Page 494 - Review of Medical Microbiology and Immunology ( PDFDrive )

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mebooksfree.com mebooksfree.com A mebooksfree.com mebooksfree.com mebooksfree.com mebooksfree.com
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CHAPTER 56 Nematodes
483

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B

C

FIGURE 56–17
A: Wuchereria bancrofti microfilaria in blood. Note that the pointed tail is free of nuclei (225–300 × 8–10 μm).
B: Onchocerca volvulus microfilaria in skin (rare) in blood) (300–350 × 5–9 μm). C: Loa loa microfilaria in blood. Note that the pointed tail
contains nuclei (250–300 × 6–9 μm). (Circles represent red blood cells.)
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Important Properties
Humans are infected when the female blackfly, Simulium,
Inflammation occurs in subcutaneous tissue, and pruritic
deposits infective larvae while biting. The larvae enter
papules and nodules form in response to the adult worm
proteins. Microfilariae migrate through subcutaneous
the wound and migrate into the subcutaneous tissue,
where they differentiate into adults, usually within der-
mal nodules. The female produces microfilariae (see
Figure 56–17B) that are ingested when another blackfly
bites. The microfilariae develop into infective larvae in
the fly to complete the cycle. Humans are the only
definitive hosts.
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mebooksfree.com mebooksfree.com Wuchereria bancrofti—filarial worm in blood. FIGURE 56–19 Wuchereria bancrofti—elephantiasis. Note mebooksfree.com
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FIGURE 56–18
massive swelling of legs bilaterally. (used with permission from Jay S. Key-
Arrow points to filarial worm in blood smear. (Source: Dr. M. Melvin, Public
stone, MD, FRCPC.)
Health Image Library, Centers for Disease Control and Prevention.)

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