This subcourse is approved for resident and correspondence course instruction. It reflects the current thought of the Academy of Health Sciences and conforms to printed Department of the Army doctrine as closely as currently possible. Development and progress render such doctrine continuously subject to change.
Students who desire credit hours for this correspondence subcourse must enroll in the subcourse. Application for enrollment should be made at the Internet website: http://www.atrrs.army.mil. You can access the course catalog in the upper right corner. Enter School Code 555 for medical correspondence courses. Copy down the course number and title. To apply for enrollment, return to the main ATRRS screen and scroll down the right side for ATRRS Channels. Click on SELF DEVELOPMENT to open the application; then follow the on-screen instructions.
For comments or questions regarding enrollment, student records, or examination shipments, contact the Nonresident Instruction Branch at DSN 471-5877, commercial (210) 221-5877, toll-free 1-800-344-2380; fax: 210-221-4012 or DSN 471-4012, e-mail [email protected], or write to:
NONRESIDENT INSTRUCTION BRANCH
2105 11TH STREET SUITE 4191
FORT SAM HOUSTON TX 78234-5064
Be sure your social security number is on all correspondence sent to the Academy of Health Sciences.
When used in this publication, words such as "he," "him," "his," and "men" 'are intended to include both the masculine and feminine genders, unless specifically stated otherwise or when obvious in context.
The initial letters of the names of some products may be capitalized in this subcourse. Such names are proprietary names, that is, brand names or trademarks. Proprietary names have been used in this subcourse only to make it a more effective learning aid. The use of any name, proprietary or otherwise, should not be interpreted as endorsement, deprecation, or criticism of a product; nor should such use be considered to interpret the validity of proprietary rights in a name, whether it is registered or not.
TABLE OF CONTENTS
1 PHYLUM PROTOZOO: RHIZOPODA AND ZOOMASTIGOPHORA
Section I. Overview of Protozoo 1-1--1-4
Section II. Class Rhizopoda 1-5--1-8
Section III. Class Zoomastigophora 1-9--1-11
2 PHYLUM PROTOZOO: CILIATA, PIROPLASMASIDA, AND SPOROZOA
Section I. Class Ciliata 2-1--2-3
Section II. Class Piroplasmasida 2-4--2-6
Section III. Class Sporozoa 2-7--2-11
3 PHYLUM PLATYHELMINTHES
Section I. Overview of Platyhelminthes 3-1--3-4
Section II. Class Trematoda 3-5--3-7
Section III. Class Cestoda 3-8--3-10
4 PHYLUM ASCHELMINTHES: PHYLUM ACANTHOCEPHAHELMINTHES: ARTHROPODS AND VECTORS
Section I. Phylum Aschelminthes 4-1--4-3
Section II. Phylum Acanthocephahelminthes 4-4--4-5
Section III. Arthropods and Vectors 4-6--4-7
APPENDIX A, Clinical Manifestations and Treatment of the Common Parasitic Diseases.
APPENDIX B, References.
APPENDIX C, Medical Parasitology.
CORRESPONDENCE COURSE OF THE U.S. ARMY MEDICAL DEPARTMENT CENTER AND SCHOOL
The focus of this subcourse is the identification forms and life cycles of parasites which infect humans. Organisms which will be discussed include parasitic members of Phylum Protozoo, Platyhelminthes, Aschelminthes, and Acanthocephahelminthes. You will be provided with descriptions of the general characteristics of the phylum and detailed illustrations of the cycle forms of significant members of the phylum.
This subcourse is the second of two subcourses which discuss parasitology. In Parasitology I, an overview of parasitology and information for the collection, preservation, and processing of clinical specimens were presented. The material provided in this subcourse will build on that information. It contains information that will help you gain knowledge and skill in the identification of human parasites. It does not attempt to cover parasitology in depth but is only intended to guide you toward becoming competent in the field. For your further learning a bibliography of supplemental sources of parasitology information is included in Appendix B.
The subcourse instructional material consists of four lessons and three appendixes as follows:
Lesson 1, Phylum Protozoo; Rhizopoda and Zoomastigophora. Lesson 2, Phylum Protozoo; Ciliata, Piroplasmasida and, Sporozoa. Lesson 3, Phylum Platyhelminthes.
Lesson 4, Phylum Aschelminthes; Phylum Acanthocephahelminthes; Arthropods and Vectors.
Appendix A, Clinical Manifestations and Treatment of the Common Parasitic
Diseases. Appendix B, References Appendix C, Medical Parasitology
Here are some suggestions that may be helpful to you in completing this subcourse:
--Read and study each lesson carefully.
