1. Paragonimus spp.

3. Paragonimus westermani
Definitive Hosts

4. Paragonimus kellicotti
Definitive Hosts

5. Chest roentgenogram of a patient with North American paragonimiasis

6. 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

7. Normal bronchiole
Worm pair

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

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

10. Treatment
Praziquantel

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

12. Epidemiology
Rice Paddies

13. 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  

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

15. 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

17. 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

18. 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

19. 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!

20. 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

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

22. What did they eat?

23. Frog Legs

24. Dr. Kevin Kazacos

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

28. Alaria sp. in bullfrog leg muscles

29. 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.

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

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

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

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

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

35. 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)

36. } 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!

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

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

39. 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!

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

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

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

43. Distribution

44. Distribution

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

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

47. 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.

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

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