THE ROUNDWORMS

1
THE ROUNDWORMS
Phylum Nematoda
2
GENERAL CHARACTERISTICS

• - 80,OOO SPECIES (MAY BE 50,000 STILL
  UNDISCOVERED)
• - MOST ARE FREE-LIVING
• -LAND, MARINE, AQUATIC
• - 150 PARASITIC SPECIES (50 IN HUMANS)
• - SEPARATE SEXES
• - PSEUDOCOLOMATES
• - SIZE 1 mm to 120 cm (4 ft.)

3
MAJOR SIGNIFICANCE

• DIGESTIVE SYSTEM
• - 2 OPENINGS
• - AREAS OF SPECIALIZATION ALONG THE TRACT

4
SPECIFIC NEMATODES

• 1. ASCARIS
• - PARASITIC
• - HOSTS PIGS, HORSES, HUMANS
• - LIVE IN THE INTESTINES
• - CAN BLOCK INTESTINES
• - ADULT FEMALE CAN GROW TO 1 FT. (MALES ARE MUCH
  SMALLER!)
• - ADULT MALE HAS HOOKED POSTERIOR END THAT IS
  USED TO HOLD FEMALE DURING MATING
• - FEMALE CAN PRODUCE 200,000 EGGS A DAY!!!

5
Ascaris taken from an intestine
6
(No Transcript)
7
ASCARIS LIFE CYCLE

• - FERTILIZED EGGS LEAVE HOST VIA FECES (CAN
  SURVIVE IN SOIL FOR YEARS WITHOUT HIGH TEMPS. OR
  DIRECT SUNLIGHT)
• - ENTER HOST BY INGESTING CONTAMINATED FOOD OR
  H2O
• - EGGS DEVELOP INTO LARVAE IN THE INTESTINE

8
ASCARIS LIFE CYCLE CONTD

• - LARVAE BORE INTO BLOODSTREAM ARE CARRIED TO
  LUNGS THROAT
• - LARVAE ARE COUGHED UP SWALLOWED AND RETURN TO
  INTESTINES
• - MATURES MATES IN THE INTESTINE
• INFECTION
• IF SEVERE INFESTATION.AIR PASSAGES CAN BE
  BLOCKED SMALL BLOOD VESSELS COULD BLEED.

9
2. HOOKWORMS

• - PARASITIC
• - MOUTH WITH CUTTING PLATES THAT CLAMP TO
  INTESTINE WALL
• - FEED ON HOSTS BLOOD
• - CAN CAUSE ANEMIA
• - IN CHILDREN, CAN CAUSE SLOW MENTAL GROWTH
• - HOST HUMANS
• - INFECT 400 MILLION WORLDWIDE (90
  TROPICAL/SEMITROPICAL)

10
HOOKWORMS
11
Hookworm mouth
12

• Hookworm
• mouth

13
HOOKWORM LIFE CYCLE

• - EGGS ARE RELEASED THROUGH HOSTS FECES
• - EGGS PRODUCE LARVAE IN WARM, DAMP SOIL
• - ENTER HOST BY BORING THROUGH FEET gtgtgt TRAVEL
  THROUGH BLOOD TO LUNGS THROAT
• - HOST COUGHS SWALLOWS TO INTESTINES WHERE THEY
  DEVELOP INTO ADULTS

14
3. TRHICHINELLA

• - HOSTS HUMANS OTHER MAMMALS (PIGS)
• - LIVE EMBEDDED IN HOSTS INTESTINE WALLS
• LIFE CYCLE
• - LARVAE TRAVEL THROUGH BLOOD TO MUSCLES, FORM
  CYSTS
• - HOSTS BECOME INFECTED BY EATING UNDERCOOKED,
  CONTAMINATED MEAT
• - INGESTED CYSTS RELEASE LARVAE WHICH BURROW INTO
  INTESTINAL WALLS THEN DEVELOP INTO ADULTS

15
Trichina entering a muscle cell
16
TRICHINOSIS

• - DISEASE FROM TRICHINELLA
• - CAUSES MUSCLE PAIN STIFFNESS
• - CAN CAUSE DEATH IF LARGE NOS. ARE IN HEART
  MUSCLE
• - RARE IN U.S. BECAUSE
• 1. FEED SCRAPS ARE COOKED PRIOR TO FEEDING PIGS
• 2. INSPECTORS EXAMINE PORK FOR CYSTS
• 3. FREEZING MEAT DURING PACKING KILLS THE WORMS

17
4. PINWORMS

• - PARASITIC
• - HOSTS 16 ADULTS, 30 KIDS
• - DO NOT CAUSE SERIOUS DISEASE
• - ABOUT .5 LONG RESEMBLE WHITE THREADS
• - CAUSE ITCH AROUND NOSTRILS RECTUM

18
(No Transcript)
19
PINWORM LIFE CYCLE

• - LIVE MATE IN LOWER INSTESTINE
• - AT NIGHT, FEMALES LEAVE INTESTINE LAY EGGS ON
  SKIN AROUND YOUR RECTUM
• - THIS CAUSES ITCHING, SCRATCHING SPREADS EGGS TO
  ANYTHING THE PERSON TOUCHES
• - SWALLOWED EGGS HATCH IN THE INTESTINE DEVELOP
  INTO ADULTS
• - MEDS TAKES CARE OF INFECTION

20
5. FILARIAL WORMS

• - DISEASE CAUSING
• - 250 MILLION PEOPLE IN TROPICAL COUNTRIESARE
  INFECTED
• A. ONE TYPE LIVES IN LYMPHATIC SYSTEM OF HUMANS
• - ADULTS CAN BE 4 LONG
• - DISEASE ELEPHANTIASIS - LARGE NUMBERS OF THIS
  WORM BLOCK LYMPH VESSELS CAUSING SWELLING IN
  ARMS, LEGS, AND CONNECTIVE TISSUE

21
(No Transcript)
22
Elephantiasis in heel

• Filarial worm

23
Asian woman with elephantiasis
24
ELEPHANTIASIS LIFE CYCLE

• - LARVAE ENTER THE BLOOD ARE TRANSFERRED TO
  MOSQUITOES
• - IN MOSQUITOES THEY DEVELOP INTO THE INFECTIVE
  STAGE
• - INFECTIVE STAGE IS INJECTED INTO A NEW HOST BY
  MOSQUITO
• - INSIDE THE NEW HOST THEY DEVELOP SETTLE INTO
  LYMPHATIC SYSTEM
• B. HEARTWORMS THAT LIVE IN THE HEART LARGE
  ARTERIES OF DOGS

25
Filarial worm leaving a boys leg
26
Phylum Rotifera
27
Rotifers

• 1,750 species
• Free-living, aquatic, transparent
• Microscopic, males are much smaller than females
• Can survive w/out H2O for long periods dry up
  and resemble grains of sand
• Feed on algae, bacteria, protozoans

28
Rotifer feeding on algae
29
Structures

• Crown of cilia sweep food into mouth and
  digestive tract
• Mastax muscular organ that breaks up food
• Cloaca common chamber which empties
  reproductive, digestive, and excretory systems
• Cephalization eyespot, cerebral ganglion