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- Fasciola hepatica
- Liver fluke
- zoonosis (cattle/sheep)
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What are the definitive hosts of Fasciola hepatica?
- definitive:
- humans, sheep, cattle
eggs released into water
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How is Fasciola hepatica transmitted?
- eggs released into water
- --> snail (produces cercari)
cercari or metacercari sit on watercress for ingestion
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How do Fasciola hepatica cause pathology?
- flukes ingested --> mesenteric veins
- --> liver
- migrate through liver and leave tracks
- adult flukes:
- produce eggs in bile ducts
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What are the clinical manifestations of Fasciola hepatica infection?
- young flukes:
- severe headache
- backache
- chills and fever
- adult flukes:
- portal vessel atrophy
- hemorrhage
- advanced: liver cirrhosis, diarrhea, anemia
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How is Fasciola hepatica infection diagnosed?
eggs in feces
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How is Fasciola hepatica treated and controlled?
- Triclabendazole
- **only one not treated with Praziquantel
- fence off snail habitats
- kill snails
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- Clonorchis inensis
- in Southeast Asia
- zoonotic (reptiles, birds, mammals)
- causes infection of bile ducts
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How is Clonorchis inensis transmitted?
- dogs, humans produce eggs
- --> snails
- --> cercariae --> metacercariae
- metacercariae ingested by fish
- --> raw fish eaten by human
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What are the clinical manifestations of Clonorchis inensis?
- 2* to bile duct irritation
- - Cholangiocarcinoma
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How do you diagnose Clonorchis inensis and how is it treated?
- Diagnose via eggs
- Treat: Praziquantel
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How is Clonorchis inensis controlled?
- water decontamination
- cook fish properly
- prevent discarding of fish carcasses
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- Paragonimus westermani
- "lung fluke"
- global distribution
- definitive hosts: dogs, cats, humans
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How is Paragonimus westermani transmitted?
- eggs released by humans, dogs, cats
- --> snail --> cercariae
- metacercariae --> crabs/shrimp
people ingest crab/shrimp
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What are the clinical symptoms of Paragonimus westermani?
- adults migrate to lungs
- - cough
- - blood/eggs in sputum
- --> diagnosis via eggs
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How is Paragonimus westermani treated/controlled?
Praziquantel
- control by decreasing snail habitats
- cook shrimp/crab
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What are the characteristics of cestodes?
- aka tapeworms
- scolex used for attachments
- hermaphrodites
- segments = proglottids
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- Taenia saginata
- - no hooks on scolex
- - over 13 branches on proglottid
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- Taenia solium
- - hook!
- - less than 13 branches on proglottid
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- Taenia solium **infective
- Taenia saginata
- Echinococcus spp. egg
- contains oncosphere
- inside proglottid
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- Taenia saginata
- cysticerci (larvae)
- grow in muscle (cow)
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How is Taenia saginata transmitted?
- eggs in humans
- ingested by cows
- cysticerci (larvae) grow in muscle
- --> meat ingested
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- Taenia saginata adult form
- --> only in humans
- causes slight abdominal discomfort
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How is Taenia saginata treated and controlled?
- Treat:
- Niclosamide
- Praziquantel
- Control:
- education, sanitation, cooking/freezing
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- Cysticercus:
- Taenia saginata/solium
- **infective
found in meat (beef)
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What is the difference between transmission of Taenia saginata and Taenia solium?
Taenia solium eggs are infective
cysticerci in both are infective
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How is Taenia solium transmitted?
- eggs in humans (*infective!)
- ingested by pigs
- cysticerci (larvae) grow in muscle
- --> meat ingested
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What are the clinical manifestations of Taenia solium?
- when eggs ingested (from humans):
- cysticercosis in humans
- - in muscle/skin
- - in eyes (ocular)
- - in brain (neuro) --> headache, seizure, hallucinations
- --> death
**tapeworm when cysticerci ingested
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- muscular cysticercosis
- 2* to Taenia solium
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- neurocysticercosis
- 2* to Taenia solium
treat with albendazole/corticosteroids
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How is Taenia solium treated?
- neurocysticercosis:
- albendazole
- corticosteroids
- (but relapse 2* to cyst calcification)
- adult worms:
- Niclosamide
- pumpkin seeds (relax worm)
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How is Taenia solium controlled?
- sanitation
- treatment (niclosamide)
- cooking/freezing pork
- inspection
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- Dipylidium caninum
- common in dogs/cats
- sometimes in children
cysticercoid stage (in fleas)
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How is Dipyildium caninum transmitted?
- egg packets (feces) eaten by fleas
- cysticercoid in fleas eaten by dogs
predilection site small intestines
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How is Dipylidium caninum diagnosed? What are the clinical symptoms?