--Complete the subcourse lesson by lesson. After completing each lesson, work the exercises at the end of the lesson, marking your answers in this booklet.
--After completing each set of lesson exercises, compare your answers with those on the solution sheet that follows the exercises. If you have answered an exercise incorrectly, check the reference cited after the answer on the solution sheet to determine why your response was not the correct one.
Upon successful completion of the examination for this subcourse, you will be awarded 12 credit hours.
To receive credit hours, you must be officially enrolled and complete an examination furnished by the Nonresident Instruction Branch at Fort Sam Houston, Texas.
You can enroll by going to the web site http://atrrs.army.mil and enrolling under "Self Development" (School Code 555).
A listing of correspondence courses and subcourses available through the Nonresident Instruction Section is found in Chapter 4 of DA Pamphlet 350-59, Army Correspondence Course Program Catalog. The DA PAM is available at the following website: http://www.usapa.army.mil/pdffiles/p350-59.pdf.
LESSON 1 Phylum Protozoo; Rhizopoda and Zoomastigophora.
LESSON ASSIGNMENT Paragraphs 1-1 through 1-11.
LESSON OBJECTIVES After completing this lesson, you should be able to:
1-1. Identify the general characteristics of Protozoans.
1-2. Identify the organism characteristics of parasitic members of Class Rhizopoda.
1-3. Select a statement that best describes the life cycle of a member of Class Rhizopoda.
1-4. Identify the organism characteristics of parasitic members of Class Zoomastigophora.
1-5. Select a statement that best describes the life cycle of a member of Class Zoomastigophora.
1-6. Identify the specimen of choice for recovery of specific protozoan organisms.
1-7. Identify the special technique required for recovery of specific protozoan organisms.
SUGGESTION After completing the assignment, complete the exercises of this lesson. These exercises will help you to achieve the lesson objectives.
PHYLUM PROTOZOO: RHIZOPODA AND ZOOMASTIGOPHORA Section I. OVERVIEW OF PROTOZOO 1-1. GENERAL COMMENTS
Protozoans are unicellular (one-celled) organisms which belong to the subkingdom Eucaryota. They vary in size from almost submicroscopic to 120 micrometers (mcm) in diameter. Each protozoan is a complete organism capable of carrying out the same physiological functions performed by many cells in a more complex organism. There are specialized and complex organelles found in protozoans which perform the functions of locomotion, metabolism, and reproduction. It has been suggested that instead of unicellular, the protozoan organisms should be termed acellular because of the intricacy of their functions and also because some of these organisms have more than one nuclei. The members of this phylum which are parasitic to humans, while preserving the general characteristics of their free living counterparts, are capable of survival in the adverse system of the host.
Some protozoans are beneficial to mankind by being part of the food chain and by serving as experimental subjects. Others have adapted well to a parasitic existence causing many diseases in humans. Much has been discovered about protozoans since Anton van Leeuwenhoek first saw the cysts of Giardia lamblia from his own stool and reported them to the Royal Academy in his treatise "Wee besties." His discoveries occurred in the late 1600's.
The various forms and functions of protozoan cells are truly amazing for what we consider as simple single-celled organisms. Whether they are amoeba, flagellates, or ciliates, they contain ultramicroscopic organelles that enable them to perform many of the activities observed in higher animals. However, the most easily recognized and identifiable structure within the protozoan cell is the nucleus. Nuclei among the protozoa usually are of two types, the vesicular nucleus with a clearly defined internal space, and the compact nucleus which appears to be a solid mass. Most of the protozoa which parasitize humans exhibit the vesicular type. Because nuclear chromatin components can be stained and easily observed within the vesicular nucleus, the arrangement of the chromatin, whether dispersed or condensed, is helpful in differentiation of the species within certain classes of the Protozoo. See figures 1-1 and 1-2.
Within the phylum Protozoo, there are five classes which contain organisms parasitic to man. The classes are: Rhizopoda, Zoomastigophorai Ciliata, Piroplasmasida, and Sporozoa. The identification forms and life cycles of Rhizopoda and Zoomastigophora will be described in this lesson. Ciliata, Piroplasmasida, and Sporozoa will be described in Lesson 2.
NP NUCLEOPLASM DISPERSED CONDENSED
PC PERIPHERAL CHROMATIN
Figure 1-1. Vesicular nucleus.
NP NUCLEOPLASM DISPERSED CONDENSED
PC PERIPHERAL CHROMATIN
Figure 1-1. Vesicular nucleus.
