Chapter 7 : Parasite Identification

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Images from left to right: The first four images are E. histolytica trophozoites (note the ingested RBCs). Image 5 is a precyst with one chromatoidal bar. This organism would need to be identified as “Entamoeba histolytica/E. dispar (might or might not be the true pathogen, E. histolytica).”

Images from left to right: The first four images are E. histolytica trophozoites (note the ingested RBCs). Image 5 is a precyst with one chromatoidal bar. This organism would need to be identified as “Entamoeba histolytica/E. dispar (might or might not be the true pathogen, E. histolytica).”

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Images from left to right: The first two images in the Entamoeba histolytica/E. dispar group are trophozoites (no ingested RBCs within the trophozoite cytoplasm). The third image is a cyst containing a chromatoidal bar. This organism would need to be identified as Entamoeba histolytica/E. dispar (it might be the true pathogen, E. histolytica, or the nonpathogenic species, E. dispar).

Images from left to right: The first two images in the Entamoeba histolytica/E. dispar group are trophozoites (no ingested RBCs within the trophozoite cytoplasm). The third image is a cyst containing a chromatoidal bar. This organism would need to be identified as Entamoeba histolytica/E. dispar (it might be the true pathogen, E. histolytica, or the nonpathogenic species, E. dispar).

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Images from left to right: The first two images are E. hartmanni trophozoites. The next two are E. hartmanni cysts containing chromatoidal bars (often the cyst contains only two nuclei). Note these amebae can often be confused with E. histolytica or E. dispar; they would be separated on the basis of size.

Images from left to right: The first two images are E. hartmanni trophozoites. The next two are E. hartmanni cysts containing chromatoidal bars (often the cyst contains only two nuclei). Note these amebae can often be confused with E. histolytica or E. dispar; they would be separated on the basis of size.

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Images from left to right: The far left two images in the bottom row are E. coli trophozoites (as is the middle image in the top row). The next two images are E. coli cysts. Note that there are five or more nuclei in the cysts.

Images from left to right: The far left two images in the bottom row are E. coli trophozoites (as is the middle image in the top row). The next two images are E. coli cysts. Note that there are five or more nuclei in the cysts.

Images from left to right: The first three images are E. gingivalis trophozoites; note the ingested PMNs. Image 4 is an E. polecki cyst; note the large inclusion in the cyst (not seen in other Entamoeba species).

Images from left to right: The first three images are E. gingivalis trophozoites; note the ingested PMNs. Image 4 is an E. polecki cyst; note the large inclusion in the cyst (not seen in other Entamoeba species).

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Images from left to right: The left-hand image is a trophozoite of E. nana. The next image is another E. nana trophozoite (note the unusual nuclear chromatin arrangement; there is tremendous nuclear variation in this species). The two images to the right are E. nana cysts (note that some are round while some are the more typical oval shape).

Images from left to right: The left-hand image is a trophozoite of E. nana. The next image is another E. nana trophozoite (note the unusual nuclear chromatin arrangement; there is tremendous nuclear variation in this species). The two images to the right are E. nana cysts (note that some are round while some are the more typical oval shape).

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Images from left to right: (Top) I. bütschlii trophozoite and cyst; (bottom), two trophozoites and one cyst containing the large glycogen vacuole.

Images from left to right: (Top) I. bütschlii trophozoite and cyst; (bottom), two trophozoites and one cyst containing the large glycogen vacuole.

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Images: (Top) Drawing of B. hominis central-body form. (Bottom) Central-body forms on a trichrome-stained smear.

Images: (Top) Drawing of B. hominis central-body form. (Bottom) Central-body forms on a trichrome-stained smear.

Plate 7.1

Row 1 (left to right): Entamoeba histolytica trophozoite, Entamoeba histolytica/E. dispar trophozoite, and Entamoeba histolytica/E. dispar cyst; row 2: Entamoeba hartmanni trophozoites (left and middle) and Entamoeba hartmanni cyst (right); row 3: Entamoeba coli trophozoite, Entamoeba coli trophozoite, and Entamoeba coli cyst; row 4: Entamoeba coli cyst (wet preparation), Entamoeba coli cyst, and Entamoeba coli cyst.

Plate 7.2

Row 1 (left to right): Blastocystis hominis central-body forms (note that the cell in the right image is dividing; this is occasionally seen in fecal specimens; row 2: Endolimax nana trophozoites (note that the middle image has nuclear variation, which is common with this organism; the right organism mimics Dientamoeba fragilis); row 3: Endolimax nana trophozoites and (on the right) Endolimax nana cyst; row 4: Iodamoeba bütschlii trophozoite and Iodamoeba bütschlii cysts.

