Axenic Culture and Characterization of Giardia ardeae from the Great Blue Heron (Ardea herodias)

Abstract

Trophozoites of Giardia ardeae were obtained from the great blue heron (Ardea herodias) and established in axenic culture using the TYI-S-33 medium. The generation time in culture for G. ardeae was 22-25 hr, which was 3-fold longer than for Giardia duodenalis (WB strain). A morphological comparison of trophozoites in the original intestinal isolate to those grown in culture revealed that they were identical for the following characteristics: a pyriform-shaped body, a ventral adhesive disc with a deep notch in the posterior border, teardrop-shaped nuclei, pleomorphism in median body structure ranging from a round-oval appearance (Giardia muris type) to that of a clawhammer (G. duodenalis type), and a single caudal flagellum on the right side (as viewed dorsally) with the left one being rudimentary. Analysis of the chromosomal migration patterns was performed by orthogonal-field-alternation gel electrophoresis and demonstrated that the pattern for G. ardeae was distinctly different from that for G. duodenalis (Portland 1-CCW strain). Bacterial symbionts were seen attached to trophozoites in the original isolate but could not be detected in cultured trophozoites using scanning electron microscopy, fluorescence light microscopy using the Hoechst 33258 dye for DNA localization, or by standard microbiological techniques using nonselective media for growing aerobic or anaerobic bacteria. This study demonstrated that avian-derived Giardia could be grown in axenic culture; based on morphological criteria and chromosomal migration patterns, that G. ardeae should be considered a distinct species; and that rationale for determining Giardia spp., based on median body structure alone, should no longer be considered adequate for classification at the species level.

Giardiasis in a White Stork in The Netherlands

“…found in the white stork, closely resembled G. ardeae observed in herons. The apparently single caudal flagellum, the deeply notched adhesive disk, the shape and position of the median body, and the nuclei were in accordance with those reported for G. ardeae of gray heron and great blue heron (Georgi et al, 1986;Erlandsen et al, 1990;Forshaw et al, 1992). The morphological characteristics of the trophozoites found in our white stork chick support the classification of these parasites within the G. ardeae group.…”

“…possessing a single caudal flagellum, which was found in a gray heron (Ardea cinerea) and was named G. ardea (Kulda and Nohý nková, 1995). More recently, G. ardeae was isolated from the great blue heron (A. herodias) and characterized genetically (Erlandsen et al, 1990). Phenotypically identical Giardia spp.…”

“…Phenotypically identical Giardia spp. were observed in the green heron (Butorides virescens), the purple heron (A. pupurea), the cocoi heron (A. cocoi) and in several species of egrets (Erlandsen et al, 1990;Kulda and Nohý nková , 1995). An Australian Giardia sp.…”

“…This assay utilizes monoclonal antibodies against a 65 kDa Giardia Specific Antigen glycoprotein (GSA 65), which is produced by the proliferating G. intestinalis trophozoites in the hosts intestinal tract and is present in both trophozoites and cysts in the stool of giardiasis patients (Rosoff and Stibbs, 1986). Experimental efforts to infect mammalian hosts with G. ardeae, or to infect avian hosts with G. intestinalis were unsuccessful (Erlandsen, 1994). Giardia sp.…”

Giardia duodenalis cysts of genotype A recovered from clams in the Chesapeake Bay subestuary, Rhode River.

“…5,7 In the wild, a wide variety of aquatic and semiaquatic mammals and birds 8 can be a source of waterborne Giardia cysts. 5,9,10 Studies on giardiasis in a variety of birds suggest they may be zoonotic reservoirs; 7,[9][10][11][12] however, these indications have not been proven. 13 As reviewed by Hopkins and others, 14 numerous studies demonstrated genetic and antigenic similarities among Giardia cyst isolates from humans and other mammalian hosts.…”