental introduction. Japan has been unconfirmed until the case presented As a consequence, attention should be paid to the here. The cat flea, Ctenocephalides felis, is the most occurrence of the human flea as a causative agent common cause of flea-related dermatitis in humans in of human dermatitis in Japan, and health personnel Japan (Maeda and Anekohji, 1983; Oka and Ohtaki, should be alerted accordingly. 1988; Takahashi and Hori, 1989; Kishi et al., 1998; Acknowledgements Yamamoto et al., 2000). Additionally, cases of humans bitten by the bird fleas Ceratophyllus gallinae dilatus We are grateful to Thomas Romig for valuable (Hattori and Takahashi, 1985; Miyamoto, 1993), C. comments on this manuscript. 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