CHAPTER 21- PARASITIC INFECTIONS

0.0(0)
studied byStudied by 6 people
learnLearn
examPractice Test
spaced repetitionSpaced Repetition
heart puzzleMatch
flashcardsFlashcards
Card Sorting

1/90

encourage image

There's no tags or description

Looks like no tags are added yet.

Study Analytics
Name
Mastery
Learn
Test
Matching
Spaced

No study sessions yet.

91 Terms

1
New cards

parasitic protozoa

of the three categories of organisms (parasitic protozoa, helminths, and arthropods) that are studied in a parasitology course, only one category—_____________________________—contains microbes.

2
New cards

Parasitism

is a symbiotic relationship that is of benefit to one party or symbiont (the parasite) at the expense of the other party (the host).

3
New cards

Parasites

are organisms that live on or in other living organisms, at whose expense they gain some advantage.

4
New cards

ectoparasites

Parasites that live outside the host’s body are

.Arthropods such as mites, ticks, and lice

5
New cards

endoparasites

parasites that live inside the host are

Parasitic protozoa and helminths are examples

6
New cards

definitive host

If more than one host is involved, the __________ is the one that harbors the adult or sexual stage of the parasite or the sexual phase of the life cycle

7
New cards

intermediate host

harbors the larval or asexual stage of the parasite or the asexual phase of its life cycle.

8
New cards

accidental host

An _________________ is a living organism that can serve as a host in a particular parasite’s life cycle, but is not a usual host in that life cycle

9
New cards

dead-end hosts

. Some accidental hosts are __________, from which the parasite cannot continue its life cycle

10
New cards

Facultative parasites

are organisms that can be parasitic but are also capable of a free-living existence.

11
New cards

Obligate parasites

have no choice; to survive, they must be parasitic

12
New cards

Medical parasitology

is the study of parasites that cause human disease

13
New cards

Parasitology Section of the Clinical Microbiology Laboratory

The overall responsibility of the _________________________ is to assist clinicians in the diagnosis of parasitic diseases—primarily, parasitic diseases caused by endoparasites such as parasitic protozoa and helminths

14
New cards

parasite life cycle stages

In general, parasitic infections are diagnosed by observing and recognizing various__________________________ in clinical specimens.

15
New cards

locomotion

Protozoa are classified taxonomically by their mode of ________. Some move by pseudopodia, others by flagella, others by cilia, and some are nonmotile

16
New cards

pseudopodia

Amebas (amebae) move by means of ______(literally, “false feet”)

17
New cards

whiplike flagella

Flagellates move by means of

18
New cards

hairlike cilia

Ciliates move by means of

19
New cards

Sporozoa (sporozoans)

Protozoa classified as__________have no pseudopodia, flagella, or cilia, and therefore exhibit no motility

20
New cards

parasitic protozoal infections

. Most _________ are diagnosed by observing trophozoites, cysts, oocysts, or spores in the specimen

21
New cards

The trophozoite

is the motile, feeding, dividing stage in the protozoal life cycle, and the cyst, oocyst, and spore are dormant stages

22
New cards

Protozoal infections

are most often acquired by ingestion or inhalation of dormant stages

23
New cards

Leishmaniasis

is caused by various species of flagellated protozoa and is usually transmitted via the bite of an infected sand fly

Reservoirs include infected humans, domestic dogs, and various wild animals.

is usually transmitted via the bite of an infected sand fly.

Transmission by blood transfusion and person-to-person contact have been reported.

Patient Care. Use Standard Precautions for hospitalized patients.

24
New cards

amastigote

. The nonmotile, intracellular form of Leishmania is called an

25
New cards

cutaneous Leishmaniasis

starts with a papule that enlarges into a craterlike ulcer Individual ulcers may coalesce, causing severe tissue destruction and disfigurement

<p>starts with a papule that enlarges into a craterlike ulcer Individual ulcers may coalesce, causing severe tissue destruction and disfigurement</p>
26
New cards

Acanthamoeba, Toxoplasma gondii

Protozoal infections of the eyes include conjunctivitis and keratoconjunctivitis (inflammation of the cornea and conjunctiva), caused by amebas in the genus __________, and toxoplasmosis, caused by the sporozoan, _____________________

27
New cards

Trichomoniasis

is a sexually transmitted protozoal disease affecting both men and women. The disease is usually symptomatic in women, causing vaginitis with a profuse, thin, foamy, malodorous, greenish-yellowish discharge.

