1. Parasites: Invertebrates

2. Classification

3. Invertebrates
35 phyla of invertebrates
Half are entirely marine

4. Classification by Developmental Pattern
Multicellular invertebrates are divided into two groups based upon the number of germ layers formed during embryogenesis.
Germ layers are groups of cells that behave as a unit during early embryonic development and give rise to distinctly different tissue systems in the adult.

5. Germ Layers Diploblastic animals have two germ layers.
Ectoderm (outermost layer)
Endoderm (innermost layer)
Triploblastic animals have three
germ layers
Ectoderm
Mesoderm
Endoderm
Purple sponge
Fuchsia flatworm

6. Triploblastic Animals
Triploblastic animals are further classified by their internal body cavity
Coelomate
Acoelomate: No internal body cavity
Pseudocoelomate: fluid-filled cavity between endoderm and mesoderm
Coelomate: internal, fluid-filled cavity between endoderm and mesoderm, lined with mesoderm

7. Acoelomate
flatworm
Pseudocoelomate
roundworm
Coelomate
Leech

8. Coelomate

9. Kingdom Animalia Sub-kingdom Invertebrata
I. Phylum Platyhelminthes (flatworms)
Tapeworms, flukes, and non-parasitic flatworms
II. Phylum Nematoda
Roundworms, hookworms, threadworms
III. Phylum Annelida
segmented worms
IV. Phylum Arthropoda
Ticks, mites, lice

11. Phylum Platyhelminthes (Flatworms)
A. Class Cestoda -tapeworms
 1. Taenia ­pisiformis – dog or cat tapeworm
B. Class Trematoda - Flukes
2. Clonorchis sinensis - liver fluke
3. Fasciolopsis buski - giant intestinal fluke
4. Schistosoma mansoni- blood fluke
C. Class Turbellaria - free-living flatworms, not parasitic
5. Planaria spp.

12. Tapeworms
Tapeworms are missing their entire digestive system. Therefore, the best place for them to live are in the intestines. Thus, they need a structure to latch onto the intestine.
Scolex (head): has suckers and hooks to grab onto the mucosa of the intestine.
Segmented into sections
The sections are called proglottids. Each proglottid has all of the organs within it. The segments are narrow like ribbons. They are muscular, so each segment can wiggle.
Gravid proglottids (filled with eggs).

13. Class Cestoda -tapeworms
Taenia ­pisiformis -dog or cat tapeworm Head (scolex) Suckers Hooks Segments (proglottids) Testes Ovaries

14. Tapeworm Scolex (head) with suckers and hooks

15. Tapeworm Segments (proglottids)

16. Tapeworm
Uterine branches in proglottid

19. Tapeworm Diseases 1. TAENIASIS (Pork and Beef)
2. CYSTICERCOSIS (Pork only)
3. Dog and cat tapeworms:
diarrhea and gas

20. Tapeworm Diseases TAENIASIS
This form of disease can be from either pork or beef intestinal infections. It is usually asymptomatic, mild GI pain, but you may see the proglottids wiggling in the stool.
CYSTICERCOSIS
This is caused by pork tapeworms only. It is much more serious, even life-threatening. The Tania egg is ingested by the fecal-oral route. Larvae embed in any tissue (esp. muscle, brain, eye). Once ingested, the eggs hatch and invade.
Dog and cat tapeworms: mild symptoms of diarrhea and gas

21. Tapeworms inside intestines

23. Fluke Diseases
Flukes differ from tapeworms in that they are non-segmented.
They live in tiny veins in humans called venuoles.
The large number of eggs is what causes the damage in the human.
They cause granulomas (inflammatory lesions).
These granulomas can occur in the brain, spinal cord, liver, and many other organs.

24. Class Trematoda - Flukes
Clonorchis sinensis - liver fluke
Oral sucker
Pharynx
Intestines (cecum)
Uterus
Testes

25. Clonorchis sinensis -liver fluke

26. Class Trematoda - Flukes
Fasciolopsis buski - giant intestinal fluke
Mouth (for feeding)
Ventral sucker (for attachment)
Intestines (cecum)
Testes

27. Fasciolopsis buski giant intestinal fluke

28. Class Trematoda - Flukes
Schistosoma mansoni
Female blood fluke:
Ventral sucker (for attachment)
Ovary
Mouth (for feeding)

29. Schistosomiasis
The blood fluke is called Schistostoma. “Schisto” means “split” and “soma” means opening.
The male’s body is split into a gynecohoric canal; this is where the females live. The female is smaller and lives within the male her whole life.
She lays thousands of eggs a day.

