1. Fascioloides magna “Giant Deer Fluke”
Different behavior and pathology in different hosts.

2. Fascioloides magna “Giant Deer Fluke”
Deer and Elk (normal hosts)—Liver migration, then matures in thin-walled fibrous cysts connected with bile ducts. (Well tolerated; eggs shed in feces).

3. Fascioloides magna “Giant Deer Fluke”
Cattle, bison and swine—Liver migration, then encapsulation in thick-walled, closed cysts and no eggs are shed!

4. Fascioloides magna “Giant Deer Fluke”
Sheep and goats: extensive, uninterrupted hepatic migration with out encapsulation; usually fatal; 1 fluke can kill a sheep or goat!

5. Pathology
Pathology in C. sinensis and D. dendriticum: distended bile ducts and erosion of epithelium lining, but no secondary pathology like in F. hepatica!

6. Treatment Praziquantel (except for F. hepatica).
Rafoxanide: is the drug of choice for F. hepatica!

7. Diagnosis Look for eggs in feces! But hard to diagnose (why?).
SPURIOUS INFECTIONS!

8. Aquatic Vegetation
Water Chestnuts

9. Pickled Fish

10. Digestive Tract Trematodes

11. Fasciolopsis buski Humans, pigs Orient Large (7.5 cm)
Life cycle similar to Fasciola

13. Pathology and Symptoms
Severity depends on worm burden
Irritation
Excess mucous secretion
Ulceration, hemorrhage, Abscess
Obstruction
Chronic diarrhea
Sensitization to worm metabolites
Leukocytosis
Anemia
Eosinophilia
Nausea/diarrhea
Edema of face and intestinal wall
Death

14. Treatment
Praziquantel

15. Epidemiology Who gets infected? Rural to semi-urban areas
School age children
Prevalence
57% China
25% Taiwan
50% Bangladesh
60% India
10% Thailand

16. Epidemiology How do you get fasciolopsiasis? Ingest metacercariae
Commercially raised aquatic plants
Water chestnut
Water caltrop
Water hyacinth
Water lotus
Water lily
Watercress

17. Epidemiology Lack of regulation on food industry Food preparation
Sanitation (sewage)
Night soil
Pigs
Habitat
Food

18. Digestive Tract Trematodes
FAMILY ECHINOSTOMATIDAE - intestinal parasites recognized by their anterior collar of spines.
Echinostoma revolutum - Cosmopolitan parasite of birds and mammals– shows low host specificity
Human cases?

19. Morphology of Adult Echinostoma revolutum
Adults are elongate, up to an inch in length.
Characteristic structure is: their circumoral collar of spines arranged in two rows.
37 spines in E. revolutum.
Internal organs are distinct and easy to identify.

20. Morphology of Adult Echinostoma revolutum
Collar of spines around oral sucker
uterus
Vitellaria Testes Mehlis’ gland Ovary

21. Life Cycle of Echinostoma revolutum
Parasite shows low host specificity throughout cycle
1. Adults occur in birds and mammals.
2. Eggs are released via the feces into an aquatic habitat.
3. Miracidia hatch, swim to snail, and penetrate.

22. Life Cycle of Echinostoma revolutum
4. Sporocysts and rediae occur within snail. Cercariae are released.
5. Cercariae penetrate (2nd intermediate hosts) and encyst as metacercariae.
6. Definitive host is infected by ingesting 2nd intermediate
host, metacercariae excyst in stomach, and adults mature
in small intestine.

23. Order Plagiorchiformes
Family Troglotrematidae: these are oval thick flukes with a spiny tegument and dense vitellaria.
Parasites of lungs, intestine, nasal passages, cranial cavities, and various ectopic locations.