Patient Care. Use Standard Precaution

is caused by Trichomonas vaginalis, a flagellate and is transmitted by direct contact with vaginal and urethral discharges of infected people

<p>is a sexually transmitted protozoal disease affecting both men and women. The disease is usually symptomatic in women, causing vaginitis with a profuse, thin, foamy, malodorous, greenish-yellowish discharge.</p><p>Patient Care. Use Standard Precaution</p><p>is caused by <mark data-color="yellow">Trichomonas vaginalis,</mark> a flagellate and is transmitted by direct contact with vaginal and urethral discharges of infected people</p>
28
New cards

. Amebic conjunctivitis and keratoconjunctivitis

are amebic infections causing inflammation of the conjunctiva, corneal ulcers, pus formation, and severe pain. These infections can lead to loss of vision. The disease process is more rapid if corneal abrasions are present.

Patient Care. Use Standard Precautions for hospitalized patients.

are caused by several species of amebas in the genus Acanthamoeba

. The amebas enter the eye from ameba-contaminated waters.

Infections have occurred primarily in people who wear soft contact lenses and have used nonsterile, homemade cleaning or wetting solutions, or have become infected in ameba-contaminated spas or hot tubs

29
New cards

Toxoplasmosis

s a systemic sporozoan infection that, in immunocompetent persons, may be asymptomatic or resemble infectious mononucleosis

Disease typically involves the central nervous system, eyes (chorioretinitis), lungs, muscles, or heart

Patient Care. Use Standard Precautions for hospitalized patients

is caused by Toxoplasma gondii, an intracellular sporozoan

30
New cards

Cerebral toxoplasmosis

is common in AIDS patients. Infection during early pregnancy may lead to fetal infection, causing death of the fetus or serious birth defects

31
New cards

Entamoeba histolytica

•Infects colon with secondary infection of liver.

•Infected patients pass noninfectious trophozoites as well as infectious cysts in stools.

• Diagnosis by presence of characteristic cysts (containing one to four nuclei) in stools.

• Therapy: Iodoquinol, metronidazole.

32
New cards

Giardia lamblia

•Infection usually results from drinking contaminated water.

•Infects duodenum, with incubation time of about ten days.

• Acute infection shows sudden onset with foul smelling, watery diarrhea.

• Diagnosis by presence of cysts or trophozoites in stools.

• Therapy: Metronidazole

33
New cards

Cryptosporidium parvum

• Infects lower small intestine.

• Organisms are intracellular parasites in epithelial cells of intestinal villi.

• Diagnosis by modified acid-fast stain of stool sample.

• Therapy: : Paromomycin (often not effective)

34
New cards

Amebiasis or amebic dysentery

. is a protozoal gastrointestinal infection that may be asymptomatic, mild, or severe and is often accompanied by dysentery, fever, chills, bloody or mucoid diarrhea or constipation, and colitis. The amebas may invade mucous membranes of the colon, forming abscesses and amebomas, which are granulomas that are sometimes mistaken for carcinoma

Patient Care. Use Standard Precautions for hospitalized patients.

is caused by Entamoeba histolytica

35
New cards

, E. histolytica has two stages: the______which is the dormant, infective stage, and the motile, metabolically active, reproducing ________

cyst stage, trophozoite stage

36
New cards

Balantidiasis

is a protozoal gastrointestinal infection of the colon causing diarrhea or dysentery, colic, nausea, and vomiting.