30. Schistosoma
Male
Female

31. Schistosoma mansoni Blood fluke

32. Schistosoma mansoni Blood fluke: Female and Male

33. Blood Fluke Diseases
Schistosomiasis
Swimmer’s Itch

34. Schistosomiasis
Schistosomiasis kills 1-2 million people per year; it’s almost as bad as malaria. It is a tropical disease. It is also known as “Male menstruation” because there is a bladder fluke which causes hematuria (blood in the urine). When Napoleon invaded Egypt, his men got this disease and called it the Curse of the Pharaoh.
Many people are asymptomatic, but the acute form (Katayama’s Fever) can occur weeks later, manifesting with fever, coughing, nausea, vomiting, diarrhea, hepatosplenomegaly, and eosinophilia (excess eosinophils, a type of white blood cell that responds to parasitic infections).

35. Schistosomiasis The schistosomulae migrate to the veins:
The females are smaller and live inside the male.
They deposit eggs in the small venules.
The eggs are moved progressively toward the lumen of the intestine and are eliminated with feces or urine.

36. Schistosomiasis
Human contact with water is necessary for infection by schistosomes.  Skin penetration is required.
Symptoms include: Katayama fever, granulomas (occasionally in brain or spinal cord).

37. Schistosomiais

38. SWIMMER’S ITCH This is the only schistosome disease in the USA.
It is caused by a schistosome that should have a bird as a host, but humans can become an accidental host. An infected duck passes the eggs in the water. Humans who are swimming in late July and August are more likely to get this.
Since the organism cannot live in humans, it dies under the skin after it penetrates. This causes an itchy reaction. The treatment is oral trimeprazine and topical cortisone (anti-inflammatory) creams. The prevention is to rub your skin hard with a towel as soon as you get out of the water to prevent the worms from penetrating.

39. Swimmer’s Itch

40. Schistosomiais: Swimmer’s Itch

42. Class Turbellaria - free-living flatworms (not parasitic)
Planaria spp.
Pharynx
Eyespots (light sensitive)
Gastrovascular cavity

43. Planaria

44. Planaria

45. Kingdom Animalia Sub-kingdom Invertebrata
I. Phylum Platyhelminthes (flatworms)
Tapeworms, flukes, and non-parasitic flatworms
II. Phylum Nematoda
Roundworms, hookworms, threadworms
III. Phylum Annelida
segmented worms
IV. Phylum Arthropoda
Ticks, mites, lice

46. Phylum Nematoda roundworms
Enterobius vermicularis – pinworm
Female
Mouth
Pharynx

47. Pinworm
Female

48. Pinworm
Pharynx
Alae (mouth)

49. Pinworm adult
Mouth
Pharynx
Eggs

50. Pinworm Disease: Enterobiasis
This is the most common roundworm in the USA, but the best one to have because it produces the least symptoms. It has a simple life cycle; humans are the only host.
The males are smaller than the female. Male tails have specialized ornamentation that are shaped into a curl which allows the male to clasp the female during copulation. The male tail also has spicules to allow attachment to the female.
The female then migrates to the rectum, crawls out onto the skin, and deposits eggs on the perianal folds. This causes itching, called anal pruritis. Self-infection occurs by transferring infective eggs to the mouth with hands that have scratched the perianal area.  This occurs more often in children since they don’t wash their hands as well. The eggs are sticky. Person-to-person transmission can also occur through handling of contaminated clothes or bed linens or contact with contaminated curtains, carpeting, etc.

51. Pinworm

53. Phylum Nematoda roundworms
Ascaris lumbricoides - intestinal round worm- (plastimount)
Male
Female

54. Ascariasis It is the biggest worm.
A female may produce approximately 200,000 eggs per day, which are passed with the feces and are ingested from soil contamination. The larvae are very migratory. They can end up in the lungs and may crawl out the nose. They develop into adults in the intestine. A heavy worm load can lead to intestinal blockage, with a bolus of worms inside; may need surgical removal.
This is the largest worm pathogen, so there are no slides. We do have the entire specimen in a plastic container.
This worm should be considered for the Hall of Fame for two reasons:
It is the biggest worm.
It causes the most infections of all the Helminthes world-wide.

55. Ascariasis

56. Ascaris: Male and Female

57. Dog and Cat Roundworms
Toxocara canis and Toxocara cati are roundworms that infect dogs and cats, but humans can become an accidental host. Preschool children are most often affected, since it is spread by ingestion of contaminated dirt.
They cause a disease in humans called Visceral larva migrans (VLM).

58. Visceral Larva Migrans (VLM)
The larvae migrate from the intestines to other tissues, especially the liver.
Most people become only mildly ill.
Others can have severe symptoms, such as brain damage, respiratory failure, cardiac arrhythmias, or eye lesions that resemble cancer or retinal detachment.