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Images from left to right: Drawing of trophozoite and cyst (left); Giardia trophozoites (center); Giardia cysts (right).

Images from left to right: Drawing of trophozoite and cyst (left); Giardia trophozoites (center); Giardia cysts (right).

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Images from left to right: The first drawing is a Dientamoeba trophozoite; the next three photographs are D. fragilis trophozoites (note that organisms can have either a single nucleus or multiple nuclei, most of which contain fragments of nuclear chromatin).

Images from left to right: The first drawing is a Dientamoeba trophozoite; the next three photographs are D. fragilis trophozoites (note that organisms can have either a single nucleus or multiple nuclei, most of which contain fragments of nuclear chromatin).

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Images from left to right: The top row shows a drawing of a C. mesnili trophozoite and cyst and then two C. mesnili trophozoites. The bottom row shows two cysts (note the curved fibril, the “shepherd’s crook”).

Images from left to right: The top row shows a drawing of a C. mesnili trophozoite and cyst and then two C. mesnili trophozoites. The bottom row shows two cysts (note the curved fibril, the “shepherd’s crook”).

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Life cycle for Trichomonas tenax.

Life cycle for Trichomonas tenax.

Images from left to right: Drawing of P. hominis; photograph of P. hominis trophozoite (note that the undulating membrane extends to the bottom of the organism and the axostyle/supporting rod extends through the bottom).

Images from left to right: Drawing of P. hominis; photograph of P. hominis trophozoite (note that the undulating membrane extends to the bottom of the organism and the axostyle/supporting rod extends through the bottom).

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Images from left to right: E. hominis trophozoite and cysts; R. intestinalis trophozoite and cyst.

Images from left to right: E. hominis trophozoite and cysts; R. intestinalis trophozoite and cyst.

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Images from left to right: (Top row) drawings of B. coli trophozoite and cyst; (bottom row) B. coli trophozoite, cyst, and trophozoites in intestinal tissue.

Images from left to right: (Top row) drawings of B. coli trophozoite and cyst; (bottom row) B. coli trophozoite, cyst, and trophozoites in intestinal tissue.

Plate 7.3

Row 1: Giardia lamblia trophozoites; row 2: Giardia lamblia trophozoites in mucus (left) and Giardia lamblia trophozoite (wet mount) (right); row 3: Giardia lamblia cysts (left and middle) and Giardia lamblia cyst (wet mount) (right); row 4 (left to right): Chilomastix mesnili trophozoite, Chilomastix mesnili cyst, and Chilomastix mesnili cyst (wet mount).

Plate 7.4

Row 1: Dientamoeba fragilis trophozoites; row 2: Dientamoeba fragilis trophozoite (the nuclear chromatin has not yet completely fragmented; it can therefore mimic Endolimax nana) (left) and Dientamoeba fragilis trophozoites (middle and right); row 3 (left to right): Pentatrichomonas hominis trophozoite, Trichomonas tenax trophozoite, and Trichomonas vaginalis trophozoite; row 4: Trichomonas vaginalis trophozoites. Trichomonas vaginalis: See section on Protozoa, Flagellates (Other Body Sites).

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Images from left to right: Cryptosporidium oocysts (4 to 6 µm) stained with modified acid-fast stain. These oocysts stain more consistently than those of Cyclospora cayetanensis. In some oocysts, the sporozoites can be seen; oocysts are infectious even if the sporozoites are not visible. In the middle are C. cayetanensis and Cryptosporidium, and an artifact can be seen (note that the Cyclospora oocyst did not retain the stain). On the right are developing Cryptosporidium at the microvillous surface (courtesy of Armed Forces Institute of Pathology).

Images from left to right: Cryptosporidium oocysts (4 to 6 µm) stained with modified acid-fast stain. These oocysts stain more consistently than those of Cyclospora cayetanensis. In some oocysts, the sporozoites can be seen; oocysts are infectious even if the sporozoites are not visible. In the middle are C. cayetanensis and Cryptosporidium, and an artifact can be seen (note that the Cyclospora oocyst did not retain the stain). On the right are developing Cryptosporidium at the microvillous surface (courtesy of Armed Forces Institute of Pathology).

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Images from left to right: The first image shows C. cayetanensis oocysts (8 to 10 µm) stained with modified acid-fast stain. There is a range of clear to deeply stained oocysts; there is a lot of variation with modified acid-fast staining (modified acid-fast variable). The second image shows autofluorescent oocysts on filters commonly used for calcofluor white staining.

