Marking Cephalic Cone

cysts lodge in bronchial ^

cysts become mature in tracheobronchial secretions

PASSAGES

f cysts transferred by congenital rout (transplacental)

and release trophozoites by congenital route cysts inhaled by suitable hosts, man (children)

cysts passed in droplet) particles of secretions

Figure 2-15. Life cycle of Pneumocystis carinii.

Figure 2-15. Life cycle of Pneumocystis carinii.

SIZE: 2 to 4 mcm. SHAPE: Irregular. CONTENTS: Central nucleus.

IMMATURE CYST

SHAPE: Spherical, often collapsed.

SIZE: 5 to 12 mcm. SHAPE: Spherical.

CONTENTS: 8 nuclei, often in "rosette" arrangement.

Figure 2-16. Stages of P. carinii.

GENERAL CHARACTERISTICS

HISTORY: Symptoms described by 1550 BC (Ebers papyrus); recovery of Countess d'El Chinchon 1623 to 1632); associated with "bad (mal) swamp air" (aria); Laveran described the parasite in 1880 AD.

COMMON NAME

Plasmodium vivax--Benign tertian malaria. Plasmodium ovale--Ovale tertian malaria. Plasmodium malariae--Quartan malaria. Plasmodium falciparum--Malignant tertian malaria.

PATHOGENESIS: Cyclic fever and chills; aches and general malaise.

Plasmodium vivax: Usually mild; parasitemia up to five percent; 47 percent of reported cases; relapses due to recurring liver phases (secondary exoerythrocytic); fever cycle (chills) are every 45 hours (average).

Plasmodium ovale: Usually mild; parasitemia less than one percent; less than one percent of reported cases; questionable relapses; fever cycle is 49 hours (average).

Plasmodium malariae: Usually mild (severe kidney involvement in children, may be fatal); parasitemia up to one percent; less than three percent of reported cases; longest incidence of recrudescence (up to 30 years); fever cycle is 72 hours.

Plasmodium falciparum: Usually severe (blocking of capillaries, involvement of major organs, algid malaria, black water fever, drug resistant strains have been recognized); parasitemia up to 40 percent; 49 percent of total reported cases; short recrudesent relapse with no secondary exoerythrocytic phases; fever cycle is 36 to 48 hours, often asynchronous.

GEOGRAPHICAL DISTRIBUTION

P. vivax--Temperate and tropic zones. P. ovale--Mainly Africa and western Pacific islands. P. malariae and P. falciparum--Tropics and subtropics.

TREATMENT

MALARIOUS ATTACK: Chloroquine and Amodiaquine are very effective drugs for rapid relief (no effect against the exoerythrocytic phase); Pyrimethamine and Chlorquanide are slow but can eradicate tissue stages of P. falciparium.

SUPPRESSION (PREVENTION OR POSTPONEMENT OF ATTACKS): Chloroquin e, Amodiaquine, Pyrimethamine, and Chlorquanide destroy the erythrocytic parasite; Primaquine is effective against gametocytes and exoerythrocytic parasites.

PROPHYLAXIS: P. falciparum-pyrimethamine and primaquine: Black water fever; corticosteroids: Resistant strains of P. falciparum; quinine, Fansidar and Mefloquine.

CONTROL: Eradication of the vector (female Anopheles mosquito); elimination of source (reservoir host and asymptomatic carriers). PROPHYLAXIS: Prevent mosquito bites and drug prophylaxis. DIRECT TRANSMISSION: Screen blood donor and pregnant female. HABITAT IN MAN: Liver and blood.

INTERMEDIATE HOST: Man is the intermediate host; the mosquito is the definitive host.

RESERVOIR HOST: Primate.

INFECTIVE FORM: To man is the sporozoite; to mosquitoes are both macrogametocytes and microgametocytes. MODE OF INFECTION: Injection.

Gastrodiscoides Hominis Comments
Figure 2-17. Life cycle of Plasmodium species.
Malaria Reservoir Host

Figure 2-18. Correlation of the fever-chill cycles and erythrocytic cycles of the human

Plasmodi.

Figure 2-18. Correlation of the fever-chill cycles and erythrocytic cycles of the human

Plasmodi.

YOUNG TROPHOZOITES--RING FORMS SPECIMEN OF CHOICE: Capillary blood.