Patient Care. Use Standard Precautions for hospitalized patients

is caused by Balantidium coli,

37
New cards

Cryptosporidiosis

is a gastrointestinal infection caused by a coccidial protozoan.

may be asymptomatic or may cause diarrhea, cramping, and abdominal pain. Less common symptoms include malaise, fever, anorexia, nausea, and vomiting.

standard and contact precautions

results from ingestion of oocysts of Cryptosporidium parvum

38
New cards

Cyclosporiasis

is a coccidial gastrointestinal infection, causing watery diarrhea (6 or more stools per day), nausea, anorexia, abdominal cramping, fatigue, and weight loss. Diarrhea lasts between 9 and 43 days in immunocompetent patients, and months in immunocompromised patients

Patient Care. Use Standard Precautions for hospitalized patients

s results from ingestion of oocysts of Cyclospora cayetanensis,

Reservoirs include fecally contaminated water sources and produce that has been rinsed with fecally contaminated water. Transmission is primarily waterborne, but outbreaks have involved contaminated raspberries, basil, and lettuce.

39
New cards

Giardiasis

is a protozoal infection of the duodenum (the uppermost portion of the small intestine) and may be asymptomatic, mild, or severe. Patients experience diarrhea, steatorrhea (loose, pale, malodorous, fatty stools), abdominal cramps, bloating, abdominal gas, fatigue, and possibly weight loss

standard and contact precautions

is caused by Giardia lamblia

Reservoirs include infected humans, possibly beavers and other wild and domestic animals

Transmission occurs via the fecal–oral route

40
New cards

Primary Amebic Meningoencephalitis

is an amebic disease causing inflammation of the brain and meninges, sore throat, severe frontal headache, hallucinations, nausea, vomiting, high fever, stiff neck. Unless diagnosed and treated promptly, death occurs within 10 days, usually on the fifth or sixth day

standard precautions

s is caused by an ameboflagellate named N. fowleri

41
New cards

class Insecta

Some people refer to all, or most, insects as bugs, but only one category of insects—________—actually contains bugs.

42
New cards

African Trypanosomiasis (African Sleeping Sickness)

s is a systemic disease caused by flagellated protozoa in the bloodstream, known as hemoflagellates. Early stages of the disease include a painful chancre at the site of a tsetse fly bite, fever, intense headache, insomnia, lymphadenitis, anemia, local edema, and rash. Later stages of the disease include body wasting, falling asleep, coma, and death if untreated.

standard precautions

43
New cards

T. brucei ssp. gambiense , T. brucei ssp. rhodesiense

. Two subspecies of Trypanosoma brucei cause African trypanosomiasis. __________in western and central Africa, causes most cases of sleeping sickness; the disease may last several years. ________, in eastern Africa

44
New cards

humans

Infected _____serve as reservoirs of T. brucei ssp. gambiense

45
New cards

wild animals and domestic cattle

are the primary reservoirs of T. brucei ssp. rhodesiense

46
New cards

American Trypanosomiasis

. In the acute stage of the disease, patients may present with an inflammatory response at the site of the reduviid bug bite, fever, malaise, lymphadenopathy, hepatomegaly (enlarged liver), and splenomegaly (enlarged spleen), although it may be asymptomatic

also known as Chagas’ disease, in honor of Carlos Chageas, who described the entire life cycle of Trypanosoma cruzi in 1909

The etiologic agent of American trypanosomiasis is T. cruzi,

standard precautions

47
New cards

Babesiosis

is a sporozoan disease that may include fever, chills, myalgia, fatigue, jaundice, and anemia. It is potentially severe and sometimes fatal, especially in splenectomized and elderly people. Patients may be simultaneously infected with Borrelia burgdorferi, the etiologic agent of Lyme disease, which is transmitted by the same species of tick.

Reservoirs include rodents for B. microti and cattle for B. divergens. Transmission occurs by tick bite and rarely, by blood transfusion.

s is caused by Babesia microti

Use Standard Precautions

48
New cards

Malaria

is a systemic sporozoan infection with malaise, fever, chills, sweating, headache, and nausea. The intermittent bouts of chills and fever are sometimes referred to as paroxysms.

Patient Care. Use Standard Precautions

a is caused by four species in the genus Plasmodium: Plasmodium vivax (the most common species), P. falciparum (the most deadly), Plasmodium malariae, and Plasmodium ovale.

Infected humans and infected mosquitoes serve as reservoirs.

49
New cards

Life cycle of malarial parasites

  1. Infected mosquito injects sporozoites.

  2. Sporozoites migrate to the liver where they form merozoites

  3. Merozoites are released and invade red blood cells.

  4. In the red blood cell, the merozoite becomes a trophozoite.

  5. In the red blood cell, the trophozoite multiplies, producing new merozoites. These are released when the red blood cell ruptures, and can infect other red blood cells.