Images from left to right: The first image shows C. cayetanensis oocysts (8 to 10 µm) stained with modified acid-fast stain. There is a range of clear to deeply stained oocysts; there is a lot of variation with modified acid-fast staining (modified acid-fast variable). The second image shows autofluorescent oocysts on filters commonly used for calcofluor white staining.

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Images from left to right: (Top row) Drawing of an immature oocyst, drawing of a mature oocyst containing two sporocysts, and an immature oocyst stained with modified acid-fast stain (note that the entire oocyst stains). (Bottom row) Immature oocyst, mature oocyst (wet mounts), and mature oocyst stained with modified acid-fast stain.

Images from left to right: (Top row) Drawing of an immature oocyst, drawing of a mature oocyst containing two sporocysts, and an immature oocyst stained with modified acid-fast stain (note that the entire oocyst stains). (Bottom row) Immature oocyst, mature oocyst (wet mounts), and mature oocyst stained with modified acid-fast stain.

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Images from left to right: The drawing illustrates the infective spore (1.5 to 2.5 µm) containing the coiled polar tubule. (Top left) Spores in stool, stained with Ryan modified trichrome blue (some of the spores show the horizontal “stripe” that indicates the presence of the polar tubule); (top right) calcofluor staining of spores in a urine sediment. (Bottom) Spore development in the human intestine. Note the small size of the spores in tissue.

Images from left to right: The drawing illustrates the infective spore (1.5 to 2.5 µm) containing the coiled polar tubule. (Top left) Spores in stool, stained with Ryan modified trichrome blue (some of the spores show the horizontal “stripe” that indicates the presence of the polar tubule); (top right) calcofluor staining of spores in a urine sediment. (Bottom) Spore development in the human intestine. Note the small size of the spores in tissue.

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Images from left to right: The drawing illustrates the infective spore (1.5 to 2.5 µm), containing the coiled polar tubule. (Top) Gram stain showing spores within a white blood cell; (bottom row left), nasopharyngeal aspirate with spores (Ryan blue modified trichrome stain); (bottom row right), urine sediment with direct FA reagent (to the genus Encephalitozoon).

Images from left to right: The drawing illustrates the infective spore (1.5 to 2.5 µm), containing the coiled polar tubule. (Top) Gram stain showing spores within a white blood cell; (bottom row left), nasopharyngeal aspirate with spores (Ryan blue modified trichrome stain); (bottom row right), urine sediment with direct FA reagent (to the genus Encephalitozoon).

Plate 7.5

Row 1: Cryptosporidium sporozoites (EM; courtesy of USDA) (left) and Cryptosporidium spp. on the surface of the intestinal tract epithelium (right); row 2: Cryptosporidium organisms on the surface of the intestinal tract (EM) (left) and Cryptosporidium oocysts stained with modified acid-fast stain (middle and right); row 3: Cyclospora cayetanensis autofluorescent oocysts (left) and Cyclospora cayetanensis oocysts stained with safranin (right); row 4: Cyclospora cayetanensis oocyst (the large object), Cryptosporidium oocyst (the medium-size object), and an artifact (the small dark-staining object at the top of the image) (left), Cyclospora cayetanensis oocysts (modified acid-fast variable staining) (center), and Cyclospora cayetanensis oocyst (mature) (right).

Plate 7.6

Row 1: Isospora belli oocysts (from left to right: modified acid-fast stain, immature, and mature); row 2: Isospora belli oocysts (from left to right: modified acid-fast stain, wet mount, calcofluor, modified acid-fast stain, wet mount); row 3: microsporidial spores in intestinal tissue (routine H&E stain) (left), spores from an eye specimen (silver stain) (center), and spores (modified trichrome stain; note the horizontal lines representing the polar tubules) (right); row 4: spores in urine sediment (calcofluor) (left), spores using experimental DFA reagent (center), and spores (modified trichrome stain) (right).

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Images from left to right: (Top row) Early ring form; the next three show developing trophozoites (note the parasite is very ameboid and there are Schüffner’s dots/stippling present); (bottom row) mature schizont containing ~16 to 18 merozoites, male microgametocyte, and female macrogametocyte. Also note the enlarged RBCs.

Images from left to right: (Top row) Early ring form; the next three show developing trophozoites (note the parasite is very ameboid and there are Schüffner’s dots/stippling present); (bottom row) mature schizont containing ~16 to 18 merozoites, male microgametocyte, and female macrogametocyte. Also note the enlarged RBCs.

