1. What is the difference between isolation and quarantine in disease control? Provide examples of situations where each measure is appropriate. Answer: Isolation is the separation of people who are infected with a contagious disease from those who are not, while quarantine is the restriction of movement of people who have been exposed to a contagious disease but are not yet symptomatic. Isolation is appropriate for people who have tested positive for COVID-19, tuberculosis, or other infectious diseases that can be transmitted through respiratory droplets or contact. Quarantine is appropriate for people who have traveled from a high-risk area, had close contact with an infected person, or are awaiting test results for a contagious disease. 2. What are the three levels of prevention in disease control? Give an example of a public health intervention for each level. Answer: The three levels of prevention are primary, secondary, and tertiary. Primary prevention aims to reduce the incidence of disease by eliminating or reducing exposure to risk factors. An example of primary prevention is vaccination against measles, mumps, and rubella. Secondary prevention aims to reduce the prevalence and severity of disease by detecting and treating it early. An example of secondary prevention is screening for cervical cancer using Pap smear tests. Tertiary prevention aims to reduce the complications and disability caused by disease by providing rehabilitation and palliative care. An example of tertiary prevention is providing physiotherapy and pain management for stroke survivors. 3. What are the four modes of transmission of infectious diseases? Explain how each mode can be prevented or controlled. Answer: The four modes of transmission are direct contact, indirect contact, droplet, and airborne. Direct contact transmission occurs when an infected person touches or exchanges body fluids with a susceptible person, such as through kissing, sexual intercourse, or blood transfusion. Direct contact transmission can be prevented or controlled by using personal protective equipment (PPE), practicing good hygiene, and avoiding sharing personal items. Indirect contact transmission occurs when an infected person contaminates an object or surface that is then touched by a susceptible person, such as through coughing, sneezing, or touching a doorknob. Indirect contact transmission can be prevented or controlled by disinfecting frequently touched surfaces, washing hands frequently, and covering coughs and sneezes. Droplet transmission occurs when an infected person expels large respiratory droplets that travel a short distance and land on the mucous membranes of a susceptible person, such as through coughing, sneezing, or talking. Droplet transmission can be prevented or controlled by wearing masks, maintaining physical distance, and avoiding crowded places. Airborne transmission occurs when an infected person expels small respiratory droplets that remain suspended in the air and are inhaled by a susceptible person, such as through breathing, singing, or aerosol-generating procedures. Airborne transmission can be prevented or controlled by improving ventilation, using high-efficiency particulate air (HEPA) filters, and wearing respirators. 4. What are the five components of the chain of infection? Describe how breaking any one of them can interrupt the spread of disease.