Biology 625
ANIMAL PARASITOLOGY
Fall semester lecture note outline

Updated: 24 September 1999

1. two embryonic membranes
2. oncospheres without flame cells
3. oligolecithal eggs (minimal vitelline component, with shell formed by embryo)
4. oncospheres not ciliated and maturing in utero, except Trypanorhynchs
5. nine orders in this taxon

Order: Nippotaeniidea (do not learn for class)

1. Scolex with single apical sucker
2. Neck short or absent
3. Strobila small
4. Proglottids each with single set of reproductive organs
5. Genital pores lateral
6. Testes anterior; ovary posterior
7. Vitelline gland singular; compact; located between testes and ovary
8. In FW teleost fish in Japan, Russia, New Zealand
9. Small group; only one family Nippotaeniidae and a handful of species
10. No life-cycles known

Order: Lecanicephalidea (do not learn for class)

1. Scolex divided into anterior and posterior regions by transverse groove
2. Anterior portion of scolex either with a cushion-like structure or with fine tentacles, which can be withdrawn into the posterior portion of the scolex forming a large, sucker-like organ
3. Posterior of scolex usually with 4 suckers
4. Neck present or absent
5. Testes numerous
6. Ovary posterior
7. Vitellaria follicular, either lateral or encircling proglottid
8. Uterine pore usually present
9. No hooks
10. In elasmobranchs, especially rays; fairly small group with 3 families
11. No life-cycles known

Order: Aporidea (do not learn for class)

1. Scolex with simple suckers or grooves, with armed rostellum
2. Constrictions between proglottids absent; proglottids only differentiated by internal structures
3. Cirrus, Mehlis gland, Ootype, and genital ducts and pores all absent
4. Most hermaphroditic; few dioecious
5. Vitelline cells mixed with ovarian cells
6. No life-cycles known
7. Single family: Nematoparataeniidae
   1. Nematoparataenia spp.
      1. 4 suckers
      2. 1000 small hooks on rostellum
      3. in small intestine of some Anseriform birds in Australia, Europe
   2. Apora spp.
      1. Scolex with 4 narrow, long grooves
      2. 10 hooks on scolex, no suckers
      3. Found in an anatid bird in Russia
   3. Gastrotaenia spp.
      1. Scolex with no grooves
      2. 10 hooks on scolex, no suckers
      3. In anatid birds in Russia, North and South America

Order: Diphyllidea (do not learn for class)

1. Scolex with armed or unarmed peduncle (short stalk)
2. Two spoon-shaped bothridia present, lined with small spines
3. Apex of scolex with insignificant apical organ or with large rostellum bearing dorsal and ventral groups of T-shaped hooks
4. Acraspedote proglottids
5. Genital pores posterior, midventral
6. Testes numerous, anterior
7. Ovary posterior
8. Vitellaria follicular, either lateral or surrounding other organs
9. Uterine pore absent
10. Uterus tubular or saccular
11. Parasites of elasmobranchs
12. Two families: Ditrachybothridiidae and Echinobothriidae; about two dozen species described total
13. No life-cycles known

Order: Litobothridea (do not learn for class)

1. Scolex a single, well-developed apical sucker
2. Anterior proglottids modified to form cruciform shape in cross section
3. Neck absent
4. Single set of reproductuve structures per proglottid
5. Proglottids craspedote
6. Testes numerous and preovarian
7. Genital pores lateral
8. Ovary with two or four lobes, posterior
9. Vitellaria follicular
10. Parasites of Elasmobranchs (Thresher sharks in Pacific)
11. Single family, Litobothridae, and only a handful of species
12. No life-cycles known

Order: Trypanorhyncha

1. Scolex elongate
2. Two or four bothridia on scolex
3. Four eversible and armed tentacles (few atrophied) armed with hooks that can be retracted into internal sheath
4. Neck present or absent
5. Genital pores usually lateral
6. Testes numerous
7. Ovary posterior
8. Vitellaria follicular, either lateral or cortical
9. Uterine pore present or absent
10. Oncotaxy (identify species based on arrangement of hooks on tentacles)
11. Parasites of elasmobranchs, many families, genera, and species
12. Only a couple life-cycles known

