Infectious Diseases Lecture Notes Review

Flashcards created from lecture notes on infectious diseases, covering transmission, pathogenesis, host interactions, and more.

What are the categories of infectious diseases?

Infectious diseases can be categorized based on their transmission, host interaction, or type of pathogen (bacteria, viruses, fungi, protozoans, etc.).

What routes can microbes use to enter the host?

Microbes can enter through breaks in the skin, respiratory tract, gastrointestinal tract, and urogenital tract, among other pathways.

What is vertical transmission?

Vertical transmission refers to the transmission of microbes from mother to fetus.

What are mucosa-associated lymphoid tissues (MALTs)?

MALTs are lymphoid nodules composed of lymphocytes, macrophages, and dendritic cells that serve as target cells for specific diseases.

Define virulence factors. How do they assist pathogens?

Virulence factors are molecules or properties of microbes that enable them to replicate and cause disease, enhancing their ability to colonize, invade, evade immune responses, and acquire nutrients.

What is transcytosis?

Transcytosis is the process by which cells transport macromolecules across their cytoplasm and expel them outside the cell.

How do RNA viruses differ from DNA viruses regarding mutation rates?

RNA viruses have a much higher mutation rate than DNA viruses, which enables them to adapt quickly but often at the cost of slower replication speeds.

What is the difference between antigenic drift and antigenic shift?

Antigenic drift involves small mutations in a virus's genome over time, while antigenic shift is a major genetic change that occurs when different strains of a virus combine to form a new subtype.

What is the consequence of endotoxins in humans?

Endotoxins, often released from dead Gram-negative bacteria, can activate proinflammatory cytokines leading to systemic effects like fever, shock, and sometimes death.

What are opportunistic fungal infections?

Opportunistic fungal infections occur when a host is immunocompromised or when usual protective bacteria flora is altered.

What is the causative agent of histoplasmosis?

The causative agent of histoplasmosis is Histoplasma capsulatum.

How does the rabies virus primarily spread within the host?

The rabies virus primarily spreads via retrograde axonal transport from peripheral nerves to the central nervous system.

What are the clinical signs of rabies in animals?

Clinical signs of rabies can include behavioral changes, neurological signs, and paralysis.

What role do siderophores play in bacterial virulence?

Siderophores help bacteria acquire iron from host tissues, which is essential for their growth and replication.

What are the outcomes of viral replication?

Outcomes of viral replication can include cell death (lysis or apoptosis), persistence/latency, and malignant transformation.

What is the primary way that prions cause disease?

Prions cause disease by inducing normal protein structures in the brain to misfold, leading to neurodegeneration and cell death.

What are mycoses?

Mycoses are fungal infections that can be superficial (skin level) or systemic (deep tissue level), caused by pathogenic fungal species.

What does the term 'opportunistic pathogen' refer to?

An opportunistic pathogen is a microbe that causes disease primarily in individuals with weakened immune systems.

What is the function of the viral capsid?

The viral capsid protects the viral genetic material and aids in the delivery of the viral genome into host cells.

How do toxigenic bacteria cause disease?

Toxigenic bacteria produce toxins that damage host tissues or disrupt normal cellular processes.

What are the characteristics of virulence factors such as adhesins?

Adhesins enable bacteria to attach to host cells, facilitating colonization and entry into tissues.

What are the clinical manifestations caused by Giardia spp.?

Giardiasis, caused by Giardia spp., results in dysfunction of microvilli leading to malabsorptive diarrhea.

What factors influence the immune system's ability to combat viral infections?

The immune response's effectiveness is influenced by factors such as the virulence of the virus, the host's overall health, and immune system status.

What role does leukocyte trafficking play in infectious diseases?

Leukocyte trafficking allows immune cells to migrate to infection sites, facilitating the containment and clearance of pathogens.

Explain the concept of 'host range' in viruses.

Host range refers to the variety of host species that a virus can infect, determined by compatibility between viral proteins and host cell receptors.

What is the significance of cell-mediated immunity in viral infections?

Cell-mediated immunity, involving cytotoxic T lymphocytes and NK cells, is crucial for recognizing and eliminating virus-infected cells.

What are prions, and how do they differ from traditional infectious agents?

Prions are misfolded proteins that can induce conformational changes in normal proteins, leading to neurodegenerative diseases and do not contain nucleic acids.