  6. Some merozoites become gametocytes.

  7. The female mosquito picks up gametocytes from an infected human. The sexual cycle occurs in the mosquito, where sporozoites are formed

50
New cards

Helminths

The word ________-means parasitic worm

51
New cards

roundworms

(nematodes)

52
New cards

Flatworms

are further divided into tapeworms (cestodes) and flukes (trematodes).

53
New cards

The stages of the typical helminth life cycle are the _______, the ______, and the ______

egg, larva, adult worm

54
New cards

hermaphroditic

Cestodes and many trematodes are __________, meaning that adult worms contain both male and female reproductive organs. Thus, it only takes one worm to produce fertile eggs.

55
New cards
56
New cards

intermediate host, definitive host.

The host that harbors the larval stage is called the ____________, whereas the host that harbors the adult worm is called the

57
New cards

three-host parasite

The fish tapeworm, for example, is what is known as a ___________, having one definitive host (human) and two intermediate hosts (a freshwater crustacean called a Cyclops and a freshwater fish) in its life cycle

58
New cards

intermediate hosts, definitive hosts.

Fleas serve as___________ in the life cycle of the dog tapeworm, whereas dogs, cats, or humans can serve as ________________

59
New cards

Helminth infections

are usually diagnosed by observing (a) whole worms or segments of worms in clinical specimens—most often, fecal specimens, or (b) larvae or eggs in stained or unstained clinical specimens

60
New cards

Onchocerciasis (also known as “river blindness”)

HELMINTH THAT CAUSES THE DISEASE: Onchocerca volvulus (N); microfilariae (tiny prelarval stages of these helminths are found in the skin

ANATOMIC LOCATION: Skin

61
New cards

Trichinosis

HELMINTH THAT CAUSES THE DISEASE: Trichinella spiralis (N)

ANATOMIC LOCATION: Muscle and Subcutaneous Tissues

62
New cards

Dracunculiasis

HELMINTH THAT CAUSES THE DISEASE: Dracunculus medinensis (N); also known as the guinea worm

ANATOMIC LOCATION: Muscle and Subcutaneous Tissues

63
New cards

Onchocerciasis

HELMINTH THAT CAUSES THE DISEASE: Onchocerca volvulus (N); microfilariae enter the eyes, causing an intense inflammatory reaction

ANATOMIC LOCATION: Eyes

64
New cards

Loiasis

HELMINTH THAT CAUSES THE DISEASE: Loa loa (N); also known as the African eyeworm

ANATOMIC LOCATION: Eyes

65
New cards

Paragonimiasis

HELMINTH THAT CAUSES THE DISEASE: Paragonimus westermani (T); the lung fluke

ANATOMIC LOCATION: Respiratory System

66
New cards

Ascariasis infection

HELMINTH THAT CAUSES THE DISEASE: Ascaris lumbricoides (N); the large intestinal roundworm of humans

ANATOMIC LOCATION: Gastrointestinal Tract

67
New cards

Hookworm infection

HELMINTH THAT CAUSES THE DISEASE: Ancylostoma duodenale (N) or Necator americanus (N)

ANATOMIC LOCATION: Gastrointestinal Tract

68
New cards

Pinworm infection (enterobiasis)

HELMINTH THAT CAUSES THE DISEASE: Enterobius vermicularis (N)

ANATOMIC LOCATION: Gastrointestinal Tract

69
New cards

Whipworm infection (trichuriasis)

HELMINTH THAT CAUSES THE DISEASE: Trichuris trichiura (N)

ANATOMIC LOCATION: Gastrointestinal Tract

70
New cards

Strongyloidiasis

HELMINTH THAT CAUSES THE DISEASE: Strongyloides stercoralis (N)

ANATOMIC LOCATION: Gastrointestinal Tract

71
New cards

Beef tapeworm infection

HELMINTH THAT CAUSES THE DISEASE: Taenia saginata (C)

ANATOMIC LOCATION: Gastrointestinal Tract

72
New cards

Dog tapeworm infection

HELMINTH THAT CAUSES THE DISEASE: Dipylidium caninum (C)

