30 Parasitology 2: Tissue nematodes Flashcards
What types of hypersensitivity does larva migrans (e.g. Toxocara canis, Ancylostoma brazilense) cause?
I and IV
T/F- clinical features of visceral Toxocara disease (larva migrans) include allergic manifestations, granulomas, and possibly death due to effects on the heart, lungs, and brain
true
Trichinella spiralis causes 100,000 cases of trichinosis in the US/year. What is the life cycle of this organism?
- animals ingest encysted larvae from striated muscle
- excystment occurs leading to adults in the large intestine
- mate and release larvae where they penetrate into tissues and encyst in striated muscle
Although trichinosis is mostly subclinical, what are some possible clinical features?
muscle weakness, fever, nausea, diarrhea, myositis, granulomas, sudden death
How is trichinosis diagnosed and treated?
- Dx: eosinophilia and remarkable history of eating undercooked meat, serologic tests for antibodies, biopsy.
- Tx: corticosteroids, mebendazole (prevents new larvae production)
T/F- filaria are adults and give rise to microfliaria in the blood which are embryos and eaten by a vector where they develop into infective larvae, which are transmitted to humans
true
How is non-optimal antibiotic therapy harmful in filarial disease?
can drive microfilaria into tissues causing sudden death
What causes elephantiasis? How are these transmitted?
Wuchereria bancrofti and Brugia malayi
Transmitted by mosquitos
How would you treat elephantiasis or filarial fever?
antihistamines, corticosteroids, diethylcarbamazine, surgery
Where is Loa loa found? How is it transmitted? What swellings are characteristic of this infection? How is it treated?
- West africa
- transmitted by deer fly
- Calabar swellings (type I hypersensitivity)
- surgical removal and diethylcarbamizine
What condition does Onchocerca volvulus cause? How is it transmitted? How is it treated?
- River blindness in tropical areas (4th leading cause of blindness)
- Transmitted by Simulium
- Ivermectin is drug of choice, or diethylcarbamazine + corticosteroids
T/F- Dracunculus medinensis is Guinuea worm in equatorial africa, very long (up to 100 cm), acquired from drinking water where “cyclops” is infected with larvae and causes type I hypersensitivity reactions and increases risk of tetanus
true
Cestodes are commonly known as what?
tapeworms
What does infections with cestodes often cause when the encysted larvae develop in tissues?
cysticercoids
Are these matched correctly?
Taenia saginata-pork tapeworm
Taenia solium- beef tapeworm
No, those are backwards
What’s the most common cause of acquired epilepsy in the world?
cysticercosis (tapeworm infection)
How is a tapeworm infection treated?
niclosamide (inhibits energy production), praziquantel (spastic paralysis in worm), albendazole (inhibits microtubule synthesis)
Does Schistosoma mansoni cause intestinal or urinary schistosomiasis? How about S. japonicum? How about haematobium?
- S. mansoni: intestinal
- S. japonicum: intestinal
- S. haematobium: urinary
Describe the blood fluke life cycle
- eggs hatch and release ciliated miracidia (larvae) that infect snails
- snail releases circariae that invade human skin
- migrate to lungs, acquire antigen coat
- mature, migrate to liver, mate
- release 3,000 eggs/day
Clinical features of blood flukes?
- Katayama fever (acute): malaise, fever, hives, abdominal pain, hepatic tenderness, CNS effects, immune complex disease
- chronic granuloma formation (hepatic), GI symptoms, painful urination, baldder cancer, anemia, pulmonary dysfunction
What is swimmers itch? how is it treated?
US form of schistosomiasis in which larvae that cannot develop in humans burrow into subQ areas and cause rash, fever, malaise, and hives
Tx: corticosteroids
How is schistosomiasis treated and diagnosed?
Dx: based on symptoms, looking for eggs
Tx: praziquantel
A 30 yr old man is windsurfing, he walks along the edge of the lake to his car. 2 days later he has intense itching lesions on both legs and is diagnosed with swimmers itch caused by bird schistosomes. What is he given to clear this infection?
topical cortisone cream
What type of hypersensitivity do blood flukes cause after they invade the human skin and lose their tails, forming metacercariae or schistosomulas?
type I
What type of hypersensitivity do blood flukes cause after they migrate to the liver, feed and mate there?
type III aka “katayama fever”
What type of hypersensitivity do blood flukes cause after they release (about 300) eggs per day?
type 4 hypersensivitiy (granulomas)