59. “My worm collection”

61. Phylum Nematoda roundworms
Necator americanus- American hookworm
Teeth
Muscular pharynx
Male
Posterior bursa
Rays

62. Male hookworm

63. Hookworm teeth
Necator americanus

64. Posterior bursa of Male Hookworm
Function is for copulation

65. Posterior bursa and rays of Male Hookworm
Function is for copulation

66. Hookworm Diseases
The larvae travel to the heart, then to the lungs, where they penetrate the alveoli, make their way up the trachea, up to the epiglottis, and then they are swallowed. They live in the small intestine lumen. They attach to the mucosa by either teeth or cutting flakes, which causes bleeding and persistent anemia. The patient may also have cardiac symptoms.
In the southern US, there is a condition known as “pica”, which is a desire to eat soil. This is caused from an iron deficiency in the diet, sometimes because of a hookworm infection.
The male has a feathered copulatory bursae,on the tail and the female’s tail is just pointy.

67. Dog and Cat Hookworms Ancylostoma braziliense
Humans are accidental hosts.
The lavae create serpentine tunnels.
Lesions are very red (erythemic) and itchy (pruitic).
If they migrate to the lungs, it is called Loeffler’s syndrome.

68. Dog and Cat Hookworms: Cutaneous Larva Migrans
This is when a dog or cat hookworm gets into a human by accident. Since we are not the right kind of host, the worm dies under the skin and causes an allergic reaction.

69. Phylum Nematoda roundworms
Trichinella spiralis- threadworm encysted in muscle
Cyst
Muscle
Larva

70. Trichinellosis
Humans are infected when eating improperly processed meat. The larvae migrate to the skeletal muscles where they encyst.
There are very few cases of this disease in the USA because by law, pigs are not allowed to free-graze. If they eat an infected rodent, they can get the disease and pass it on to humans. Pigs are fed only grains to deter them from a desire to eat meat. However, sometimes they eat each other’s tails!
Within the US, this disease is most common in Alaska, where wild bear meat might be undercooked. The bears can be infected.

71. Trichinella cyst

72. Trichinella cysts
Muscle
Larvae
Cyst

73. Trichinella

74. Kingdom Animalia Sub-kingdom Invertebrata
I. Phylum Platyhelminthes (flatworms)
Tapeworms, flukes, and non-parasitic flatworms
II. Phylum Nematoda
Roundworms, hookworms, threadworms
III. Phylum Annelida
segmented worms
IV. Phylum Arthropoda
Ticks, mites, lice

75. Phylum Annelida segmented worms
Class Hirudinea
Leech (Hirudo medicinalis)
Anterior sucker (for cutting skin)
Mouth (for feeding)
Intestine
Posterior sucker (for attachment)

76. Leech

77. Leech Leeches have been used as a medicinal agent for centuries.
They were first used in ancient Egypt to bleed people of “bad blood” that they thought was causing illness.
In medieval times, they were used in conjunction with blood letting by incisions.
They are used today for patients with finger amputations, to keep the veins open until the finger can be reattached because their saliva has anesthesia and prevents clotting.

78. Leech The leech has two suckers:
The posterior sucker attaches to the host
The anterior sucker makes a slit in the host’s skin so it can suck the blood.
The leech can take in up to 5 times its weight in blood.
Leeches are only used for one person for medicinal purposes, then they are destroyed to prevent disease transmission.

79. Kingdom Animalia Sub-kingdom Invertebrata
I. Phylum Platyhelminthes (flatworms)
Tapeworms, flukes, and non-parasitic flatworms
II. Phylum Nematoda
Roundworms, hookworms, threadworms
III. Phylum Annelida
segmented worms
IV. Phylum Arthropoda
Ticks, mites, lice

80. Phylum Arthropoda (Jointed feet)
Class Arachnia (ticks and mites)
Class Insecta (fleas and lice)

81. Dermacentor spp.- tick Head Thorax Abdomen Legs
Class Arachnia

83. Hard Ticks Soft Ticks Have a hard body
Mouth parts are visible from the top surface
Feed for days
Soft Ticks
Have a soft, leathery body
Mouth parts are on the bottom surface
Feed from minutes to hours

84. Diseases Transmitted by Hard Ticks
Dermacenter
Ehrlichiosis (Ehrlichia spp)
Rocky Mountain Spotted Fever (Rickettsia rickettsii)
Ixodes
Lyme Disease (Borrelia burgdorferi)
Babbesiosis (Babesia microti; USA protozoa)
Amblyomma
Ehrlickiosis
Diseases Transmitted by Hard Ticks

85. Rocky Mountain Spotted Fever
Ehrlichiosis
Fever, headache, fatigue, and muscle aches
Rocky Mountain Spotted Fever
Fever, headache, abdominal pain, vomiting, and muscle pain. A rash may also develop, but is often absent in the first few days, and in some patients, never develops.  Rocky Mountain spotted fever can be a severe or even fatal illness if not treated in the first few days of symptoms.

