Pathology Of Infectious diseases Flashcards

1
Q

What is the definition of infectious diseases?

A

Infectious diseases are diseases in which tissue damage or dysfunction is produced by microorganisms.

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2
Q

Name the major groups of infectious agents.

A

Prions, Viruses, Bacteria, Mycoplasma, Rickettsiae, Chlamydia, Fungi, Parasites.

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3
Q

What is the relationship between virulence and host immune response in determining the outcome of infection?

A

The outcome depends on the virulence of the microorganism and the nature of the host immune response.

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4
Q

Define symbiosis in the context of host-organism interaction.

A

Symbiosis is a cooperative association between two dissimilar organisms, beneficial to both.

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5
Q

What is the difference between commensalism and parasitism?

A

Commensalism benefits one organism without harming the other, while parasitism benefits one organism at the expense of the other.

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6
Q

Name the major protective barriers against infection in the skin.

A

Epidermal barrier.

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7
Q

How do microbes gain entry into the human body via the gastrointestinal tract?

A

By overcoming acidic secretions, bile, pancreatic enzymes, and protective flora.

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8
Q

How do microorganisms evade host adaptive immunity?

A

By modulating their surface structure (antigenic variability).

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9
Q

What are some ways that microbes inhibit phagocytosis?

A

Through resistance to microbial peptides and inhibition of phagosome-lysosome fusion.

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10
Q

Describe the role of cytokines in host defense evasion by microorganisms.

A

Microorganisms resist cytokine-mediated defense mechanisms.

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11
Q

What is the main cellular event that leads to vascular damage in viral hemorrhagic fevers?

A

Direct infection and damage to endothelial cells or dendritic cells.

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12
Q

Which cells are responsible for removing apoptotic hepatocytes during yellow fever?

A

Kupffer cells.

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13
Q

What is the pathogenesis of yellow fever at the cellular level?

A

It involves midzonal necrosis of hepatocytes, apoptosis, and the formation of Councilman bodies.

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14
Q

How do viruses cause cellular death in host cells?

A

By preventing the synthesis of critical macromolecules or by activating apoptotic machinery.

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15
Q

What types of immune responses contribute to tissue damage in viral infections?

A

Antiviral immune responses such as cytotoxic T cell-mediated tissue damage.

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16
Q

Which body fluids are potential sources of transmission for Lassa fever?

A

Urine, saliva, semen, and other secretions.

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17
Q

What are the primary signs of Lassa fever in its initial stage?

A

General weakness and high fever.

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18
Q

How does Lassa fever cause hepatocellular necrosis?

A

Through high viral content and inflammatory damage.

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19
Q

What viral family does the Ebola virus belong to?

A

Filoviridae.

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20
Q

How is Ebola transmitted from animals to humans?

A

Through direct contact with infected animals or their fluids.

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21
Q

How does the Ebola virus affect immune cells?

A

It targets macrophages and dendritic cells, impairing immune responses.

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22
Q

What are the clinical features of dengue hemorrhagic fever?

A

High fever, myalgia, bleeding, hemoconcentration, and thrombocytopenia.

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23
Q

What is the role of monocytes in dengue virus infection?

A

Monocytes are infected by the virus, contributing to the immune response and disease progression.

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24
Q

How does hemorrhage occur in dengue hemorrhagic fever?

A

Due to thrombocytopenia, coagulopathy, and increased vascular permeability.

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25
Q

What distinguishes dengue hemorrhagic fever from dengue fever?

A

Dengue hemorrhagic fever is more severe and involves bleeding, while dengue fever is a milder, self-limiting illness.

26
Q

Which mosquito species is responsible for the transmission of yellow fever?

A

Aedes aegypti.

27
Q

How is the complement system involved in the pathogenesis of dengue hemorrhagic fever?

A

Activation of the complement system leads to vascular leakage and coagulopathy.

28
Q

Which strain of Ebola has the highest mortality rate?

A

Zaire ebolavirus.

29
Q

What is the significance of petechiae in viral hemorrhagic fevers?

A

They indicate microvascular damage and thrombocytopenia.

30
Q

How do viruses manipulate host cell metabolism to evade immune detection?

A

By altering cellular processes and evading apoptosis.

31
Q

Name two genera of viruses that cause viral hemorrhagic fevers.

