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Questions and Answers
What is the primary cause of Enteric Fever?
What is the primary cause of Enteric Fever?
What is a characteristic symptom of Typhoid Fever?
What is a characteristic symptom of Typhoid Fever?
Which of the following best describes the bacterial attachment mechanism in enteric fever?
Which of the following best describes the bacterial attachment mechanism in enteric fever?
Which laboratory findings are commonly associated with acute Typhoid Fever?
Which laboratory findings are commonly associated with acute Typhoid Fever?
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What challenge does Salmonella Typhi face upon initial infection?
What challenge does Salmonella Typhi face upon initial infection?
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What is the first step in the process of infection?
What is the first step in the process of infection?
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Which process allows pathogens to evade the host's innate immune response?
Which process allows pathogens to evade the host's innate immune response?
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How might the immune response contribute to disease pathology?
How might the immune response contribute to disease pathology?
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What is a consequence of the local or general spread of infection within the body?
What is a consequence of the local or general spread of infection within the body?
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Which of the following best describes the exit stage of infection?
Which of the following best describes the exit stage of infection?
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Which organism is detected using anti-Leishmania antibodies in diagnosis?
Which organism is detected using anti-Leishmania antibodies in diagnosis?
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Which microscopy method is used for identifying simian vacuolating virus 40 in brain tissue?
Which microscopy method is used for identifying simian vacuolating virus 40 in brain tissue?
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What is a key limitation of diagnostic histopathology in emerging infectious diseases?
What is a key limitation of diagnostic histopathology in emerging infectious diseases?
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Which infection is confirmed using a PCR assay according to the content?
Which infection is confirmed using a PCR assay according to the content?
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Which organism is associated with granulomatous inflammation in lung infections?
Which organism is associated with granulomatous inflammation in lung infections?
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What technique is primarily used for studying the interaction between Bacillus anthracis and endothelial cells?
What technique is primarily used for studying the interaction between Bacillus anthracis and endothelial cells?
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Which of the following diseases is NOT categorized as emerging infectious diseases?
Which of the following diseases is NOT categorized as emerging infectious diseases?
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Which diagnostic method is recommended for detecting Cryptococcus in tissue samples?
Which diagnostic method is recommended for detecting Cryptococcus in tissue samples?
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What is the primary focus of epidemiology in infectious diseases?
What is the primary focus of epidemiology in infectious diseases?
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Which branch of infectious disease epidemiology focuses on the cause of diseases?
Which branch of infectious disease epidemiology focuses on the cause of diseases?
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What is one effective method for reducing the spread of infectious diseases?
What is one effective method for reducing the spread of infectious diseases?
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Which method is commonly used to protect against disease vectors like mosquitoes?
Which method is commonly used to protect against disease vectors like mosquitoes?
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What does the term 'quarantine' refer to in the context of infectious diseases?
What does the term 'quarantine' refer to in the context of infectious diseases?
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Which of the following is a method used in the diagnosis of infectious diseases?
Which of the following is a method used in the diagnosis of infectious diseases?
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In what way can microscopy be utilized in diagnosing infectious diseases?
In what way can microscopy be utilized in diagnosing infectious diseases?
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Which inflammatory reaction type is associated with a specific microbe?
Which inflammatory reaction type is associated with a specific microbe?
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What are the key characteristics of acute infectious diseases?
What are the key characteristics of acute infectious diseases?
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Which of the following accurately describes chronic infectious diseases?
Which of the following accurately describes chronic infectious diseases?
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How is a latent infectious disease characterized?
How is a latent infectious disease characterized?
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What distinguishes systemic infectious diseases from local infections?
What distinguishes systemic infectious diseases from local infections?
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Which of the following conditions is classified as a local infectious disease?
Which of the following conditions is classified as a local infectious disease?
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What is a common symptom associated with the early stages of Ebola?
What is a common symptom associated with the early stages of Ebola?
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Which virus is associated with the transformation of cells into malignant carcinoma?
Which virus is associated with the transformation of cells into malignant carcinoma?
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What is the typical onset period for ringworm infection?
What is the typical onset period for ringworm infection?
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Which statement is true regarding the spread of the herpes simplex virus (HSV)?
Which statement is true regarding the spread of the herpes simplex virus (HSV)?
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What type of infectious disease is characterized by a state of quiescence in the neuron nucleus?
What type of infectious disease is characterized by a state of quiescence in the neuron nucleus?
