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Microbiology > Parasitic, Protozoa, Helminths & Arthropod Vectors Ch. 23 > Flashcards

Parasitic, Protozoa, Helminths & Arthropod Vectors Ch. 23 Flashcards

1
Q

Where are most parasitic diseases in humans found? (i.e. in what parts of the world?)

A

Worldwide, among people in rural, undeveloped, or overcrowded places.

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2
Q

What are two types of hosts that parasitic infections commonly involve?

A

Definitive hosts and intermediate hosts

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3
Q

What three ways can parasites infect humans?

A

-Ingestion
{Fecal-oral, direct ingestion}
-Vectorborne transmission
{Kissing bug, Mosquito, sand fly, Tsetse fly}
-Direct contact
{Skin, sexual contact, inhalation, penetration of the eyes}

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4
Q

What are the two morphological forms of protozoa and describe.

A

-Trophozoite
{Feeding and reproducing stage that lives within the host}

-Cyst
{Infective form that survives in the environment, undergoes excystment when ingested, developing into trophozoites}

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5
Q

What is the only ciliate to cause disease in humans?

A

Balantidium coli – Balantidiasis

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6
Q

What are the signs associated with Balantidium coli infection in humans?

A

Persistant diarrhea, abdominal pain, and weight loss. Severe infection may produce dysentery and ulceration of the intestinal mucosa.

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7
Q

What are the general characteristics of Amoebae?

A
  • Protozoa with no truly defined shape
  • Move and acquire food through the use of pseudopods
  • Found in water sources throughout the world
  • Few cause disease
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8
Q

Where is Entamoeba found?

A

Carried asymptomatically in the digestive tracts of humans

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9
Q

What are the three types of amebiasis caused by Entamoeba? Which types are fatal?

A
  • Luminal amebiasis (asymptomatic infections in healthy individuals)
  • Invasive amebic dysentery (severe diarrhea, colitis, appendicitis, and ulceration of the intestinal mucosa)
  • Invasive extraintestinal amebiasis (trophoziotes in the blood are carried through the body)

–Amebic dysentery and invasive extraintestinal amebiasis can be fatal

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10
Q

How does Acanthamoeba enter the body?

A

Through cuts, scrapes, the conjunctiva, or inhalation

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11
Q

What are the signs of infection of Acanthamoeba?

A

Headache, altered mental state, neurological defects and eventually death.

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12
Q

How does Naegleria enter the body?

A

When swimmers inhale contaminated water

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13
Q

What are the signs of infection of Naegleria?

A

Causes hemorrhage, coma, and usually death

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14
Q

How are flagellates identified?

A
  • Possess at least one flagellum

- Number and arrangement of flagella help determine species

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15
Q

What disease is caused by Trypanosoma cruzi?

A

Chagas disease

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16
Q

How is Trypanosoma cruzi transmitted?

A

Through bite of insect in genus Triatoma “kissing bugs” that feed from blood vessels in the lips

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17
Q

What are the four stages of Chagas Disease?

A
  • Acute stage characterized by chagomas
  • Generalized stage
  • Asymptomatic chronic stage
  • Symptomatic stage characterized by congestive heart failure following formation of pseudocysts
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18
Q

What is the disease caused by Trypanosoma brusei?

A

African sleeping sickness

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19
Q

What is the vector of Trypanosoma brusei?

A

The tsetse fly

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20
Q

What are the three stages of Trypanosoma brusei?

A
  • Site of the fly bite becomes a lesion with dead tissue
  • Parasites in the blood trigger fever, lymph node selling, and headaches
  • meningoencephalitis
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21
Q

What are the hosts of Leishmania sp?

A

Wild and domestic dogs and small rodents

22
Q

What are the two developmental stages of Leishmania sp?

A

-Amastigotes
(multiply in host’s macrophages and monocytes)

-Promastigotes
(Develop extracellularly within a vector’s gut)

23
Q

What are the three clinical forms of Leishmania sp?