Section II. CLASS RHIZOPODA
Members of this class include protozoans which use pseudopodia (false feet) for locomotion. There are many species of this class that are free living and therefore will not be discussed here. The attention is focused instead on those organisms which are parasites of man. There are six genera recognized as human parasites. These include the pathogens: Entamoeba histolytica and Naegleria fowleri, and some species of the genera AcanthamoTba and Hartmanella, as well as commensal organisms from the genera: Entamoeba, Endolimax, and lodamoeba. One commensal amoeba, Entamoeba gingivalis, is found in the mouth of mammals.
Locomotion and ingestion are accomplished by the use of the pseudopodia. Once the food substance is contained within the cell, the organism goes through the processes of enzymatically breaking down and absorbing the nutrients. Egestion of unused residue is performed by the expulsion of the vacuole out of the cell.
Respiration is performed by simple absorption of dissolved oxygen from the liquid environment. Excretion of gases and waste is performed by diffusion out of the organism through the cell membrane. Liquid regulation inside the body is controlled by contractile vacuoles which serve as two-way pumps that control the hydrostasis between the organism and the environment. These organisms reproduce through asexual reproduction consisting of simple cell division.
The amoebic organisms exist in two states. The vegetative state is called the trophozoite. This is the metabolic stage of the protozoan which is very sensitive to the changes of the environment. As unfavorable conditions set in, the organisms go through a process called encystation. The cyst is the resistant state or stage of the amoebic organisms. Excystation takes place with the return of favorable conditions. Some species in this class also use the encystation process for the purpose of reproduction. In this case one cyst yields more than one organism. See figure 1-3.
class rhizopoda class rhizopoda
legend as achromatic striation c chromatin cb chrqmatoid body cw cyst wall g golgi body gv glycogen vacuole k karyosome l lysosome cyst ft mitochondria n nucleus r ribosomes v vaculoe
ORGANISM 1 -- Entamoeba histolytica
COMMON NAME: Montezuma's revenge.
GEOGRAPHICAL DISTRIBUTION: Cosmopolitan prevalent in the tropics and subtropics. PATHOGENESIS: Pathogenic. HABITAT
Primary Site: Intestional Mucosa (colon). Secondary Site: Liver, lungs, brain. INTERMEDIATE HOST: None. RESERVOIR HOST: Other mamalls. INFECTED FORM: Mature quadrinucleated cyst. MODE OF INFECTION: Ingestion. LABORATORY IDENTIFICATION: SPECIMEN SOURCE: Feces.
Entamoeba histolytica (cont)
SIZE: 11 to 60 mcm. SHAPE : Irregular. NUCLEUS: Vesicular, dispersed. NUMBER: One.
PERIPHERAL CHROMATIN: Finely granular and evenly distributed. KARYOSOME: Small, discrete, and usually centrally located. NUCUEOPLASM Clean. CYTOPLASM: Clean.
APPEARANCE: Finely granular. INCLUSIONS: Occasional RBCs. MOBILITY: Directional and progressive with finger-like pseudopodia.
SIZE: 11 to 20 mcm. SHAPE : Spherical. NUCLEUS:
NUMBER: One to four; the mature cyst has four. PERIPHERAL CHROMATIN: Finely granular and evenly distributed. KARYOSOME: Small, discrete, and usually centrally located. NUCUEOPLASM Clean. CYTOPLASM: Finely granular.
CHROMATOID BODIES: If present, cigar-shaped, rounded ends; diagnostic feature.
GLYCOGEN: Diffused, in vacuoles for young cysts.
ORGANISM 2 -- Entamoeba hartmanii
COMMON NAME: None.
GEOGRAPHICAL DISTRIBUTION: Cosmopolitan. PATHOGENESIS: Nonpathogenic.
LABORATORY IDENTIFICATION: Morphologically identical to E. histolytica except for the size and inclusions in the trophozoite. SPECIMEN SOURCE: Feces.
SIZE: 5 to 10 mcm. INCLUSIONS: Bacteria.
ORGANISM 3 -- Entamoeba coli
COMMON NAME: None.
GEOGRAPHICAL DISTRIBUTION: Cosmopolitan.
PATHOGENESIS: Nonpathogenic, often confused with E. histolytica.
HABITAT: Large intestine (colon).
INTERMEDIATE HOST: None.
RESERVOIR HOST: Primates.
INFECTED FORM: Mature cyst with eight nuclei.
MODE OF INFECTION: Ingestion.
SPECIMEN SOURCE: Feces.
TROPHOZOITE * IN COLON Of- MAN
TROPHOZOITE * IN COLON Of- MAN
SIMPLE BINARY FISSION WITH ADDITIONAL NUCLEAR DIVISION A OCCURS
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