PHYLUM NEMATODA: Round Worms

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PHYLUM NEMATODA Round Worms
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PHYLUM NEMATODA Round Worms I. Anatomy
A. Basic body plan tube within a tube
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PHYLUM NEMATODA Round Worms I. Anatomy
B. Movement -- hydrostatic skeleton --
sinusoidal movement
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Fluid
longitudinal muscles contract region of
body shortens
longitudinal muscles relax region of
body elongates
Fluid
Fluid
Fluid
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PHYLUM NEMATODA Round Worms I. Anatomy
C. Cuticle -- non-living secreted by
hypodermis (epidermis) -- molted 4 times
during development
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PHYLUM NEMATODA Round Worms I. Anatomy
D. Gut -- one cell thick -- no muscles
-- muscular pharynx
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PHYLUM NEMATODA Round Worms I. Anatomy
E. Reproductive system -- separately sexed
1. female system
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oviducts
uterus
vagina
uterus
gut
vagina


ovaries
ovaries
oviducts
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PHYLUM NEMATODA Round Worms I. Anatomy
E. Reproductive system -- separately sexed
1. female system ovary -- germinal zone
oogonia -- growth zone oocyte maturation
Ovary growth zone xs
cytoplasmic bridges
forming oocytes
central rachis
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PHYLUM NEMATODA Round Worms I. Anatomy
E. Reproductive system -- separately sexed
2. male system -- spermatogonia in germinal
zone -- sperm not flagellated -- copulatory
spicules
vas deferens
testis
seminal vesicle
gut

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Copulatory spicules
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PHYLUM NEMATODA Round Worms I. Anatomy
F. Development 1. fertilization -- egg
shell formation -- eutely
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PHYLUM NEMATODA Round Worms I. Anatomy
F. Development 2. molting 5 larval stages
4 molts egg ? L1 (rhabditiform) ? molt 1 ? L2
? molt 2 ? L3 (filariform infective
retains L2 cuticle) ? invades host ? molt 3
? L4 ? molt 4 ? L5 ? adult
L3 filariform larva
L1 rhabditiform larva
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PHYLUM NEMATODA Round Worms I. Anatomy
F. Development 3. hypobiosis L3 ex dog
hookworm, Ancylostoma caninum
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PHYLUM NEMATODA Round Worms II. Taxonomy
A. Trichuris trichiura human whip worm --
in large intestines of human common in children
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PHYLUM NEMATODA Round Worms II. Taxonomy
A. Trichuris trichiura 1. Life cycle
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PHYLUM NEMATODA Round Worms II. Taxonomy
A. Trichuris trichiura 2. Pathology
-- lt 100 worms usually symptomless --
children particularly prone to infection
200-1000 worms -- anemia, growth retardation,
compromised cognitive function -- clubbing of
fingers and toes -- prolapsed rectum
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PHYLUM NEMATODA Round Worms II. Taxonomy
B. Capillaria
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PHYLUM NEMATODA Round Worms II. Taxonomy
B. Capillaria 1. Capillaria hepatica
a. Life Cycle -- host rodents humans cases
recorded -- adult worm in liver eggs
deposited -- eaten by carnivore eggs
liberated and out with feces --
larva develop to L3 inside egg in damp,
shady soil -- egg ingested L3 hatches moves
to liver
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PHYLUM NEMATODA Round Worms II. Taxonomy
B. Capillaria 1. Capillaria hepatica
b. pathology -- liver damage --
gt80 of rats in New York infected -- 28
confirmed cases in humans -- symptoms in
humans similar to other liver diseases
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PHYLUM NEMATODA Round Worms II. Taxonomy
B. Capillaria 2. Capillaria
philippinensis -- gut parasite of piscivorous
birds and humans (zoonosis) a. Life cycle
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egg
L3 (infective)
Sylvatic cycle
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PHYLUM NEMATODA Round Worms II. Taxonomy
B. Capillaria 2. Capillaria
philippinensis b. pathology -- adult
worms repeatedly penetrate gut mucosa
degeneration of gut lining --
malabsorption of food violent diarrhea
-- death is common -- first reported in
1963
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PHYLUM NEMATODA Round Worms II. Taxonomy
C. Trichinella spiralis the trichina
worm -- causes trichinosis -- world wide
distribution more common in northern
hemisphere -- can use any carnivore as host
same animal acts as both IH and DH
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PHYLUM NEMATODA Round Worms II. Taxonomy
C. Trichinella spirallis 1. Life
cycle -- adults embedded in intestinal
mucosa -- females larviposit L1 into blood
stream
male
female
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PHYLUM NEMATODA Round Worms II. Taxonomy
C. Trichinella spirallis 1. Life
cycle -- L1 invade muscle cell encyst --
muscle cell becomes nurse cell downregulation
of genes associated with muscle-specific
proteins upregulation of vascular endothelium
growth factor (VEGF) -- encysted larvae often
become calcified -- L1 can remain viable in
cyst for up to 39 years
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PHYLUM NEMATODA Round Worms II. Taxonomy
C. Trichinella spirallis 1. Life
cycle -- muscle eaten by carnivore L1
digested out of cyst -- penetrates gut mucosa
4 molts ? adult -- adults reach sexual
maturity within 30 hrs. mate males die
females live several weeks
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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• C. Trichinella spirallis
• b. Pathology severity dose dependent
• 1) 3 stages of infection
• Intestinal (penetration) stage adults in gut
  L1 invade gut mucosa
• -- diarrhea cramps vomiting
• Migration stage about 9 days post infection
  large number of L1 enter
• circulatory system and spread throughout body
• -- can cause great pain
• -- preorbital edema
• -- difficulty chewing, swallowing, breathing
• -- can cause heart failure kidney failure
• -- if death occurs, most likely at this stage
• Encystment stage about 6 wks post-
• infection mostly in tongue,

