PUBUG HEALTH LIBRAIV MORPHOLOGY OF DIAGNOSTIC o 1984 STAGES or 33,, \" INTBSTINAL 3 HUMANS US. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers For Disease Control Atlanta, Georgia 30333 ' -.;' I-: j I- l I. I I I_ —'-I-l I. I-L'”. 4'.'_ f. _I. :L-‘ir'l r l in; I: ”Ir-III" .-' LIII-II.. 'i-'.IIII - _ .- .L' '_ 11ml. -". IIII I ' ,. Lie-I I I. . I- 4- _II _ _ _ . III II I.III III II -.-_II. _ _ ' III :L' 'I' . . _.I_I,_ _ . II '. II _ _ . II_ II_I _ _._-__II'r..I . .I-.-.I .I' II.I_ -,._ _...._III. _.IIII- -'_= --|f'll: .I "J l I Th' .1.- _.I . -I..I II. ,- . I- .IIII_ II .' ' .- '. I"" “ ' ' I ' 'I ' '4 I. - - " ' II .II.: .'“ - '. . 'Ié - II I II '4 - _I - -_ _ -II. -‘.L ' IF __.-_— _ a- : I- I-_I I H '- _II .I- : f. I" '.' I I_! I_-'. -Ir _' _ _ - .- - a. . . _ .I-' ..I. .- _' ‘4 --' i' 5" _ .I I II' I _ -- i II ' " FIIII .‘f-rr _ - u .I - .,_r.-.. III-Jim! 4'. . .. I |"..' I 'II- _ I-H 'l _' ' I I"-II II'I I I JI '-II- - .-. _ '- .'._ 1'4": -11 In. - .'- "--. 1. ' ' II II~II .I .. -.I . .-4 - d4 ' i - ' “I'|_ - | l— " I II I _ .' .- I ' .- II. I '- I ' _ ' - _lI _ . I -_I I III _ __ _-_. _-, . _ _ I ‘2 F 1 1' I.)- 1'. 1i 2% _III I 3;. 'I Til 'I I' 31:: -.':_ I g . .I- I. _.I 4' '-.:'_I-"" '- I l l u _—l I . I -. : I' I _I‘I - ' II _ I u I II I I_ I I I II I- -- - u _ “I .I'fi . - .I ‘i‘ . I __ __ I -I .I -: - l h.- a-- . I. In. - ”takuzosé. L-‘li- I_ . I I'- ii" I. 3’9'54 z- 4.. :5 Immv‘I-‘I 7.‘ I II - 'uTu'I I ---I -"I I . . r - Irl-_ -_ I-__'-II _ I l' MORPHOLOGY OF DIAGNOSTIC STAGES OF INTESTINAL PARASITES OF HUMANS rooke, Sc.D. M. M. B D. M. Melvin, Ph.D. Division of Laboratory Training and Consultation Laboratory Program Office Second Edition 1984 US. DEPARTMENT OF HEALTH AND HUMAN SERVICES Public Health Service Centers For Disease Control Atlanta, Georgia 30333 HHS Publication No. (CDC) 84—8116 #7I7é7w7 pm QL757 572 MW PMBL PREFACE Although the morphology of the diagnostic stages of the intestinal parasites found in humans is described in many textbooks and manuals, it is not generally readily available in the average laboratory. The characteristics commonly used to distinguish species are tabulated and illustrated in this publication. Thus, the technologist performingparasitol- ogy examinations in public health and medical laboratories can quickly refer to them. The booklet is designed to assist the microscopist in identifying the organisms found, but it is not a substitute for the practical training in laboratory procedures and differentiation of species under the supervision of persons experienced in diagnostic parasitology. In this second edition, several species of flagellates, coccidia, and schistosomes have been added. Because of the increased number of dra wings, those of the flagellates and of the ciliate and coccidia have been separated into two figures. We thank Mrs. Margery Borom and Miss Jean Ryan, formerly of the Centers for Dis- ease Control (CDC), for preparing the original drawings of the organisms and Mr. Ed Biel, Chief, Publications, Graphics Section, CDC, for the revisions and additions. M. M. Brooke, Sc.D. Associate Director Division of Laboratory Training and Consultation Dorothy M. Melvin, Ph.D. Chief, Parasitology Training Section iii CONTENTS INTRODUCTION ................................................................. vii PROTOZOA ....................................................................... 1 Amebae ......................................................................... 1 Flagellates ........................................................................ 2 Ciliate ........................................................................... 3 Coccidia ......................................................................... 3 Blastocystis ....................................................................... 4 HELMINTHS ...................................................................... 5 Nematodes ....................................................................... 5 Cestodes ......................................................................... 6 Trematodes ....................................................................... 6 TABLES 1. Characteristics of Intestinal Amebae Visible in Different Types of Fecal Preparations ..................................................... 2 2. Characteristics of Intestinal Flagellates, Ciliate, and Coccidia Visible in Different Types of Fecal Preparations .................................... 4 3. Differential Morphology of Protozoa Found in Stool Specimens of Humans: Amebae— Trophozoites ............................................. 8 4. Differential Morphology of Protozoa Found in Stool Specimens of Humans: Amebae — Cysts .................................................... 9 5. Differential Morphology of Protozoa Found in Stool Specimens of Humans: Flagellates—Trophozoites ........................................... 10 6. Differential Morphology of Protozoa Found in Stool Specimens of Humans: Flagellates — Cysts ................................................. 1 1 7. Differential Morphology of Protozoa Found in Stool Specimens of Humans: Ciliate, Coccidia, and Blastocystis ..................................... 12 8. Differential Morphology of Diagnostic Stages of Helminths Found in Humans: Eggs ...................................................... 13 9. Differential Morphology of Diagnostic Stages of Helminths Found in Humans: Larvae ..................................................... 18 10. Differential Morphology of Diagnostic Stages of Helminths Found in Humans: Tapeworm Gravid Proglottids .................................. 19 11. Differential Morphology of Diagnostic Stages of Helminths Found in Humans: Tapeworm Scoleces .......................................... 20 FIGURES 1. Protozoa Found in Stool Specimens of Humans— Amebae ............................. 21 2. Protozoa Found in Stool Specimens of Humans— Flagellates ........................... 22 3. Protozoa Found in Stool Specimens of Humans—Ciliate, Coccidia, Blastocystis ......................................................... 23 4. Nematode and Cestode Eggs Found in Stool Specimens of Humans ................................................................. 24 5. Trematode Eggs Found in Stool Specimens of Humans ............................... 25 6. Relative Sizes of Helminth Eggs .................................................. 26 7. Hookworm and Strongyloides Larvae .............................................. 27 8. Gravid Proglottids and Scoleces of Cestode Parasites of Humans ......................................................... 28 REFERENCES .................................................................... 