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Images from left to right: (Top row) Ring in the accolé or appliqué form, double rings per cell, and developing rings (RBCs contain Maurer’s clefts); (bottom row) mature schizont, male microgametocyte, and female macrogametocyte (note the crescent shape of gametocytes).

Images from left to right: (Top row) Ring in the accolé or appliqué form, double rings per cell, and developing rings (RBCs contain Maurer’s clefts); (bottom row) mature schizont, male microgametocyte, and female macrogametocyte (note the crescent shape of gametocytes).

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Images from left to right: (Top row) Two developing ring forms and two typical band forms; (bottom row) mature schizont “rosette” formation, male microgametocyte, and female macrogametocyte.

Images from left to right: (Top row) Two developing ring forms and two typical band forms; (bottom row) mature schizont “rosette” formation, male microgametocyte, and female macrogametocyte.

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Images from left to right: (Top row) Two developing ring forms and two developing trophozoites (note that all four images contain true stippling, Schüffner’s dots; dots appear later in the cycle in P. vivax); (bottom row) mature schizont, male microgametocyte, and female macrogametocyte. Note the enlarged RBCs, oval shape, and the fimbriated edges of some of the RBCs.

Images from left to right: (Top row) Two developing ring forms and two developing trophozoites (note that all four images contain true stippling, Schüffner’s dots; dots appear later in the cycle in P. vivax); (bottom row) mature schizont, male microgametocyte, and female macrogametocyte. Note the enlarged RBCs, oval shape, and the fimbriated edges of some of the RBCs.

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Images from left to right: (Top row) Babesia rings (note the Maltese cross formation in some of the RBCs; also note the three rings outside of the RBC in the first image, a situation that occurs with Babesia but very rarely with Plasmodium spp.). (Bottom row) Babesia rings; the third image is photographed at a lower magnification.

Images from left to right: (Top row) Babesia rings (note the Maltese cross formation in some of the RBCs; also note the three rings outside of the RBC in the first image, a situation that occurs with Babesia but very rarely with Plasmodium spp.). (Bottom row) Babesia rings; the third image is photographed at a lower magnification.

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Images from left to right: (Top) T. gondii tachyzoites seen in bone marrow and bradyzoites seen in human tissue. (Bottom) Intracellular tachyzoites and extracellular tachyzoites from the mouse peritoneal cavity.

Images from left to right: (Top) T. gondii tachyzoites seen in bone marrow and bradyzoites seen in human tissue. (Bottom) Intracellular tachyzoites and extracellular tachyzoites from the mouse peritoneal cavity.

Plate 7.7

Plasmodium vivax. Row 1: developing ring forms (in some RBCs there may be more than one ring; this is more commonly seen in P. falciparum, but does occur in P. vivax infections); row 2: developing trophozoites (note ameboid forms and Schüffner’s dots); row 3: developing schizonts; row 4 (left to right): mature schizont, female macrogametocytes, and male microgametocyte.

Plate 7.8

Plasmodium falciparum and Babesia spp. Row 1: developing ring forms of P. falciparum (note multiple rings per cell, “headphone” rings, and, in the third image, an appliqué form); row 2: ring forms (in the second image note the Maurer’s clefts [not true stippling]) (left and middle) and crescent-shaped gametocyte (right); row 3: gametocyte, exflagellation of the male microgametocyte (can occur in any of the species of Plasmodium in a tube of EDTA blood if the cap is removed and the blood cools to room temperature; parasites assume they are in the mosquito) (middle), and ookinete (occurs in the mosquito cycle and can mimic a gametocyte) (right); row 4: various ring forms of Babesia spp. (some of the rings are in the “Maltese cross” configuration).

Plate 7.9

Plasmodium malariae. Rows 1 and 2: developing trophozoites (note the band form configuration); row 3: developing schizonts; row 4: mature “rosette” schizont (the last two images are from thick blood films).

Plate 7.10

Plasmodium ovale. Rows 1 and 2: developing trophozoites (the parasites are much less ameboid than P. vivax; note the presence of Schüffner’s dots and the oval RBCs); row 3: developing schizonts; row 4: mature schizont and male and female gametocytes.

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Images from left to right: Drawing of amastigotes in bone marrow (visceral leishmaniasis). (Top) Amastigotes in bone marrow. (Bottom) Promastigote stages from culture.

Images from left to right: Drawing of amastigotes in bone marrow (visceral leishmaniasis). (Top) Amastigotes in bone marrow. (Bottom) Promastigote stages from culture.