TIME OF COLLECTION: About 8 to 12 hours after the fever peak and about 8 to 12 hours intervals thereafter (midway between the fever peaks results in clearly defined morphology.

REPORT AS PLASMODIUM SPECIES: Unless 5 or more young rings per oil immersion field without Schuffner's granules are present: this case represents P. falciparum (thin smear only).

CHROMATIN DOT: Small; magenta-red.

CYTOPLASM: Light blue; 1 to 3 mcm in size.

HEMOZOIN PIGMENT: Usually absent.

INFECTED ERYTHROCYTE: May be macrocytic and pale with Schuffner's granules in cases of P. vivax and P. ovale.

NOTE: See Figures 1-1, 2-1, and 4-1 in Appendix C for additional illustrations.

Figure 2-19. Ring forms of Plasmodia.

Figure 2-19. Ring forms of Plasmodia.

GROWING TROPHOZOITES

P. vivax

CHROMATIN MASS: Small to medium; light magenta. CYTOPLASM

COLOR: Light blue. DENSITY: Flimsy; amoeboid shape. SIZE--8 to 10 mcm; spreads out through the erythrocyte. VACUOLES: Multiple.

HEMOZOIN PIGMENT: Diffused; light gold rods.

INFECTED ERYTHROCYTE: Enlarged; pale; fine Schuffner's granules.

CHROMATIN MASS--Medium to large; dark magenta. CYTOPLASM

COLOR--Darker blue than P. vivax. Density-Slight amoeboid activity. SIZE--4 to 7 mcm; less than half of erythrocyte filled. VACUOLES--May have one to two. HEMOZOIN PIGMENT--Golden brown; often diffused.

INFECTED ERYTHROCYTE--Slightly enlarged; pale Schuffners granules appear early; may be oval and/or fimbriated

P. ovale

Figure 2-20. Growing trophozoite s, Plasmodium. (continued)

P. malariae

CHROMATIN MASS: Medium to large; dark magenta. CYTOPLASM

COLOR: Darker blue. DENSITY: Band forms; basket forms. SIZE: 4 to 7 mcm. VACUOLES: May have multiple. HEMOZOIN PIGMENT: Dark brown.

INFECTED ERYTHROCYTE: Normal appearance; may be slightly microcytic. NOTE: See Figures 1-3, 2-2, 2-3, 3-1 in Appendix C for additional illustrations.

CHROMATIN MASS: Very small; some with double masses; applique forms common;

magenta.

CYTOPLASM

COLOR: Blue.

DENSITY: Delicate; flame shapes common. SIZE: 2 to 4 mcm.

HEMOZOIN PIGMENT: Dark brown; usually not seen. INFECTED ERYTHROCYTE: Normal appearance.

P. falciparum

Figure 2-20. Growing trophozoite s, Plasmodium. (concluded)

MATURE TROPHOZOITE

P. vivax

CHROMATIN MASS: Small to medium. CYTOPLASM

COLOR: Light blue. DENSITY: Somewhat amoeboid. SIZE: 8 to 10 mcm; more condensed than growing trophozoite. VACUOLES: Usually one.

HEMOZOIN PIGMENT: Diffused; light, golden brown rods. INFECTED ERYTHROCYTE: Enlarged; pale; even-size Schuffner's granules numerous.

CHROMATIN MASS: Medium to large. CYTOPLASM

COLOR: Darker blue. DENSITY: Compact. SIZE: 5 to 7 mcm. VACUOLE: Singular.

HEMOZOIN PIGMENT: Gold; somewhat diffused.

INFECTED ERYTHROCYTE: Slightly enlarged; pale; coarse and uneven Schuffner's granules; may be oval and/or fimbriate.

P. ovale

Figure 2-21. Mature trophozoite Plasmodium. (continued)

P. malariae

CHROMATIN MASS--Medium to large. CYTOPLASM

COLOR--Darker blue. DEN SITY--Com pact. SIZE: 4 to 7 mcm.

VACUOLE: Singular; may have multiple.

HEMOZOIN PIGMENT--Dark green; coarse; usually on the edge of the parasite; abundant.

INFECTED ERTHYROCYTE: Normal appearance (often slightly microcytic).

Normally not found in the peripheral circulatory system except in high parasitemia.

CHROMATIN MASS: Small. CYTOPLASM:

COLOR: Blue. DENSITY: Slightly compact. SIZE: 2 to 4 mcm. VACUOLE: Singular.