A

-Cutaneous leishmaniasis
(large painless skin ulcers form at the bite wounds)
-Mucocutaneous leishmaniasis
(skin lesions enlarge to encompass mucous membranes of the mouth, nose, or soft palate)
-Visceral leishmaniasis
(macro-phages carry the parasite to the liver, spleen, bone marrow, and lymph nodes. Fatal in 95% of untreated cases)

24
Q

What is the pathogenesis and disease of Giardia intestinalis?

A
  • Giardiasis
  • Found in intestinal tracts of animals and in the environment
  • Ingest cysts in contaminated water or when swimming
  • Life cycle similar to Entamoeba (trophozoites multiply in the small intestines)
  • ranges from asymptomatic infection to severe GI disease (Diarrhea, pain, bloating, nausea, vomiting, and fever)
25
Q

What is the pathogenesis and disease of Trichomonas vaginalis?

A
  • Vaginosis
  • Most common protozoan causing human disease in industrialized world
  • lives in genitourinary system of men and women
  • transmitted almost exclusively via sex
  • Occurs in people with preexisting STD or multiple sex partners
  • Infection in men typically assymptomatic
  • in women (causes odorous discharge, vaginal and cervical lesions, abdominal pain, and painful urination and intercourse)
26
Q

Where is the family Apicomplexians found?

A
  • Alveolate protozoa
  • Infective form characterized by complex organelles at their apical end
  • parasites of animals
  • life cycles involve at least two types of hosts
27
Q

How do Apicomplexians reproduce?

A

Schizogony (multinucleate schizonts form before the cells divide)

28
Q

How many hosts are required for the life cycle of the family Apicomplexians?

A

two

29
Q

What is the vector (specific) for Plasmodium sp?

A

Anopheles mosquitoes

30
Q

What are the symptoms of malaria?

A
  • Fever, chills, diarrhea, and headache

- Erthrocyte loss causes anemia, weakness, and fatigue

31
Q

Are the symptoms of malaria caused by the parasite or the disease?

A

Associated with cycles of erythrocyte lysis

32
Q

What is the pathogenesis of Toxoplasma gondii?

A
  • T. gondii is causative agent of toxoplasmosis
  • One of the world’s most widely distributed parasites
  • Wild and domestic mammals and birds are major reservoir
  • Infection due to consumption of under-cooked meat containing the parasite
  • Ingestion or inhalation of contaminated soil can also occur
33
Q

What is the definitive host of Toxoplasma gondii?

A

cats

34
Q

How does Toxoplasma gondii affect its host?

A
  • Fever-producing illness combined with other symptoms

- Usually self-limited infection

35
Q

In which two populations in Toxoplasma gondii most severe?

A
  • AIDS patients

- Fetuses

36
Q

What is the transmission of Cryptosporidium parvum?

A
  • Usually results from drinking contaminated drinking water

- Fecal-oral transmission can occur

37
Q

What is the disease presentation of Cryptosporidium enteritis?

A

-severe diarrhea accompanied by headache, muscle pain, cramping, and fluid & weight loss

38
Q

Describe Helminths

A
  • Macroscopic, multicellular, eukaryotic worms
  • Complex life cycles
  • Intermediate hosts are often needed to support larval stage
  • Adult worms are either dioecious or monoecious
  • Three groups of helminths
39
Q

What is the general information of cestodes?

A
  • Commonly called tapeworms
  • Flat, segmented, intestinal parasites
  • All tapeworms lack digestive systems
  • All possess the same general body plan
40
Q

What is the pathogenesis of Taenia sp?

A
  • Cattle and swine serve as the intermediate hosts
  • Humans living close to livestockor with inadequate sewage treatment have highest incidence of infection
  • Adults attach to the intestinal epithelium
  • Most individuals shed strobila without having symptoms
  • Intestinal blockage can occur if the tapeworm is too large
41
Q

What is Taenia saginata?