A

Arenaviridae, Flaviviridae.

32
Q

What are the common zoonotic viral hemorrhagic fevers in Nigeria?

A

Lassa fever, Yellow fever, Dengue fever.

33
Q

How does yellow fever virus cause hepatic failure?

A

Through midzonal necrosis, apoptosis, and hepatocyte degeneration.

34
Q

What are Councilman bodies, and when are they observed?

A

Councilman bodies are apoptotic hepatocytes observed in viral hepatitis and yellow fever.

35
Q

Describe the morphologic changes seen in the liver during Lassa fever.

A

Multifocal hepatocellular necrosis, eosinophilic Councilman bodies, mild inflammatory infiltrate.

36
Q

How does Lassa fever cause multi-organ damage?

A

Through widespread necrosis and vascular injury in organs like the liver, spleen, and lungs.

37
Q

What is the typical clinical progression of Ebola virus infection?

A

Initial flu-like symptoms followed by severe gastrointestinal, vascular, and neurological complications.

38
Q

What role do endothelial cells play in the pathogenesis of viral hemorrhagic fevers?

A

Endothelial cells are directly infected, leading to vascular damage and leakage.

39
Q

How do viral hemorrhagic fevers cause disseminated intravascular coagulation (DIC)?

A

Through endothelial injury, cytokine production, and consumption of clotting factors.

40
Q

What are the primary differences between arenaviruses and flaviviruses in causing viral hemorrhagic fevers?

A

Arenaviruses primarily affect rodents, while flaviviruses are often mosquito-borne.

41
Q

How do cytokines contribute to the severe systemic effects of Ebola virus infection?

A

They cause vasodilation, increased permeability, and shock through inflammatory responses.

42
Q

What are the diagnostic methods for detecting dengue virus?

A

Serologic testing, RT-PCR, and immunofluorescence.

43
Q

Why is jaundice a common feature in yellow fever?

A

Hepatocyte necrosis reduces liver function, leading to bilirubin accumulation.

44
Q

What is the role of Kupffer cells in the liver during viral infections?

A

Kupffer cells phagocytose infected hepatocytes and apoptotic cells.

45
Q

Describe the pathologic changes in the kidney during severe dengue infection.

A

Petechial hemorrhages, renal failure, and tubular necrosis.

46
Q

What are the risk factors for developing severe Lassa fever?

A

Poor nutrition, weakened immune system, and close contact with rodents.

47
Q

How do flaviviruses like yellow fever affect liver cells?

A

They cause direct hepatocyte infection leading to apoptosis and necrosis.

48
Q

What is the incubation period of yellow fever?

A

3-6 days.

49
Q

How does Lassa fever affect the spleen?

A

It causes splenic necrosis and immune cell damage.

50
Q

Which viruses are primarily responsible for the transmission of Ebola in humans?

A

Zaire ebolavirus, Sudan virus, Bundibugyo virus.

51
Q

Describe the morphologic changes in the lungs during Ebola infection.

A

Intra-alveolar edema and hemorrhage.

52
Q

What is the most common route of transmission for yellow fever?

A

Mosquito bites.

53
Q

How do viral hemorrhagic fevers lead to shock?

A

Through vascular dysregulation and leakage of fluids from the bloodstream.

54
Q

Which laboratory tests are most useful in diagnosing Lassa fever?

A

Serological tests for antibodies and PCR for viral RNA.

55
Q

What is the typical cause of death in severe yellow fever cases?

A

Hepatic and renal failure.

56
Q

How do necrotic foci form in the spleen during viral hemorrhagic fevers?

A

Through direct viral damage and immune-mediated destruction of splenic tissue.

57
Q

What is the relationship between hepatocellular steatosis and yellow fever?

A

Hepatocellular steatosis occurs due to metabolic dysfunction in infected liver cells.

58
Q

How does the immune system respond to Ebola virus infection?

A

By releasing inflammatory cytokines and recruiting immune cells, though the virus often evades full immune response.

59
Q

How is renal damage manifested in severe cases of yellow fever?

A

Through coagulative necrosis of the renal tubules.

60
Q

How does the body respond to a widespread viral infection that causes hemorrhagic fever?

A

By mounting an immune response that can lead to systemic inflammation, shock, and multi-organ failure.