HEMOZOIN PIGMENT: Black; one or two clumps. INFECTED ERTHYROCYTE: Normal appearance.

NOTE: See Figures 1-4, 2-4, 3-4 and 4-4 in Appendix C for additional illustrations.

P. falciparum

Figure 2-21. Mature trophozoite Plasmodium. (concluded)

MATURE SCHIZONT

P. vivax

SIZE OF MEROZOITES: Medium.

NUMBER OF MEROZOITES: 12 to 24 mcm in random order. SHAPE: Attempts to fill the RBC. HEMOZOIN PIGMENT: Gold; central cluster of rods. INFECTED ERYTHROCYTE: Enlarged; pale; Schuffner's granules.

SIZE OF MEROZOITES: Medium-large.

NUMBER OF MEROZOITES: 4 to 16 mcm in random order.

SHAPE: Fills one-half of the RBC.

HEMOZOIN PIGMENT: Gold; central cluster.

INFECTED ERYTHROCYTE: Enlarged; pale; Schuffner's granules.

SIZE OF MEROZOITES: Medium-large.

NUMBER OF MEROZOITES: 6 to 12 mcm, usually in rosette arrangement. SHAPE: Fills the RBC.

HEMOZOIN PIGMENT: Dark green;central cluster of granules. INFECTED ERYTHROCYTE: Normal.

P. ovale

P. malariae

Figure 2-22. Mature schizonts, Plasmodium. (continued)

P. falciparum

Rarely seen, poor prognosis.

SIZE OF MEROZOITES: Very small.

NUMBER OF MEROZOITES: 8 to 32 mcm in random order.

SHAPE: Fills about 1/2 of the RBC.

HEMOZOIN PIGMENT: Black; peripheralclump.

INFECTED ERYTHROCYTE: Normal.

Figure 2-22. Mature schizonts, Plasmodium. (concluded)

NOTE: See Figures 1-6, 2-6, 3-6 in Appendix C for additional illustrations.

DIFFERENTIATION: No vacuoles present.

MACROGAMETOCYTE: Dark blue and compact cytoplasm; peripheral and compact chromatin.

MICROGAMETOCYTE: Light blue and diffused cytoplasm; thready chromatin.

SHAPE: Oval. CYTOPLASM: Pale blue. CHROMATIN MASS: Medium to large. SIZE: Fills the entire RBC.

HEMOZOIN PIGMENT: Gold; abundant; scattered.

INFECTED ERYTHROCYTE: Enlarged; pale; Schuffner's granules.

Figure 2-23. Gametocytes, Plasmodium. (continued)

GAMETOCYTES

P. vivax

P. ovale

SHAPE: Oval. CYTOPLASM: Dark blue. CHROMATIN MASS: Medium-large. SIZE: Almost fills the RBC.

HEMOZOIN PIGMENT: Gold-brown; abundant; scattered. INFECTED ERYTHROCYTE: Enlarged; pale; Schuffner's granules.

SHAPE: Oval.

CYTOPLASM: Dark blue.

CHROMATIN MASS: Medium-large.

SIZE: Fills three-fourths of the RBC.

HEMOZOIN PIGMENT: Dark green;abundant; scattered.

INFECTED ERTHYROCYTE: Normal appearance.

Figure 2-23. Gametocytes, Plasmodium. (continued)

P. malarie

P. falciparum

SHAPE: Crescent; banana. CYTOPLASM: Light blue. CHROMATIN MASS: Central; fragmented. SIZE: Longer than the RBC's diameter.

HEMOZOIN PIGMENT: Red-black; clustered about the chromatin. INFECTED ERYTHROCYTE: Stretched; ghost cell.

Figure 2-23. Gametocytes, Plasmodium. (concluded)

NOTE: See Figures 1-7, 1-8, 2-7, 2-8, 3-7, 4-6 and 4-7 in Appendix C for additional illustrations.

THICK DROP PREPARATION

SPECIATION: Most difficult to accomplish except with the gametocyte of P. falciparum, CYTOPLASM: Scattered or fractured; blue. CHROMATIN MASS: Red to deep magenta. HEMOZOIN PIGMENT: Clumped,

ERYTHROCYTES: Lysed; may be seen outlined by the granules. PROPER DENSITY OF SMEAR: 10 to 30 WBC's per oil immersion field. FIBRIN: Only a few bluish strands are acceptable.