A

Beef tapeworm

42
Q

What is Taenia solium?

A

Pork tapworm

43
Q

What is the pathogenesis and disease of Echinococcus granulosus?

A
  • Canine tapeworm
  • Canines infected by eating cysticerci in various herbivore hosts
  • Humans are accidental intermediate hosts (consume food or water contaminated from dog feces)
  • Causes hydatid disease (Larvae travel throughout body and form hydatid cysts, symptoms follow enlargement of cysts in infected tissue)
44
Q

General information of trematodes

A
  • commonly called flukes
  • Flat, leaf shaped worms
  • Lack complete digestive tract
  • Attach to host tissues via a ventral sucker to obtain nutrients
  • Geographical distribution limited because the intermediate host is limited
  • Grouped according to the site in the body they parasitize
45
Q

Pathogenesis and disease of Fasciola sp

A
  • liver fluke
  • Infect sheep and cattle worldwide
  • Humans accidental definitive hosts (ingest metacercariae from aquatic vegetation)
  • Chronic infections occur when flukes reside in the bile ducts (symptoms coincide with episodes of bile duct obstruction and inflammation)
46
Q

General information of Schistosoma sp

A
  • Dioecious blood fluke
  • Causative agent of schistosomiasis
  • most cases occur in sub-Saharan Africa
  • Humans are the principal definitive host
  • 3 geographically limited species infect humans
  • S. mansoni
  • S. haematobium
  • S. japocicum
47
Q

Pathogenesis and disease of Schistosoma sp

A
  • Cercariae burrow through skin of humans who contact contaminated water
  • larvae mature and mate in the circulatory system
  • eggs move to the intestines or the urinary bladder and ureters
  • dermatitis may occur at the site where cercariae entered
  • swimmers itch may develop at the site of cercariae entry
  • infections can become chronic and can be fatal
48
Q

General information of nematodes

A
  • Commonly called roundworms
  • Long, cylindrical worms that taper at each end
  • Possess complete digestive tracts
  • Have a protective outer cuticle
  • Parasites of almost all vertebrates
49
Q

What are the features of the lifecycle of roundworms

A
  • Number of reproduction strategies
    1. Intestinal nematodes shed eggs into lumen of the intestine (eggs are consumed in contaminated food or water)
    2. Larvae of some intestinal nematodes hatch in the soil (Larvae actively penetrate the skin of a host)
    3. Some nematodes encyst in muscle tissue (consumed in raw or undercooked meat)
    4. Mosquitoes transmit a few species of filarial nematodes

-Adult sexually mature stages are found only in definitive hosts.

50
Q

Pathogenesis and disease of Ascaris lumbricoides

A
  • Endemic in the rural SE United States
  • Causitive agent of Ascariasis
    a. Most common nematode infection of humans worldwide
    b. eggs are ingested in water or on vegetables
    c. Adult worms grow and reproduce in the small intestine
    d. Most infections are asymptomatic
    e. Abdominal pain, nausea, vomiting, and intestinal obstruction can occur if the worm burden is high
51
Q

Pathogenesis and disease of Ancylostoma duodenale and Necator americanus

A
  • Hookworms are the 2nd most common nematode infection
  • 2 hookworms infect humans (Ancylostoma duodenale, Necator americanus)
  • Larvae in soil burrow through skin
    a. travel to the heart, lungs, and eventually the small intestine.
    b. Adult worms suck the blood of their hosts. Causes chronic anemia, iron and protein deficiencies.
    c. Ground itch occur at the site of larvae penetration)
52
Q

Pathogenesis and signs of infection with Enterobius vermicularis

A
  • Commonly known as pinworm
  • Most common parasitic worm found in the US
  • Humans are the only host for Enterobius
  • Female pinworms deposit their eggs in the anus
  • Infections can be asymptomatic
  • Intense perineal itching occurs if symptomatic

Microbiology (2 decks)

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