29 INTRODUCTION The diagnostic stages of intestinal parasites are differentiated on the basis of specific morpho- logic features that can be seen microscopically. The characteristics that are visible in different types of preparations are listed in tables 1 and 2', the characteristics commonly used to distin- guish species are presented in tables 3-11 for the microscopist’s ready reference. The descrip- tions, however, do not include all the morphologic characteristics of the various stages, and supplemental references may be needed in some cases. Although Dientamoebafragilis is a flagellate (Camp et al., 1974', Honigberg, 1974), morphologi- cally, it resembles the amebae. Therefore, in this manual it is included with the amebae to faci- litate species identification. Several parasite species were added to this second edition. Drawings of the trophozoites and cysts of Enteromonas hominis and Retortamonas intestinalis were included with those of the other flagellates. Information on the coccidia was updated, and both descriptions and diagrams of the diagnostic stages of Sarcocystis and Cryptosporidium were included. Blastocystis homim‘s, now identified as a protozoan, was also included in the tables and figures. Because of the in- creased number of drawings, diagrams of the flagellates and the ciliate and coccidia were separated into two figures. Also in this edition, two additional species of trematodes, Schistoso- ma mekongi and Schistosoma intercalatum, were described in the table of differential morpholo- gy of helminth eggs. Drawings of these eggs, however, were not included in the figures. Some of the parasites listed occur only infrequently or accidentally in humans; but, since their diagnostic stages may be confused with those of the more common organisms, they were included here. For example, Entamoeba polecki is rarely found in human feces; however, it closely resembles Entamoeba histolytica and Entamoeba coli, and microscopists unaware of its existence may mistake it for these species. Similarly, several helminth species of lower animals that occasionally parasitize humans are included. The diagnostic stages may be misidentified by inexperienced microscopists. For example, Trichostrongylus (Nematode) eggs may be confused with hookworm eggs, and Hymenolepis diminuta (Cestode) eggs may be confused with Hymeno- lepis nana eggs. The protozoa found in the mouth, Entamoeba gingivalis and Trichomonas tenax, were omitted from this manual, since the diagnostic stages of these parasites are not found in feces. Trichomo- nas vaginalis was not included because it is a parasite of the urogenital system rather than of the intestinal tract. Technical methods for examining specimens are presented in the manual “Laboratory Proce- dures for the Diagnosis of Intestinal Parasites” (Melvin and Brooke, 1982). The morphology of the intestinal parasites is described in many parasitology textbooks. Some of those which emphasize morphology of the diagnostic stages and have good illustrations are listed in the references. vii 1' '\ PROTOZOA The intestinal protozoa of humans belong to four groups: amebae, flagellates, ciliates, and coc- cidia. In addition to these, Blastocystis hominis now has been identified as a protozoan (Zierdt and coworkers, 1967, 1973, 1976, 1983).With the exception of the coccidia and Giardia lamblia (flagellate) which inhabit the small intestine, the protozoa live in the caecum and colon. The coccidia differ from the other protozoan species in being obligatory tissue parasites. Oocysts or sporocysts, passed in the feces, are the diagnostic stages. Organisms belonging to the three other groups have two stages, trophozoites and cysts, in their life cycle, except Dientamoeba fragilis and Trichomonas hominis (flagellates), which have only a trophozoite stage. Both trophozoites and cysts are passed in feces and are diagnostic stages. The features listed in tables 3-7 are those commonly seen in fecal preparations and used for identifications. Features or structures that are difficult to see or are demonstrated only by spe- cial techniques are omitted. Not all of the characteristics listed, however, can be seen in a single type of preparation. The fecal preparations used to demonstrate protozoa are either wet mounts or permanently stained smears. Wet mounts may be unstained (saline or formalin) or stained (iodine, buffered methylene blue, Quensel’s stain, merthiolate-iodine-formaldehyde [MIF], or other temporary stains). Iodine is primarily a cyst stain, and iodine preparations are usually routinely prepared in examining fecal specimens for protozoa. Buffered methylene blue and Quensel’s stains are used to stain amebae trophozoites. Others, such as MIF, will stain both stages, but they may be less satisfactory for trophozoites than for cysts. Fecal smears may be permanently stained with hematoxylin, trichrome, chlorazol black, or other suitable stains. Scaled drawings of the intesti- nal protozoa are presented in figures 1-3. AMEBAE Characteristics used to distinguish species of intestinal amebae are as follows: Trophozoites Motility— progressive or nonprogressive. Cytoplasm Appearance—finely granular, coarsely granular, or vacuolated. Inclusions-erythrocytes, bacteria, molds. Nucleus Number present. Peripheral chromatin—present or absent. If present, the distribution along the inner surface of the nuclear membrane and the size of the granules are important. Karyosome—location and size. Size Sizes overlap, but they can be used as a secondary distinguishing feature. Size is the chief criterion for distinguishing Entamoeba histolytica from Entamoeba hartmanni. Cysts Nucleus Number present. Peripheral chromatin—present or absent. If present, the distribution of the granules along the inner surface of the nuclear membrane is important. Karyosome—location and size. Cytoplasm Chromatoid bodies—present or absent. If present, the shape is important. Glycogen — appearance. Size Sizes overlap, but they can be used as a secondary distinguishing feature. Size is the major criterion for distinguishing Entamoeba histolytica from Emamoeba hartmanni. Shape Shapes vary, but they may be useful as a secondary distinguishing feature. As stated above, both unstained and stained preparations are necessary to demonstrate all of the features. Table 1 indicates the structures or characteristics that can be seen in different types of preparations. Species identification of trophozoites can rarely be made from single features, such as nucleus or cytoplasm, or from a single organism. Several features and several organisms should be examined. Cysts are less variable and can usually be more easily identified than trophozoites. Tables 3 and 4 list the common morphologic characteristics of the amebae. Drawings of the trophozoite and cyst stages are presented in figure 1. TABLE 1 CHARACTERISTICS OF INTESTINAL AMEBAE VISIBLE IN DIFFERENT TYPES OF FECAL PREPARATIONS Unstained Temporary Stains Permanent Stains Iodine Buffered Methylene Characteristic Saline Formalin (Cysts) Blue (Trophs)‘ Trophozoites Motility ................... + — _ _. Cytoplasm ................ appearance .............. + + + + inclusions (rbc. bacteria). . . . + + + + Nucleus .................. — +2 + + Cysts Nuclei ................... — + + + Chromatoid bodies .......... + + +3 + Glycogen ................. — — + _ (vacuole present) ‘Ouensel's stain may be substituted for buffered methylene blue. 2Nuclei oi trophozoites are visible in formalin-fixed material but are usually not sufficiently distinctive for species identifiéaiion. aChromatoid bodies are more easily seen in unstained wet mounts than in iodine preparations. FLAGELLATES Characteristics used to distinguish flagellate species are as follows: Trophozoites Motility Shape Number of nuclei. The appearance of the nucleus is not commonly used to distinguish speCIes. Other features such as undulating membrane, sucking disk, and prominent cytostome. Number and location of flagella. Although the number and location of flagella vary with the species, they are often difficult to see and count. Therefore, the number and location of flagella are not practical diagnostic features for routine identification. Cysts Shape Size Number of nuclei Fibrils As with amebae, not all of the characteristics of flagellates can be seen in a single type of prepa- ration, and both unstained and stained preparations may be necessary. Nuclei are not visible in unstained saline mounts, but they can be seen in formalin-fixed material. Most of the other features can be seen in either saline or formalin unstained mounts. Cyst structures are usually easily seen in iodine preparations. Quensel’s and buffered methylene blue solutions, however, do not stain the trophozoites. If fresh feces are available, trophozoites can be readily distin- guished by their characteristic motion in saline mounts. Methocel solutions can be used to slow the motion, particularly of Trichomonas, for better observation of flagella and undulating mem- branes. Neutral red dye added to the solution will stain the trophozoites to some extent. Table 2 indicates the structures or characteristics that can be seen in different types of preparations. Tables 5 and 6 list the diagnostic characteristics of the intestinal flagellates. Drawings are pre- sented in figure 2. CILIATE Only one ciliate species, Balantidium coli (figure 3), parasitizes humans. It is also the largest pro- tozoan parasite of humans, and the trophozoites and cysts are easily detected in saline mounts of fresh feces. The size, shape, and motility of the trophozoites are readily recognized by even beginning parasitology students. Although the cysts are less easily identified, they, too, present few real diagnostic problems. In formalin-fixed feces, the trophozoites may be somewhat dis- torted, but they are usually recognizable. Formalin does not significantly alter the appearance of the cyst. Good stained preparations of B. coli are difficult to obtain. Most of the structural details, how- ever, can be seen in unstained mounts, and neither temporary nor permanent stains are needed. The organism is so characteristic in appearance that identification is usually made with- out difficulty. The common diagnostic characteristics are listed in table 7 and drawings of the trophozoite and cyst are presented in figure 3. COCCIDIA The coccidia species of humans belong to the genera Isospora, Sarcocystis, and Cryptosporidium. The diagnostic stages are often difficult to locate in feces, and they are easily overlooked be- cause of their almost transparent appearance. Correct lighting and careful focusing are essential for detection. In Isospora belli infections, immature oocysts are generally passed in feces, al— though fully mature oocysts may be present in some cases. In Sarcocystis hominis and Sarcocystis suihomim‘s infections, mature oocysts or free single sporocysts are usually passed in feces. The oocysts and sporocysts of S. hominis and S. suihominis are more or less identical and reliable spe- cies identification cannot be made from these stages. When found, they are reported as “Sar- cocystis species.” Species differentiation is based on the intermediate host involved (cattle for S. hominis and swine for S. suihomim‘s) and differences in the sarcocyst stage in the tissues of these hosts. In Cryptosporidium infections, either immature oocysts or mature oocysts contain- ing four naked sporozoites (no sporocysts are present) are passed. The usual permanently stained fecal smears are of little or no value in demonstrating coccidia. Cryptosporidium oocysts, however, can be identified in acid-fast stains and stained preparations are routinely examined in diagnosing cryptosporidiosis. Giemsa stains are also used but acid- fast stains are preferred by most workers. Unstained wet mounts are generally used to detect and identify oocysts of [sospora and Sar- cocystis, and may be of value for Cryptosporidium. Iodine and MIF stains, also may be helpful in some cases; iodine is particularly useful for distinguishing Cryprosporidium oocysts, which do not stain, from yeasts, which stain brown or yellow. The diagnostic characteristics of coccidia are listed in table 7; oocysts and sporocysts are presented in figure 3. The immature oocysts of Isospora species frequently cannot be readily distinguished from immature oocysts of Eimeria species, which parasitize lower animals. Occasionally, Eimeria may be accidentally ingested with animal tissue and passed out in human feces. Therefore, if the genus of coccidia is in doubt, it is preferable to identify the organisms as “coccidia” and attempt to obtain mature oocysts for positive identification. This can be done by mixing the feces con- taining oocysts with 2% potassium dichromate solution and letting them stand at room tem— perature for 48 hours or longer. Mature oocysts of Eimeria contain 4 sporocysts with 2 sporo- zoites each; those of Isospora contain 2 sporocysts with 4 sporozoites each. BLASTOCYSTIS Blastocystis hominis, long considered to be a yeast, has now been identified as a protozoan (Zierdt et al., 1967; Zierdt, 1973) and is currently classified in the subphylum Sporozoa (Zierdt and Tan, 1976; Zierdt, 1983). There is evidence to suggest that it may be pathogenic in some cases. Several forms, including round “granular forms” and “ameba forms,” have been de- scribed from feces and cultures (Zierdt and Tan, 1976; Zierdt, 1973; Zierdt er al., 1967) but the stage most often recognized in stool specimens is the spherical “vacuolated form” (McClure et al., 1980). This form is described in table 7 and depicted in figure 3. TABLE 2 CHARACTERISTICS OF INTESTINAL FLAGELLATES, CILIATE, AND COCCIDIA VISIBLE IN DIFFERENT TYPES OF FECAL PREPARATIONS Unstained Temporary Stains Permanent Stains Iodine Neutral Red 1 Characteristic Saline Formalin (Cysts) (Trophs) Flagellates Trophozoites Motility ................. + —— + _ Shape .................. + + + + (may be distorted) Nucleus ................. — + + + Flagella ................. i — + 1 Other features? ........... + + + + Cysts Shape .................. + + + + Nuclei .................. — + + + Fibrils .................. i + + + Ciliate (Belem/diam cal/7 Trophozoites Motility ................. + — + _ Macronucleus ............ + + + + Cilia .................... + + + + Cysts Macronucleus ............ + + i + Coccidia Uocysts/Sporocysts ......... + + + -_r-3 INeutral red dye in methocel solutions. 2The undulating membrane of Trichamanas and the spiral groove of Chi/amastix may not be visible in all cases. 