Biology 625
Fall semester lecture note outline

Updated: 24 September 1999

The text below simply represents a crude lecture outline of one of the topics covered in class. It is not meant to substitute for attending lectures or ignoring the textbook. Additional material, including line drawings, kodachromes, and more extensive information on life-cycles and basic biology, will be supplied in the lectures.

Topic #23. The Order: Spirurida (spiruroids)

  1. This is a diverse group which use arthropod intermediate hosts.
  2. Probably a polphyletic group
  3. Most females produce eggs with fully developed L1s; develop to L3s in arthropod intemediate host

SUBORDER: Camallanina (2 superfamilies and 7 families)

Camallanus oxycephalus (Superfamily: Camallanoidea; Family: Camallanidae)

  1. In picivorous and planktonivorous fish (i.e. bass, perch, drum, smelt, shiners, crappie, alewife) in North America
  2. Buccal capsule has been replaced with a pair of large, clam-shaped valves used to clamp down upon the host mucosa.
  3. Gravid "reddish" females protrude from anus and rupture, releasing L1s
    1. Ingested by copepods; penetrate gut
    2. Molt 2x to L3s
    3. Eaten
    4. Molt 2x into adults

Dracunculus insignis (Superfamily: Dracunculoidea: Family: Dracunculidae)

  1. In dermis of raccoons, canids, mustelids, and other carnivores in North America
  2. Life-cycle
    1. Females inder skin; ankles/wrists common
    2. L1s released when tissues contact water
    3. Larvae ingested by copepods; mature to L3
    4. Ingested by definitive host
    5. Cross gut; migrate through tissues
    6. Males and females mature; copulate; male dies
    7. Female migrates to skin, completes last remaining level of maturation in route
  3. Many species have males that are as yet unknown
  4. Similar species include Dracunculus medinensis in humans; D. ophidensis in garter snakes

Philometroides nodulosa (Superfamily: Dracunculoidea: Family: Philometridae)

  1. In skin of the head and fins in suckers in North America
  2. Cuticle covered with bosses (Philometra spp. smooth)
  3. Mouth small; esophagus short; no sclerotized buccal capsule
  4. Life-cycle
    1. Females under skin
    2. Release L1s into water
    3. Eaten by copepod; mature to L3s
    4. Eaten by definitive host
    5. Cross gut and enter tissues
    6. Mate and mature; males die; migrate to dermal tissues

SUBORDER: Spirurina (9 superfamilies and 20 families)

  1. Diverse group
  2. All species use arthropod intermediate hosts. Gnathostomes that use copepods; other taxa use insects or various crustacea.
  3. Most have L1 larvae with cephalic hooks and spines

Superfamily: Gnathostomatoidea

  1. Small group
  2. Very large and complex pseudolabia, and often spinous cephalic inflations
  3. Four genera occur in lower vertebrates; Gnathostoma spp. occur in mammals

Gnathostoma procyonis (Family: Gnathostomatidae)

  1. In tumorous growths in stomach wall of raccoons
  2. Life-cycle
    1. Females produce unembryonated eggs with prominent swelling at one end
    2. Embryonate in water
    3. L2s hatch from eggs
    4. Ingested by copepods
    5. Develop to L3
    6. Ingested by fish
    7. Do not molt, but grow and apparently mature since L3s in copepods not infective for definitive host; encapsulate in muscles
    8. Paratenic hosts can be used (i.e. frogs, snakes, lizards, turtles, birds, alligator, bowfin, mammals)
    9. Ingested by raccoons
    10. L3s cross gut, undergo 2-4 month tissue migration
    11. Return to stomach; mature in 3-6 months post-infection
    12. Other related species
      1. Echinocephalus spp. (elasmobranchs)
      2. Gnathostoma doloresi (stomach of swine in Asia)
      3. Gnathostoma spinigerum (stomach of cats and dogs in Asia)
      4. Tanqua spp. (reptiles)

Superfamily: Physalopteroidea

  1. Consists of 7-8 genera, but only Physaloptera spp. have been well studied
  2. Mainly in stomach of reptiles, birds, mammals
  3. Attach to gastric mucosa with large dentate pseudolabia
  4. Collarette a distinctive feature, which presses into the mucosa
  5. Eggs tend to ovoid, with thick smooth shells and a fully developed L1
  6. Life-cycles
    1. Females attached to stomach
    2. Eggs out with feces
    3. Ingested by arthropods
    4. Hatch; invades wall of gut; becomes encapsulated
    5. Grows and molts to L3
    6. Paratenic hosts may be employed such as snakes, birds
    7. Ingested by definitive host
    8. Attach to stomach wall; grow and mature into adults
  7. Representative species
    1. Physaloptera hispida (cotton rats in North America)
    2. Physaloptera maxillaris (skunk in North America)
    3. Physaloptera praeputialis (felids worldwide)
    4. Physaloptera rara (coyotes in North America)
    5. Skrjabinoptera phrynosoma (horned toads)
    6. Turgida turgida (opossums in the Western hemisphere)

