Pathology Of Infectious diseases

Question 1

What is the definition of infectious diseases?

Answer 1

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

Question 2

Name the major groups of infectious agents.

Answer 2

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

Question 3

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

Answer 3

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

Question 4

Define symbiosis in the context of host-organism interaction.

Answer 4

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

Question 5

What is the difference between commensalism and parasitism?

Answer 5

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

Question 6

Name the major protective barriers against infection in the skin.

Answer 6

Epidermal barrier.

Question 7

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

Answer 7

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

Question 8

How do microorganisms evade host adaptive immunity?

Answer 8

By modulating their surface structure (antigenic variability).

Question 9

What are some ways that microbes inhibit phagocytosis?

Answer 9

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

Question 10

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

Answer 10

Microorganisms resist cytokine-mediated defense mechanisms.

Question 11

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

Answer 11

Direct infection and damage to endothelial cells or dendritic cells.

Question 12

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

Answer 12

Kupffer cells.

Question 13

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

Answer 13

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

Question 14

How do viruses cause cellular death in host cells?

Answer 14

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

Question 15

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

Answer 15

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

Question 16

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

Answer 16

Urine, saliva, semen, and other secretions.

Question 17

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

Answer 17

General weakness and high fever.

Question 18

How does Lassa fever cause hepatocellular necrosis?

Answer 18

Through high viral content and inflammatory damage.

Question 19

What viral family does the Ebola virus belong to?

Answer 19

Filoviridae.

Question 20

How is Ebola transmitted from animals to humans?

Answer 20

Through direct contact with infected animals or their fluids.

Question 21

How does the Ebola virus affect immune cells?

Answer 21

It targets macrophages and dendritic cells, impairing immune responses.

Question 22

What are the clinical features of dengue hemorrhagic fever?

Answer 22

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

Question 23

What is the role of monocytes in dengue virus infection?

Answer 23

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

Question 24

How does hemorrhage occur in dengue hemorrhagic fever?

Answer 24

Due to thrombocytopenia, coagulopathy, and increased vascular permeability.

Question 25

What distinguishes dengue hemorrhagic fever from dengue fever?

Answer 25

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

Question 26

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

Answer 26

Aedes aegypti.

Question 27

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

Answer 27

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

Question 28

Which strain of Ebola has the highest mortality rate?

Answer 28

Zaire ebolavirus.

Question 29

What is the significance of petechiae in viral hemorrhagic fevers?

Answer 29

They indicate microvascular damage and thrombocytopenia.

Question 30

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

Answer 30

By altering cellular processes and evading apoptosis.

Question 31

Name two genera of viruses that cause viral hemorrhagic fevers.

Answer 31

Arenaviridae, Flaviviridae.

Question 32

What are the common zoonotic viral hemorrhagic fevers in Nigeria?

Answer 32

Lassa fever, Yellow fever, Dengue fever.

Question 33

How does yellow fever virus cause hepatic failure?

Answer 33

Through midzonal necrosis, apoptosis, and hepatocyte degeneration.

Question 34

What are Councilman bodies, and when are they observed?

Answer 34

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

Question 35

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

Answer 35

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

Question 36

How does Lassa fever cause multi-organ damage?

Answer 36

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

Question 37

What is the typical clinical progression of Ebola virus infection?

Answer 37

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

Question 38

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

Answer 38

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

Question 39

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

Answer 39

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

Question 40

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

Answer 40

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

Question 41

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

Answer 41

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

Question 42

What are the diagnostic methods for detecting dengue virus?

Answer 42

Serologic testing, RT-PCR, and immunofluorescence.

Question 43

Why is jaundice a common feature in yellow fever?

Answer 43

Hepatocyte necrosis reduces liver function, leading to bilirubin accumulation.

Question 44

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

Answer 44

Kupffer cells phagocytose infected hepatocytes and apoptotic cells.

Question 45

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

Answer 45

Petechial hemorrhages, renal failure, and tubular necrosis.

Question 46

What are the risk factors for developing severe Lassa fever?

Answer 46

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

Question 47

How do flaviviruses like yellow fever affect liver cells?

Answer 47

They cause direct hepatocyte infection leading to apoptosis and necrosis.

Question 48

What is the incubation period of yellow fever?

Answer 48

3-6 days.

Question 49

How does Lassa fever affect the spleen?

Answer 49

It causes splenic necrosis and immune cell damage.

Question 50

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

Answer 50

Zaire ebolavirus, Sudan virus, Bundibugyo virus.

Question 51

Describe the morphologic changes in the lungs during Ebola infection.

Answer 51

Intra-alveolar edema and hemorrhage.

Question 52

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

Answer 52

Mosquito bites.

Question 53

How do viral hemorrhagic fevers lead to shock?

Answer 53

Through vascular dysregulation and leakage of fluids from the bloodstream.

Question 54

Which laboratory tests are most useful in diagnosing Lassa fever?

Answer 54

Serological tests for antibodies and PCR for viral RNA.

Question 55

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

Answer 55

Hepatic and renal failure.

Question 56

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

Answer 56

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

Question 57

What is the relationship between hepatocellular steatosis and yellow fever?

Answer 57

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

Question 58

How does the immune system respond to Ebola virus infection?

Answer 58

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

Question 59

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

Answer 59

Through coagulative necrosis of the renal tubules.

Question 60

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

Answer 60

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