Microbiology-Parasitic Infection Flashcards
Which parasite is the most prominent world wide?
Trichinella spiralis
When dissecting your cadaver, where would you expect to find larvae if he died from a parasitic infection? Where would they go after hatching if he were still alive?
The intestinal mucosa. They lie wait here until they hatch, then break through the mucosa, enter the lymphatics, get into the blood stream, leaves capillaries and penetrates into myocytes
Ingestion of what food puts you at risk for trichinella spiralis infection?
Pork
Why does the immune system have a difficult time finding trichinella spiralis adult worms?
They weave themselves in and out of epithelial cells.
How does a trichinella infection usually proceed from first exposure?
The parasite gets into the intestinal lumen where it reproduces and deposits larvae in the mucosal walls. This usually takes 3-5 days and the larvae become adults within 30-40 hours. The infection will persist until cleared by T-cells, which in a first infection usually takes about a month to clear.
How does trichinella modify a myocyte after it penetrates it?
It modifies the host protein by inserting its DNA into the host genome. The type of collagen made by the cell is altered, mitochondria are disabled, and the nurse cell releases EGF to increase angiogenesis.
What symptoms are common in a parasitic infection?
Vasculitis causing circumorbital edema and splinter hemorrhages in nails, muscle pain, eosinophilia and death if they get into the heart, diaphragm and lungs.
When would you use a stool sample to diagnose a trichinella parasitic infection? What is the best diagnostic test?
Never. The larvae leave the gut and the adults get digested before stool is passed. Muscle biopsy is the most definitive diagnosis, but you can miss a positive test early on.
Why is an antibody test not as reliable in a parasitic infection?
They take a long time to rise after infection (5 weeks) and will still be positive if they were infected previously.
Why aren’t people with parasitic infections at risk for renal failure?
There is no myolysis
How do you treat a trichinella infection?
Corticosteroids reduce vasculitis. Mebendazole attacks the worms.
Why would you think twice about giving someone corticosteroids in a trichinella infection?
Corticosteroids can lengthen adult parasite lifespan
What are the recommendations for prevention of trichinella infection via pork?
Freeze uncooked pork for 14 days at -15C. Cook food thoroughly and cook the food you give the pigs.
What would you expect to see regarding parasitic infection if you moved your practice to Alaska?
Increase in parasitic infection because they are resistant to low temperatures when freezing pork
What parasitic infection releases millions of eggs and creates calcified cysts in muscle and brain?
Taenia solium…leading cause of epilepsy in children in Mexico
What contributes to the large calcifications and smaller calcifications in this patient? What food is particularly common in spreading these infections?
Sarcocystis (smaller cysts) taenia solium (larger cysts). Duck meat.