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PHYLUM NEMATODA Round Worms II. Taxonomy
C. Trichinella spirallis b. Pathology
severity dose dependent 2) infection
levels -- heavily infected pork gt
100,000 encysted larvae/oz. -- if ½
female each female liberates 1500 L1 --
one bite of poorly cooked pork ? 1.5 million
larvae in human body -- general rule 5
larvae/g of body weight is fatal
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PHYLUM NEMATODA Round Worms II. Taxonomy
C. Trichinella spirallis b. Pathology
severity dose dependent 3) history
-- infection rate in U.S. used to be 16 because
pigs were fed garbage -- is now 5
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PHYLUM NEMATODA Round Worms II. Taxonomy
D. Dioctophyma renale Giant kidney worm
-- adult female in kidney of mammal host --
eggs out with urine
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PHYLUM NEMATODA Round Worms II. Taxonomy
D. Dioctophyma renale Giant kidney worm
-- egg ingested by aquatic annelid -- hatches
into L1, encysts ? L3 -- annelid swallowed
-- L3 moves to kidneys matures
Aquatic annelid
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PHYLUM NEMATODA Round Worms II. Taxonomy
D. Dioctophyma renale Giant kidney worm
-- completely hollows out kidney
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PHYLUM NEMATODA Round Worms II. Taxonomy
E. Strongyloides stercoralis human thread
worm
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PHYLUM NEMATODA Round Worms II. Taxonomy
E. Strongyloides stercoralis human thread
worm 1. Life cycle can be parasitic or
free living (facultative parasite) --
parasitic forms are all parthenogenetic females
anterior end embedded in gut
mucosa
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PHYLUM NEMATODA Round Worms II. Taxonomy
E. Strongyloides stercoralis human thread
worm 1. Life cycle -- eggs
released -- hatch into L1 (rhabditiform larva)
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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• E. Strongyloides stercoralis human
  thread worm
• 1. Life cycle
• -- fate of L1 rhabditiform
• out with feces develop into infective L3
  (filariform larva)
• out with feces develop into free living L3 ?
  free living female
• and male adults several generations
• ? eventually give rise to infective L3
• develop into L3 filariform before exiting host
  autoinfection
• usually held in check by host immune responses
• exacerbated by corticosteroids

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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• E. Strongyloides stercoralis human
  thread worm
• 1. Life cycle
• -- fate of infective L3 filariform
• Ingested develops into parthenogenetic female
  in gut mucosa
• Penetrates skin of host into blood ? heart ?
  lungs rupture out of alveoli ? up trachea
  swallowed ? become parthenogenetic female in gut

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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• E. Strongyloides stercoralis human
  thread worm
• 2. Pathology
• -- spread by fecal contamination transmammary
• -- most common in warm, moist climates (tropics
  subtropics)
• 3 stages of infection
• invasion stage if L3 penetrate skin, intense
  itching
• pulmonary stage coughing, pneumonia-like
  asthma-like symptoms
• if misdiagnosed and treated with corticosteriods,
  can cause fatal autoinfection
• Intestinal stage can cause severe pain and
  burning
• erode gut mucosa secondary
  infections
• Usually asymptomatic, but can cause death