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Images from left to right: T. brucei gambiense or T. brucei rhodesiense trypomastigotes (stained with any blood stain [Giemsa, Wright-Giemsa combination, any of the rapid blood stains]).

Images from left to right: T. brucei gambiense or T. brucei rhodesiense trypomastigotes (stained with any blood stain [Giemsa, Wright-Giemsa combination, any of the rapid blood stains]).

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Images from left to right: T. cruzi amastigotes in cardiac tissue, and typical trypomastigotes (note the large kinetoplast, much larger than that seen in the African sleeping sickness trypomastigotes).

Images from left to right: T. cruzi amastigotes in cardiac tissue, and typical trypomastigotes (note the large kinetoplast, much larger than that seen in the African sleeping sickness trypomastigotes).

Plate 7.11

Row 1 (left to right): Leishmania amastigotes within macrophage (note the nucleus and bar within each amastigote) (courtesy of the Centers for Disease Control and Prevention), Leishmania donovani in bone marrow and amastigotes in bone marrow; row 2 (left to right): Leishmania donovani promastigotes in culture (wet mount), promastigotes stained with a blood stain, and individual promastigotes (higher power); row 3 (left to right): Leishmania cutaneous lesion (active), Leishmania cutaneous lesion (healed), and Leishmania cutaneous lesion; row 4 (left to right): Leishmania cutaneous lesion (the bandage slipped, inoculating the skin; hence, there are now two lesions), Leishmania mucocutaneous lesions (note the lack of nasal septum), and Leishmania donovani (visceral leishmaniasis/kala azar, hepatomegaly and splenomegaly).

Plate 7.12

Row 1: Trypanosoma brucei gambiense or T. b. rhodesiense (African trypomastigotes); row 2 (left to right): Trypanosoma brucei gambiense or T. b. rhodesiense (African trypomastigote), Winterbottom’s sign (African trypanosomiasis, swollen lymph node at posterior cervical region), and Romaña’s sign (Chagas’ disease, edema of the eyelid); row 3: Trypanosoma cruzi trypomastigotes (left and middle) and heart showing cardiomyopathy (dilation and thinning of the apical myocardium and marked concentric muscular hypertrophy) (right) (from A Pictorial Presentation of Parasites: a cooperative collection prepared and/or edited by H. Zaiman); row 4 (left to right): Trypanosoma cruzi amastigotes in tissue, Trypanosoma cruzi amastigotes in tissue (higher magnification), and xenodiagnosis (trypanosome-free bugs are allowed to feed on individuals suspected of having Chagas’ disease; if organisms are present in the blood meal, the parasites multiply and can be detected in the bug’s intestinal contents, which should be examined for 3 months).

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Images from left to right: (Top) N. fowleri trophozoite (stained), trophozoites in brain tissue, and trophozoites and cysts on the surface of an agar plate (growth on nonnutrient agar with bacterial overlay as a food source). (Bottom) Flagellated stage, indirect immunofluorescence of trophozoites in tissue (courtesy of CDC), and trophozoite (fresh, wet preparation).

Images from left to right: (Top) N. fowleri trophozoite (stained), trophozoites in brain tissue, and trophozoites and cysts on the surface of an agar plate (growth on nonnutrient agar with bacterial overlay as a food source). (Bottom) Flagellated stage, indirect immunofluorescence of trophozoites in tissue (courtesy of CDC), and trophozoite (fresh, wet preparation).

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Images from left to right: (Top) Acanthamoeba trophozoites (note the spiky pseudopods) and cyst (note the double wall). (Bottom) Acanthamoeba skin lesion (courtesy of G. H. Healy), Acanthamoeba cyst in corneal tissue, Balamuthia trophozoites in brain tissue, and Sappinia trophozoite (note the double nuclei in upper left) (courtesy of G. Visvesvara).

Images from left to right: (Top) Acanthamoeba trophozoites (note the spiky pseudopods) and cyst (note the double wall). (Bottom) Acanthamoeba skin lesion (courtesy of G. H. Healy), Acanthamoeba cyst in corneal tissue, Balamuthia trophozoites in brain tissue, and Sappinia trophozoite (note the double nuclei in upper left) (courtesy of G. Visvesvara).

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Images from left to right: Drawing of T. vaginalis (note that the undulating membrane stops about halfway down the organism), wet mount of organisms, and stained T. vaginalis trophozoite.

Images from left to right: Drawing of T. vaginalis (note that the undulating membrane stops about halfway down the organism), wet mount of organisms, and stained T. vaginalis trophozoite.

