Infections of Two Isthmiophora Species (Digenea: Echinostomatidae) in Wild Mammals from Republic of Korea with Their Morphological Descriptions

Abstract

<i>Isthmiophora</i> <i>hortensis</i> (Digenea: Echinostomatidae) is a dominant echinostome in animal reservoir hosts and humans in the Republic of Korea (Korea). We intended to investigate the infection status with this echinostome species in the several species of wild animals and describe the morphological characteristics in the faunistic view point. A total of 175 animal carcasses belonging to 3 families, i.e., Canidae, Felidae and Mustelidae, were collected from the southern regions of Korea from March 2010 to July 2017. <i>Isthmiophora</i> spp. worms were recovered from the small intestines of each animal under a stereomicroscope after washing of intestinal contents. <i>Isthmiophora</i> <i>hortensis</i> was recovered from 4 species of wild carnivores, i.e., <i>Nyctereutes</i> <i>procyonoides</i> (3/107: 2.8%), <i>Mustela</i> <i>sibirica</i> (11/31: 35.5%), <i>Meles</i> <i>lucurus</i> (2/3: 33.3%) and <i>Martes</i> <i>flavigula</i> (1/2: 50%). The other 3 carnivores comprising stray dogs, cat and leopard cat were negative for <i>I</i>. <i>hortensis</i> infection (0/2, 0/10 and 0/12, respectively). Specimens obtained from the <i>Lutra</i> <i>lutra</i> (6/8: 75%) were identified as a distinct species, <i>I</i>. <i>inermis</i>, by morphological comparison. <i>Isthmiophora</i> <i>inermis</i> has thinner body, elongate testes and different anterior limits of vitelline fields. Detailed morphological descriptions and comparisons with the morphological characteristics are provided. Conclusively, it was confirmed for the first time that 3 species of mustelid mammals, i.e., <i>M</i>. <i>sibirica</i>, <i>M</i>. <i>lucurus</i>, and <i>M</i>. <i>flavigula</i>, are to be the new definitive hosts of <i>I</i>. <i>hortensis</i> in Korea. Additionally, <i>I</i>. <i>inermis</i> is to be newly added in the Korean echinostome fauna.