Identify a key mechanism by which bacteria acquire antibiotic resistance.

Bacteria can acquire antibiotic resistance through horizontal gene transfer mechanisms such as conjugation, transformation, and transduction.

What clinical signs are associated with Clostridium botulinum infection?

Clostridium botulinum infection can cause flaccid paralysis, difficulty swallowing, and respiratory failure.

Describe the impact of fungal cell wall components on the immune response.

Fungal cell wall components like glucans can inhibit phagocytosis and activate an inflammatory response, which may lead to granulomatous inflammation.

How does antigenic shift in influenza viruses affect vaccine efficacy?

Antigenic shift leads to new virus strains that may not be targeted by existing vaccines, requiring updates to vaccine formulations.

What type of host do spongiform encephalopathies require?

Spongiform encephalopathies, caused by prions, rely primarily on mammals as hosts.

What is the diagnostic approach for prion diseases?

Prion diseases are typically diagnosed post-mortem through immunohistochemistry on brain tissue; pre-symptomatic tests are emerging.

What are mycotoxins?

Mycotoxins are toxic metabolites produced by fungi that can cause disease in humans and animals through ingestion.

What are the main differences between endotoxins and exotoxins?

Endotoxins are part of the bacterial cell wall and released upon cell lysis, while exotoxins are secreted by living bacteria and can act directly on host cells.

Explain the term 'pathogenesis' in the context of infectious diseases.

Pathogenesis refers to the biological mechanism that leads to disease, including the interaction between pathogens and host defenses.

How are protozoa characterized in medical microbiology?

Protozoa are single-celled organisms that can be classified based on their means of locomotion, such as flagella or pseudopodia.

What is the role of inflammatory cytokines in response to infection?

Inflammatory cytokines mediate the immune response, promoting inflammation and recruiting immune cells to the site of infection.

What role do necropsy and post-mortem examinations play in understanding infectious diseases?

Necropsy allows for the examination of tissues and lesions to determine the cause of infection and understand the progression of disease.

Define the term 'infectious agent'.

An infectious agent is a pathogen (bacteria, virus, fungus, protozoa, or prion) that can cause disease in a host.

What is the effect of Clostridium tetani's toxin on the nervous system?

The toxin of Clostridium tetani prevents the release of inhibitory neurotransmitters, leading to spastic paralysis.

How can stress affect the susceptibility to opportunistic fungal infections?

Chronic stress can suppress the immune response, making the host more susceptible to opportunistic fungal infections.

Describe the clinical manifestations of rabies in the prodromal phase.

In the prodromal phase of rabies, clinical signs may include behavioral changes, fever, and subtle neurological symptoms.

What are the potential effects of Fungal mycosis?

Fungal mycosis can lead to direct tissue invasion, chronic inflammation, and can be systemic, affecting multiple organ systems.

What constitutes a definitive host in a parasitic life cycle?

A definitive host is the organism that harbors the adult or sexually reproductive form of a parasite.

Explain how some viruses evade the immune system.

Some viruses can evade the immune system by rapidly mutating, hiding within host cells, or interfering with host immune responses.

What is the importance of leukocyte trafficking in response to infections?

Leukocyte trafficking is important for bringing immune cells to sites of infection, aiding in the containment and clearance of pathogens.

How do the characteristics of yeast and filamentous fungi differ?

Yeasts are typically single-celled and reproduce asexually through budding, while filamentous fungi form branching hyphae and reproduce through spores.

What are the potential consequences of prions accumulating in neural tissue?

Accumulation of prions in neural tissue results in neurodegeneration, loss of neuronal function, and ultimately leads to fatal outcomes.

How do bacterial toxins cause cell lysis?

Bacterial toxins can cause cell lysis through actions such as pore formation, enzymatic degradation of membranes, or inhibition of essential cellular processes.

What is meant by the term 'host cell tropism' in viruses?

Host cell tropism refers to the specific cell types that a virus can infect, determined by the interaction between viral proteins and host cell receptors.

How does the presence of a capsule affect bacterial virulence?

The presence of a capsule helps bacteria to evade phagocytosis, thus increasing their virulence and ability to cause disease.

What actions do leukocytes carry out during the immune response to an infection?

Leukocytes perform functions such as phagocytosis of pathogens, release of inflammatory mediators, and coordination of the immune response.

What is the function of the viral envelope?