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Images from left to right: (Top) Unfertilized egg, fertilized egg, decorticate egg (lost the bumpy coat), and adult male worm. (Bottom) Unfertilized egg (note the very bumpy shell and somewhat elongated shape), fertilized egg, fertilized egg containing larva, and fertilized egg containing larva (the shell is less bumpy than most).

Images from left to right: (Top) Unfertilized egg, fertilized egg, decorticate egg (lost the bumpy coat), and adult male worm. (Bottom) Unfertilized egg (note the very bumpy shell and somewhat elongated shape), fertilized egg, fertilized egg containing larva, and fertilized egg containing larva (the shell is less bumpy than most).

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Images from left to right: (Top) Drawings of T. trichiura eggs. (Bottom) The first three images are typical eggs, with the barrel shape and polar plugs; the last egg is Capillaria, which has striations on the eggshell that are not found on the Trichuris eggshell.

Images from left to right: (Top) Drawings of T. trichiura eggs. (Bottom) The first three images are typical eggs, with the barrel shape and polar plugs; the last egg is Capillaria, which has striations on the eggshell that are not found on the Trichuris eggshell.

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Images from left to right: (Top) Drawing of a hookworm egg (N. americanus or A. duodenale), drawing of a Trichostrongylus egg (it appears longer, with one end more pointed than the hookworm egg), and the mouth parts of adult Necator (note the cutting plates). (Bottom) Three typical hookworm eggs (the third contains a larval worm; this finding suggests that fresh, unpreserved stool was left at room temperature for some time before being examined or being placed in fixative; if this egg hatches, the rhabditiform larva would have to be differentiated from that of S. stercoralis) (left and middle) and the mouth parts (teeth) of Ancylostoma (right).

Images from left to right: (Top) Drawing of a hookworm egg (N. americanus or A. duodenale), drawing of a Trichostrongylus egg (it appears longer, with one end more pointed than the hookworm egg), and the mouth parts of adult Necator (note the cutting plates). (Bottom) Three typical hookworm eggs (the third contains a larval worm; this finding suggests that fresh, unpreserved stool was left at room temperature for some time before being examined or being placed in fixative; if this egg hatches, the rhabditiform larva would have to be differentiated from that of S. stercoralis) (left and middle) and the mouth parts (teeth) of Ancylostoma (right).

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Images from left to right: (Top) Short mouth opening of Strongyloides rhabditiform larva, longer mouth opening of hookworm rhabditiform larva, drawing of slit in tail of Strongyloides filariform larva, and pointed tail of hookworm filariform larva. (Bottom) Short mouth (buccal) opening and packet of genital primordial cells of the Strongyloides rhabditiform larva.

Images from left to right: (Top) Short mouth opening of Strongyloides rhabditiform larva, longer mouth opening of hookworm rhabditiform larva, drawing of slit in tail of Strongyloides filariform larva, and pointed tail of hookworm filariform larva. (Bottom) Short mouth (buccal) opening and packet of genital primordial cells of the Strongyloides rhabditiform larva.

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Images: The photograph on the left shows an adult pinworm full of eggs. The photograph on the right shows the typical eggs (football shaped with one side somewhat flattened). These eggs are often embryonated, containing larval forms. (Photomicrograph of adult worm by Zane Price [from L. S. Garcia, Diagnostic Medical Parasitology, 5th ed., ASM Press, Washington, DC, 2007].)

Images: The photograph on the left shows an adult pinworm full of eggs. The photograph on the right shows the typical eggs (football shaped with one side somewhat flattened). These eggs are often embryonated, containing larval forms. (Photomicrograph of adult worm by Zane Price [from L. S. Garcia, Diagnostic Medical Parasitology, 5th ed., ASM Press, Washington, DC, 2007].)

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Images from left to right: (Top) Linear tracts on the bottom of the foot and linear tracts on the hand. (Bottom) Linear tracts on the buttocks of a child (who had sat down in a sandbox containing sand contaminated with dog/cat hookworm larvae). (From A Pictorial Presentation of Parasites: a cooperative collection prepared by H. Zaiman.)

Images from left to right: (Top) Linear tracts on the bottom of the foot and linear tracts on the hand. (Bottom) Linear tracts on the buttocks of a child (who had sat down in a sandbox containing sand contaminated with dog/cat hookworm larvae). (From A Pictorial Presentation of Parasites: a cooperative collection prepared by H. Zaiman.)

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Images from left to right: T. canis (left) and T. cati eggs (middle two images); Adult Toxocara worms (right). Notice the similarity of these eggs to those of A. lumbricoides.