3[fry/1tas'pan'dium oocysts can be demonstrated in acid—last stains. HELMINTHS The common helminth parasites of humans belong to three groups: nematodes (roundworms), cestodes (tapeworms), and trematodes (flukes). The diagnostic stages of helminths are more easily identified by most technologists than the diagnostic stages of protozoa. Their distinguish- ing features are less variable, and being larger, they are more readily detected. Although the laboratory occasionally receives adult helminths, especially Ascaris and Enterobius, diagnosis is usually made from eggs, or in some cases, larvae, or body segments (proglottids). Differential characteristics of eggs are listed in table 8; characteristics of larvae are listed in table 9', and pro- glottids and scoleces are described in tables 10 and 11, respectively. Diagrams of eggs are pre- sented in figures 4,5, and 6; larvae are shown in figure 7', proglottids and scoleces are depicted in figure 8. Characteristics used to identify species of eggs are as follows: Size Shape Stage of development when passed in the feces Thickness of the eggshell Color Presence of structures such as mammillated coat, operculum, spine, or plugs Helminth eggs and larvae are best seen in unstained wet mounts. Neither temporary nor permanent stains are needed. Proglottids and scoleces usually require special clearing or stain- ing procedures. NEMATODES The common diagnostic stage of the nematodes is the egg, except for Strongyloides stercoralis in which the first stage, or rhabditiform, larva is the usual diagnostic stage. Occasionally, hook- worm larvae may also be present in feces and must be distinguished from those of Strongyloides. The rhabditiform larvae of hookworm and Strongyloides can be differentiated by the length of the buccal cavity and by the appearance of the genital primordium. In rare cases, filariform (third stage) larvae may be found in feces or they can be obtained by culturing specimens con- taining eggs or rhabditiform larvae. Filariform larvae differ from rhabditiform larvae in size and in the appearance of the esophagus. The third stage larva is about twice as long as the first stage larva and lacks the bulb configuration of the esophagus that is characteristic of the rhabdi- tiform larva. The filariform larvae of Strongyloides are distinguished from those of hookworm by the appearance of the tip of the tail and the length of the esophagus. Characteristics of the eggs are listed in table 8; those of the larvae are described in table 9. Drawings of the nematode eggs are presented in figures 4 and 6; the larvae are presented in figure 7. Eggs of the nematode species are shed more or less continuously and may be present in every fecal specimen from an infected individual. Strongyloides larvae, however, are passed irregularly and will not be found in every specimen. CESTODES In certain of the cestodes (Hymenoleflis nana, Hymenolepis diminuta, and Diphyllobothrium latum), the egg is the usual diagnostic stage. In other species ( Taenia and Dipylidium caninum), eggs may be present in feces, but the proglottid is the usual diagnostic stage. Except in the case of D. latum, the cestode eggs are embryonated when they leave the worm’s body. The embryo is a six-hooked, spherical structure called an oncosphere. Diphyllobothrium latum eggs are unsegmented when passed and become embryonated outside of the host. They may resemble the eggs of hookworm, infertile Ascaris, or Paragonimus wester- mani and must be distinguished from these species. Occasionally, portions of the strobila (chain of proglottids) are passed, and the species can be identified by the characteristic appear— ance ofthe proglottids. The eggs of Taenia saginata and Taem'a solium are identical, and species identification cannot be made from this stage. When found, they should be reported as “ Taenia species.” The common diagnostic stage, however, is the gravid proglottid rather than the egg. Proglottids, either singly or in short chains, become detached from the strobila and are passed with the feces. Taem'a saginata proglottids occasionally migrate out of the anus independent of defecation. Specific identification is based on the number of lateral uterine branches in the gravid proglot- tid. These can be seen in uncleared segments, but they are more distinct in cleared proglottids. A hand lens or dissecting microscope can be used to observe the structural details. The primary branches from one side of the central uterine stern are counted to distinguish between T saginata and T solium. Less frequently, and usually after treatment, scoleces may be obtained for species identification. Dipylidium caninum, a cestode parasite of dogs, cats, and occasionally humans, is also more fre- quently diagnosed by finding proglottids rather than eggs in the specimen. The eggs, when found, are usually contained in packets or capsules of 5 to 15 or more eggs. In rare cases, the scolex may be obtained for diagnosis. The eggs of the intestinal cestode species are described in table 8; the gravid proglottids are de- scribed in table 10; the scoleces are described in table 11. Drawings of the eggs are presented in figures 4 and 6, and drawings of gravid proglottids and scoleces are presented in figure 8. TREMATODES The diagnostic stage of the trematode species parasitic in humans is the egg. The characteristics of the eggs of human species are described in table 8', drawings are presented in figures 5 and 6. The eggs of Clonorchis, Opisthorchis, Heterophyes, and Metagonimus closely resemble each other, and for this reason, they are difficult to separate. The characteristics described in table 8 are not always apparent. The eggs of Fasciola hepatica and Fascia/opsis buski are also very simi- lar, and it may be difficult to differentiate these species. Descriptions of the eggs of two additional species of schistosomes, Schistosoma mekongi, found in the Mekong River area of Southeast Asia, and Schistosoma intercalatum, found in Africa, are included in table 8. Both of these species inhabit the mesenteric venules, and eggs are passed in feces. The eggs of S. mekongi closely resemble those of Schistosoma japonicum except S. mekongi eggs are slightly smaller (see description in table 8). The eggs of S. intercalatum resem- ble those of S. haematobium except for minor differences in shape and size, as described in table 8. The S. intercalatum egg is longer and thinner than the S. haematobium egg, and the tip of the terminal spine of S. intercalatum may be bent. Because the eggs of these newer species so closely resemble those of species already included in the drawings and because of space limita- tions, diagrams of S. mekongiand S. intercalatum are not included in figures 5 and 6. The eggs of two of the human trematode parasites are ordinarily passed in urine (Schistosoma haematobium) or sputum (Paragonimus westermam‘).1 Eggs of both, however, are occasionally . found in feces. Since trematode eggs are usually found at irregular intervals in feces, several specimens may need to be examined to demonstrate their presence. lSeveral species of Paragonimus have been identified as parasites of humans, but only P. westermam‘ is included in this manual. The eggs of all species are similar but vary slightly in size and shape. TABLE 3 DIFFERENTIAL MORPHOLOGY OF PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS AMEBAE — TROPHOZOITES NUCLEUS CYTOPLASM Size Species (Length) Motility Peripheral Karyosomal Number Chromatin Chromatin Appearance Inclusions Entamaeba 10-60 pm. Usual Progressive with 1 Fine granules. Usually Small, discrete. Finely granular. Red blood cells histo/ytica range, 15-20 um— hyaline. finger— Not visible in un- evenly distributed and Usually centrally occasionally. Non- commensal form.