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69 Cards in this Set
- Front
- Back
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What are helminths?
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Macroparasitic worms that range from 10mm to 10m in length adn are classified as:
Cestodes (tapeworms) Nematodes (roundworms) Trematodes (flukes) |
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How do Helminths replicate?
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1) Helminth enters the host form the environment through ingestion or through skin penetration
2) Matures and produces/sheds eggs or larvae within the host 3) Reenters the environment 4) Invades specific hosts, replicate asexually/sexually, and mature 5) Released into the environment ready to infect humans |
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How are most helminth infections diagnosed?
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Microscopic examination of fecal samples for organisms
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What are the three types of helminths?
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Cestodes
Trematodes Nematodes |
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What are the differences between helminths?
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1) Segmented or nonsegmented body types
2) Presence or absence of a digestive system |
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When infected wiht a helminth, what changes are seen on a complete blood count (CBC)?
What are five additional conditions that are associated with this finding? |
Eosinophilia, i.e., increase in eosinophils
NAACP Neoplasm Allergic reaction Asthma Collagen vascular disease Parasites |
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What type of organisms are cestodes?
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Segmented, ribbon-like worms that are primarily intestinal parasites and lack a digestive system
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What are the cestodes?
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Taenia solium (pig tapeworm)
Taenia saginata (beef tapeworm) Hymenolepsis nana (dwarf tapeworm) Echinococcus sp. Diphyllobothrium latum (fish tapeworm) |
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What are cestodes composed of?
What is the function of these structures? |
Scolex - head
Hooks and suckers to anchor parasites to the intestinal wall Strobila - body Hermaphroditic proglottids which each have the capacity to generate fertilized eggs |
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How is T. solium contracted?
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Eating T. solium larvae from unercooked pork or by eating eggs found in human feces.
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What is cysticercosis?
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When ingested, eggs of T. solium hatch in the small intestine and migrate to form cysts in tissues.
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What is neurocysticercosis?
What are symptoms associated with this? |
T. solium cysts in the brain
Seizures, obstructive hydrocephalus, neurological deficits, meningitis |
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How is T. saginata contracted?
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Eating T. saginata larvae from undercooked beef
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Can T. saginata cause cysticercosis?
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NO
cysticercosis is a disease entity specific to T. solium |
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For which cestode are humans the only host?
How is it acquired? |
H. nana (dwarf tapeworm)
Fecal-oral route |
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What disease are associated with the Echinococcus species?
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1) Hydatid cyst disease (Echinococcus granulosis)
2) Alveolar cyst disease (Echinococcus multilocularis) Alveolar cyst disease caused by E. multilocularis is more aggressive than hydatid cyst disease, with invasion of tissue in a tumor-like fashion |
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What is hydatid cyst disease?
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Infection affecting liver and lungs that is contracted from dogs
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What are two clinical manifestations of hydatid cysts?
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Anaphylactic reaction to parasite antigens.
Mass effects of cyst enlargement or rupture |
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What complication can occur by removing cysts?
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The fluid in the cysts is highly allergenic and accidental rupture can cause a fatal anaphylactic reaction. Therefore cysts are more commonly drained by US guided needle aspiration
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How is D. latum acquired?
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By ingesting larvae in raw fish
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What hematologic condition is D. latum associated with?
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Cobalamin (vitamin B12) deficiency
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What is the treatment for tapeworm infections?
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Praziquantel or niclosamide
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What type of organisms are nematodes?
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Nonsegmented, elongated parasitic worms with a complete digestive system
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What are the intestinal nematodes?
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PWASH
Pinworm (Enterobius vermicularis) Whipworm (Trichuris trichiura) Ascaris lumbricoides, (giant roundowrm) Strongyloides stercoralis, (small roundworm) Hookworm (Necator americanus; Ancylostoma duodenale) |
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Which are acquired by ingestion?
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Pinworm
Whipworm Ascaris |
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Which are acquired by penetration through skin?
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Strongyloides
Hookworm |
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What are the clinical manifestations of pinworm infection?
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Perianal pruritus
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How is pinworm infection diagnosed?
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Morning Scotch tape touch prep on perianal region
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In what population is pinworm infection common?
Why? |
All children, but especially those who attend day care centers
Children are more prone to scratch themselves and less likely to wash hands in the heat of playtime |
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What are the clinical manifestations of whipworm infections?
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Rectal prolapse with the worms seen on the rectum (coconut cake)
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ID the manifestations of Ascaris infection in the intestine.
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Small-bowel obstruction
Pancreatitis Hepatosplenomegaly |
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ID the manifestations of Ascaris infection in extrainestinal infections.