ANATOMIC LOCATION: Gastrointestinal Tract

73
New cards

Dwarf tapeworm infection

HELMINTH THAT CAUSES THE DISEASE: Hymenolepis nana (C)

ANATOMIC LOCATION: Gastrointestinal Tract

74
New cards

Fish tapeworm infection

HELMINTH THAT CAUSES THE DISEASE: Diphyllobothrium latum (C)

ANATOMIC LOCATION: Gastrointestinal Tract

75
New cards

Pork tapeworm infection

HELMINTH THAT CAUSES THE DISEASE: Taenia solium (C)

ANATOMIC LOCATION: Gastrointestinal Tract

76
New cards

Rat tapeworm infection

HELMINTH THAT CAUSES THE DISEASE: Hymenolepis diminuta (C

ANATOMIC LOCATION: Gastrointestinal Tract

77
New cards

Fasciolopsiasis

HELMINTH THAT CAUSES THE DISEASE: Fasciolopsis buski (T); an intestinal fluke

ANATOMIC LOCATION: Gastrointestinal Tract

78
New cards

Fascioliasis

HELMINTH THAT CAUSES THE DISEASE: Fasciola hepatica (T); a liver fluke

ANATOMIC LOCATION: Gastrointestinal Tract

79
New cards

Clonorchiasis

HELMINTH THAT CAUSES THE DISEASE: Clonorchis sinensis (T); also known as the Chinese or Oriental liver fluke

ANATOMIC LOCATION: Gastrointestinal Tract

80
New cards

Filariasis

HELMINTH THAT CAUSES THE DISEASE: Wuchereria bancrofti (N) and Brugia malayi (N); microfilariae of these helminths are found in the bloodstream

ANATOMIC LOCATION: Circulatory System

81
New cards

Schistosomiasis (also known as bilharzia)

HELMINTH THAT CAUSES THE DISEASE: Trematodes in the genus Schistosoma

ANATOMIC LOCATION: Circulatory System

82
New cards

Cysticercosis

HELMINTH THAT CAUSES THE DISEASE: Cysts (the larval stage) of the pork tapeworm (Taenia solium) are found in the brain

ANATOMIC LOCATION: central nervous system

83
New cards

Hydatid cyst disease

HELMINTH THAT CAUSES THE DISEASE: Echinococcus granulosis (C) or Echinococcus multilocularis (C); in addition to the brain, hydatid cysts (the larval form of these helminths) can form in many other locations in the body

ANATOMIC LOCATION: central nervous system

84
New cards

The arthropod may actually be the cause of the disease.

Scabies, a disease in which microscopic mites live in subcutaneous tunnels and cause intense itching

85
New cards

The arthropod may serve as the intermediate host

Flea in the life cycle of the dog tapeworm. Beetle in the life cycle of the rat tapeworm. Cyclops sp. in the life cycle of the fish tapeworm. Tsetse fly in the life cycle of African trypanosomiasis. Simulium black fly in the life cycle of onchocerciasis. Mosquito in the life cycle of filariasis.

86
New cards

The arthropod may serve as the definitive host

Female Anopheles mosquito in the life cycle of malarial parasites

87
New cards

The arthropod may serve as a vector in the transmission of an infectious disease

Oriental rat flea in the transmission of plague. Tick in the transmission of Rocky Mountain spotted fever and Lyme disease. Louse in the transmission of epidemic typhus

88
New cards

insects

The ________studied include lice, fleas, flies, mosquitoes, and reduviid bugs. Arachnids include mites and ticks

89
New cards

Crustaceans

include crabs, crayfish, and certain Cyclops species.

90
New cards

Mechanical vectors

__________ merely pick up the parasite at point A and drop it off at point B, similar to an overnight delivery service.

For example, a housefly could pick up parasite cysts on the sticky hairs of its legs while walking around on animal feces in a meadow. The fly might then come through an open kitchen window and drop off the parasite cysts while walking on a pie cooling on the counter

91
New cards

biologic vector

is an arthropod in whose body the pathogen multiplies or matures (or both). Many arthropod vectors of human diseases are biologic vectors