- proglottids (segments) in feces
- egg packets in feces
usually asymptomatic
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How is Dipylidium caninum treated?
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- Diphyllobothrium latum
- "broad tapeworm"
- eggs detected in feces
hosts: fish-eating animals
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How is Diphyllobothrium latum transmitted?
- eggs (feces) -->
- freshwater fleas -->
- freshwater fish -->
- vertebrates
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What is the treatment for Diphyllobothrim latum?
-
What are the clinical manifestations of Diphyllobothrium latum?
megaloblastic anemia
parasite outcompetes host for vit B12
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- Echinococcus granulosus
- - cystic hydatid disease
- - cystic echinococcosis
large end contains eggs and shed
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What are the definitive hosts of Echinococcus granulosus?
- dogs, jackals, dingos, coyotes
- --> adult tapeworm in intestines
eat hydatid cysts ( protoscolicies)
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What are the intermediate hosts of Echinococcus granulosus?
- humans
- and everything else
- eat eggs
- produce hydatid cysts
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- hydatid cysts (liver/lung)
- filled with protoscolicies
- diagnostic in livestock
- fed to dogs
- --> adult tapeworm
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How does Echinococcus granulosus travel in intermediate hosts?
- eggs ingested
- oncosphere penetrates gut
- --> mesenteric veins
- --> liver (slow symptoms)
- --> lungs (fast symptoms)
- --> elsewhere
- oncosphere --> metacestode
- cysts form where stuck
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- Hydatid cysts
- 2* to Echinococcus granulosus
- contains protoscolicies
- +/- laminated membranes
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How is Echinoccocus granulosus diagnosed in dogs?
- autopsy
- Arecoline purgation
- coproantigens (dipstick)
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What is secondary hydatid disease?
- 2* to Echinococcus granulosus
- when cysts spill
- cysts develop in abdomen
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How is Echinococcus granulosus diagnosed in humans?
- ELISA
- imaging (X-Ray, CT, MRI, ultrasound)
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- Echinococcus granulosus
- natural progression
- CL/CE1/CE2:
- - active
- - cysts/daughter cysts
- CE3: transitional
- - cysts begin to die
- C4/C5: inactive
- - cysts die
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How is Echinococcus granulosus treated surgically?
- Active phase (unilocular cyst):
- PAIR with ultrasound guidance
- penetrate, aspiration, injection, re-aspiration
- (injection to kill protoscolicies)
- Active/Transitional (daughter cysts):
- Albendazole
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How is Echinococcus granulosus treated medically?
- for inoperable/simple cases
- albendazole
- --> laminated membrane peels away
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How is Echinococcus granulosus prevented?
- education
- "don't feed cysts to dogs"
- inspection
- de-worm dogs
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- children with hydatid cysts
- 2* to Echinococcus granulosus
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What are the clinical symptoms of Echinococcus granulosus in humans?
- abdominal distention
- abdominal presssure
- blindness (ocular hydatid cysts)
- cyst rupture -> anaphylaxis
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What is the distribution of Echinococcus multilocularis?
- Northern temperate climates
- but widespread
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What is Echinococcus multilocularis?
- Alveolar Hydatid Disease
- --> multilocular cysts in liver
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What are the definitive hosts for Echinococcus multilocularis?
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What are the intermediate hosts of Echinococcus multilocularis?
- eggs infective to:
- rodents
- voles, lemmings
- humans
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- Echinococcus multilocularis
- in liver
- tumor-like growth
- angioma/hematoma appearance
- --> death without treatment
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What is the treatment for Echinococcus multilocularis?
- Albendazole (lifelong)
- - stops growth/spread
- Hepatectomy
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What are some characteristics of nemotodes?
- host specific
- eggs develop larvae
- larvae infective
- under go hepatic-tracheal migration
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What are the geohelminth nematodes?
- transmitted through soil
- not zoonotic
- - hookworms
- - Ascaris lumbricoides
- - Trichuris trichuria
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- hookworm egg
- 30,000 produced per day
- Ancylostoma duodenale
- Necator americanus
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When do hookworms become infective?
- L3 larval stage
- maturation in soil
- --> skin penetration
- **Ancylostoma duodenale also transmitted by oral infection
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How are hookworms transmitted?
- eggs in feces
- -->--> L3 larvae in environment
- L3 larvae penetrate skin
- eggs shed in feces
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What are the clinical manifestations of hookworm?
- skin penetration
- - ground itch
- hepatic-tracheal migration:
- - mild pneumonitis
- - cough --> hookworms swallowed
- small intestines
- - anemia
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- hookworm in small intestines
- --> macerates microvilli
- --> pumps blood out
- --> anemia
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What are the symptoms of hookworm anemia (HWA)?
