Rollinson / Stothard Advances in Parasitology

1. Auflage 2015
ISBN: 978-0-12-802467-6
Verlag: Elsevier Science & Techn.
Format: EPUB
Kopierschutz: 6 - ePub Watermark

E-Book, Englisch, Band Volume 88, 338 Seiten

Reihe: Advances in Parasitology

First published in 1963, Advances in Parasitology contains comprehensive and up-to-date reviews in all areas of interest in contemporary parasitology. Advances in Parasitology includes medical studies of parasites of major influence, such as Plasmodium falciparum and trypanosomes. The series also contains reviews of more traditional areas, such as zoology, taxonomy, and life history, which shape current thinking and applications. The 2013 impact factor is 4.36 - Informs and updates on all the latest developments in the field - Contributions from leading authorities and industry experts

Autoren/Hrsg.

Rollinson, David

Stothard, Russell

Leseproben

2. Historical Perspective and Taxonomy
2.1. Cryptosporidium
Cryptosporidium was first discovered by Ernest Edward Tyzzer in 1907. He identified life cycle stages of a parasitic protist in the gastric glands of laboratory mice and proposed the name Cryptosporidium muris for this new species (Tyzzer, 1910). Subsequently, another new species, called Cryptosporidium parvum, was described by Tyzzer in 1912. C. parvum infected the small intestine, and the oocysts were smaller than those of C. muris. After its first discovery by Tyzzer, Cryptosporidium was not recognized as an economically or medically important parasite for the next 50 years. In 1955, it was first identified as a potentially disease-causing agent, when it was isolated from diarrhoeic turkeys (Slavin, 1955). In 1971, Cryptosporidium was reported to be associated with diarrhoea in young calves, for the first time (Panciera et al., 1971). Five years later, the first two human cases of cryptosporidiosis were reported (Meisel et al., 1976; Nime et al., 1976). Then, in 1982, the Centers for Disease Control (CDC) reported cryptosporidiosis in 21 HIV/AIDS patients in the USA (MMWR, 1982), after which Cryptosporidium received major attention around the world. Traditionally, Cryptosporidium taxa have been identified based on oocyst morphology, host specificity and/or predilection site within the host (Ryan and Xiao, 2014). Subsequently, using immunological or molecular methods, many distinct species and genotypes have been identified within Cryptosporidium. Over the years, the taxonomy of Cryptosporidium has undergone substantial change, leading to some controversies. The development of new molecular tools has allowed the identification and characterisation of species and/or genetic variants (genotypes) (reviewed by Jex et al., 2011a; Ryan and Xiao, 2014). The genus Cryptosporidium belongs to the Phylum Apicomplexa, Order Eucoccidiorida and Family Cryptosporidiidae (Fayer and Xiao, 2008). Presently, more than 26 species of Cryptosporidium have been recognised (Chalmers and Katzer, 2013; Ryan and Xiao, 2014). In addition, there are more than 40 genotypes that have not yet been formally recognised as species, because of a lack of sufficient morphological, biological and molecular data to comply with the International Code for Zoological Nomenclature (ICZN) rules of describing new species (Table 1) (cf. Jex et al., 2011a; Ryan and Xiao, 2014). Table 1 Recognised species of Cryptosporidium Cryptosporidium andersoni Cattle Abomasum Lindsay et al. (2000) Cryptosporidium baileyi Birds Bursa, cloaca, intestine Current et al. (1986) Cryptosporidium bovis Cattle Intestine Fayer et al. (2005) Cryptosporidium canis Canids Intestine Fayer et al. (2001) Cryptosporidium cuniculus Rabbit, human Intestine Inman and Takeuchi (1979)a Cryptosporidium fayeri Marsupials Intestine Ryan et al. (2008) Cryptosporidium felis Cats Intestine Iseki (1979) Cryptosporidium fragile Amphibians Intestine Jirku et al. (2008) Cryptosporidium galli Birds Proventriculus Pavlasek (1999)b Cryptosporidium hominis Humans Intestine Morgan-Ryan et al. (2002) Cryptosporidium macropodum Marsupials Intestine Power and Ryan (2008) Cryptosporidium meleagridis Birds (humans) Intestine Slavin (1955) Cryptosporidium molnari Fishes Stomach Alvarez-Pellitero and Sitja-Bobadilla (2002) Cryptosporidium muris Rodents Stomach Tyzzer (1910) Cryptosporidium parvum Mammals (humans) Intestine Tyzzer (1912) Cryptosporidium ryanae Cattle Intestine Fayer et al. (2008) Cryptosporidium scophthalmic Fishes Intestine Alvarez-Pellitero et al. (2004) Cryptosporidium scrofarum Pigs Intestine Kvác et al. (2013) Cryptosporidium serpentis Snakes Stomach Levine (1980) Cryptosporidium suis Pigs Intestine Ryan et al. (2004) Cryptosporidium varanii Reptiles Intestine Pavlásek et al. (1995) Cryptosporidium viatorum Humans Intestine Elwin et al. (2012) Cryptosporidium wrairi Rodents Intestine Vetterling et al. (1971) Cryptosporidium xiaoi Sheep Intestine Fayer and Santín (2009) a See Robinson et al. (2010). b See Ryan et al. (2003). c No molecular data available for this ‘species’. 2.2. Giardia
Although Giardia was first observed in 1681 by Antonie van Leeuwenhoek, the first detailed description of this protist was not published until 1859. Subsequently, species of Giardia were described based on the host occurrence, because of a lack of characteristic or differentiating morphological features. Later, in 1952, an increasing number of Giardia species and uncertainty regarding host specificity led to a taxonomic rationalisation. Based on this classification, most members infecting vertebrates were named as one group, Giardia duodenalis (Filice, 1952). Although this ‘species’ was isolated from humans and many animal hosts, the zoonotic significance of Giardia was controversial until the World Health Organization (WHO) recognised it as a zoonotic agent in 1979 (WHO, 1979). Giardia is a binucleate, flagellate protist belonging to Phylum Metamonada, Order Giardiida and Family Giardiidae (Plutzer et al., 2010). Other recognised species of Giardia include Giardia agilis, Giardia ardae, Giardia microti, Giardia muris and Giardia psittaci (Table 2) (Thompson, 2011). At the trophozoite stage, they can be distinguished based on morphological characteristics using light and electron microscopy. Giardia duodenalis (syn. Giardia intestinalis, Giardia lamblia) is known to infect at least 40 host species, including humans (Thompson, 2011). The other species are known to be host specific or have a limited host range: G. agilis in amphibians, G. ardae and G. psittaci in birds and G. microti and G. muris in rodents (Adam, 2001). Currently, G. duodenalis is recognised as a complex of at least eight different assemblages (A–H) (Koehler et al., 2014a; Monis et al., 2003). Although there are little or no morphological differences, there is substantial genetic diversity among these assemblages (Nash et al., 1985; Nash, 1992). Assemblages A and B are described to have a relatively broad host range, including humans and various other mammals. The other assemblages are either host specific or have narrow host ranges. Assemblages C and D are commonly found in dogs, whereas assemblage F mainly infects cats. Assemblage E is found in cloven-hoofed animals, and G is found in rodents (Feng and Xiao, 2011; Xiao and Fayer, 2008). Recently, assemblage H was identified in marine vertebrates (Lasek-Nesselquist et al., 2010). Table 2 Currently recognised species of Giardia and genetic groupings (assemblages) within Giardia duodenalis G. duodenalis Assemblage A Humans, primates, dogs, cats, livestock, rodents, wild mammals Assemblage B Humans, primates, dogs, cattle, some species of wild mammals Assemblage C Dogs, other...