Parasite 25, 31 (2018) © F. Beugnet et al., published by EDP Sciences, 2018 https://doi.org/10.1051/parasite/2018029 Available online at: www.parasite-journal.org RESEARCH ARTICLE Analysis of Dipylidium caninum tapeworms from dogs and cats, or their respective fleas Part 2. Distinct canine and feline host association with two different Dipylidium caninum genotypes Frédéric Beugnet1,*, Michel Labuschagne2, Christa de Vos3, Dionne Crafford3, and Josephus Fourie3 1 Boehringer Ingelheim Animal Health, 29 Av T. Garnier, 69007 Lyon, France 2 Clinomics, P.O. Box 11186, Universitas, Bloemfontein, 9321, South Africa 3 Clinvet, P.O. Box 11186, Universitas, Bloemfontein, 9321, South Africa Received 10 January 2018, Accepted 21 April 2018, Published online 28 May 2018 Abstract- -Initial investigations suggested the existence of two distinct genotypes of Dipylidium caninum from infected cat fleas (Ctenocephalides felis). One genotype was found almost always (> 95%) in fleas collected from, and proglottids shed by, domestic dogs. The other was found almost always (> 95%) in fleas collected from, and proglottids shed by, domestic cats. Molecular investigations (Part 1, in this journal) confirmed the presence of two distinct genotypes. Due to the apparent host association observed, these were referred to as the “D. caninum canine genotype” and the “D. caninum feline genotype”. The current article reports on an in vivo experimental infection study assessing the host-parasite interaction for each genotype. Mixed infections with the two genotypes in both dogs and cats were conducted. The specific genotyping of proglottids allowed us to assess the specific prepatent periods, prolificity, and longevity of each genotype in dogs versus cats. The possible hybridisation was also studied through molecular evaluation of the proglottids expelled by infected dogs and cats. Results demonstrate a clear distinct host interaction. The canine D. caninum genotype occurred at a higher frequency in dogs, with a shorter prepatent period and a longer lifespan; and the feline genotype occurred at a higher frequency in cats, with a shorter prepatent period and a longer lifespan. The absence of any hybrids in the mixed infections of both dogs and cats confirm the hypothesis of two distinct genotypes, suggesting the possibility of two distinct species within Dipylidium caninum. Key words: Dipylidium caninum, Ctenocephalides felis, dogs, cats, genotypes, host association Résumé- - Analyse des ténias Dipylidium caninum des chiens et des chats, ou de leurs puces respectives. Partie 2. Association distincte des hôtes canins et félins avec deux génotypes différents de Dipylidium caninum. Des investigations initiales ont suggéré l’existence de deux génotypes distincts au sein de Dipylidium caninum issus de puces infectées (Ctenocephalides felis). Un génotype est trouvé dans plus de 95 % des cas chez des puces ou des proglottis collectés sur des chiens. L’autre est trouvé dans plus de 95 % des cas sur des puces collectées sur des chats ou des proglottis éliminés par les chats. Les investigations moléculaires publiées (Partie 1, dans ce journal) ont confirmé l’existence de ces deux génotypes. Du fait de l’apparent tropisme d’hôte, ces deux génotypes sont désignés comme génotype canin et génotype félin. Le présent article présente les résultats d’infestations expérimentales ayant pour objectif d’étudier l’interaction hôte-parasite pour chaque génotype. Des infestations mixtes ont été réalisées avec les deux génotypes chez des chiens et des chats. Le génotypage spécifique a permis d’étudier les périodes prépatentes, la prolificité et la longévité de chaque génotype chez chaque hôte. La possible hybridation a aussi été étudiée par évaluation moléculaire des proglottis éliminés par les chiens et les chats infestés. Les résultats ont démontré une interaction hôte-parasite bien distincte. Le génotype canin de D. caninum a une fréquence plus élevée chez les chiens, avec une période de prépatence plus courte et une durée de vie plus longue, et le génotype félin a une fréquence plus élevée chez les chats, avec une période prépatente plus courte et une durée de vie plus longue. L’absence de tout hybride dans les infections mixtes des chiens et des chats confirme l’hypothèse de deux génotypes distincts, suggérant la possibilité de deux espèces distinctes au sein de Dipylidium caninum. *Corresponding author: [email protected] This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. 