Lacistorhynchus dollfusi and Lacistorhynchus tenuis

1. Adults of the first species in leopard sharks; in leopard sharks and dogfish sharks for the latter
2. Life-cycle (1989, J. Parasitol. 75: 806-808)
   1. Adults in spiral valve
   2. Eggs out with proglottids
   3. Coracidia hatch
   4. Eaten by copepods
   5. Procercoids
   6. Ingested by teleosts (i.e. croakers)
   7. Pleurocercoids form
   8. Eaten by definitive host
   9. Mature in gut

Order: Tetraphyllidea

1. Scolex with highly variable shaped bothridia
2. Sometimes with hooks, spines, or suckers
3. Hermaphroditic; rarely dioecious
4. Genital pores usually lateral
5. Testes numerous
6. Ovary posterior
7. Vitellaria follicular, usually lateral
8. Uterine pore present or absent
9. Vagina crosses vas deferens
10. Parasites of elasmobranchs; four families but many genera and species
11. No complete life-cycles known; pleurocercoids in molluscs, crustacea, and fish (1978, Proc Helminthol Soc Wash 45: 132-134)

Order: Protocephalidea

1. Scolex with 4 suckers, often with prominent apical organ
2. Armed rostellum sometimes present
3. Neck usually present
4. Genital pores lateral
5. Testes numerous
6. Ovary posterior
7. Vitelline glands follicular, usually lateral
8. Uterine pore either present or absent
9. Eggs of most species float and are ingested; no ciliated coracidium
10. flame cells absent in most, if not all, oncospheres
11. Procercoid with well developed scolex; sometimes referred to as pleurocercoid I; with cercomer. Cermomer lacking embryonic hooks. Procercoid directly infective for definitive host in most cases; only some species have pleurocercoids
12. Paratenic hosts very common
13. Parasites of fish, amphibia, or reptiles
14. Two families; numerous species
15. Good review of the genus Proteocephalus (1999, J. Helminthol 73: 1-19)
16. Typical species include Corallobothrium fimbriatum in catfish, Acanthotaenia shipleyi in varanid lizards, and those presented below

Proteocephalus ambloplites

1. In bass in North America; also bowfin, yellow perch
2. Life-cycle
   1. Adults in gut
   2. Proglottids with eggs released
   3. Eggs ingested by copepods
   4. Hatch; oncosphere crosses gut
   5. Procercoid develops 4 suckers
   6. Eaten by lepomid (i.e. pumpkinseed sunfish; young bass)
   7. Pleurocercoid; matures in coelom
   8. Eaten by definitive host
   9. Matures
3. If pleurocercoid immature and eaten by definitive host, migrates to coelom and often enters gonads. When it matures, can cause parasitic castration of fish

Ophiotaenia perspicua

1. In Nerodia rhombifer and Nerodia sipedon (water snakes); Thamnophis sirtalis in North America
2. Life-cycle
   1. Adults in gut
   2. Eggs passed in feces
   3. Ingested by copepod
   4. In about 14 days, procercoid forms
   5. Eaten by tadpoles
   6. Pleurocercoids form in liver, mesenteries
   7. Anuran metamorphosis into adult frog (pleurocercoids may break out into the coelom)
   8. Eaten by snake
   9. Matures

Order: Cyclophyllidea

1. Scolex usually with 4 suckers
2. Rostellum present or absent; if present, armed or unarmed
3. Neck present or absent
4. Strobila usually with distinct segments
5. Monecious (rarely dioecious, in Dioecocestidae, which are parasites in some aquatic birds)
6. Genital pores lateral (except in the Mesocestoididae)
7. Vitelline gland singular and compact (except double in Mesocestoididae)
8. Vitelline gland posterior to ovary (except in Tetrabothriidae)
9. Uterine pore absent
10. Single ovary; 1-100 testes
11. Numerous families and species
12. In amphibia, reptiles, birds, and mammals

Mesocestoides corti (Family: Mesocestoididae)

1. No complete life-cycle yet known
2. Definitive hosts birds or mammals
3. Second intermediate hosts rodents, reptiles, and occasionally amphibia; cyticercoid-type larval stage occurs termed a tetrathyridium (long slender body but invaginated scolex with 4 suckers)
4. Eggs not infective to the known intermediate hosts (i.e. rodents, reptiles, or amphibia). Thus, probably a first intermediate host.
5. One isolate of Mesocestoides corti has tetrathyridium that undergoes fairly rapid longitudinal binary fission of the scolex. Other isolates do not do this, at least to this degree.
6. A couple of reports of cysticercoids developing in free-living in mites Russia when fed eggs. Not yet reproduced.
7. Scolex with 4 suckers
8. No rostellum or hooks
9. Each proglottid with one set of female and male reproductive organs
10. Genital pores mid-ventral
11. Paruterine organ (fibromuscular organ) replaces true uterus