24. Nanophyetus salmincola
Fish Eating
Mammal
(Birds)
Freshwater
Snail
Salmonid fish

25. Nanophyetus salmincola
Northwest N. America
Northeast Asia
Crypts of the small intestine
Human infections
98% prevalence in Siberian villages
Pathology

26. Nanophyetus salmincola
Salmon poisoning
Highly pathogenic
Neorickettsia helminthoeca
Rickettsia
Intracellular bacterium
Typhus
Nanophyetus salmincola is a vector for Neorickettsia helminthoeca.

27. Nanophyetus salmincola
Disease
High Fever
Edema of face
Vomiting
Diarrhea
Death in 10 days to 2 weeks.

28. Lung Flukes Paragonimus bronchiolar lumen and peribronchial tissues
Antigenic
Become encapsulated
granuloma

30. Paragonimiasis Paragonimus
9 species in Asia, Sub-Saharan Africa, Central, North and South America
Paragonimus westermani

31. Life cycle of Paragonimus

32. Paragonimus westermani
1st Int. Host
Freshwater snails
Streams
Rice paddies
Melanoides tuberculata

33. Paragonimus cercaria

34. Paragonimus westermani
2nd Int. Hosts:
Potamon
Rice Paddies
Eriocheir
Streams
Larvae develop in brackish water

35. Paragonimus kellicotti
Crayfish serve as 2nd IH in North America.
Metacercariae are found in the heart.

36. Paragonimus A number of birds and mammals are know to serve as PH!
Guinea pigs are known to serve as PARATENIC HOSTS for Paragonimus spp. in South America!

37. Paragonimus spp.

38. Paragonimus westermani
Definitive Hosts

39. Paragonimus kellicotti
Definitive Hosts

40. Chest roentgenogram of a patient with North American paragonimiasis

41. Pathology and Symptoms
Juveniles
Asymptomatic
Adults
Tissue damage
Ciliated epithelium
Inflammatory response
Worms become encapsulated
Fibrosis (Granuloma)
Fibroblasts, eosinophils, lymphocytes
Chest pain, dry cough, rusty sputum, dyspnea etc.
Loss of lung function
Ectopic infections
Eggs
Fibrosis

42. Normal bronchiole
Worm pair

43. Plain skull film of a patient with chronic cerebral paragonimiasis

44. Diagnosis Look for eggs In ________________ Or in ______________
85 X 50 μm

45. Treatment
Praziquantel

46. Epidemiology
How do people get infected?
Infective stage?
Mechanism?

47. Epidemiology
Rice Paddies

48. STRIGEOID TREMATODES - trematodes that inhabit the small intestine of birds and mammals
  Alaria spp. 
Many species of Alaria occur in the small intestine of carnivores.
Alaria canis in dogs.
Alaria americana in foxes.
Alaria mustelae in mink and weasels.
Alaria taxideae in badgers  

49. Morphology of Adult Alaria
Body is divided into 2 regions.
Three suckers are present
Common genital pore is posterior.

50. Life Cycle of Alaria
LIFE CYCLE is unusual in that 3 or 4 hosts may be involved.
 1. Adults in small intestine of carnivore definitive host.
 2. Eggs in feces hatch in water releasing miracidia that penetrate snail first intermediate host.
 3. Cercariae released from snail penetrate a tadpole second intermediate host and transform into an unencysted stage called the Mesocercaria. 1 2 3

52. Life Cycle of Alaria
4. If tadpole is eaten by frogs, snakes, or mice the mesocercariea can serve in these peratenic hosts and mesocercariae undergo no further development.  
5. Carnivore becomes infected by eating tadpole or paratenic host. 5 4

53. Life Cycle of Alaria
6. The mesocercariae penetrate the intestine, burrow through the diaphragm, and reach the lungs. Here they become metacercariae.
7. Metacercariae migrate up the respiratory tree and are swallowed.
Adults in the carnivore's intestine.  
6 & 7

54. Life Cycle of Alaria
In one species, the mesocercariae can be transmitted to juvenile definitive hosts through the milk of the mother!
When a lactating cat ingests mesocercariae, they disseminate throughout the tissues and are transmitted through the milk of the mother to the offspring!