2 F. Beugnet et al.: Parasite 2018, 25,31 Introduction cats belong to the feline genotype, and that the Dipylidium caninum collected by East et al., (2013) [17], also belong to Dipylidium caninum sensu lato is an important cestode the same feline genotype [29,31]. The Dipylidium from the parasite with a worldwide distribution, as is evident from two genotypes are kept in dogs and cats at Clinvet, surveys performed in wild canids and felids, domestic cats, Bloemfontein, South Africa, allowing the present study. domestic dogs, or concurrent surveys assessing both This paper reports on an in vivo experimental infection domestic cats and dogs [1,3,4,6,8–11,13–19,21,25,26,28,30, study, designed to investigate potential host association with 32,34–37,40,41,43–48]. Apart from infecting both canids and reference to the canine and feline D. caninum genotypes [29]. felids, this cestode may also occasionally infect humans The objectives of this study were thus two-fold: firstly, [2,24,42]. to establish whether the two D. caninum genotypes show The intermediate hosts for this parasite are the cat and distinct host interaction, i.e. prepatent period, longevity, dog fleas (Ctenocephalides felis and Ctenocephalides and rate of infection; and secondly, to establish whether canis, respectively), as well as the dog and cat chewing the genotypes could have sexual reproduction during lice, Trichodectes canis, and Felicola subrostratus, mixed infection in either dogs or cats. respectively [31]. Due to its worldwide distribution, and fl its ability to infest dogs and cats, the cat ea, C. felis,is Materials and Methods considered to be the main intermediate host [5,12,27,46]. Flea larvae ingest D. caninum eggs, with the rate of Ethics development in the flea greatly affected by temperature The study was approved by the Institutional Animal [38,39]. When adults fleas infected with suitably developed Care and Use Committee (IACUC). The study conformed metacestodes are ingested by the canine or feline host, the to the principles defined and explained in the European parasite establishes in the small intestine. Here it develops Convention for the Protection of Vertebrate Animals used to an adult tapeworm, with shed proglottids visible in for Experimental and Other Scientific Purposes and its faeces from between 17 and 19 days after infection [22,23]. appendix. In addition, the authors have involved the Beugnet et al. [8] investigated the occurrence of D. minimum number of animals in the experimental infection caninum in fleas from client-owned cats and dogs in study for the purpose of adequate experimental infection Europe, using a new PCR detection assay. The results model validation. Animals were observed daily for general indicated that easy and regular Dipylidium sp. re- health, with physical examinations performed by a infections of both cats and dogs in European households veterinarian to ensure suitability for inclusion in the were likely. Thus, for the first time, the spread of D. study. Throughout the study, the health of the animals caninum between fleas on dogs and cats was confirmed was monitored by veterinary personnel. No abnormal throughout Europe. In this European survey, 2.23% of clinical signs were observed during either clinical exami- 1969 cat fleas collected from cats were found to be infected nations or daily health observations. As a result, none of by Dipylidium sp. larvae, compared to 5.2% of 732 cat fleas the animals required concomitant therapy or veterinary collected from dogs and 3.1% of 2828 dog fleas collected care during the study. After termination of the animal from dogs. Preliminary analyses performed during this phase, the animals received the necessary concomitant survey, indicated genetic differences between D. caninum therapy (deworming based on praziquantel oral adminis- metacestodes in fleas collected from dogs and cats, tration), after which they were returned to the Clinvet respectively. Low, in 2017, suggested the presence of colony holding facility in order to undergo a resting period. two clades within D. caninum species [31]. Labuschagne et al., 2018, using the DNA extracted from the initial flea Study design collect from dogs and cats in Europe [8], and adding new fleas collected in the United States, as well as Dipylidium The study was designed as a parallel group, non- proglottids from Europe, Africa, and Asia, demonstrated blinded, randomised, single-centre study, to determine the the existence of the two distinct genotypes [29]. The initial efficiency in infecting dogs and cats with two different D. genetic analysis started in 2012 during an epidemiological caninum genotypes (Figure 1). The D. caninum were survey assessing the infection rate of fleas by Dipylidium sourced from donor cats or dogs, and served to infect fleas. caninum using a new PCR probe [8]. In the recent paper, The study was based on an experimental flea infestation Labuschagne et al., 2018, established a correspondence model previously published [7,22], in combination with the between the host origin of Dipylidium-infected fleas and newly developed PCR hydrolysis probe assay [29]. the genotype. They demonstrated that the genotypes are not related to geography but to hosts. The so-called feline Animal details genotype of D. caninum was found almost exclusively in C. felis collected from cats (95.1%), whereas the so-called Three dogs (group 1) and three cats (group 2), all canine-genotype was found almost exclusively in C.felis females, were included in the study.