The viral envelope is a lipid membrane that surrounds some viruses, aiding in entry into host cells and evading the immune response.

What are the common clinical signs associated with fungal infections?

Common clinical signs can include inflammation, ulceration, tissue necrosis, and, in severe cases, systemic illness.

Describe the relationship between protozoan parasites and their vectors.

Protozoan parasites often rely on vectors, such as mosquitoes, to transfer them between hosts during their lifecycle.

How does Toxoplasma gondii affect fetal development in infected animals?

Infected animals can experience fetal resorption, malformations, and other reproductive issues if Toxoplasma gondii is transmitted during gestation.

What are the implications of increased antibiotic resistance in bacterial infections?

Increased antibiotic resistance can lead to treatment failures, prolonged infections, and increased mortality rates.

What are the morphological differences between Gram-positive and Gram-negative bacteria?

Gram-positive bacteria have thick peptidoglycan layers, while Gram-negative bacteria have a thin layer surrounded by an outer membrane.

What can lead to misdiagnosis in prion diseases?

Misdiagnosis in prion diseases can occur due to the lack of nucleic acids in prions and the need for post-mortem tissue examination for accurate diagnosis.

What is malabsorptive diarrhea, and which pathogen is commonly associated with it?

Malabsorptive diarrhea is a type of diarrhea due to impaired absorption of nutrients, commonly associated with Giardia spp.

Describe the granulomatous inflammatory response in fungal infections.

Granulomatous inflammation occurs as a chronic response to non-degradable fungal cell wall components, characterized by the aggregation of macrophages.

How can environmental conditions affect the virulence of fungi?

Environmental conditions such as temperature and moisture can influence the growth patterns, form, and pathogenicity of fungal species.

What mechanisms do intracellular protozoan parasites use to evade the host immune response?

Intracellular protozoan parasites can evade the immune response by replicating within host cells and preventing lysosomal fusion.

List the stages of viral replication.

The stages of viral replication typically include attachment, entry, replication, assembly, and release.

What are the contributing factors for the emergence of antibiotic-resistant bacteria?

Factors include overuse/misuse of antibiotics, genetic mutations, and the capacity for horizontal gene transfer among bacteria.

Identify the types of targets for viral infection in host cells.

Viruses often target cells of the immune system, epithelial cells, and other specific cell types depending on their mode of transmission.

What are the roles of macrophages in combating infections?

Macrophages phagocytose pathogens, release cytokines to recruit other immune cells, and present antigens to T lymphocytes.

How can stress influence the immune response to infections?

Stress can suppress the immune system, reducing its ability to fight infections and increasing susceptibility to opportunistic diseases.

What is infectious disease epidemiology?

Infectious disease epidemiology is the study of how infectious diseases spread, their impact, and the factors that influence their transmission.

What role does the microbiome play in health and disease?

The microbiome influences immune response, pathogen competition, metabolism, and overall health, potentially aiding in disease resistance.

What are the common laboratory techniques used to diagnose infectious diseases?

Common techniques include culture, PCR, serology, and microscopy to identify pathogens and understand their characteristics.

What clinical indications suggest a bacterial infection?

Signs of bacterial infection can include fever, increased leukocyte counts, and local symptoms such as redness, swelling, and pain.

What kind of hypersensitivity reactions can protozoal infections trigger?

Protozoal infections can trigger Type III hypersensitivity reactions leading to immune complex deposition and tissue damage.

How do vaccines work to prevent infectious diseases?

Vaccines stimulate an immune response to a specific pathogen, allowing the body to recognize and fight the actual infection more effectively.

What are the characteristics of Candidiasis as a fungal infection?

Candidiasis can manifest as superficial infections, affecting mucosal surfaces, or systemic infections in immunocompromised individuals.

How does the lifecycle of protozoans typically manifest in hosts?

Protozoans often have complex life cycles involving multiple developmental stages and may depend on vectors for transmission.

What is a mechanical vector in the context of infectious disease?

A mechanical vector is an organism, often an insect, that transmits pathogens without being part of the pathogen's lifecycle.

How do viral diseases differ in their presentation across species?

Viral diseases may exhibit varying clinical signs and severity depending on the host species due to differences in immune response.

What factors can influence the severity of disease caused by viral infections?

Factors include the virulence of the virus, the susceptibility of the host, co-infections, and the host's immune status.