PROBLEMS: Confusion with other structures such as: platelets, WBCs, bacteria, cellular debris, stain crystals, and other artifacts. PRECIPITATE: Proper rinsing and procedure should eliminate background elements.

Sporozoans Gliding
Figure 2-24. Parasite morphology on thick smear.

Continue with Exercises

EXERCISES, LESSON 2

INSTRUCTIONS: Answer the following exercises by marking the lettered response that best answers the exercise, by completing the incomplete statement, or by writing the answer in the space provided at the end of the exercise.

After you have completed all the exercises, turn to "Solutions to Exercises" at the end of the lesson and check your answers. For each exercise answered incorrectly, reread the material referenced with the solution.

1. Motility of Sporozoans is accomplished by:

a. Gliding.

b. Undulation of longitudinal ridges.

c. Body flexion.

d. All of the above.

2. The size of mature oocysts of Cryptosporidium is:

3. A Sporozoan organism that frequently causes birth defects in humans is:

a. Sarcocystis hominis.

b. Cryptosporidium.

c. Toxoplasma gondii.

d. Pneumocystis carinii.

4. The human infective form of all Plasmodium species is the:

a. Macrogametocyte.

b. Microgametocyte.

c. Sporozoite.

d. Trophozoite.

5. The two Plasmodium species which account for most (96alinfections are:

a. Plasmodium vivax and Plasmodium malariae.

b. Plasmodium falciparum and Plasmodium vivax.

c. Plasmodium malariae and Plasmodium ovale.

d. Plasmodium falciparum and Plasmodium malariae.

6. Members of the Class Ciliata use small hair-like structures f ormovement and for:

a. Controlling hydrostasis.

b. Food procurement.

c. Protection.

d. Diffusion.

7. If a Plasmodium trophozoite occupies most of an enlarged infect edenythrocyte it is:

a. Plasmodium vivax.

b. Plasmodium malariae.

c. Plasmodium ovale.

d. Plasmodium falciparum.

8. Hemozoin pigment in the schizont form of Plasmodium malariae is:

9. The reservoir host of Balantidium coli is the:

a. Rabbit.

d. Monkey.

10. Crescent shape gametocytes are typical of:

a. Plasmodium vivax.

b. Plasmodium malariae.

c. Plasmodium falciparum.

d. Plasmodium ovale.

11. A well prepared thick drop smear for Plasmodium will have_WBC's per oil immersion field.

12. Organisms belonging to the Genus Babesia can best be described as small, multiciliate, and ameboid in shape.

13. Redwater fever is transmitted to man by:

a. Ingestion of contaminated water.

b. Transfusion of infected blood.

c. Injection by hard ticks.

d. Injection by Anopheles mosquitoes.

14. The organisms of Eimeria species, if present in the host, a rerecovered from which of the following sources?

a. Pleural effusions.

b. Fecal specimens.

c. Sputum.

d. Cerebral spinal fluid.

15. The specimen of choice for the recovery of malarial parasites is:

a. Tissue impression smears.

b. Venous blood.

c. Oxalated blood.

d. Capillary blood.

16. In the life cycle of malarial parasites, the definitive host is:

a. Primates.

b. Female Anopheles mosquitoes.

c. Human beings.

d. Domestic animals.

17. Respiration among the ciliates is accomplished by diffusion through the cell membrance a. True.

18. Infections of Isospora belli are initiated:

a. Following the bite of the tick vector.

b. When the oocyst is ingested by the host.

c. Following the ingestion of mature cysts.

d. When hosts are biten by infected sand flies.

19. Which of the following characteristics help to identify t hezoitocyst of Sarcocystis hominis?

a. A limiting membrane with radial striations.

b. Elongated and cylindrical shape.

c. Internal septae and compartments.

d. All of the above.

20. A spherical mature cyst with 8 nuclei arranged in a "rosette" pattern relates to which of the following organisms?

a. Pneumocystis carinii.

b. Toxoplasma gondii.

c. Crytosporidium species.

d. Sarcocystic hominis.

21. Both asexual and sexual reproductive cycles are known to occur among members of the class Sporozo.

22. The term used to describe the asexual cycle of members of the family Plasmodiidae is:

a. Gametogony.

b. Sporogony.

c. Schizogony.

d. None of the above.