- tiredness
- myalgia
- pallor
- breathlessness
- --> leads to generational poverty
- --> iron deficiency anemia
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- iron deficiency anemia
- 2* hookworm
- - hypochromatic/microcytic RBC
- - pigmented neutrophils
- - high platelet count
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How is hookworm diagnosed?
- eggs in feces
- fresh sample
- (before eggs hatch into larvae)
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How is hookworm treated?
- Albendazole (more effective, single dose, low side effects)
- Mebendazole
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How is hookworm controlled?
- sanitation
- school based treatment
- treat individuals
- screening not really done anymore
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- Ascaris lumbricoides
- very common!!
- widespread (e.g. in Cuba, southeast Asia, etc.)
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- Ascaris lumbricoides egg
- found in human feces
200,000 eggs produced per day
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When is Ascaris lumbricoides infective?
- L2 larval stage
- ingested from environment
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What are the clinical manifestations of Acaris lumbricoides?
- Larvae:
- Loeffler's syndrome
- fever, cough, wheeze, eosinophilia
- *migration can be seen in lungs
- Adults:
- mechanical obstruction, jaundice, appendicitis, diarrhea, asphyxia
- colic
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Where do Ascaris lumbricoides adults live?
- intestinal parasite
- **can penetrate other tissues
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How is Ascaris lumbricoides diagnosed?
eggs in stool
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How is Ascaris lumbricoides treated?
- Albendazole
- Ivermectin
- --> large numbers of worms excreted
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- Trichuris trichiura
- whipworm
- found in human feces
- 20,000 eggs per day
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When are whipworms infective?
- L1 larval stage
- (ingestion)
no hepato-tracheal migration
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- Trichuris trichiura
- whipworm
embeds in cecum
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What are the clinical symptoms of Trichuris trichiura?
- bloody diarrhea
- abdominal pain
- 2* rectal prolapse
- anemia
- impaired growth
- reduced cognitive function
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What is the treatment for Trichuris trichirua?
- Albendazole
- (slightly less effective for T. trichiura vs. other worms)
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- Enterobius vermicularis
- "pinworm"
no mortality
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- Enterobius vermicularis egg
- (pinworm)
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How is Enterobius vermicularis transmitted?
- fecal-oral ingestion
- L3 eggs
**NO hepatic-tracheal migration
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What are the clinical symptoms of Enterobius vermicularis?
itchy anus
- female lays eggs in perianal area at night
- causes person to itch
- --> eggs (L3) ingested
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How is Enterobius vermicularis treated?
Albendazole
prevent via hygiene/treatment
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- Strongyloides stercoralis
- zoonotic
- common in children
- 5 produced per day
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What are the hosts for Strongyloides stercoralis?
humans, dogs
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- Strongyloides stercoralis
- L3 larvae
- skin penetrating
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How is Strongyloides stercoralis transmitted?
- skin penetration by L3 larvae
- (5 larvae per day born)
- larvae transmitted in feces
- **can be free-living
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- Larva currens
- Strongyloides stercoralis
- --> skin penetration of L3 larvae migrating through skin to hepatic-tracheal migration
leads to autoinfection
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How is Strongyloides stercoralis diagnosed?
- direct:
- larvae in fresh stool
- -> only parasite with larvae in stool
- -> use as PCR machine
- indirect: not useful
- ELISA
- eosinophilia
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What are the acute clinical symptoms of Strongyloidses stercoralis?
- itchiness
- cough/wheeze
- upper abdominal pain
- diarrhea
- weight loss
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What are the symptoms of chronic Strongyloides stercoralis?
- intestinal symptoms
- malabsorption (+/- 2* anemia)
- smelly yellow stool
- chronic diarrhea
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What is the treatment for Strongyloides stercoralis?
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- Ancylostoma caninum
- Ancylostoma braziliense
- causes Cutaneous Larva Migrans (CLM)
- Eosinophilic Enteritis (rare)
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What are the hosts of Ancylostoma caninum/braziliense?
dogs, humans
**cats also share Ancylostoma braziliense
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How is Ancylostoma caninum/braziliense transmitted?
- skin penetration
- L3 larvae
- larvae transmitted in feces
- *can be free-living
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What are the clinical manifestations of cutaneous larva migrans in humans?
- 2* to Ancylostoma caninum/braziliense
- cutaneous larva migrans
- - itchiness
- - 2* bacterial infection
- - no hepatic-tracheal migration (occurs only when parasite infects dogs)
- Eosinophilic enteritis
- - L4 larvae found in gut
- - does not produce eggs
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How is Ancylostoma caninum/braziliense diagnosed?