‘ like pseudopods. stained preparations. uniform in size. located, but invasive organisms Over 20 ,um— occasionally is may contain bacteria. invasive form.2 eccentric. Entamaeba 5-12 um. Usual Usually non~ 1 Similar to Small, discrete, Finely granular. Bacteria. hartmenni range, 8-10 pm. progressive but Not visible in un- E. hism/yt/‘ca. often eccentric. may be progressive stained preparations. occasionally. Entomoeba 15-50 p. m. Usual Sluggish, non- 1 Coarse granules, Large, discrete, Coarse, often Bacteria, yeasts. ca/i range, 20-25 ,um. progressive, with Often visible in un- irregular in size and usually eccentric. vacuolated. other materials. blunt pseudopods. stained preparations. distribution. Entamaaba 10-25 pm. Usual Usually sluggish, 1 Usually fine granules Small, discrete, eccen- Coarsely granular. Bacteria, yeasts. po/ac/ri range, 15-20 pm. similar to E. coli. Maybe slightly visible evenly distributed. tric. Occasionally may resemble Occasionally in in unstained prepara- Occasionally, granules large, diffuse, or E. col/Z Contains diarrheic specimens, tions. Occasionally may be irregularly irregular. numerous vacuoles. motility may be distorted by pressure arranged. Chromatin progressive. from vacuoles in cyto- sometimes in plaques plasm. or crescents. Endo/I'max 6-12 /.L m. Usual Sluggish, usually 1 None. Large, irregularly Granular, vacuolated. Bacteria. ”8/15 range, 8-10 um. nonprogressive with Visible occasionally in shaped, blot-like. blunt pseudopods. unstained preparations. ladamoeba 8-20 ,u.rn. Usual Sluggish, usually 1 None. Large, usually central. Coarsely granular. Bacteria, yeasts, or [Hirsch/ii range, 12-15 urn. nonprogressive. Not usually visible in Surrounded by refrac- vacuolated. other material. unstained preparations. tile, achromatic granules. These granules are often not distinct even in stained slides. Dientamoelza 5-15 pm. Usual Pseudopods are 2 None. Large cluster of 4-8 Finely granular. Bacteria; occasion- frag/7is3 range, 9-12 pm. angular, serrated, or (In approximately 20% granules. ally red blood cells. broad lobed, and hyaline. almost transparent. of organisms only 1 nucleus is present.) Nuclei invisible in unstained preparations. 1Commensal form—usually found in asymptomatic or chronic cases,- may contain bacteria. 2Invasive form—usually found in acute cases; often contain red blood cells. 3Flagellate—includetf with amebae for diagnostic purposes. TABLE 4 DIFFERENTIAL MORPHOLOGY OF PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS AMEBAE—CYSTS NUCLEUS CYTOPLASM Size Species (Diameter Shape Peripheral Karyosomal Chromatoid or length) Number Chromatin Chromatin Bodies Glycogen [ntamoeba 10-20 pm Usually spherical. 4 in mature cyst. Peripheral chromatin Small, discrete, Present. Elongated Usually diffuse. hista/yt/L'a Usual range, Immature cysts with 1 present. Fine, uni- usually centrally bars with bluntly Concentrated mass 12-15 ,urn. or 2 occasionally seen. form granules, evenly located. rounded ends. often present in distributed. young cysts. Stains reddish brown with iodine. Entamaeba 5-10 pm Usually spherical. 4 in mature cyst. Similar to Similar to Present. Elongated Similar to hanmanni Usual range, Immature cysts with 1 E histolytica. E. hisra/yt/ca. bars with bluntly E. hista/yrica. 6-8 pm. or 2 often seen. rounded ends. Emamoeba 10-35 pm Usually spherical. 8 in mature cyst. Peripheral chromatin Large. discrete, Present, but less Usually diffuse. co/i Usual range, Occasionally oval, Occasionally super- present. Coarse gran- usually eccentric frequently seen than but, occasionally 15-25 um. triangular, or nucleated cysts with ules irregular in size but occasionally in E. hista/ytica. well defined mass other shapes. 16 or more are seen. and distribution, but centrally located. Usually splinter-like in immature cysts. Immature cysts with 2 often appear more with pointed ends. Stains reddish brown or more occasionally uniform than in with iodine. seen. trophozoites. Entamoe/Ja 9-18 pm Spherical or oval. 1 Usually fine granules Usually small and Present. Many small Usually small, diffuse po/ec/ri Usual range, Rarely 2. Occasionally evenly distributed. eccentric. bodies with angular masses stain reddish 11-15 um. visible in unstained or pointed ends, or brown with iodine. A preparations. few large ones. May dark area called an be oval, rod-like, "inclusion mass" (pos- or irregular. sibly concentrated cytoplasm) is often also present. Mass does not stain with iodine. Enda/I'max 5-10 pun. Spherical, ovoidal, 4 in mature cysts. None Large (blot-like), Occasionally granules Usually diffuse. Con- nana Usual range, or ellipsoidal. Immature cysts with usually central. or small oval masses centrated mass seen 6-8 pm. less than 4 rarely seen, but bodies as occasionally in young seen. seen in Entamaeba cysts. Stains reddish spp. are not present. brown with iodine. Iao'amaeba 5-20 pm. Ovoidal,ellipsoidal, 1 in mature cyst. None Large, usually ec- Occasionally granules Compact, well-defined kitsch/ii Usual range, triangular, or other centric. Refractite, present, but chroma- mass. Stains dark 10-12um. shapes. achromatic granules on one side of kary- osome. lndistinct in iodine preparations. toid bodies as seen in Entomoeba spp. are not present. brown with iodine. 01 TABLE 5 DIFFERENTIAL MORPHOLOGY OF PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS FLAGELLATES—TROPHOZOITES Size Species (Length) Shape Motility Number of Nuclei Number of Flagella' Other Features 7'ric/mmonas 8—20 ,urn. Pear shaped. Nervous. jerky. 1 3-5 anterior. Undulating membrane extending length of body. [mm/Iris Usual range, Not visible in un- 1 posterior. 11-12 urn. stained mounts. L‘lri/amast/x 6-24 tun. Pear shaped. Stiff. rotary. 1 3 anterior. Prominent cytostome extending 1/3-1/2 length of body. mesni/i Usual range. Not visible in un- 1 in cytosome. Spiral groove across ventral surface. 10-15 pm. stained mounts. (Ward/a 10-20 pm. Pear shaped. "Falling leaf." 2 4 lateral. Sucking disk occupying 1/2-3/4 of ventral surface. Median bodies lamb/fa Usual range. Not visible in m 2 ventral. lying horizontally or obliquely in lower part of body. 12-15 pun. stained mounts. 2 caudal. Enteromonas 4-10 ,um. Oval. Jerky. 1 3 anterior. One side of body flattened. Posterior flagellum extends hominis Usual range, Not visible in un- 1 posterior. free posteriorly or laterally. 