Check Your Answers on Next Page

SOLUTIONS TO EXERCISES, LESSON 2

End of Lesson 2

LESSON ASSIGNMENT

Phylum Platyhelminths.

Paragraphs 3-1 through 3-10.

After completing this lesson, you should be able to:

3-1. Identify the general characteristics of members of Phylum Platyhelminthes.

3-2. Identify the organism characteristics of parasitic members of Class Trematoda.

3-3. Select a statement that best describes the life cycle of a member of Class Trematoda.

3-4. Identify the organism characteristics of parasitic members of Class Cestoda.

3-5. Select a statement that best describes the life cycle of a member of Class Cestoda.

3-6. Identify the specimen of choice for recovery of specific Platyhelminthes.

3-7. Identify the special technique required for recovery of specific Platyhelminthes.

SUGGESTION After completing the assignment, complete the exercises of this lesson. These exercises will help you to achieve the lesson objectives.

LESSON ASSIGNMENT LESSON OBJECTIVES

PHYLUM PLATYHELMINTHS Section I. OVERVIEW OF PLATYHELMINTHES 3-1. GENERAL COMMENTS

The organisms that belong to this phylum show a dorsoventral flattening that gives them the common name of flat worms. The internal structures are organized in a bilateral symmetry. The body may consist of only one part (monozoic) or of two or more parts (polyzoic). Because flat worms are adapted to parasitism, the necessity for certain functions is no longer needed. Therefore, the organs involved in those functions were eliminated. On the other hand, with the new demands of parasitism, some of the organs have adapted to enhance their capabilities.

3-2. STRUCTURE

Skeletal, circulatory, and respiratory structures are lacking within these organisms. They have no body cavity (acoelomates) and the internal organs are embedded in a cellular matrix called the parenchyma. The digestive tract may be either incomplete or totally absent. The nervous system varies from a very primitive network found in the free living forms, to a well developed arrangement present in the parasitic forms, that is composed of a pair of anterior ganglia each having a longitudinal nerve cord. The excretory system varies with each species. There may be flame cells, long ducts with exterior exit, or bladders with excretory pores.

3-3. REPRODUCTION

With a few exceptions (for example, schistosomes), the phylum is characterized by a monoecious arrangement of the reproductive systems, in which both male and female reproductive organs are present within a single individual worm. Fertilization is internal and the exchange of spermatozoa between individuals or between two segments is the preferred method of fertilization.

3-4. CLASSES

There are three classes in the phylum. The class Turbellaria consists of free living organisms (for example, genus Planaria), while the classes Trematoda and Cestoda contain all parasitic species.

Section II. CLASS TREMATODA 3-5. GENERAL COMMENTS

Flukes which parasitize humans have been found in most of the systems and organs of the body. Flukes use more than one host, alternating asexual generations in one or more hosts (intermediate hosts) with the sexual generation in another host (definitive host). The flukes are monozoic (one body part), leaf-shaped organisms that have two heavily muscled suckers. The oral sucker is used as a mouth while the ventral sucker, acetabulum, is used as an organ of attachment to the host. The digestive system is incomplete with internal and external digestion. The nervous system is well developed. Some anatomical structures (for example, the shape and length of the intestinal ceca, the size and location of the acetabulum, hooklets around the oral sucker, and the location, the shape, and number of testes) are used for taxonomical differentiation.

3-6. SUBCLASSES

The members of the class Trematoda are commonly known as flukes. The class is divided into three subclasses: Monogenea, Aspidobothria, and Digenea. The subclass Monogenea is characterized by having only one host, and its members are ectoparasites of poikilothermic vertebrates (such as fish, amphibians, and reptiles). Members of the subclass Aspidobothria are characterized by a relatively simple life cycle without asexual generations, and are ectoparasites of fish, turtles, and mollusks. The third subclass, Digenea, is the largest of the three, and encompasses all trematodes which are parasitic to man. Some members of this subclass are parasites of many other animals. The subclass Digenea is further subdivided into two orders: Strigeatoidea which contains the schistosomes, and Prosostomatea which contains the other parasitic flukes.