Images from left to right: T. canis (left) and T. cati eggs (middle two images); Adult Toxocara worms (right). Notice the similarity of these eggs to those of A. lumbricoides.

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Images from left to right: The drawing shows an encysted larva; both photographs show larvae, the one on the right being sectioned (histopathology).

Images from left to right: The drawing shows an encysted larva; both photographs show larvae, the one on the right being sectioned (histopathology).

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Images from left to right: Diagrams of human microfilariae—W. bancrofti, B. malayi, O. volvulus, L. loa, M. perstans, M. streptocerca, and M. ozzardi. (Illustration by Nobuko Kitamura.)

Images from left to right: Diagrams of human microfilariae—W. bancrofti, B. malayi, O. volvulus, L. loa, M. perstans, M. streptocerca, and M. ozzardi. (Illustration by Nobuko Kitamura.)

Plate 7.13

Row 1 (left to right): Brugia malayi microfilaria (note the sheath and two terminal nuclei), Brugia malayi head (sheath not visible), and Brugia malayi tail (again, note the sheath and two terminal nuclei); row 2 (left to right): Loa loa microfilaria (note the sheath), Loa loa tail (note that nuclei run all the way to the end of the tail; the sheath is not visible), and Loa loa tail (note that nuclei go to the tip of the tail; the sheath is visible); row 3: Loa loa in eye (left and middle) and Loa loa calabar swelling (note the swollen left knee) (right) (all three images from A Pictorial Presentation of Parasites: a cooperative collection prepared and/or edited by H. Zaiman); row 4 (left to right): Wuchereria bancrofti head of microfilaria (note the nuclei and sheath), Wuchereria bancrofti tail (note that the nuclei end before the end of the tail; the sheath is visible), and elephantiasis (occurs with certain types of filariasis) (right image from A Pictorial Presentation of Parasites: a cooperative collection prepared and/or edited by H. Zaiman).

Plate 7.14

Row 1 (left to right): Onchocerca volvulus (removal of nodule from scalp), Onchocerca volvulus (organisms seen in skin biopsy), and Onchocerca volvulus (cross section of worms within a nodule); row 2 (left to right): Onchocerca volvulus (worms removed from nodule), Onchocerca volvulus (example of “river blindness”), and Mansonella ozzardi (this microfilaria does not have a sheath); row 3: Dracunculus medinensis (worm removal) (left and middle) and Dirofilaria spp. in the heart of a dog (right) (three images courtesy of Armed Forces Institute of Pathology); row 4 (left to right): Dirofilaria spp. (worm in eyelid), Dirofilaria spp. (worm being removed from eye) (two images from A Pictorial Presentation of Parasites: a cooperative collection prepared and/or edited by H. Zaiman), and Dirofilaria spp. (worm in cross section), (courtesy of A. Linscott).

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Images from left to right: The drawings depict the scolex, egg, and gravid proglottid of T. saginata; the photographs show the same structures. Note the number of uterine branches (many more than in T. solium). Also, note that the scolex does not contain hooklets, like that of T. solium (see p. 353).

Images from left to right: The drawings depict the scolex, egg, and gravid proglottid of T. saginata; the photographs show the same structures. Note the number of uterine branches (many more than in T. solium). Also, note that the scolex does not contain hooklets, like that of T. solium (see p. 353).

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Images from left to right: The drawings depict the scolex, egg, and gravid proglottid of T. solium; the photographs show the same structures. Note the number of uterine branches (many fewer than that in T. saginata). Also note that the scolex has hooklets, unlike that of T. saginata (see p. 351).

Images from left to right: The drawings depict the scolex, egg, and gravid proglottid of T. solium; the photographs show the same structures. Note the number of uterine branches (many fewer than that in T. saginata). Also note that the scolex has hooklets, unlike that of T. saginata (see p. 351).

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Images from left to right: The drawings depict the scolex, egg, and gravid proglottid of D. latum; the photographs show the same structures. The gravid proglottids are often passed as a chain (which can be several feet long). Some of the eggs are seen with “popped” open opercula (trapdoors).

Images from left to right: The drawings depict the scolex, egg, and gravid proglottid of D. latum; the photographs show the same structures. The gravid proglottids are often passed as a chain (which can be several feet long). Some of the eggs are seen with “popped” open opercula (trapdoors).

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Images from left to right: The drawing depicts the H. nana egg; the photographs show the same structures. Note the six-hooked embryo (oncosphere) and the polar filaments that lie between the oncosphere and the thin eggshell. The key difference between this egg and that of the rat tapeworm (H. diminuta) is the lack of polar filaments in the latter.