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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 1. General life cycle
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L3 moves to heart? pulmonary artery ? Lungs ?
rupture from alveoli ? up trachea, swallowed ? gut
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 2. taxonomy a. Necator
americanus New World human hookworm --
accounts for 95 of hookworm disease world
wide -- females lay about 9000 eggs/day
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 2. taxonomy a. Necator
americanus New World human hookworm --
acounts for 95 of hookworm disease world wide
-- females lay about 9000 eggs/day b.
Ancyclostoma duodenale Old World human
hookworm -- Europe, Asia, Africa, India
-- females lay 25,000-30,000 eggs/day
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 2. taxonomy a. Necator
americanus New World human hookworm --
acounts for 95 of hoodworm disease world wide
-- females lay about 9000 eggs/day b.
Ancyclostoma duodenale Old World human
hookworm -- Europe, Asia, Africa, India
-- females lay 25,000-30,000 eggs/day c.
Ancyclostoma caninum dog hookworm
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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• F. Hookworms
• 3. Pathology
• a. Severity of disease depends on
• number of worms
• lt 25 worms asymptomatic
• 25-100 light symptoms
• 100-500 moderate symptoms moderate damage
• 500-1000 severe symptoms and damage
• gt1000 can cause death

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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• F. Hookworms
• 3. Pathology
• a. Severity of disease depends on
• nutritional status
• race whites 10X more susceptible than blacks

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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• F. Hookworms
• 3. Pathology
• b. 3 stages of infection
• cutaneous stage
• when filariform larvae penetrate skin
• usually unnoticed
• non-human species can cause creeping eruption
  (cutaneous larval migrans)

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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• F. Hookworms
• 3. Pathology
• b. 3 stages of infection
• cutaneous stage
• pulmonary stage
• Filariform migrating through lungs
• heavy infections cause severe damage

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• PHYLUM NEMATODA Round Worms
• II. Taxonomy
• F. Hookworms
• 3. Pathology
• b. 3 stages of infection
• cutaneous stage
• pulmonary stage
• intestinal phase
• Adults in gut
• anemia protein deficiencies

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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 3. Pathology c.
consequences of chronic anemia and protein
deficiency
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 3. Pathology c.
consequences of chronic anemia and protein
deficiency -- pica (abnormal cravings)
desire to eat soil (geophagy) Some people
have actually been known to consume White Dirt
regularly and not only like the taste but crave
it. It has been said that the taste of white dirt
is akin to the fresh way that the ground smells
when it's real dry and a little sprinkle of rain
falls. Dirt-eating is an ancient tradition that
is practiced all over the world and although the
demise of the practice has been predicted for
many years, it still persists, particularly in
rural areas of the South. (http//www.whitedirt.co
m/whitedirt.html)
FREE SHIPPING ON ALL ORDERS OVER 60.00.
kaolin
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 3. Pathology c.
consequences of chronic anemia and protein
deficiency -- pica (abnormal cravings)
desire to eat soil (geophagy) -- mental
dullness apathy lethargy -- poor white
trash disease
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 3. Pathology c.
consequences of chronic anemia and protein
deficiency -- poor white trash disease
http//www.jstor.org/view/00224642/di982321/98p042
6v/0 segment of the southern population known
as the clay eaters Early reminiscences and
travel accounts inform us that the clay eaters
were the most degraded of the poor white trash
and lived in the barren and sandy areas of the
Carolinas and Georgia. instantly recognized by
their sickly, sallow, and most unnatural
complexions Ignorant, dirty, shiftless, uncouth,
and morally degraded, they were thoroughly
despised
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Hookworm infection was another noncontagious
disease that was politically volatile. Southern
"crackers" were described as lazy and indifferent
to work. In 1901, Dr. Charles Wardell Stiles
discovered the American hookworm while working
for the U.S. Department of Agriculture and
realized that it was the cause of the anemia that
plagued so many Southern workers. The press
hailed him as the discoverer of the "germ of
laziness."
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1913?
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 3. Pathology d. control
sanitation wearing shoes
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PHYLUM NEMATODA Round Worms II. Taxonomy
F. Hookworms 4. Immunology -- adult
worms IgE activated mast cells -- migrating
larvae humoral response IgA in gut