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Microbiology > Exam #7: Parasitic Infections of the Circulatory, RES, & Lymphatic System > Flashcards

Exam #7: Parasitic Infections of the Circulatory, RES, & Lymphatic System Flashcards

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Biology 101 flashcards
1
Q

What is Africacn Trypanosomiasis?

A

African Sleeping Sickness

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2
Q

What organism causes African Sleeping Sickness?

A

Trypanosoma brucei

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3
Q

What is the insect vector for African Sleeping Sickness?

A

Tsetse fly

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4
Q

What is the animal reservoir of Trypanosoma brucei?

A

Cattle

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5
Q

What are the 2 subspecies of Trypanosoma brucei?

A

T. brucei gambiense= human-to-human spread ONLY

T. brucei rhodesiense= human-to-human & animal-to-human spread

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6
Q

What are the symptoms of early African Sleeping Sickness?

A

In early stage infection, organisms are in the blood & peripheral lymph nodes leading to:

  • Fever
  • Myalgia
  • Chills
  • Lymphadenopathy
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7
Q

What are the late symptoms of African Sleeping Sickness? Which form of Trypanosomiasis leads to late stage faster?

A

Late stage infection is characterized by invasion of the CNS

  • Headache
  • Seizures
  • Tremors
  • Encephalitis
  • Periods of sleeplessness & lethargy
  • Coma
  • Death

Eastern African form leads to CNS involvement in 3-4 weeks vs. weeks to years for the West African form

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8
Q

How is Trypanosoma brucei infection diagnosed?

A

Detection of parasites in blood smear, lymph nodes aspirates, or CSF

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9
Q

Describe the antigenic variation seen in African Sleeping Sickness.

A
  • Trypanosoma brucei is coated with a surface glycoprotein
  • 150 genes encode different glycoproteins
  • We produce antibodies to these glyocproteins, but the organisms rapidly switch their surface antigenicitiy (glycoprotein), preventing absolute clearance
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10
Q

How is African Sleeping Sickness treated?

A

Melarsoprol–“If the parasite doesn’t kill you, the treatment will.”

DFMO (difluoromethylornithine)–much greater efficacy than melarsoprol that is now made by Doctor’s Without Borders

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11
Q

What is Chagas disease?

A

American Trypanosomiasis that is endemic to South and Central America

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12
Q

What organism causes Chagas disease?

A

Trypaosoma cruzi

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13
Q

Describe the lifecycle of Trypanosoma cruzi.

A

Fecal pellet

Blood

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14
Q

What is the zoonic host of Trypaosoma cruzi?

A

Reduviid Bug

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15
Q

What are the symptoms of Chagas Disease?

A
  • Chagoma- a hardened red nodule
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16
Q

What is Romana’s sign?

A

Chagoma of the eye

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17
Q

Describe the acute phase of Chagas Disease. What symptoms are seen in this stage?

A

Fever
Malaise
Myalgia
Hepatosplenomegaly

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18
Q

Describe the intermediate phase of Chagas Disease.

A
  • This is the asymptomatic phase of the disease; there are few parasites in blood & high levels of Ab
  • This is where most infected individuals remain
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19
Q

What are the characteristics of chronic phase Chagas Disease?

A
  • Infection of cardiac muscle & myeneteric plexus
  • Develops years to decades after infection
  • Cardiac & GI involvement is seen including: Myocarditis, Megacolon, and Megaesophagus
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20
Q

How is Chagas Disease diagnosed? How does detection in the acute phase differ from the chronic phase?

A

Acute phase= paraistes in peripheral blood

Chronic= serology

*****Note that as with many tropical/ exotic disease, a travel history that is consistent with exposure aids in diagnosis

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21
Q

What are the three major forms of Leishmaniasis? What species are responsible for these different infections?

A

1) Cutaneous
2) Mucocutaneous
3) Visceral= L. donovani, L. infantum, & L. chagasi

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22
Q

What is the vector for Leishmaniasis?

A

Infected female sand flies

23
Q

What cells are infected by Leishmaniasis?

A

Phagocytes

24
Q

What patient populations are most susceptible?

A

Leishmaniasis has increasingly been recognized as an “opportunistic” pathogen in HIV+ individuals, primarily in the Mediterranean

25
Q

What are the symptoms of visceral Leishmaniasis?

A

Leishmaniasis involves dissemination of parasites throughout the RES; they can be found in macrophages of the liver, spleen, & bone marrow. Symptoms include:

  • Irregular low grade fever
  • Weight loss
  • hepato-splenomegaly
  • “wasting”

*Note that systemic immunosuppression is common with full blown disease, and death is typically caused by secondary bacterial or viral infection

26
Q

Describe the mechanism of visceral Leishmaniasis.

