Paragonimus spp.

Paragonimus westermani Definitive HostsDefinitive Hosts

Paragonimus kellicotti

Pathology and Symptoms JuvenilesJuveniles –Asymptomatic AdultsAdults –Tissue damage Ciliated epitheliumCiliated epithelium Inflammatory response Worms become encapsulatedWorms become encapsulated Fibrosis (Granuloma)Fibrosis (Granuloma) –Fibroblasts, eosinophils, lymphocytes –Chest pain, dry cough, rusty sputum, dyspnea etc. –Loss of lung function –Ectopic infections EggsEggs –Fibrosis

Normal bronchiole Worm pair

Diagnosis Look for eggsLook for eggs In ________________In ________________ Or in ______________Or in ______________ 85 X 50 μm

Treatment PraziquantelPraziquantel

Epidemiology How do people get infected?How do people get infected? –Infective stage? –Mechanism?

Epidemiology Rice PaddiesRice Paddies

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

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

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

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. 4 5

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

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

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

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

What did they eat?

Frog Legs

Dr. Kevin Kazacos

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

Alaria sp. in bullfrog leg muscles

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.

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

Blood Flukes VeinsVeins Mesenteric veinsMesenteric veins –Anterior (superior) Small intestineSmall intestine –Posterior (inferior) Large intestineLarge intestine Urinary bladderUrinary bladder

Schistosoma Small elongate 1-2 cmSmall elongate 1-2 cm DioeciousDioecious Gynecophoric canalGynecophoric canal Male helps female eatMale helps female eat

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

Schistosomiasis SchistosomaSchistosoma BilharziaBilharzia –1850 Theodor Bilharz Egyptian papyri Egyptian papyri Egyptian mummiesEgyptian mummies Joshua’s curse on JerichoJoshua’s curse on Jericho 1800 Napoleon’s army1800 Napoleon’s army

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

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

Schistosomiasis Estimates 1947: 114,000, : 114,000, : 118,000, : 118,000, : 125,000, : 125,000, : 200,000, : 200,000,000 Current: More than 200,000,000Current: More than 200,000,000

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

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

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

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

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

Distribution

Distribution

How do the eggs get out of the body?

Female worm leaves the male and migrates down to lay eggs.Female worm leaves the male and migrates down to lay eggs.

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

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

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