Gastrodiscoides Hominis Comments
Figure 3-1. External fluke structure.
Fluke 9510
Figure 3-2. Internal fluke structure.
Figure 3-3. Osmoregulatory system of a fluke.
Figure 3-4. Digestive system of a fluke.
Digestive System Schistosoma
Figure 3-5. Digestive system of a fluke.
Male Reproductive System Key Stage
Figure 3-6. Reproductive system of a fluke--male.
Male Reproductive System Key Stage
Figure 3-7. Reproductive system of a fluke--female.
Gastrodiscoides Hominis Comments
Figure 3-8. Reproductive system of schistosome.
Figure Miracidium Larval Stage

M ETA C ERC4RIA Figure 3-9. Larval stages of flukes.

KEY TO IMPORTANT ADULT HUMAN TREMATODES

1.

Dioecious trematodes (one sex per worm)

Schistosoma species.

Monoecious trematodes (both sexes per worm)

2

2.

Small flukes: size under 5 mm

3

Large flukes: size range 20 to 45 mm

4

Medium flukes: size range 5 to 20 mm

5

3.

Gonotyl absent; ventral sucker offset to one side; intestinal ceca straight; testes oval and oblique

Metagonimus yokogawai

Gonotyl present; ventral sucker central; intestinal ceca straight; testes oval and para

Heterophyes heterophyes

4.

Cephalic cone present; intestinal ceca branched; testes tandem and dendritic

Faciolopsis hepatica

Cephalic cone absent; intestinal ceca undulating; testes tandem and dendritic Faciolopsis buski

5.

Anterior testes

6

Posterior testes

7

6.

Intestinal ceca straight; testes oblique and lobate; wide acetabulum at posterior end; gourd-shaped body

. Gastrodiscoides hominis

Intestinal ceca straight; testes oblique and lobate; Elongated

Dicrocoelium dendriticum

7.

Circlet of spines around oral sucker; intestinal ceca straight; testes tandem and lobate

Echinostoma species

Intestinal ceca straight; testes oblique and lobate

Opisthorchis species

Intestinal ceca straight; testes tandem and highly branched

Opisthorchis sinensis

Intestinal ceca undulating; testes para and lobate

Paragonimus westermani

Table 3-1. Key to important adult human trematodes.

Table 3-1. Key to important adult human trematodes.

3-7. COMMON PARASITES OF CLASS TREMATODA

ORGANISM 1--Schistosoma japonicum

GENERAL CHARACTERISTICS

COMMON NAME: Oriental blood fluke GEOGRAPHICAL DISTRIBUTION: Far East

PATHOGENESIS: Embolic eggs cause more severe lesions than other schistosome splenomegaly, cellularspecies, infiltration of vital organs; liver f ibrosis and cirrhosis, infiltration, ulceration. HABITAT: Venules surrounding the small intestine. INTERMEDIATE HOST

FIRST: Snail (Oncomelaria). SECOND: None. RESERVOIR HOST: Mammals. INFECTIVE FORM: Cercaria. MODE OF INFECTION: Active penetration. SPECIMEN OF CHOICE: Feces.

life cycle

ADULTS IN VENULES ( SURROVJNOIN9 \ I VITAL ORGANS J

Ml S »ATI ON TO APPROPRIATE HABITAT

(in venules)

egs deposited Along venule wall (miracidium present)

enter liver f develop to \ (adults and mat ij i pass through hurt, luhss

penetrate skin of most

ESS PASSES THR0U6H TISSUES (7-8 days)

enter circulatory system

SCHISTOSOMA SPR

EEC PASSED I« FECES OR URINE

EGG MUST REACH WATER

MIRÀCIPIUM HATCHED IN WATFR

cercaria leave snail enters snail (time critical)

SNAIL GENERA flULINUS BIOMPHRLABIA AUSTBALORT5 ONCOHELAHIA

larval

STAGES - DAYS

daughter sporocvst ceacaria

Figure 3-10. Life cycle of Schistosoma japonicum.

SIZE: 90 x 70 mcm (medium). SHAPE: Oval to round COLOR: Yellow brown OPERCULUM: Absent

CONTENT: Shouldered miracidium surrounded by vitelline membrane (double linear outline); short lateral spine sometimes curved (inconspicuous). Fecal debris adhering to shell.

ADULTS

SIZE:

MALE: 1.0 to 2.2 cm long by 0.5 mm wide. FEMALE: 1.2 to 2.6 cm long by 0.3 mm wide. SHAPE: Elongated with gynecophoral canal in males. COLOR: Greyish white

INTESTINAL CECA: Join very late (posterior third of body). TESTES: Anterior (6 to 8) OVARIES: Middle of body UTERUS: Long with 50 to 100 ova.