Superfamily: Rictularioidea (no need to learn taxon)

  1. Lacks pseudolabia
  2. Possess a denticulate, hexagonal oral opening and a large buccal cavity with teeth
  3. Large body spines common
  4. Worms free in lumen, or attached to gut wall
  5. Arthropods as intermediate hosts
  6. i.e. Pterygodermatites coloradensis in rodents in North America

Superfamily: Thelazioidea (3 families)

  1. Diverse biology
  2. Hexagonal mouth; lack lips; buccal cavity well developed

Thelazia californiensis (Family: Thelaziidae)

  1. Parasite of dogs, sheep, deer, coyotes, cats, and bears in North America
  2. Life-cycle
    1. Adults in orbit of the eye
    2. Eggs embryonate in utero, and L1s deposited into lachrymal secretions
    3. Muscid flies pick up (ingest) larvae
    4. Encapsulate and molt 2x to L3s
    5. Mature L3s break out of capsule, move to head of fly
    6. When fly feeds around eyes of another host, larvae exit and enter orbit
    7. Mature into adults
  3. Similar species
    1. Oxyspirura mansoni in chickens, ducks, and passeriforms worldwide
    2. Thelazia lacrymalis in equids in Europe, Asia, and North and South America

Superfamily: Spiruroidea (4 families and 21 genera)

  1. Mainly in stomachs in birds and mammals
  2. All species produce thick shelled eggs containing L1 larvae. The larvae all possess a cephalic hook and rows of tiny spines around a blunt anterior end
  3. Eggs hatch in gut of an insect, invade hemocoel, mature into L3, and encapsulate
  4. Paratenic hosts common
  5. Definitive hosts become infected by ingesting third stage larvae
  6. Representative species
    1. Ascarops strongylina in stomach of swine worldwide
    2. Gongylonema ingluvicola in esophagus of quail in North America
    3. Gongylonema pulchrum in mouth and esophagus of large herbivorous mammals worldwide
    4. Protospirura numidica in stomach and esophagus of carnivores and rodents worldwide
    5. Vigisospirura potekhina in stomach of carnivores in North America
    6. Spirocerca lupi
      1. Adults in tumors in esophagus, stomach, dorsal aorta of canids
      2. Eggs out into gut through aperatures
      3. Ingested by arthropods, especially beetles
      4. Mature to L3 in arthropods
      5. Paratenic hosts common, especially chickens; both birds and mammals
      6. Ingested by canids
      7. Larvae penetrate gut wall; migrate through tissues to aorta
      8. Attach to aorta and migrate through wall of blood vessel; extensive tissue damage to wall of aorta
      9. Mature into young adults (9-10 weeks)
      10. Migrate to esophageal wall; tissue hyperplasia to form tumors containing the worms
      11. Highly pathogenic, and can result in host death; correlated with esohageal and aortic sarcomas in canids

Superfamily: Habronematoidea

  1. Diverse group
  2. Pseudolabia small
  3. Median lips present
  4. All species use arthropod intermediate hosts
  5. Females of some genera (i.e. Tetrameres and Microtetrameres) expand to a very large size when gravid
  6. Representative species
    1. Habronema microstoma in horses and uses stable flies as intermediate hosts
    2. Habronema muscae in horses and use muscid flies as intermediate hosts
    3. Microtetrameres centuri in proventriculus meadowlarks
    4. Microtetrameres helix in proventriculus corvids
    5. Tetrameres americana (=T. confusa?) in proventriculus of quail and chickens
    6. Tetrameres crami in proventriculus of ducks
    7. Spinitectus micracanthus (transverse, denticate rings around anterior ends of body) in intestine of bluegills

Superfamily: Acuariodea (no need to learn taxon)

  1. Medium to small worms
  2. Mainly in gizzard, proventriculus, sometimes esophagus, of birds (few in mammals)
  3. Cordons at anterior end

Superfamily: Aproctoidea (no need to lerarn taxon)

  1. Small to medium-sized worms
  2. In air sacs and nasal cavities, subcutaneous tissues of head and neck, and orbits of birds

Superfamily: Diplotriaenoidea (no need to learn taxon)