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Pulmonary eosinophilia
Retinal granuloma |
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How many people worldwide are infected by Ascaris?
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More than 2 billion people affected worldwide
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What condition is associated iwth dog Ascaris?
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Visceral larval migrans (humans are a dean-end host)
Cutaneous larval migrans is seen with dog hookworm while visceral larval migrans is seen with dog Ascaris |
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What are the clinical manifestations of Strongyloides infection?
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Relatively benign in healthy individuals
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What is hyperinfection syndrome?
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Severe condition in an immuno-compromised host, resulting in pneumonitis and colitis, and potentially fatal septic shock and gram-negative meningitis
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In what three ways is Strongyloides replication unique?
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1) Can multiply in host
2) Only larvae are seen in stool; eggs are never seen 3) Infection can persist for 45 years Strongyloides is the only nematode that can replicate in the host |
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What are the clinical manifestations of hookworm infection?
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Anorexia
Ulcer-like symptoms Anemia secondary to continual intestinal blood loss |
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What condition is associated with dog or cat hookworm?
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Cutaneous larval migrans secondary to penetration through skin and migration eneath epidermis
Visceral larval migrans is seen with dog Ascaris whereas cutaneous larval migrans is seen with dog hookworm. |
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What type of organisms are nematodes?
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Nonsegmented, elongated parasitic worms with a complete digestive system.
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What are the tissue nematodes?
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Trichinella spiralis (trichinosis)
Filariae (Brugia malayi, Loa loa, Onchocerca volvulus, Wuchereria bancrofti) |
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What nematodes are acquired by ingestion?
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Trichinella
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Which nematodes are acquired by arthropod vector?
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Filariae
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What are teh clinical manifestations of Trichinella infection?
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Periorbital edema
Myositis Abdominal pain |
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What is a risk factor for contraction of Trichinella?
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Consumption of homemade pork sausage or undercooked pork
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What causes significant clinical manifestation in filariae?
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Occlusion of lymphatics by parasite
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What is the vector for Brugia malayi?
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Mosquitoes
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What is the vector for Wuchereria bancrofti?
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Mosquitoes
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What is the vector for Loa loa?
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Deer fly
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What is the vector for Onchocerca volvulus?
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Black fly
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What are the clinical manifestations of Brugia malayi and Wucheria bancrofti infections?
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Elephantiasis
Tropical pulmonary eosinophilia |
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What are the clinical manifestations of Loa Loa infection?
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Skin lesions
Conjunctivitis |
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What are the clinical manifestations of Onchocerca volvulus infection?
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River blindness
Subcutaneous nodules with severe pruritus |
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What type of organisms are trematodes?
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Nonsegmented, small flat, leaf-like parasitic worms with complete digestive systems that infest various organs
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What is the intermediate host for all trematodes?
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Water snails
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What are five trematodes?
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Blood flukes (Schistosoma mansoni)
Chinese liver fluke (Clonorchis sinensis) Liver fluke (Opisthorchis, Fasciola hepatica) Intestinal fluke (Fasciolopsis buski, Heterophyes heterophyes) Lung Fluke (Paragonimus westermani) |
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What are three diseases associated with schistosomiasis?
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1) Dermatitis (swimmer's itch)
Acute schistosomiasis (Katayama fever) Chronic schistosomiasis (pipestem fibrosis caused by granulomas in the liver and intestines) |
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How is schistosomiasis transmited?
What is the pathogenesis? |
Direct skin contact, often from swimming in fluke-infested freshwater.
Inflammatory response to parasite |
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What are the long-term clinical manifestations of schistosomiasis?
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1) Leading caue of portal hypertension worldwide
2) Schistosoma haematobium is associated with squamous cell carcinoma of the bladder |
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What are the clinical manifestations of liver fluke infection?
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Cholangitis
Cholangiocarcinoma |
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What is the host for C. sinensis?
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Fish or fish-eating animals
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What is the host for Opisthorchis?
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Cats or dogs
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What is the host for F. hepatica?
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Sheep and acquatic plants (watercress)
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What enables pathogenesis by intestinal flukes?
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High parasite load
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Where can parasites be found for G. buski?
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Aquatic plants of the Orient
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Where can parasites be found for H. heterophyes?
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Freshwater or brackish fish
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What are the clinical manifestations of P. westermani?
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Pulmonary involvement resulting in fluke eggs in sputum
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What is the host for P. westermani?
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Crayfish and freshwater crabs
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What is the treatment for trematode infections?
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Praziquantel
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