Raillietina cesticillus (Family: Davaineidae)

1. Large rostellum with hundreds of tiny, hammer-shaped hooks
2. Strobila long
3. Poultry parasite in North America
4. Life-cycle
   1. Adults in chickens (and other birds)
   2. Proglottids with eggs released in feces
   3. Eggs ingested by beetles
   4. Cysticercoid forms
   5. Eaten by definitive host; matures
5. Heavy infections can cause weight loss, diarrhea, and death in birds
6. Similar species
   1. Other Raillietina spp. in mammals, especially rodents
   2. Davainea spp. in galliform birds and uses terrestrial molluscs as intermediate hosts. Strobila short.

Moniezia expansa; Moniezia benedeni (Family: Anoplocephalidae)

1. The whole family tends to have a large, unarmed scolex, large strobila, and proglottids that are wider than long
2. In ruminants worldwide
3. No rostellum or hooks
4. Two sets of reproductive organs, marginal, with marginal genital pores
5. Life-cycle
   1. Adults in gut
   2. Eggs passed in proglottids
   3. Eaten by oribatid mites
   4. Cysticercoid forms in about four months
   5. Ingested by definitive host
   6. Adults in gut, about 600 cm long, in 5-6 weeks
6. May cause intestinal obstruction in heavy infections; weight loss

Thysanosoma actinioides (Family: Anoplocephalidae)

1. "Fringed tapeworm"
2. Lives in bile ducts and pancreatic ducts, small intestine, of sheep, cattle, and deer in North America
3. Strobila 15-30 cm x 8 mm
4. Segments elongate, wider than long, with frilled posterior margin
5. Life-cycle
   1. Adults in bile ducts and pancreatic ducts, small intestine
   2. Eggs out with feces
   3. Eaten by Psocid lice (live on vegetation)
   4. Cysticercoid
   5. Eaten by definitive host; matures
6. Can obstruct flow of bile; condemation of livers during meat inspections

Hymenolepis diminuta (Family: Hymenolepidae)

1. "Rat tapeworm"
2. Small-medium sized worms; up to 90 cm long
3. Unarmed rostellum present (but, most members of family armed)
4. Life-cycle
   1. Adults in domestic rats worldwide
   2. Eggs out with feces
   3. Ingested by over 90 species of arthropod (especially grain beetles)
   4. Cysticercoid forms
   5. Eaten by definitive host; matures

Vampirolepis (syn. Rodentolepis) nana (syn. Hymenolepis nana) (Family: Hymenolepidae)

1. "Dwarf tapeworm"
2. Armed rostellum; rostellum permanently protruded
3. Life-cycle
   1. Adults in rodents, especially old world rats; primates
   2. Eggs out with feces
   3. Eggs eaten by arthropod
      1. Cysticercoid
      2. Eaten by rodent or primate
      3. Matures into adult worm
   4. Eggs eaten by rodent or primate; sometimes hatch before eggs exit the outside world
      1. Oncosphere penetrates mucosa of gut
      2. Enters villi
      3. Cysticercoid forms
      4. In 5-6 days, cysticercoid emerges
      5. Matures
4. Prevalence about 1% in humans in North America; 8-9% in South America
5. Numbers can build up tremendously because some eggs can hatch in the gut and cause "autoinfection." Gut inflammation.

Dipylidium caninum (Family: Dilepididae)

1. Occurs in small intestine in dogs, cats, occasionally humans
2. Each proglottid with 2 sets of male and female reproductive organs and a genital pore on either side
3. Armed rostellum that is retractable
4. Life-cycle
   1. Adults in gut
   2. Proglottids in feces
   3. Eggs encapsulated in uterine membranes in packets
   4. Ingested by arthropod; especially fleas
   5. Cysticercoid
   6. Eaten by definitive host; matures

Family: Taeniidae (one of the largest families of terrestrial cestodes)

1. Most with rostellum that is armed with 1-2 circles of hooks
2. Rostellum, if present, not retractable
3. Strobila usually medium-large in size
4. Radial striations (air pores) in egg shells
5. In mammals. Representative species as follows:

Taenia saginatus (Family: Taeniidae)

1. "Beef tapeworm"
2. Cosmopolitan
3. 10-75 feet long; scolex unarmed (armed cysticercus)
4. Life-cycle
   1. Adults in small intestine of humans
   2. Proglottids in feces
   3. Dry; rupture; eggs released
   4. Eaten by bovids
   5. Cysticercus in muscles (about 2 months)
   6. Eaten by definitive host
   7. Matures in gut
5. Famous opera singer Maria Callas is reputed to have harbored this parasite. Most sources claim she accidently acquired the infection by eating steak and liver tartare. One account claims she may have ingested gelatin capsules containing larvae as a method of weight loss, although other sources claim this to be untrue.

Taenia solium (Family: Taeniidae)

1. "Pork tapeworm"
2. Cosmopolitan
3. 6-30 feet long; scolex armed
4. Life-cycle
   1. Adults in small intestine of humans
   2. Proglottids in feces
   3. Dry; rupture; eggs released
   4. Eaten by swine
   5. Cysticercus in muscles (about 2 months)
   6. Eaten by definitive host
   7. Matures in gut
5. Cysticercosis in humans
   1. Eggs ingested by humans, or eggs produced by adult worm in gut hatch in gut
   2. Oncosphere crosses gut, enters other tissues throughout body
   3. Cysticerci form in humans

Other Taenia spp. (Family: Taeniidae)

1. Taenia multiceps
   1. Definitive hosts canids; intermediate hosts sheep
   2. Coenurus forms, may enter brain and cause neurological problems
   3. Especially Australia and New Zealand
2. Taenia serialis
   1. Definitive hosts canids; intermediate hosts rodents and lagomorphs
   2. Coenurus forms, may enter brain and cause neurological problems
   3. In North America
3. Taenia pisiformis
   1. Definitive hosts canids; intermediate hosts rabbits
   2. Cysticerci throughout peritoneum/viscera
   3. In North America and elsewhere
4. Taenia taeniaeformis
   1. Definitive hosts felids; intermediate hosts rats and mice
   2. Strobilicerci in liver; may cause cancer
   3. In North America and elsewhere

Echinococcus granulosus (Family: Taeniidae)

1. Worldwide
2. Small tapeworm; scolex and 3-4 segments
3. 3-6 mm long; often in high numbers in the intestine
4. Genital pore equatorial on proglottids; 45-65 testes
5. Scolex armed; with rostellum
6. Life-cycle
   1. Adults in gut of carnivores; especially canids (dogs, coyote, dingo, wolf); also in felids
   2. Eggs in feces
   3. Ingested by herbivores; i.e. sheep, moose, reindeer, swine, camels, wallaby, etc.
   4. Unilocular hydatid cyst with many protoscolices; gradual growth; maturation in 5-6 years
   5. Eaten by carnivore
   6. In slightly under 2 months, many adult worms

Echinococcus multilocularis (Family: Taeniidae)

1. Boreal in distribution; Europe, Asia, North America down to Nebraska; introduced into South Carolina, Iowa, Ohio, South America, New Zealand, etc.
2. Small tapeworm; scolex and 3-4 segments
3. 1.2-3.7 mm long; often in high numbers in the intestine
4. Genital pore pre-equatorial; 15-30 testes
5. Scolex armed; with rostellum
6. Life-cycle
   1. Adults in gut of canids, especially in foxes; occasionally in felids
   2. Eggs in feces
   3. Ingested by voles
   4. Multilocular hydatid cyst with many protoscolices; gradual growth; maturation in about 2 months; cyst often invasive in abnormal hosts
   5. Eaten by carnivore
   6. In slightly under 2 months, many adult worms
7. Recent epidemiological survey in the midwest (2002, J. Parasitol. 88: 420-422).

Other Echinococcus spp.

1. Echinococcus vogeli
   1. South America (esp. Venezuela, Colombia, Equator, Panama)
   2. Canids, felids definitive hosts. One common host the bush dog, Speothus venaticus.
   3. Intermediate host is the paca (Cuniculus paca), a rodent
   4. Polycystic hydatid disease
2. Echinococcus oligarthrus
   1. South America (esp. Venezuela, Brasil, Panama, Central America)
   2. Felids main definitive hosts
   3. Intermediate hosts paca, opossum, spiny rats, agouti, rabbits