- clinical symptoms
- - cutaneous larva migrans
- - itchiness
- - pain
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How is Ancylostoma caninum/braziliense treated?
- Ivermectin
- Albendazole
- Thiabendazole (topical)
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- Infected cutaneous larva migrans
- 2* to Ancylostoma caninum/braziliense infection
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- Eosinophilic enteritis
- L4 larvae
- of Ancylostoma caninum
- found in small intestines
- does not produce eggs
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How is toxocara canis transmitted to dogs?
- ingestion of L2 eggs (feces/soil)
- vertical transmission via placenta
- L3 larvae in milk
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What are the predilection sites of Toxocara canis?
- dogs: intestines (larvae to go tissues)
- humans:
- liver (visceral larva migrans)
- eye (ocular larva migrans)
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How do people become infected with toxocara canis?
- ingestion of L2 eggs
- in soil
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- Toxocara canis
- L2 egg
- infective stage
- maturation in environment
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What are the clinical symptoms of visceral larva migrans?
- 2* to Toxocara canis
- inflammation of internal organs
- inflammation of CNS
- fever
- cough, asthma
- abdominal pain
- nausea
death is rare
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- Toxocara canis with visceral larva migrans
- occurs in liver
- --> hepatomegaly, eosinophilia
- L2 larvae seen
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- Ocular larva migrans
- Toxocara canis
- L2 larvae under retina
- --> retinoblastoma-like appearance
- eosinophilia --> fibrous granulomata
- leads to blindness
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How is Toxocara canis treated?
- Albendazole
- corticosteroids
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What is covert toxocariosis?
- due to Toxocara canis
- chronic coughing
- fever
- abdominal pain
- headache
- behavior change
- associated with asthma
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What is neurotoxocariosis?
- due to Toxocara canis
- seizures
- headaches, etc.
rare!
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How is Toxocara canis controlled?
- deworm puppies
- deworm kittens
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- Trichinella spp.
- zoonosis
- humans are intermediate host
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What are the different types, hosts, and distribution of Trichinella spp.?
- Trichinella spiralis:
- pigs, rats, horses
- Europe/Americas
- Trichinella nelsoni:
- hyenas, boar, warthog
- Africa
- Trichinella nativa:
- polar bears, wolves
- Arctic
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How is Trichinella spp. transmitted?
ingesting raw/undercooked meat
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What is the life cycle of Trichinella spp.?
- L1 larvae ingested
- reproduce in gut
- L1 larvae become trapped in muscle
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What are the clinical symptoms of Trichinella spp.?
- Enteric phase (mild):
- nausea, vomiting, colic, diarrhea, sweating
- Migratory (invasive) phase:
- immunopathy, fever, periorbital edema,
- eosinophilia, myalgia
- Encystment phase:
- fever, edema, elevated IgE antibodies
- dehydration and eosinophilia subside
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What is the treatment for Trichinella spp.?
- Mebendazole
- prolonged - against larvae
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How is Trichinella spp. diagnosed?
- Direct: Muscle Biopsy
- Post mortem exam
Direct: ELISA
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How is Trichinella spp. controlled?
- freezing meat (except for T. nativa)
- pig management
- not feeding meat to horses (T. spiralis)
- Cooking of meat
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What are characteristics of filaria?
- L1 microfilariae produced by female
- --> ingested by vector
- L1 --> L3 in vector
- L3 infects human
- **none are zoonotic!!
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- Loa Loa (filaria)
- found in central Africa
subcutaneous human filariasis
-
- Chrysops fly
- bites during the daytime
- Loa loa vector
- picks up L1 microfilariae
- bites to release L3
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- Calabar swelling
- 2* to migration of Loa loa
- allergic reaction when adult worm damaged during migration
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What is the treatment for Loa loa?
- Ivermectin
- DEC (**prophylactic)
- Albendazole
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How is Loa loa controlled?
- light colored clothing
- insect repellant
- DEC prophylaxis
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- Dracunculuc medinensis (filaria)
- found in Sudan, Ghana, Mali, Ethiopia
- subcutaneous human filariasis
- guinea worm
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- Cyclops water flea
- vector for Dracunculuc medinensis (guinea worm)
- ingests L1 larvae
- people drink L3 with infected flea
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How does Dracunculuc medinensis cause pathology?
- female migrates to extremities
- causes painful cutaneous ulcer
- (debilitating)
pain relieved by water --> female protrudes uterus to release L1 larvae
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What is the treatment for Dracunculuc medinensis?
- Albendazole
- Thiabendazole
- Moist bandage (relieves pain)
--> relaxes worm to allow faster removal
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How is Dracunculuc medinensis controlled?
- clean drinking water
- filter/boil water
- infected not to enter water source
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