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Questions and Answers
Which mode of transmission best describes diseases that spread via respiratory secretions through coughing or sneezing?
Which mode of transmission best describes diseases that spread via respiratory secretions through coughing or sneezing?
Which type of contamination is most likely responsible for spread through waterborne transmission?
Which type of contamination is most likely responsible for spread through waterborne transmission?
What characteristic must a pathogen have to be transmitted via airborne droplets?
What characteristic must a pathogen have to be transmitted via airborne droplets?
Which of the following is an example of indirect transmission of disease?
Which of the following is an example of indirect transmission of disease?
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Which of the following diseases is associated with airborne transmission?
Which of the following diseases is associated with airborne transmission?
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What does 'vectors' refer to in the context of disease transmission?
What does 'vectors' refer to in the context of disease transmission?
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In the context of indirect transmission, which of these substances can act as fomites?
In the context of indirect transmission, which of these substances can act as fomites?
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What distinguishes vertical transmission from horizontal transmission of disease?
What distinguishes vertical transmission from horizontal transmission of disease?
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Which statement about direct transmission is accurate?
Which statement about direct transmission is accurate?
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In what way does indirect transmission differ from direct transmission?
In what way does indirect transmission differ from direct transmission?
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What is a characteristic of pathogens involved in indirect transmission?
What is a characteristic of pathogens involved in indirect transmission?
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Which of the following examples represents horizontal transmission?
Which of the following examples represents horizontal transmission?
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Which of the following infections is NOT primarily spread through blood or body fluids?
Which of the following infections is NOT primarily spread through blood or body fluids?
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What is the primary function of the blood-brain barrier in the context of disease prevention?
What is the primary function of the blood-brain barrier in the context of disease prevention?
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Which mechanism is NOT associated with preventing ingress of disease according to the provided content?
Which mechanism is NOT associated with preventing ingress of disease according to the provided content?
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Which of the following is true regarding the transmission of infections through saliva?
Which of the following is true regarding the transmission of infections through saliva?
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Which type of infectious disease transmission involves direct contact between mucous membranes?
Which type of infectious disease transmission involves direct contact between mucous membranes?
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Which of the following statements accurately describes the transmission of typhoid?
Which of the following statements accurately describes the transmission of typhoid?
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What is the primary reason mosquitoes are considered effective vectors for diseases?
What is the primary reason mosquitoes are considered effective vectors for diseases?
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Which of the following diseases is NOT spread by mosquitoes?
Which of the following diseases is NOT spread by mosquitoes?
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In which way can soil contribute to the spread of infections?
In which way can soil contribute to the spread of infections?
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Food and fecal-oral transmission predominantly affects which part of the body?
Food and fecal-oral transmission predominantly affects which part of the body?
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How are enteric pathogens often shed from the body?
How are enteric pathogens often shed from the body?
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What role do insects generally play in the transmission of diseases?
What role do insects generally play in the transmission of diseases?
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Which of the following statements about fomites is correct?
Which of the following statements about fomites is correct?
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Which group of organisms prominently includes intestinal parasites that can be transmitted by insects?
Which group of organisms prominently includes intestinal parasites that can be transmitted by insects?
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What is the global annual death toll attributed to vector-borne diseases?
What is the global annual death toll attributed to vector-borne diseases?
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Study Notes
Transmission of Disease
- Horizontal transmission: Person-to-person.
- Vertical transmission: Mother-to-child.
- Direct transmission: Physical contact (kissing, touching, sexual contact, body lesions).
- Indirect transmission: Through objects or vectors (air, water, food, fomites, blood, saliva). Pathogen survival outside a host is key to direct vs. indirect classification.
Indirect Transmission Methods
- Airborne: Droplets or dust containing microbes suspended in air (e.g., tuberculosis, chickenpox, measles). Organisms must be resistant to drying.
- Waterborne: Water contaminated with animal or human excreta (e.g., typhoid). Accounts for 4.1% of the global disease burden.
- Vectors: Insects (mosquitoes for malaria, West Nile virus, etc.). Transmission via saliva, faeces, or secretions. Few diseases directly caused by insects themselves.
- Soilborne: Contact with soil (e.g., tetanus). Spores can survive for long periods. Transmits intestinal worms.
- Foodborne: Contaminated food or water (e.g., Salmonella). Poor handwashing by food handlers is a major concern.
- Fomites: Contaminated inanimate objects.
- Bloodborne/Body Fluid Transmission: Contact with infected blood or fluids (e.g., Hepatitis B, Hepatitis C, HIV). Sexual contact is a key transmission route for various STIs.
- Saliva: Contains bacteria, fungi, and viruses. Direct contact (kissing) or indirect contact with contaminated objects.
Preventing Ingress (Disease Prevention)
- Skin: A tough, keratinized barrier. Constantly renewed.
- Blood: Clotting prevents further ingress.
- Blood-brain barrier: Protects the brain and spinal cord.
- Tears: Contain antibacterial agents.
- Saliva: Contains antibacterial agents; lavage effect.
- Gingival crevicular fluid: Antibacterial; contains immune defense mechanisms.
- Mucous membranes (Mucociliary escalator): Mucus traps microbes; cilia sweep them out.
- Stomach acid: Kills many bacteria.
- Sweat: Fatty acids and salt inhibit bacterial growth.
Dealing with Ingress (Host Response)
- Immune response: Recognizes and destroys foreign substances. Distinguishes between self and non-self. Memory cells provide faster responses to previously encountered antigens.
- Lymphocytes: White blood cells (B and T lymphocytes).
- B lymphocytes: Produce antibodies (humoral immune response). Form memory cells for long-term immunity.
- T lymphocytes: Control immune response; directly destroy antigens (cell-mediated immune response).
Factors Affecting Host Response
- Smoking, poor diet, stress – negative impacts on the immune system.
- Biofilm formation: Inflammation (redness) is a key indicator. Oral hygiene removes biofilm.
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Description
Explore the various methods of disease transmission, including horizontal and vertical transmission, as well as direct and indirect methods. The quiz covers details about airborne, waterborne, vector, and soilborne transmission. Understand how pathogens survive and spread in different environments.
