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GLOSSARY 291

Digenetic Reproductive functions include two stages of multi- Ellipsoidal Elongated circle with three planes that are based
plication, one sexual in the mature forms and the other asexual on three coordinate axes.
in the larval stages. Emaciation Term describes the substantial loss of fat and
Dioecious Presence of separate individuals that possess either other tissue, causing the organism to appear extremely thin.
male or female sexual characteristics relating to organisms. Embryonated eggs Female parasite deposits embryonated
Direct tests Procedure that tests for the actual organism or eggs as a prelarval stage, giving rise to microfilaria which
antigen, rather than antibodies formed against the particular grow into an infective stage that are generally passed to others
organism. through the bites of insects.
Dissected The prefix dis- means to separate into parts and Embryos This is the term for the developing young of a living
-sect means to separate and to cut. Quite often the word is mis- organism and is the young stage of development. From the mo-
pronounced as di’sect, which would merely mean “to cut into ment of fertilization the zygote that will eventually become the
only two parts, as in bisect” (dis·sect/, d˘ı-sekt'). offspring is undergoing a period of rapid growth.
Disseminated Term meaning that a condition is spread over Empyema Fluid gathered in the thoracic cavity between the
a large area of the body. lungs and the chest wall.
Dorsoventrally Refers to the back and the belly surfaces of Encapsulated Confined in or surrounded by a capsule or a
the body and passing from the back to the belly surface. membranous sac.
Dracunculiasis Infection with a genus of nematode parasites, Encapsulated zygote An encysted or encapsulate zygote of
including Dracunculus medinensis (guinea worm), a threadlike a sporozoan protozoan is called an oocyst protozoa, which de-
worm, widely spread over India, Africa, and Arabia; burrows velops into a sporozoite or a sporocyst that contains a number
into subcutaneous and intermuscular tissues of humans and of sporozoites.
other animals, particularly the lower limbs, causing dramatic Encephalitis Inflammation of the lining of the central ner-
swelling (elephantiasis). vous system.
Duckworms Common term for intestinal trematodes com- Encystation Transformation into a cyst from a trophozoite.
mon in a number of areas including coastal New Jersey where Endemic The term means that a specific illness occurs with
duck and other water fowl that are infected may contaminate predictable regularity in a specific geographic region or in a
the water and infect humans. population group.
Duodenal fluid Both fresh liquid stool specimens and duo- Endoparasites Group of parasites that inhabit the atria and
denal aspirates (fluid in the aspirates duodenum of the intes- organs inside the host’s body.
tine) may yield trophozoites of Giardia lamblia or the antigens Endoplasm The central cytoplasmic fluid of a cell as separate
of the organism. from the ectoplasm.
Duodenum First and shortest segment (approximately 1 foot Endoplasmic reticulum Endoplasmic reticulum (ER) in-
long) of the small intestine originating from the pylorus of the volves organelles that form a network of tubules, vesicles, and
stomach. storage areas within the reticulum.
Dysentery Diarrhea that contains blood and mucus, and Endosome In a eukaryotic cell which has an organized nu-
originates with extreme inflammation of the intestines. cleus, an endosome is a membrane-bound compartment in the
cytoplasm.
E Enterocytes These cells are simple columnar epithelial cells
for absorption that are found within the small intestines and
Echinococcosis Infection with an Echinococcus organisms the colon.
(tapeworm). Eosinophilia Condition of an increase above approximately
Ectoparasites Lice and mites that live outside the human 3 percent in the white blood cells called eosinophils; often re-
body. lated to immune reactions such as those found in allergic con-
Ectoplasm The outermost layer of the protoplasm of animal ditions and parasitic infections where the tissue is invaded by
cells. the parasitic organisms.
Edema Swelling or accumulation of fluids in a region of the Eosinophilic enteritis Inflammation of the intestines, which
body; may be generalized. includes colitis, eosinophilic enteritis, celiac disease, other
EDTA Anticoagulant to prevent blood from clotting; preserves malabsorptive disease, lactase deficiency, and obesity.
morphology of RBCs. Epidemiological surveillance Often conducted by gov-
Ehrlichiosis Caused by a bacterium of the family called Rick- ernmental agencies and universities, where gathering and ana-
ettsiae, which causes significant numbers of serious diseases lyzing data related to disease states, drawing inferences, and
around the world. These diseases include Rocky Mountain interpreting the data derived, its significance and the distribu-
spotted fever and typhus, and all are spread by the bites of tion of important epidemiologic.
ticks, mites, and fleas. There are two types in the United States Epigastric Upper central region of the abdomen just under
called human monocytic ehrlichiosis (HME) and human gran- the sternum.
ulocytic ehrlichiosis (HE). Epsom salts May be used as a purgative to aid in eliminating
Elephantiasis Grotesque swelling of lower limbs and genitals toxins and parasites following administration of parasiticidal
as a result of D. medinensis infection (guinea worm). medications.