Images from left to right: The drawing depicts the H. nana egg; the photographs show the same structures. Note the six-hooked embryo (oncosphere) and the polar filaments that lie between the oncosphere and the thin eggshell. The key difference between this egg and that of the rat tapeworm (H. diminuta) is the lack of polar filaments in the latter.

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Images from left to right: The drawing depicts the H. diminuta egg; the photographs show the same structures. Note the six-hooked embryo (oncosphere) and the lack of polar filaments. The key difference between this egg and that of H. nana is the presence of polar filaments between the onco-sphere and the thin eggshell in H. nana eggs.

Images from left to right: The drawing depicts the H. diminuta egg; the photographs show the same structures. Note the six-hooked embryo (oncosphere) and the lack of polar filaments. The key difference between this egg and that of H. nana is the presence of polar filaments between the onco-sphere and the thin eggshell in H. nana eggs.

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Images from left to right: (Top) The drawings depict the scolex, gravid proglottid, and egg packet of D. caninum. (Bottom) The photographs demonstrate the typical egg packets. Note the six-hooked embryo (oncosphere) and striated eggshells of the individual eggs within the egg packet. Individually, the eggs normally resemble Taenia eggs.

Images from left to right: (Top) The drawings depict the scolex, gravid proglottid, and egg packet of D. caninum. (Bottom) The photographs demonstrate the typical egg packets. Note the six-hooked embryo (oncosphere) and striated eggshells of the individual eggs within the egg packet. Individually, the eggs normally resemble Taenia eggs.

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Images from left to right: (Top) The photographs depict the hydatid cyst showing daughter scolices and the immature scolices (hydatid sand). (Bottom) Higher magnification of the immature scolices and the hooklets that remain after the scolices have disintegrated.

Images from left to right: (Top) The photographs depict the hydatid cyst showing daughter scolices and the immature scolices (hydatid sand). (Bottom) Higher magnification of the immature scolices and the hooklets that remain after the scolices have disintegrated.

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Images from left to right: Drawing and photograph of F. buski egg. The operculum blends into the shell; there are no opercular shoulders into which the operculum fits. In the photograph, the operculum has popped open. This egg and that of several other trematodes, including F. hepatica, look almost identical and cannot be differentiated visually.

Images from left to right: Drawing and photograph of F. buski egg. The operculum blends into the shell; there are no opercular shoulders into which the operculum fits. In the photograph, the operculum has popped open. This egg and that of several other trematodes, including F. hepatica, look almost identical and cannot be differentiated visually.

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Images from left to right: The drawings on the left show D. latum (A) and P. westermani (B). Although the eggs are different sizes, there is some similarity between the two. The photograph shows P. westermani. Note the opercular shoulders visible with P. westermani. It is critical that these eggs be measured carefully, including specimens used for proficiency testing.

Images from left to right: The drawings on the left show D. latum (A) and P. westermani (B). Although the eggs are different sizes, there is some similarity between the two. The photograph shows P. westermani. Note the opercular shoulders visible with P. westermani. It is critical that these eggs be measured carefully, including specimens used for proficiency testing.

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Images from left to right: Drawing and photograph of F. hepatica egg. The operculum blends into the shell; there are no opercular shoulders into which the operculum fits. In the photograph, the operculum has popped open. This egg and that of F. buski (and several other trematodes) look almost identical and cannot be differentiated visually.

Images from left to right: Drawing and photograph of F. hepatica egg. The operculum blends into the shell; there are no opercular shoulders into which the operculum fits. In the photograph, the operculum has popped open. This egg and that of F. buski (and several other trematodes) look almost identical and cannot be differentiated visually.

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Images from left to right: The drawing and first three eggs are those of C. sinensis, while the photograph of the egg on the right is another similar egg, either H. heterophyes or M. yokogawai. Differentiation of these three trematodes can be difficult.

Images from left to right: The drawing and first three eggs are those of C. sinensis, while the photograph of the egg on the right is another similar egg, either H. heterophyes or M. yokogawai. Differentiation of these three trematodes can be difficult.

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Images from left to right: The eggs on the left with the large lateral spines are S. mansoni, those in the middle with the terminal spines are S. haematobium, and those on the right with the very small lateral spines are S. japonicum.

Images from left to right: The eggs on the left with the large lateral spines are S. mansoni, those in the middle with the terminal spines are S. haematobium, and those on the right with the very small lateral spines are S. japonicum.