Parasite Case Study Worksheet

What common name are the nematodes called?

Pinworms

What is this parasite (genus and species)?

Enterobius vermicularis

What test is performed to recover eggs of Enterobius vermicularis?

Why?

Cellophane tape test

Eggs (the diagnostic form of Enterobius vermicularis) may not be observed in the feces. The gravid female pinworm crawls out of the anus at night to lay eggs in the perianal folds. These eggs can be recovered by pressing clear cellophane tape onto the perianal region.

How does one become infected with Enterobius vermicularis?

Ingestion or inhalation of eggs. Eggs may be ingested via infected food or contaminated hands.

How is the infection of Enterobius vermicularis maintained?

Autoinfection. Scratching the perianal folds will pick up the eggs. Eggs may be consumed directly from the contaminated hands, or from eating food while hands are contaminated.

What other parasites may be carried by Enterobius vermicularis?

Dientamoeba fragilis

What is the common name of the cestodes?

Tapeworms

What is this parasite (genus and species)?

Diphyllobothrium latum

How does one become infected with Diphyllobothrium latum?

Ingestion of undercooked freshwater fish that are infected with the plerocercoid larval form

Besides Diphyllobothrium latum, what other parasite(s) could you get from eating undercooked fish?

Clonorchis (Opisthorchis) sinensis

What are some complications from long-term infection with Diphyllobothrium latum?

Vitamin B12 deficiency, pernicious anemia, intestinal obstruction

What is this parasite (genus and species)?

What is its morphological form?

Schistosoma haematobium

Egg

What disease does Schistosoma haematobium cause?

Schistosomiasis, AKA bilharziasis

What is the first intermediate host of Schistosoma haematobium?

Freshwater snail

What is the mode of transmission for Schistosoma haematobium?

Snail: miracidium penetrates tissue

Human: cercaria uses tail (and loses it) to penetrate skin

What parasite is this (genus and species)?

Entamoeba histolytica

What is the primary characteristic used to differentiate and identify Entamoeba histolytica?

Chromatin bars with rounded ends

What other disease manifestations can occur if Entamoeba histolytica infection progresses beyond the intestinal tract?

All three are possible

How could one become infected with Entamoeba histolytica?

Drinking contaminated water

What is this skin rash called?

Erythema migrans

What parasite is likely to cause an erythema migrans? How would one become infected?

Borrelia burgdorferi transmitted by Ixodes spp.

Besides Borrelia burgdorferi, the Ixodes spp. ticks can transmit all EXCEPT which of the following infections?

Rickettsia rickettsia