A
  • Dissemination of parasites throughout the reticuloendothelial system
  • Parasites can be found in the marcophages of liver, spleen, bone marrow

*****Note that within an infected individual, only intracellular forms are found; therefore, antibodies afford little or no protection

27
Q

What part of the immune system resolves Leishmaniasis?

A

Resolution of infection is dependent on cell-mediated immunity

28
Q

How is Leishmaniasis controlled? How is it treated?

A

Control= eliminating the vector i.e. sand fly

Treatment= high toxic heavy metal compounds

29
Q

What is the most important of all the tropical & parasitic diseases?

A

Malaria

30
Q

What causes malaria?

A

Plasmodium

31
Q

What species of Plasmodium cause most cases of Malaria?

A

P. falciparum

P. vivax

32
Q

Describe the lifecycle of Plasmodium.

A
  • Transmission occurs by the bite of an infected mosquito
33
Q

What two species of Plasmodia can lay dormant in the liver?

A

P. vivax

P. ovale

34
Q

What is the major clinical presentation of Malaria? What is the major complication of malaria?

A

Malaraia paroxysm, which is associated with the synchronous release of merozoites & the lysis of RBCs, leading to cycles of flu-like symptoms including:

  • Fever
  • Chills
  • Headache
  • Muscle ache

Complication= anemia

35
Q

Describe the duration and pattern of paroxysm for the different species of Plasmodia.

A

P. vivax & ovale= Q48 hours

P. malariae= Q72 hours

P. falciparum= Q48 hours

Thus, the most common types of malaria recur every 48 hours

36
Q

What are the three mechanisms involved in the pathogenesis of anemia?

A
  • **Anemia is the most common complication of malaria. The asexual stage of the parasite destroys RBCs each time it completes a cycle of replication. Three mechanisms in the pathogenesis of anemia include:
    1) RBC lysis
    2) Suppression of erythropoiesis by cytokines
    3) Destruction of RBC’s by spleen
37
Q

What species causes the most severe and frequent anemia?

A

P. falciparum

  • Infects both young and old RBCs
  • Highest parasitemia
38
Q

What cell type do P. vivax & P. ovale infect?

A

Reticulocytes; thus, these species of plasmodium cause a less severe anemia compared to P. falciparum

39
Q

Aside from anemia, what are other complications of malaria?

A
  • Splenomegaly
  • Hypoglycemia/ lactic acidosis*
  • Microvascular sequestration*
  • Cerebral malaria

*Note that these are specific to P. falciparum

40
Q

How is malaria diagnosed?

A

1) Recognize syndrome
2) Travel history
3) Blood smear positive for parasites

41
Q

What are the features of a positive blood smear for malaria?

A

“Purple banana”

Plasmodium falciparum

42
Q

How is Malaria prevented?

A
  • Eradicate the insect vector/ breeding ground
  • Prophylaxis for travelers

*Note that vaccine trials have been disappointing and that drug resistance is a major concern

43
Q

What is Babesiosis?

A

A form of malaria seen in the US, which is most common in New England, the Upper Midwest, & California

44
Q

How is Babesiosis transmitted?

A

Tics

45
Q

What are the symptoms of Babesiosis?

A

Symptoms developed 1-8 weeks after tic bite and include:

  • Fever, chills, myalgia
  • Hemolytic anemia
46
Q

What patient population is highly susceptible to Babesiosis?

A
  • Elderly
  • Asplenic
  • Immunosuppressed
47
Q

What cytological feature is diagnostic of Babesiosis?

A

Maltese Cross

48
Q

What is Filariasis?

A
  • Filariasis is also known as “elephantiasis,” and is caused by filarial nematodes
  • This is a mosquito transmitted helminth infection
49
Q

What helminths cause Filariasis?

A

Wuchereria bancrofti
Brugia malayi

*Note that the adult form of both of these worms reside within the lumen of lymphatic vessels

50
Q

How is Filariasis transmitted?

A
  • Bite of infected mosquitoes
  • Larvae from bite wound enter lymphatics & mature into adults

*Note that this typically occurs in the lymphatics of the upper & lower extremities, and male genitalia

51
Q

What are the symptoms of acute Filariasis?

A

Fever
Chills
Lymphadenitis

  • Painful swelling may last for weeks & frequently recurs
52
Q

What proportion of the patients with Filariasis develop “elephantiasis?”

A

A small percentage

53
Q

How is Filariasis diagnosed?

A

Observing microfilariae in blood smears that are collected at night.

54
Q

What is Schistosomiasis?

A

Schistosomiasis is also known as bilharzia or “snail fever”, and is a parasitic disease carried by fresh water snails.

Microbiology (49 decks)

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