  1. Large worms
  2. In air sacs of reptiles and birds

Superfamily: Filarioidea

  1. In tissues and tissue cavities of all classes of vertebrates except fish
  2. Cephalic structures simple
  3. Pseudolabia absent
  4. Cephalic papillae well developed
  5. All transmitted by blood-sucking arthropods
  6. Many (but not all) species with endosymbiotic rickettsia, Wolbachia spp., in hypodermis, oocytes, and microfilariae
    1. transovarian transmission
    2. often essential for worm fertility. Antibiotics, i.e. tetracycline derivitives, that deplete the bacteria cause reduction in worm fertility
    3. endotoxin produced, resulting in recruitment of neutrophils and enhanced immunopathology. Much of the pathology associated with filarid infections seems to be associated with the rickettsia
  7. Two families
    1. Filariidae
      1. small to medium size
      2. vulva anterior the nerve ring
      3. elicit skin lesions and release eggs or larvae that attract arthropod vectors, mainly flies
      4. small group, few genera
      5. representative species, all in mammals
        1. Parafilaria spp. in various herbivores
        2. Stephanofilaria stilesi in cattle
          1. Adult worms in dermis, along mid-ventral line
          2. Lesions with with microfilariae release by female
          3. Microfilariae ingested from lesions by horn flies
          4. Develop to L3 in fly
          5. L3 migrate to proboscis of fly
          6. When flies feed, L3s deposited
          7. Lesions with worms appear on cattle 2 weeks post- infection
    2. Onchocercidae
      1. various sizes, some up to one meter in length
      2. blood or skin inhabiting microfilariae that are transmitted by arthropods that themselves pierce the skin and suck blood
      3. some microfilariae exhibit periodicity
      4. 70-80 genera, many species
      5. Typical life-cycle
        1. Adults produce microfilariae
        2. Ingested by arthropod vector
        3. Microfilariae develop to L3s
        4. Larvae migrate anteriorly in arthropod
        5. L3 enter definitive host when arthropod takes a blood meal
        6. Worms mature; mate; females produce offspring
      6. Representative genera and species
        1. Acanthocheilonema reconditum (=Dipetalonema reconditum) (subcutaneous tissues of canids; microfilariae in blood and unsheathed; vectors fleas)
        2. Brugia beaveri (lymphatics of raccoon; microfilariae in blood and sheathed; mosquito vectors)
        3. Brugia malayi (adults in lymphatics of humans; microfilariae in blood and sheathed; mosquito vectors)
        4. Chandlerella quiscali (in pia mater of cerebrum of grackles; microfilariae in blood and are sheathed; vectors midges)
        5. Dirofilaria immitis (right ventricle, pulmonary artery, right atrium, and vena cava of canids; microfilariae in blood and unsheathed; mosquitos vectors)
        6. Dirofilaria ursi (subcutaneous in bears; microfilariae in blood and unsheathed; vectors are blackflies)
        7. Elaeophora schneideri (adults coiled in carotids of deer and elk; microfilariae in blood and sheathed; vectors tabanids)
        8. Litomosoides carinii (pleural and body cavity of cotton rats; microfilariae in blood and are sheathed; vectors are rat mites)
        9. Loa loa (wandering subcutaneous adults in humans; microfilariae in blood and sheathed; deer flies used as vectors)
        10. Mansonella llewellyni (subcutaneous tissue of raccoons; microfilariae in blood; vectors midges)
        11. Molinema sprenti (= Dipetalonema sprenti) (peritoneum and pleural cavities of beaver; microfilariae in blood and unsheathed; vectors mosquitos)
        12. Onchocerca cervicalis (in nodules of neck ligaments of horses; microfilariae migrate throughout skin and are unsheathed; vectors midges)
        13. Onchocerca gutturosa (in nodules of neck; femuro-tibia of cattle; microfilariae migrate throughout skin and are unsheathed; vectors blackflies)
        14. Onchocerca lienalis (in gastro-splenic region of cattle; microfilariae migrate throughout skin of belly and are unsheathed; vectors blackflies)
        15. Onchocerca reticulata (in nodules of fetlock ligaments of horses; microfilariae migrate throughout skin and are unsheathed; vectors midges)
        16. Onchocerca volvulus (in nodules in dermis of humans; microfilariae migrate throughout skin and are unsheathed; vectors blackflies)
        17. Setaria labiatopapillosa (peritoneal cavity of cattle and many other large herbivores worldwide; microfilariae in blood and sheathed; vectors mosquitos)
        18. Waltonella spp. (body cavity/mesentery of anurans; microfilariae in blood and sheathed; vectors mosquitos)
        19. Wuchereria bancrofti (adults in lymphatics of humans; microfilariae in blood and sheathed; vectors moquitos)
      7. I ran across an old Tahitian spell to inflict elephantiasis upon an enemy. You simply mix urine of an infected person with food and feed it secretly to your enemy. Your enemy will then (supposedly) develop elephantiasis

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