title: Multi-host model-based identification of Armillifer agkistrodontis (Pentastomida), a new zoonotic parasite from China.
abstract: BACKGROUND
  Pentastomiasis is a rare parasitic infection of humans. Pentastomids are dioecious obligate parasites requiring multiple hosts to complete their lifecycle. Despite their worm-like appearance, they are commonly placed into a separate sub-class of the subphylum Crustacea, phylum Arthropoda. However, their systematic position is not uncontested and historically, they have been considered as a separate phylum.
  
  
  RESULTS
  An appraisal of Armillifer agkistrodontis was performed in terms of morphology and genetic identification after its lifecycle had been established in a multi-host model, i.e., mice and rats as intermediate hosts, and snakes (Agkistrodon acutus and Python molurus) as definitive hosts. Different stages of the parasite, including eggs, larvae and adults, were isolated and examined morphologically using light and electron microscopes. Phylogenetic and cluster analysis were also undertaken, focusing on the 18S rRNA and the Cox1 gene. The time for lifecycle completion was about 14 months, including 4 months for the development of eggs to infectious larvae in the intermediate host and 10 months for infectious larvae to mature in the final host. The main morphological difference between A. armillatus and Linguatula serrata is the number of abdominal annuli. Based on the 18S rRNA sequence, the shortest hereditary distance was found between A. agkistrodontis and Raillietiella spp. The highest degree of homology in the Cox 1 nucleic acid sequences and predicted amino acid sequences was found between A. agkistrodontis and A. armillatus.
  
  
  CONCLUSIONS
  This is the first time that a multi-host model of the entire lifecycle of A. agkistrodontis has been established. Morphologic and genetic analyses supported the notion that pentastomids should be placed into the phylum Arthropoda.
authors.affiliation: National Institute of Parasitic Disease, Chinese Center for Disease Control and Prevention, WHO Collaborating Center of Malaria, Schistosomiasis and Filariasis, Shanghai, People's Republic of China.
authors.forename: Shao-Hong
authors.initials: SH
authors.lastname: Chen
authors.forename: Qin
authors.initials: Q
authors.lastname: Liu
authors.forename: Yong-Nian
authors.initials: YN
authors.lastname: Zhang
authors.forename: Jia-Xu
authors.initials: JX
authors.lastname: Chen
authors.forename: Hao
authors.initials: H
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Chen
authors.forename: Peter
authors.initials: P
authors.lastname: Steinmann
authors.forename: Xiao-Nong
authors.initials: XN
authors.lastname: Zhou
mesh_terms: D017836:Agkistrodon; D000818:Animals; D017821:Boidae; D002681:China; D016000:Cluster Analysis; D051545:Cyclooxygenase 1 / Q000235:genetics; D004275:DNA, Ribosomal / Q000737:chemistry / Q000235:genetics; D006801:Humans; D008018:Life Cycle Stages; D051379:Mice; D008969:Molecular Sequence Data; D010272:Parasitic Diseases / Q000469:parasitology*; D010273:Parasitic Diseases, Animal / Q000469:parasitology*; D057078:Pentastomida / Q000033:anatomy & histology* / Q000235:genetics* / Q000472:pathogenicity; D010802:Phylogeny; D012337:RNA, Ribosomal, 18S / Q000235:genetics; D051381:Rats; D017422:Sequence Analysis, DNA; D015047:Zoonoses / Q000469:parasitology*
chemical_list: D004275:DNA, Ribosomal; D012337:RNA, Ribosomal, 18S; D051545:Cyclooxygenase 1
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