8-9 p. or. stained mounts. flotartamaflas 4-9 ,urn. Pear shaped or Jerky. 1 1 anterior. Prominent cytostome extending approximately 1/2 length Intestinal/s Usual range, oval. Not visible in un- 1 posterior. of body. 6-7 ,um. stained mounts. 'Not a practical feature for identification of species in routine fecal examinations. [I TABLE 6 DIFFERENTIAL MORPHOLOGY OF PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS FLAGELLATES — CYSTS Size Species (Length) Shape Number of Nuclei Other Features 7'r/chamonas No cyst. from/Iris Chi/amastix 6-10 mn. Lemon shaped with 1. Not visible in unstained preparations. Cytostome with supporting fibrils. Usually visible in stained preparations. mes/717i Usual range, anterior hyaline knob. 8»9 um. Giardia 8-19 pm. Dval or ellipsoidal. Usually 4. Not distinct in unstained Fibrils or flagella longitudinally in unstained cysts. Deep staining fibers or lamb/i5 Usual range, preparations. Usually located at fibrils may be seen lying laterally or obliquely across fibrils in lower part of 11-12 pm. one end. cyst. Cytoplasm often retracts from a portion of cell wall. Enteramanas 4-10 Mm. Elongated or oval. 1-4, usually 2 lying at Resembles E. nana cyst. Fibrils or flagella are usually not seen. homin/‘s Usual range. opposite ends of cyst. Not 6-8 ,um. visible in unstained mounts. fielortamanas 4-9 run. Pear shaped or 1. Not visible in unstained mounts. Resembles Chi/amastix cyst. Shadow outline of cytostome with supporting fibrils intestine/is Usual range, slightly lemon shaped. extends above nucleus. 4-7 um. TABLE 7 DIFFERENTIAL MORPHOLOGY OF PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS CILIATE, COCCIDIA, AND BLASTOCYSTIS Z1 Size Species (Length) Shape Motility Number of Nuclei Other Features CILIATE Balant/d/bm ca/i Trophozoite 50-70 pm or Ovoid with taper- Rotary, boring. 1 large, kidney shaped macronucleus. 1 small Body surface covered by spiral, longitudinal rows of cilia. more. Usual range, ing anterior end. subspherical micronucleus immediately Contractile vacuoles are present. 40-50 p.m. adjacent to macronucleus. Macronucleus occasionally visible in unstained preparations as hyaline mass. Cyst 45-65 pm. Spherical or oval. — 1 large macronucleus visible in unstained Macronucleus and contractile vacuole are visible in young Usual range, preparations as hyaline mass. cysts. In older cysts, internal structure appears granular. 50-55 tun. COCCIDIA lsaspora Oocyst: Ellipsoidal. Nonmotile. Usual diagnostic stage is immature oocyst with single [Ia/Ii 2530 um. granular mass (zygote) within. Mature oocyst contains 2 Usual range, sporocysts with 4 sporozoites each. 2830 p.m. Sarcocystis Sporocyst‘ Oval. Nonmotile. Mature oocysts with thin wall collapsed around 2 sporo- ham/Iris 13.17 Mm- cysts or free fully mature sporocysts with 4 sporozoites Usual range, inside are usually seen in feces. 14-16 tun. sui/mmin/s 1 1-15 pm. Usual range, 12-13 ,um. Cryptospor/d/um Oocyst: Spherical or oval. Nonmotile. Mature Dl"“YSl contains 4 "naked" sporozoites. "0 3.3 “m. sporocysts are present. Usual range, 4-5 tun. BLASIUCYST/S B/astocyst/s [tom/Iris-2 Vacuolated 5-30 pm. Spherical, oval, Nonmotile. 1, usually, but 2-4 may be present. Cell contains large central body, or "vacuole" with a thin form Usual range. or ellipsoidal. Located in “rim" of cytoplasm. ln band, or "rim," of cytoplasm around the periphery. 8-10 pm. binucleated organisms, the 2 nuclei Occasionally a ring of granules may be seen in cytoplasm may be at opposite poles. in quadri- nucleated forms, the 4 nuclei are evenly spaced around periphery of cell. and the cell appears to have a "beaded rim." 1Sizes are based on information from Rommel and Heydom (1972) and Heydom e! a/. (1975). 2Description based on information from Ziardt, 1973 and McClure at at. (1980). SI TABLE 8 DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES OF HELMINTHS FOUND IN HUMANS EGGS Stage of Development Specific Features and Species Size Shape Color When Passed Variations NEMATIJDES Entered/21.9 55 um x 26 um. Elongated, asym- Colorless. Embryonated. Contains C shaped or Smooth, thin eggshell with one flattened side. Occasionally may vermicu/aI/Zs Range, 50-60 ,um metrical with one tadpole-like embryo. contain fully developed larva. (More readily found on anal swabs x 20-32 pm. side flattened, than in feces.) other side convex. Ascaris lamb/icoidas fertile egg 60 um x 45 um. Round or ovoidal. Brown or I cell, separated from the shell at Mammillated albuminous coat or covering on outer shell. Coat is Range, with thick shell. yellow brown. both ends. sometimes lost and decorticated eggs have a colorless shell with 45-70 pm x gray or black internal material. Eggs may be in 2, 4, or more 35—45 pun. cells, or contain a fully developed larva. infertile egg 90 pm x 40 um. Elongated, Brown. Internal material is a mass of irregular Mammillated covering attenuated or missing in many cases. Range, occasionally globules and granules that fills shell. 85-95 pm x triangular, kidney- 35-45 run. shaped or other bizarre forms. Shell often very thin. Tric/ruris 54 um x 22 um. Elongated, Yellow to 1 cell or unsegmented. Polar plugs are distinctive. Eggs occasionally are oriented in a trio/liars Range, barrel-shaped brown. vertical or slanted position and may not be readily recognized. A 49-65 run x with a polar "plug" "Plugs" are gentle tap on the coverslip will usually reorient the egg. On rare 20-29 pm. at each end. colorless. occasions, atypical eggs lacking polar plugs maybe seen. Hookworm Ancy/astama 60 pm x 40 um. Oval or ellipsoidal Colorless 4- to 8-cell stage. Occasionally. eggs in advanced cleavage (16 or more cells) or duodena/a Range, with a thin shell. with greyish even embryonated may be seen. Rhabditiform larvae may be 57-76 pm x cells. present if the specimens are old. Species identification can- 35-47 pm. not be made on eggs alone; therefore, eggs should be reported and simply as hookworm. Necetor 65 um x 40 ,um. aman'canus Range, 57-76 ,um x 35—47 pm. Trichostrongy/us 90 um x 40 um. Elongated with one Colorless Maybe in advanced cleavage or Egg resembles hookworm egg but is larger and more pointed species flange, or both ends more with greyish morula stage. at the ends. 75-95 pm x pointed than hook< cells. 40-50 ,um. worm. TABLE 8 — Continued DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES OF HELMINTHS FOUND IN HUMANS 171 EGGS Stage of Development Specific Features and Species Size Shape Color When Passed Variations CESTDDES Kean/e 35 um. Spherical or sub- Walnut brown. Embryonated. 6-hooked oncosphere Thick, striated shell. Eggs of I sol/um and I say/Irate are sag/nets Range, spherical with thick present inside a thick shell. indistinguishable and species identification should be made from Teen/a 31 43 um. striated shell. proglottids or scoleces. "Teen/a”spp. should be reported if only sn/ium eggs are found. Hymeno/ep/Ls 47 ,um x 37 ,u.m. Oval or subspher- Colorless, Embryonated. 6-hooked oncosphere Polar filaments. Ira/m Range, ical. Shell con- almost inside shell. 