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What was the main focus of the Human Microbiome Project?
What was the main focus of the Human Microbiome Project?
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Which of the following conditions has been linked to Helicobacter pylori infection?
Which of the following conditions has been linked to Helicobacter pylori infection?
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What is the significance of the Henle-Koch postulates in the study of infectious diseases?
What is the significance of the Henle-Koch postulates in the study of infectious diseases?
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Which population aspect is analyzed in the study of cervical cancer elimination targets by Canfell et al.?
Which population aspect is analyzed in the study of cervical cancer elimination targets by Canfell et al.?
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What is a consequence of untreated Helicobacter pylori infection as suggested by Mohamed et al.?
What is a consequence of untreated Helicobacter pylori infection as suggested by Mohamed et al.?
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What is primarily being evaluated in the research by Bowen et al. on HIV-associated infections?
What is primarily being evaluated in the research by Bowen et al. on HIV-associated infections?
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What is the goal of personalized treatment benefit index in antiretroviral therapy as mentioned by Xiao et al.?
What is the goal of personalized treatment benefit index in antiretroviral therapy as mentioned by Xiao et al.?
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What kind of modeling analysis is applied to assess the impact of cervical cancer elimination targets?
What kind of modeling analysis is applied to assess the impact of cervical cancer elimination targets?
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Study Notes
Integrated Pathology: Infectious Disease
- Infectious disease is detected when pathological effects occur in tissues/cells caused by a contagious agent that transmits infection.
- This has implications for diagnosis, treatment, prognosis, and disease prevention.
- Infectious diseases have a causative agent (aetiological agent) typically microscopic (microorganism/microbes).
- Substances containing the infectious microorganism are called etiological agents.
- An infection is damage to tissues/cells leading to symptomatic disease.
Learning Outcomes
- LO1: Understand how infectious diseases are characterized in relation to disease stages.
- LO2: Explain the causes of pathology due to infectious diseases.
- LO3: Discuss how infectious diseases cause varied pathologies with named examples.
Pathology and Infectious Diseases
- Infectious diseases are caused by pathogens;
- Diagnosis, treatment, prognosis, and prevention strategies vary based on the causative agent.
- Knowing the causative agent is essential for all these aspects.
Pathological Effects of Infectious Diseases
- Infectious diseases are easily transmitted, especially through air or water.
- The causative agent typically consists of microorganisms or microbes.
Causes of Infectious Disease
- Infectious diseases are caused by a variety of agents:
- Bacteria (prokaryotes)
- Viruses (non-cellular)
- Fungi (eukaryotes)
- Protozoa (eukaryotes)
- Prions (proteins, non-cellular)
- Helminths (non-microbial, eukaryotes)
- Arthropods (non-microbial, eukaryotes)
- Archaea (have no infectious agent identified thus far but may have a role in periodontal disease)
- Each of these agents has unique characteristics (e.g., organism type, replication process, structure, composition, and genetics) influencing how they interact with the host and cause disease.
When Infectious Diseases Occur
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The human microbiome includes Archaea, bacteria, fungi, and viruses.
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Commensal organisms are part of the normal microbiome.
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Obligate pathogens always cause disease.
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Opportunistic pathogens cause disease under specific conditions.
Koch's Postulates (1890)
- The causative agent must be present in all cases of the disease and not present in healthy individuals.
- The causative agent must be isolated in pure culture.
- The agent from pure culture must cause the disease in a model system.
- The agent must be re-isolated from the diseased model.
- Establishing causation cannot be based solely on association.
Routes of Transmission
- Aerosol (inhalation)
- Oral (ingestion of contaminated food/water)
- Direct contact (contact with infected individual tissues/bodily fluids)
- Fomite transmission (contaminated surfaces of inanimate objects)
- Vector-borne (other living organisms)
- Zoonotic (originating from other animals)
Transmission of Disease-Causing Agents
- Infectious agents must be transmitted between hosts.
- Transmission routes depend on the microorganism and the type of tissue/cell affected.
- Example: Rhinoviruses (common cold) infect the respiratory tract, spreading through droplets from coughing/sneezing.
Case Study: Bacillus anthracis
- Gram-positive bacilli, endospore-forming, found in soil, water, and contaminated animal products (e.g., wool, hides, hair).
- Occurs globally.
- Has a capsule and two toxins (lethal factor and edema factor).
