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Fascioloides magna “Giant Deer Fluke”
Different behavior and pathology in different hosts.
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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).
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Fascioloides magna “Giant Deer Fluke”
Cattle, bison and swine—Liver migration, then encapsulation in thick-walled, closed cysts and no eggs are shed!
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Fascioloides magna “Giant Deer Fluke”
Sheep and goats: extensive, uninterrupted hepatic migration with out encapsulation; usually fatal; one fluke can kill a sheep or goat!
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Pathology Pathology in C. sinensis and D. dendriticum: distended bile ducts and erosion of epithelium lining, but no secondary pathology like in F. hepatica!
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Treatment Praziquantel (except for F. hepatica).
Rafoxanide: is the drug of choice for F. hepatica!
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Diagnosis Look for eggs in feces! But hard to diagnose (why?).
SPURIOUS INFECTIONS!
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Aquatic Vegetation Water Chestnuts
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Pickled Fish
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Digestive Tract Trematodes
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Fasciolopsis buski Humans, pigs Orient Large (7.5 cm)
Life cycle similar to Fasciola
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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
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Treatment Praziquantel
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Epidemiology Who gets infected? Rural to semi-urban areas
School age children Prevalence 57% China 25% Taiwan 50% Bangladesh 60% India 10% Thailand
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Epidemiology How do you get fasciolopsiasis? Ingest metacercariae
Commercially raised aquatic plants Water chestnut Water caltrop Water hyacinth Water lotus Water lily Watercress
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Epidemiology Lack of regulation on food industry Food preparation
Sanitation (sewage) Night soil Pigs Habitat Food
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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.
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Nanophyetus salmincola
Fish Eating Mammal (Birds) Freshwater Snail Salmonid fish
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Nanophyetus salmincola
Northwest N. America Northeast Asia Crypts of the small intestine Human infections 98% prevalence in Siberian villages Pathology
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Nanophyetus salmincola
Salmon poisoning Highly pathogenic Neorickettsia helminthoeca Rickettsia Intracellular bacterium Typhus Nanophyetus salmincola is a vector for Neorickettsia helminthoeca.
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Nanophyetus salmincola
Disease High Fever Edema of face Vomiting Diarrhea Death in 10 days to 2 weeks.
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Lung Flukes Paragonimus bronchiolar lumen and peribronchial tissues
Antigenic Become encapsulated granuloma
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Paragonimiasis Paragonimus
9 species in Asia, Sub-Saharan Africa, Central, North and South America Paragonimus westermani
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Life cycle of Paragonimus
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Paragonimus westermani
1st Int. Host Freshwater snails Streams Rice paddies Melanoides tuberculata
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Paragonimus cercaria
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Paragonimus westermani
2nd Int. Hosts: Potamon Rice Paddies Eriocheir Streams Larvae develop in brackish water
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Paragonimus kellicotti
Crayfish serve as 2nd IH in North America. Metacercariae are found in the heart.
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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!
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Paragonimus spp.
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Paragonimus westermani
Definitive Hosts
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Paragonimus kellicotti
Definitive Hosts
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Chest roentgenogram of a patient with North American paragonimiasis
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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
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Normal bronchiole Worm pair
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Plain skull film of a patient with chronic cerebral paragonimiasis
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Diagnosis Look for eggs In ________________ Or in ______________
85 X 50 μm
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Treatment Praziquantel
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Epidemiology How do people get infected? Infective stage? Mechanism?
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Epidemiology Rice Paddies
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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
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Morphology of Adult Alaria
Body is divided into 2 regions. Three suckers are present Common genital pore is posterior.
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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
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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
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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
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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!
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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
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We had two cases in Asian American men from Chinatown in San Francisco!
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What did they eat?
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Frog Legs
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Dr. Kevin Kazacos
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Bullfrog Over 70% of them were infected with Alaria sp.!
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Alaria sp. in bullfrog leg muscles
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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.
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Blood Flukes (Schistosomes)
Infect mammals, and birds. Live in the mesenteric veins (most species); some in urinary plexus veins, nasal veins, and dorsal aorta.
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Blood Flukes Veins Mesenteric veins Anterior (superior)
Small intestine Posterior (inferior) Large intestine Urinary bladder
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Schistosoma Small elongate 1-2 cm Dioecious Gynecophoric canal
Male helps female eat
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Schistosomiasis Major Parasitic disease, with million people infected. many are school age children
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Schistosomiasis Schistosoma Bilharzia Egyptian papyri Egyptian mummies
1850 Theodor Bilharz Egyptian papyri Egyptian mummies Joshua’s curse on Jericho 1800 Napoleon’s army
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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)
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} 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!
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Schistosomiasis Estimates
1947: ,000,000 1968: ,000,000 1972: ,000,000 1979: ,000,000 Current: More than 200,000,000
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Why the Increase? Due to irrigation farming and building of dams to facilitate irrigation. Snail habitat has expanded and increases exposure to people.
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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!
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Eggs have spines, no operculum, also have prominent secretory glands!
S. mansoni S. japonicum S. haematobium
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Eggs Eggs are shed to outside through excrement (feces or urine).
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Chemical Signaling with arginine
Life Cycle Chemical Signaling with arginine Adults can live years 3 weeks Release Eggs in 5-8 Weeks
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Distribution
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Distribution
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How do the eggs get out of the body?
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How do the eggs get out of the body?
Female worm leaves the male and migrates down to lay eggs.
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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.
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Granuloma can move with the eggs by peristaltic action.
Immune response Granuloma (Eosinophils, macrophages, neutrophils) Granuloma can move with the eggs by peristaltic action.
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Schistosomiasis Big picture the key to schisto pathology is the eggs not the adult worms!
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