40-60 pun sists of 2 dis- transparent. x 30»5D um. tinct membranes. 0n inner membrane are two small "knobs" or poles from which 4 to 8 filaments arise and spread out between the two membranes. Hymena/e/Iis 72 um. Round or slightly Yellow Embryonated. 6-hooked oncosphere Resembles If. none but lacks polar filaments. Poles are dim/Imta' Range, oval. Striated outer inside shell. rudimentary and often hard to see. 70-86 /.Lm membrane and thin x 60-80 pm. inner membrane with slight poles. Space between membranes may appear smooth or faintly granular. D/py/I‘d/um 35-40 pm. Spherical, subspher- Colorless. Embryonated. 6-hooked oncosphere Eggs are contained in a sac or capsule which ranges in size from can/1mm" Range, ical or oval. 5-15 inside shell. 58 pm to 60 ,um x 170 ,um. Occasionally, capsules are ruptured 31-50 PU“ eggs (or more) are and eggs are free. x 27-48 pm. enclosed in a sac or capsule. Dlphy/labnthrium 66 p.rn x 44 pm. Dval or ellipsoidal Yellow to Unembryonated. Germinal cell is Egg resembles houkworm egg but has a thicker shell and an larum Range, with an inconspicuous brown. surrounded by a mass of yolk cells operculum. 58-76 ,um operculum at one end which completely fills inner area x 40-51 pm. and a small "knob" at of shell Germinal cell is usually the other end. not visible. ‘Usually found in lower animals, only occasionally found in humans. 91 OF HELMINTHS FOUND IN HUMANS TABLE 8 — Continued DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES EGGS Stage of Development Specific Features and Species Size Shape Color When Passed Variations TREMATUDES Schl’stosama 140 um x 66 pm. Elongated with mom Yellow or Embryonated. Contains mature lateral spine. Found in feces; in rare cases, in urine also. Eggs mansam' Range. inent lateral spine yellow brown. miracidium. are discharged at irregular intervals and may not be found in 114—180 um near posterior end. every stool specimen. Are rare in chronic stages of the infection. x 45-73 um. Anterior end tapered and slightly curved. Schistosama 90 p.m x 71] um, Oval or subspherical. Yellow or Embryonated. Contains mature Found in feces. Often coated with debris and may be overlooked. japan/cum Range, Small lateral spine yellow brown. miracidium. 68-100 pm is often seen or may x 45-80 ,um. appear as a small hook or “knob" lo- cated in a depres' sion in the shell. Sch/stosama 143 um x 60 um. Elongated with Yellow or Embryonated. Contains mature Terminal spine. Found in urine, occasionally in feces. Egg often haematob/um Range, rounded anterior yellow brown. miracidium. covered with debris. 112-170 ,um x end and terminal 40-70 pm. spine at posterior end. Sch/stasoma 175 um x 60 um. Elongated with Yellow or Embryonated. Contains mature Terminal spine long, slender with bent tip. Resembles S. interca/atum Range, tapered anterior yellow brown. miracidium. haematollium egg except it is longer, is thinner, and has a longer 140-240 um x end and terminal spine. Found in feces. May have debris adhering to shell. 50-85 pt m. spine. Sometimes "spindle-shaped." Sch/stamina 69 um x 56 um‘ Spherical or sub- Yellow or Embryonated. Contains mature Found in feces. Closely resembles .S'. japan/cum egg except it is me/rangi Range, spherical. Small yellow brown. miracidium. smaller. May be coated with debris. 51 -73 um x lateral spine, not 39-66 um. always visible or may appear as a small "knob" in a depression in the shell. ’Based on sizes of eggs in human fecal specimens reported by Harinasuta and Kruatrachue (1962) and Taylor and Moose (197l). 91 OF HELMINTHS FOUND IN HUMANS TABLE 8 - Continued DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES EGGS Stage of Development Specific Features and Species Size Shape Color When Passed Variations TREMATODES — Cont. Clanarc/Ii: 30 um x 16 um. Small, ovoidal, or Yellow brown. Embryonated. Contains mature Small size. operculum and “knob" on posterior end. Shell often is sine/rsis Range, 27-35 um elongated with miracidium. covered by adhering debris. x 11-20 pm. broad rounded posterior end and a convex opercu- lum resting on "shoulders." A small "knob" may be seen on the posterior end. 0p/st/mrc/7is 30 um x 12 um. Elongated with Yellow brown. Embryonated. Contains mature Lacks prominent shoulders characteristic of Clonorc/ris and has fell/mus Range, 26-30 urn operculum on an miracidium. more tapered end. x11—15 pm. terior end and pointed terminal "knob" on posterior end. Hateraphyes 28 um x 15 pm. Small, elongated Yellow brown. Embryonated. Contains mature Resemhles Elana/chi: egg but with less distinct shoulders. heteraphyes Range, 28-30 pm or slightly miracidium. 0perculum is broader than in Clone/this. x 154 7 pm. ovoidal. 0percu- |um. Slight "knob" at pos- terior end. Motown/mus 28 um x 17 um. Small, elongat- Yellow or Embryonated. Contains mature Resembles Clonorchis and Hatemp/ryas eggs. Shell is slightly ya/rogawa/ Range, 26-30 pm ed or ovoidal. yellow brown. miracidium. thinner than Heterophyes. 0percu|um is broader than Clone/Chis. x 15-20 urn. 0percu|um.No "shoulders" at anterior end. Small "knob" often seen on posterior end. LI TABLE 8 — Continued DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES OF HELMINTHS FOUND IN HUMANS EGGS Species Size Shape Color Stage of Development When Passed Specific Features and Variations TREMATDDES —Cont. Paragon/Mus 85 um x 53 ,um. westermani Range, 68-118 p.m x 39-67 pm. Fascia/a 145 pm x 80 ,um hepatica Range, 120-150 um x 63-90 pm. Fascia/owls 140 u m x 80 um. bus/(i Range, 130—159 um x 78-98 pm. Ovoidal or elon- Yellow brown gate with thick shell. Operculum is slightly flat- tened and fits into shoulder area of shell. Poster- ior end is thick- ened. Egg often asymmetrical with one side slightly flattened. Ellipsoidal, Yellow to thin shell. light brown. Small, indistinct operculum. Ellipsoidal, Yellow thin shell. brown. Small, indistinct operculum. to dark brown. Unembryonated. Filled with yolk material in which a germinal cell is imbedded. Cells are irregular in size. Unembryonated. Filled with yolk cells in which an indistinct germinal cell is imbedded. Unembryonated. Filled with yolk cells in which an indistinct germinal cell is imbedded. Found in sputum, occasionally in feces. Resembles egg of D. latum but is larger, slightly asymmetrical and the operculum is smaller and flatter. The widest part of the Paragon/mus egg is usually anterior to the center,- in [7. larum, the widest area is around the center. Large size. Broadly oval eggs. Large size. Resembles F. llapDI/L'E egg and cannot be easily distinguished from Fascia/a. 81 TABLE 9 DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES OF HELMINTHS FOUND IN HUMANS LARVAE Rhabditiform Larva (First Stage. Has bulbed esophagus.) Filariform Larva (Third Stage. Lacks prominent bulb in esophagus.) Species Size Genital Primordium Buccal Cavity Size Length of Esophagus Tip of Tail Snoopy/aides 225 ,um x 16 pm. Prominent. Is an elongate, tapered, Short, about 1/3—1/2 as long 550 p.m x 20 um Extends approximately 1/2 Notched. stercara/is Range, 200- or pointed structure located as the width of the anterior Range, length of body. 300 pun x along ventral wall about midway end of the body. 500-550 tun x 16~20 pm. the body length. 