86. Lyme Disease Babesiosis
Fever, headache, fatigue, and a characteristic skin rash called erythema migrans. If left untreated, infection can spread to joints, the heart, and the nervous system.
Babesiosis
Fever, chills, sweating, myalgias (muscle aches), fatigue, hepatosplenomegaly (enlargement of the liver and spleen) and hemolytic anemia (anemia due to break-up of red cells). Symptoms typically occur after an incubation period of 1 to 4 weeks and can last several weeks. The disease is more severe in patients who are immunosuppressed, splenectomized (lack their spleen), or elderly. It can cause death.

87. Diseases Transmitted by Soft Ticks
Ornithidoros
Endemic relapsing fever (Borrelia hermsii)
High fever, rigors, severe headache, muscle pains, weakness, anorexia, weight loss, and cough. Systemic complications can include nausea, vomiting, upper abdominal pain due to liver and spleen involvement, and a dry cough. Other manifestations include splenomegaly, hepatomegaly, jaundice, rash, respiratory symptoms, and central nervous system involvement.
Diseases Transmitted by Soft Ticks

88. Tick Diseases Tick paralysis More common in children than adults.
It is an ascending flaccid paralysis, accompanied by fever and toxemia (toxins in their saliva) that can lead to respiratory compromise and death.
Tick Diseases

89. Sarcoptes scabiei - itch mite Mouth Legs Bristles on rear legs Bristles on abdomen
Class Arachnia

90. Scabies Scabies is an itchy, highly contagious skin disease.
Mites are small eight-legged parasites (in contrast to insects, which have six legs).
They are tiny, just 1/3 millimeter long. The mite is harmless, but causes an allergic reaction when it burrows into the skin to produce intense itching (pruitis), which tends to be worse at night.
They prefer thin skin like the areas between the fingers, and the bends of the elbows, wrists, and knees. They can move one inch a minute.
They are sometimes transmitted by contact with contaminated gym equipment.
Scabies

91. Itch Mite

92. Dermatophagoides spp.- dust mite
Thorax
Legs
Abdomen
Class Arachnia

93. Dust mites feed on organic detritus such as flakes of shed human skin.
They are a common cause of asthma and allergic symptoms. The mite's gut contains potent digestive enzymes that persists in their feces and are major inducers of allergic reactions such as wheezing. The mite's exoskeleton can also contribute to allergic reactions.
A dust mite allergy can range from mild to severe. A mild case of dust mite allergy may cause an occasional runny nose, watery eyes and sneezing. In severe cases, the condition may be ongoing, or chronic, resulting in persistent sneezing, cough, congestion, facial pressure or severe asthma attack.

94. Dust Mite

95. Phylum Arthropoda Class Arachnia (ticks and mites)
Class Insecta (fleas and lice)

96. Class Insecta
Flea Head Thorax Abdomen Legs

97. Fleas are vectors for diseases
Fleas do not live on their hosts. They take their blood meal and return to their nest (carpet, etc).
Bubonic plague (Yersinia pestis)
Wiped out almost 1/3 of Europe
Still have outbreaks from rodent population on West Coast (Squirrels in San Bernardino)
Endemic typhus (Rickettsia typhi)
Rodents in Texas
The fleas that are vectors for the above diseases prefer to use a rodent for a host.
Tapeworms in pets
When the dog or cat ingests the flea, it ingests the eggs and larvae inside the flea.

98. Class Insecta
Pediculus humanis corporus - human body louse Abdomen Thorax Head Antennae (for feeling) Eyes Plates (protection) Legs

99. Human Body Louse

100. Human Body Louse Nests in the seams of clothing, and lays eggs there.
It comes out for a blood meal.
They are associated with crowded, unsanitary conditions, such as during war, famines, and natural disasters.
Diseases Transmitted by Body Lice
Epidemic Typhus (Rickettsia prowasekii)
Relapsing Fever (Borrelia recurrentis and B. hermsii)
Treatment
Clothing must be treated with insecticide or dry cleaning.
In the old days, they would boil the clothes.
The host also is also treated with Lindane solution and washed off 4-24 hours later.

101. Class Insecta
Pthirus pubis- crab louse
Thorax
Abdominal segments
Eyes
Legs
Antennae

102. Crab Louse

103. Crab Louse
Crab lice tend to infest human pubic hair. The species may also live on other areas with hair, including the eyelashes.
They feed exclusively on blood.
Humans are the only known hosts.
The main symptom is itching, usually in the pubic-hair area, resulting from hypersensitivity to louse saliva, which can become stronger over two or more weeks following initial infestation.
Pubic lice usually infect a new host only by close contact between individuals, usually through sexual intercourse because they primarily spread through sweat, body fluids. Parent-to-child infestations are more likely to occur through routes of shared towels, clothing, beds or closets. Adults are more frequently infested than children.