- Types of anthrax:
- Cutaneous
- Gastrointestinal
- Inhalation
- Injection
- Welder's
- Transmission route determines the type of anthrax.
Case Study: Pathologies and Transmission: Bacillus anthracis
- Different transmission routes result in distinct pathologies:
- Cutaneous anthrax: wound contamination; ~95% cases
- Gastrointestinal anthrax: Spores from infected meat; >50% fatality if untreated.
- Inhalation anthrax: Breathing contaminated spores; 100% mortality if untreated
- Injection anthrax: Needles with contaminated soil/material.
- Welder's anthrax: similar to infection, with pneumonia as diagnosis
Pathogenesis of Infectious Diseases (General)
- Agents cause disease through various mechanisms, including:
- Toxin production (destroying cells/tissues)
- Direct invasion/destruction of host cells
- Triggering immune responses in the host (e.g., fever, sneezing, vomiting).
Steps in Infection
- Entry and attachment to the body
- Colonization (local/general spread)
- Replication
- Exit (shedding from the body)
- The pathology of infectious diseases results from these steps.
Pathogenesis of Infectious Diseases (Skin and Soft Tissue)
- Mucocutaneous lesions
- Abscess formation
- Spreading infections
- Necrotizing infections
- Skin manifestations from systemic infections
- Different skin structures can be affected in various ways; i.e. epidermis, dermis, hair follicles.
Insight to Site-Specific Pathogenesis (Skin Infections)
- Superficial to invasive skin infections have different causative agents and site of infection.
Classification of Infectious Diseases
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By location: Local (confined to an area of the body), Systemic (multiple body sites/tissues)
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By timing: Primary (initial infection in a healthy person), Secondary (infection in a weakened person).
Case Study: Influenza Syndrome
- Causative agent: Influenza virus (segmented negative-sense RNA genome).
- Symptoms: fever, cough, sore throat, congestion, muscle/body aches, fatigue, vomiting, diarrhea.
Clinical Signs and Symptoms (Covid-19, Flu & Cold)
- A table comparing symptom frequency in Covid-19, Flu, and Cold. (using a chart with different icons for each disease)
Characteristics of Infectious Diseases (By Duration)
- Acute: Develops and progresses quickly
- Chronic: Develops slowly, less severe, but long-lasting
- Latent: No symptoms between outbreak and illness
Case Study: Enteric Fever (S. Typhi)
- Gram-negative bacteria
- Human-specific—high fever, fatigue, headache, nausea, abdominal pain, and constipation or diarrhea
- Host tropism—Vi capsule attaches to human cells.
- Primary infection; secondary infection; carrier state
- Low initial immunological response, regulation of Vi capsule
Reducing the Spread of Infectious Diseases
- Removing the infectious agent (e.g., good hygiene/sanitation, handwashing, vector control).
- Prevention against vectors.
- Quarantine of infected individuals.
Diagnosis of Infectious Diseases
- Clinical presentation and symptoms
- Detection methods include signs & symptoms, detection of microorganism, pathology (diagnostic histopathology, molecular pathology, immunohistochemistry, in situ hybridization).
- Determining the type of inflammatory response.
Diagnosis using Microscopy
- Staining methods—staining microbes for visualization (A-Leprosy, B-Histoplasmosis, C-Cryptococcus, D-Syphilis).
- Immunohistochemistry: tissue staining with antibodies for various microbes.
- Other methods—use of in situ hybridization with electron microscopy, molecular biology (PCR)-infection localization, types of inflammatory reaction.
Diagnosis of Infectious Diseases (Emerging)
- Diagnostic histopathology is useful in emerging infections, like Zika, HIV, and others.
- Limitations include antibody availability and the potential for genomics replacement.
Emerging Infectious Diseases
- Recent diseases with increasing incidence.
- Examples: Gonorrhea (antibiotic resistance), Measles (vaccine inefficacy), and Zika virus
Use of Infectious Disease Epidemiology
- Epidemiology is the study of disease patterns, helping to understand and control infectious diseases.
- Epidemiologists use several methods: Disease etiology, outbreak investigation, screening and surveillance, and comparisons of treatments.
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Description
Test your knowledge on infectious diseases, specifically focusing on enteric fever and typhoid fever. This quiz covers key symptoms, mechanisms of infection, laboratory findings, and diagnostic methods related to various pathogens. Perfect for students studying microbiology and infectious disease pathology.