Figure 3-11. Stages of Schistosoma japonicum. (continued)

Anatomi Scistosoma Mansoni
Figure 3-11. Stages of Schistosoma japonicum. (concluded)

ORGANISM 2--Schistosoma mansoni GENERAL CHARACTERISTICS

COMMON NAME: Manson's blood fluke.

GEOGRAPHICAL DISTRIBUTION: Central and North Africa; Equatorial regions of

South America; West Indies and Puerto Rico. PATHOGENESIS: Infiltration of vital organs; hemorrhages, anemia, hepato-

splenomegaly, liver cirrhosis, fibrous tissue proliferation, ulcerations. HABITAT: Venules surrounding the large intestine. INTERMEDIATE HOST

FIRST: Snail (Biomphalaria, Australorbis). SECOND: None. RESERVOIR HOST: Rarely monkeys. INFECTIVE FORM: Cercaria. MODE OF INFECTION: Active penetration. SPECIMEN OF CHOICE: Feces.

Schistosoma Japonicum Life Cycle
Figure 3-12. Life cycle of Schistosoma mansoni.

SIZE: 155 x 65 mcm (large). SHAPE: Elongated. COLOR: Yellow brown. OPERCULUM: Absent.

CONTENT: Shouldered miracidium surrounded by vitelline membrane (double linear outline). Large lateral spine.

ADULTS

SIZE

MALE: 0.6 to 1.4 cm long by 1.1 mm wide. FEMALE: 1.2 to 1.6 cm long by 0.2 mm wide. SHAPE: Elongated with gynecophoral canal in males. COLOR: White to cream

INTESTINAL CECA: Join early (in anterior portion of body). TESTES: Anterior (3 to 13). OVARY: In anterior half of body. UTERUS: Short with 1 to 5 ova.

ORGANISM 3--Schistosoma haemotobium

GENERAL CHARACTERISTICS

COMMON NAME: Vesical blood fluke.

GEOGRAPHICAL DISTRIBUTION: Africa; Asia Minor; Mediterranean regions PATHOGENESIS: Toxic irritations, lesions of urinary bladder and genitalia, cystitis, occlusions of ureters and urethra, hematuria, eosinophilia. HABITAT: Venules surrounding the urinary bladder. INTERMEDIATE HOST

FIRST: Snail (Bulinus, Biomphalaria). SECOND: None RESERVOIR HOST: None INFECTIVE FORM: Cercaria MODE OF INFECTION: Active penetration. SPECIMEN OF CHOICE: Urine (also feces)

Gastrodiscoides Hominis Comments
Figure 3-14. Life cycle of Schistosoma haemotobium.

SHAPE: Elongated.

COLOR: Hyaline to light yellow. OPERCULUM: Absent

CONTENT: Shouldered miracidium surrounded by vitelline membrane (double linear line). Terminal spine.

ADULTS

SIZE

MALE: 1.0 to 1.5 cm long x 0.9 mm wide. FEMALE: 2.0 to 2.5 cm long by 0.25 mm wide. SHAPE: Elongated with gynecophoral canal in males. COLOR: Greyish white

INTESTINAL CECA: Join late (near middle of body). TESTES: Anterior (4 to 5) OVARIES: In posterior half of body. UTERUS: Long with 20 to 30 ova.

Figure 3-15. Stages of Schistosoma haemotobium. (continued)

Stages Paragonimus

ORGANISM 4--Paragonimus westermani GENERAL CHARACTERISTICS

COMMON NAME: Lung fluke.

GEOGRAPHICAL DISTRIBUTION: Asia and South America PATHOGENISIS: Pulmonary lesions, fibrous tissue capsules, pleurisy, pneumonitis. HABITAT: Lung. INTERMEDIATE HOST FIRST: Snail.

SECOND: Crab or crayfish. RESERVOIR HOST: Piscivores (fish-eating animals). INFECTIVE FORM: Metacercaria. MODE OF INFECTION: Ingestion. SPECIMEN OF CHOICE: Sputum (also feces).

life cycle adult

BECOMES A Dt/LT IM LUNGS

\NGESTE0 BY

DEFINITIVE KOST /

CRAB -AND CRAYFISH

metacercaria IN paragonimus

PERICARDIAL CAVITY

+1 0

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