Biology 625
ANIMAL PARASITOLOGY
Fall semester lecture note outline

Updated: 24 September 1999

1. with cilia, or ciliary organelles, at some stage in life-cycle; subpellicular ciliature is present even when cilia themselves are absent
2. most species with 2 types nuclei
   1. large macronucleus, multicopy, ellipsoidal, dumb-bell or U-shaped
   2. 1-more micronuclei, single copy, involved in sexual reproduction
3. asexual reproduction typically by transverse binary fission; some species with multiple fission or budding
4. sexual reproduction by conjugation
5. most species with contractile vacuole
6. most free-living; a few are parasitic
7. some taxonomists divide the ciliates into multiple phyla. However, most make distinctions at superclasses and/or class levels. You will not be tested over the various ciliate taxa; only individual species.
   1. Superclass: Postciliodesmatophora
      1. Class: Karyorelictea
      2. Class: Spirotrichea (includes the heterotrichs, hypotrichs, and stichotrichs)
   2. Superclass: Rhabdophora
      1. Class: Prostomatea
      2. Class: Litostomatea (includes the trichostomatids and haptorians)
   3. Superclass: Cyrtophora
      1. Class: Phyllopharyngea (includes the chonotrichs, suctorians, and phyllopharyngians)
      2. Class: Oligohymenophorea (includes the oligohymenophorans, hymenostomes, tetrahymenans, peritrichs, sessilidans, astomatids, and apostomatids)
      3. Class: Colpodea
8. life-cycles of parasitic species
   1. typically involving transverse binary fission; sexual reproduction by conjugation
   2. some species form cysts

Nyctotherus spp. (class: Spirotrichea; order: Clevelandellida)

1. conspicuous and well developed undulating membrane extends from anterior end deep into cytopharynx
2. body ciliature tiny and arranged in longitudinal rows
3. large and ellipsoidal, trophozoites up to 200 micrometers long; cysts produced
4. macronucleus very large; micronucleus small
5. many species, including N. cordiformis in the colon of anurans and N. ovalis in cockroaches and millipedes

Balantidium coli (class: Litostomatea; order: Vestibuliferida)

1. cilia over body, with more dense cilia near apical end
2. vestibulum (depression) leading into cytostome at apical end
3. large macronucleus with small micronucleus
4. trophozoites large, up to 150 micrometers in length; yellowish or greenish in appearence
5. in colon of swine and primates; some isolates infect guinea pigs, rats, and other mammals
6. cysts spheroidal, 40-60 micrometers in diameter
7. occasionally can invade mucosa, causing inflammation and ulceration, diarrhea and weight loss
8. other members of the genus in invertebrates, fish, amphibia, ostriches, and mammals

Entodinium spp. (class: Litostomatea; order: Entodiniomorphida)

1. posses large ciliary tufts (fused cilia) whereas most of body is devoid of cilia
2. numerous related species in other genera
3. commensals in rumen of herbivores; other species in large intestine of horses and primates
4. ruminal cilates in Kansas bison (1988, Appl Environment Microbiol 54: 2733-2736)

Ichthyophthirius multifilis (class: Oligohymenophorea; order: Hymenostomatida)

1. body dense with cilia
2. buccal cavity well defined on ventral surface
3. trophozoites large, up to 1 mm in diameter, with large macronucleus and single micronucleus
4. life-cycle
   1. mature trophozoites (trophonts) encysted in skin of freshwater fish
   2. rupture free; settle on the bottom
   3. encysts
   4. undergoes multiple transverse binary fissions, producing hundreds of cells termed tomites
   5. tomites rupture from cyst, and these free swimming stages are now termed theronts (about 40 micrometers in length)
   6. burrows into skin of new fish via a conical area at the anterior end
   7. gradually grows while in skin; some speculation about conjugation occurring between newly penetrating theronts and established trophozoites
   8. multiplies in skin of fish, perhaps by transverse binary fission, so that a cluster of trophonts eventually ruptures out (1988, J Protozool 35: 549-552)
5. heavy infections result in excess mucus production, skin irritation, and ulceration of skin
6. similar species include Ichthyophthirus marinus and Cryptocaryon irritans in marine fish

Epistylis spp. (class: Oligohymenophorea; order: Sessilida)

1. colonial ciliates, with stalks; several related genera
2. often colonize skin, gills, and fins of fish; carapace and skin of turtles

Trichodina spp. (class: Oligohymenophorea; order: Mobilida)

1. individual ciliates with aboral scopula, a structure at the posterior pole that functions as a holdfast (basal adhesive disc); ring of sclerotized teeth that aid in penetration located within disc
2. oral ciliature prominent; somatic ciliature reduced
3. oral membranelles present
4. mobile; settle down and attach using basal disc
5. species destinguished by number, shape, and arrangement of the teeth
6. generally non-pathogenic; heavy infections on gills may cause ulcerations
7. typical species
8. Trichodina californica on gills of salmon
9. Trichodina urinicola in urinary bladder of amphibia