Leishmania donovani Amastigotes

Leishmania donovani amastigotes in a spleen smear, spleen section and liver section.

IDENTIFICATION of Giardia lamblia

Giardia lamblia - trophozoite
10-20 µm long by 5-15 µm wide
1. Note sucking disk.
2. Iron-hematoxylin stain

Giardiasis is diagnosed by finding cysts or trophozoites in the feces, and both life cycle stages have a characteristic appearance.

The trophozoites average 10-20 μm in length, 5-15 μm in width, have a distinct “teardrop” or “pear” shape and two nuclei at the anterior end .........

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A case of Scabies

A35-year-old woman presents with a pruritic rash that has been present over the last few weeks. The area affected is in the webs of the fingers, and symptoms are reported to be worse at night. Topical over-the-counter steroids have not been beneficial. The likely diagnosis is:

• A)poison ivy
• B)dyshidrotic eczema
• C)scabies
• D)tinea corporis
• E)psoriasis

The answer is ( C ). (Scabies) 
The condition of scabies is associated with intense pruritus that is noted predominantly at night. The lesions are brownish in color and often form irregular burrow lines that may be marked with scaling at one end and a vesicle at the other end. The lesions are typically found in intertriginous areas and warm, protected areas such as the finger webs, inframammary areas, and axilla. The mite Sarcoptes scabei is responsible. Scrapings of the lesion are treated with 10% potassium hydroxide solution and studied under light microscopy. The mite is often identified. Treatment consists of permethrin cream 5% applied from head to toes and left in place for 12 hours before being washed off. Lindane can also be used as an alternative, but not in infants or in pregnant women.

Diphyllobothrium latum during Colonoscopy

A 46-year-old woman presented with a history of 3 days of pruritus in the anal area and 1 day of excretion of tapelike materials. During the year before presentation, she had reported intermittent colicky abdominal pain and loose stool, which had been attributed to irritable bowel syndrome. Laboratory evaluation was unremarkable, with no evidence of anemia. Colonoscopy revealed a long, moving tapeworm, Diphyllobothrium latum, located in the terminal ileum and extending to the sigmoid colon.

D. latum is a fish tapeworm that can infect humans after they consume infected undercooked or raw fish. The patient had a history of eating raw fish and recalled eating raw trout most recently 2 months before presentation. She was treated with a single dose of praziquantel. After administration, the abdominal pain resolved, but she continued to have intermittent loose stool.