2024 um. Hookworm 250 um x 17 pm. lnconspicuous. Rarely distinct. Long. Approximately as 500 ,um Extends about 1/4 length of Pointed. Range, 200- When seen, is small, located long as the width of the Range, body. 300 um x nearer the tail than that body. 500-700 nm x 14-17 pm. of Snoopy/aides. 20-24 pun. 61 TABLE 10 DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES OF HELMINTHS FOUND IN HUMANS TAPEWORM GRAVID PROGLOTTIDS Species Size Appearance ot Uterus Other Teen/a 12mm in length x 5-7mm wide. Central "stem" or trunk with 7-13 main Usually on surface of fecal material. May he in sol/urn lateral branches on each side. short chains of 2-3 proglottids. Teen/a 16-20mm long x 5-7mm wide. Central "stem" or trunk with 15-20 main lateral Usually on surface of fecal material. Maybe soyinata branches on each side. single detached proglottids. DlphyI/abathr/um 2—4mm long x 10-12mm wide. Coiled into a rosette appearance. Occasionally, portion of worm may be passed, Egg latum Broader than long. is usual diagnostic stage. D/py/idium 12mm long x 3mm wide. Pumpkin- Uterus not visible. Proglottid filled with Proglottids may be passed singly or in chains. can/”um seed shape; tapers at each end. capsules containing eggs. Often resemble rice grains in stool. Hymeno/ep/Is .2-.3mm long x .8-.9mm wide. Uterus not visible. Proglottid filled with eggs. Proglottids usually disintegrate in the intestinal [78/78 Broader than long. tract and are rarely seen in stools. Egg is usual diagnostic stage. Hymeno/epis .7-.8mm long x 3-4mm wide. Uterus not visible. Proglottid filled with eggs. Proglottids usually disintegrate in the intestinal dim/flute Broader than long. tract and are rarely seen in stools. Egg is usual diagnostic stage. OZ TABLE 11 DIFFERENTIAL MORPHOLOGY OF THE DIAGNOSTIC STAGES OF HELMINTHS FOUND IN HUMANS TAPEWORM SCOLECES Suckers Species Size Shape No. Appearance Other Teen/a Approximately 1mm in diameter. Globular or rounded. 4 Cup~|ike. Double row of 25-30 large and small brown chitinous hooks sol/um arranged around a rostellum (small projection) at the top at the scolex. Taania l to 2mm in diameter. Rounded or slightly 4 Cup-like. Does not have a rostellum or hooks. sag/nets pyriform. Bibby/lobothrium 2 to 3mm in length x 1mm wide. Almond-shaped or 2 Grooves. Does not have a rostellum or hooks. Deep grooves (suckers) are latum spatulate. located dorsally and ventrally on the scolex, but often appear to be lateral. D/py/idium 0.35 x 0.37mm. Rhomboid or rounded. 4 Oval, cup-like. Prominent conical or avoid rostellum with 30-150 small can/hum thorn-shaped hooks arranged in several rows (1-7 rows). Rostellum may be retracted into a depression at the upper margin of the scolex. Hymona/epis 0.3mm in diameter. Globular. 4 Cup—like. Retractile rostellum with a single row of 20 to 30 books. nana Hymena/epis 0.2-0.4mm in diameter. Globular or club-shaped. 4 Cup-like. Rudimentary apical rostellum without hooks. diminuta [K Figure 1 PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS AM EBAE Entamoeba Entam oeba Entamoeba Entamoeba Endolimax Iodamoeba Dientam oeba histolytica hartmanni coli polecki ‘ nana bfitschlii fragilis 2 8 '5 N o .C: a. 8 [-‘ a No cyst 0 1Rare, probably of animal origin Scale: I 0 5 1 0 p. m Adapted from Brooke and Melvin, I 964 l._.l__.l 2Flagellate ZZ Figure 2 PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS FLAGELLATES Trichomonas hominis C hilomastix mesnili Giardia lamblia Emeromonas hominis Retortamonas imesrinalis Trophozoite Cyst No cyst Scale: 5 10 L—L_l um ‘53 Figure 3 PROTOZOA FOUND IN STOOL SPECIMENS OF HUMANS CILIATE COCCIDIA BLASTOCYSTIS Balamia’ium lsospora bel/i Sarcocysn‘s spp Cryptosporidium Blaslocysris coli ' Spp. hominis @ 20 40 ,um mature oocysl Scale: single sporocyst 10 20 Q) :1 O N O .= a. E [— immature mature oocyst mature oocyst oocysl .. (I) >a U. 30 ,um Scale: 0 10 20,1117: 1—1—4 VZ Figure 4 NEMATODE AND CESTODE EGGS FOUND IN STOOL SPECIMENS OF HUMANS NEMATODES Scale: 0 24 48 p. m |_—_L_J Enterobius Trichuris Ascaris lumbricoides Ascaris Iumbricoides . vermicularis trichiura fertile infertile Hookworm Trlchostrongylus C ESTOD ES Scale: 0 24 48,um l—L—l H ymenolepis nana H ymenolepis diminuta Diphylloboth rium Iatum Dipylidium caninum Dipylidium caninum egg packet Adapred from Melvin, Brooke, and Sadun, I 95 9 SZ Figure 5 TREMATODE EGGS FOUND IN STOOL SPECIMENS OF HUMANS TREMATODES Scale: 0 24 48 p. m L—J—l Clon orchis Opisthorchis Heteroph yes Metagonimus sinensis felineus heteroph yes yokoga wai Schistosoma Schistosoma Schistosoma japonicum mansoni haematobium 1 ....................... J ‘Usually passed in urine 2Usually found in sputum Paragonimus Fasciola Fasciolopsis westermam' 2 hepatica buski Adapted from Melvin, Brooke, and Sadun, 1 95 9 9Z MICROMETERS (MICRONS) (um) 90 60 30 150 120 90 60 30 Memganimus Helemphyes Opislhorchis Clonarrhis Taem'a yokogawai hetemphyes felineus :inensis Pamgom’mus Trichoslmngylus Asmn‘s lumbricoides westermani infertile 'ScthIosoma mekangi and Schlstasama intercalamm have been omitted. Hymenalepis nana Schismsoma japonicum Figure 6 RELATIVE SIZES 0F HELMINTH EGGS* Enterobius v ermicularis Trichuris Irichiura Schisrosoma haematobium Ascaris lumbn'coides fertile Schistosoma mansoni Hookworm Diphyllobolhrium [mum Fasciola hepatica H ymenolepis diminura Fasciolopsis buski 90 60 30 150 120 90 30 LZ Figure 7 HOOKWORM AND STRONGYLOIDES LARVAE RHABDITIFORM STAGE Scale: 0 45 90 p. m I___1 Buccal ca vity — Hookworm Sirongyloides FILARIFORM STAGE Hookworm Esophagus Strongyloides 8K Figure 8 GRAVID PROGLOTTIDS AND SCOLECES OF CESTODE PARASITES OF HUMANS Scale: 0 5. 5 11 2 Scale: L11_1__1 mm 3 Taenia solium Taenia saginata Dip/1 y/lobolhrium larum Dipylidium caninum H ymenolepis nana U) E ‘5 O!) e I- 9.. Ta 9 n i a s 0 [la m Ta en [-0 s a gin a t a Dip/1 ylloboI/zrium Dipylia’ium H ymenolepis H ymen olepis Iatum caninum nana diminuta Scale: 0 1 0 I 2 Scale: |_*__1 mm mm m 0 U 2 O 0 m H ymenolepis diminuta REFERENCES TEXTBOOKS AND MANUALS: Ash, L. R. and Orihel, T. C. 1980. Atlas of Human Parasitology. American Society of Clinical Pa- thologists, Chicago, Illinois. Beaver, P. C., Jung, R. C., and Cupp, E. W. 1984. Clinical Parasitology. Lea and Febiger, Philadelphia. Belding, D. L. 1965. Textbook of Parasitology. 3rd ed. Appleton-Century-Crofts, New York. Brooke, M. M., Melvin, D. M., and Healy, G. R. 1983. Common Intestinal Protozoa ofHumans, Life Cycle Charts. Government Printing Office, Supt. of Documents, Washington, DC. 20402. (GPO Stock #017-023-00164-7) (NTIS #PB 80-186984)* Brown, H. W. and Neva, F. A. 1983. Basic Clinical Parasitology. 5th ed. Appleton- Century-Crofts, New York. Burrows, R. B. 1965. Microscopical Diagnosis of the Parasites of Man. Yale University Press, New Haven, Connecticut, and London. Centers for Disease Control. 1976. Amebiasis: Laboratory Diagnosis - Part 11: Identification of In- testinal Amebae. HEW Pub. no. CDC-77-8327, Part II. 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