55. Pathology of Alaria infections
PATHOLOGY - Adult parasites cause severe damage to the small intestine of the carnivore.
HUMAN INFECTION – few cases involved infection with mesocercariae!
Most cases involved mesocercariae

56. We had two cases in Asian American men from Chinatown in San Francisco!  

57. What did they eat?

58. Frog Legs

59. Dr. Kevin Kazacos

62. Bullfrog
Over 70% of them were infected with Alaria sp.!

63. Alaria sp. in bullfrog leg muscles

64. Pathology of Alaria infections
PATHOLOGY - Adult parasites cause severe damage to the small intestine of the carnivore.
HUMAN INFECTION – few cases involved infection with mesocercariae!
Most cases involved mesocercariae migrating to the eye
One fatal case occurred in Canada from ingestion of poorly cooked frogs!
Mesocercariae were identified in nearly every organ at autopsy.
Photo shows mesocercaria in lung.

65. Blood Flukes (Schistosomes)
Infect mammals, and birds.
Live in the mesenteric veins (most species); some in urinary plexus veins, nasal veins, and dorsal aorta.

66. Blood Flukes Veins Mesenteric veins Anterior (superior)
Small intestine
Posterior (inferior)
Large intestine
Urinary bladder

67. Schistosoma Small elongate 1-2 cm Dioecious Gynecophoric canal
Male helps female eat

68. Schistosomiasis
Major Parasitic disease, with million people infected.
many are school age children

69. Schistosomiasis Schistosoma Bilharzia Egyptian papyri Egyptian mummies
1850 Theodor Bilharz
Egyptian papyri
Egyptian mummies
Joshua’s curse on Jericho
1800 Napoleon’s army

70. Species that infect humans
Schistosoma japonicum
Anterior mesenteric veins
Schistosoma mansoni
Posterior mesenteric veins
Schistosoma haematobium
Veins draining the urinary bladder
Schistosoma intercalatum
Intestinal schistosomiasis in Africa
Schistosoma mekongi
Small intestine like S. japonicum (Vietnam)

71. } Species Schistosoma japonicum Schistosoma mansoni Big three!
Anterior mesenteric veins
Schistosoma mansoni
Posterior mesenteric veins
Schistosoma haematobium
Veins draining the urinary bladder
Schistosoma intercalatum
Intestinal schistosomiasis in Africa
Schistosoma mekongi
Small intestine like S. japonicum (Vietnam)
Big three!

72. Schistosomiasis Estimates
1947: ,000,000
1968: ,000,000
1972: ,000,000
1979: ,000,000
Current: More than 200,000,000

73. Why the Increase?
Due to irrigation farming and building of dams to facilitate irrigation.
Snail habitat has expanded and increases exposure to people.

74. Life Cycle
Schistosomes live in blood vessels that drain tissues such as the bladder, S. intestine and L. intestine.
They produce eggs within blood vessels!

75. Eggs have spines, no operculum, also have prominent secretory glands!
S. mansoni S. japonicum S. haematobium

76. Eggs
Eggs are shed to outside through excrement (feces or urine).

77. Chemical Signaling with arginine
Life Cycle
Chemical Signaling with arginine
Adults can live years
3 weeks
Release Eggs in 5-8 Weeks

78. Distribution

79. Distribution

80. How do the eggs get out of the body?

82. How do the eggs get out of the body?
Female worm leaves the male and migrates down to lay eggs.

83. How do the eggs get out of the body?
Female worm leaves the male and migrates down to lay eggs.
Egg spines help the eggs work their way into the tissue, but the miracidia also produces enzymes.

84. Granuloma can move with the eggs by peristaltic action.
Immune response
Granuloma
(Eosinophils, macrophages, neutrophils)
Granuloma can move with the eggs by peristaltic action.

85. Schistosomiasis
Big picture the key to schisto pathology is the eggs not the adult worms!