Lesson 1: infectious diseases

• Infectious diseases are illnesses caused by pathogenic microorganisms such as bacteria, viruses, parasites, or fungi.
• microorganisms can be transmitted from one person to another
• Pathogens are tiny organisms that can cause infectious diseases.
• Koch established and published experimental steps known as Koch’s postulates, which are rules for demonstrating that an organism causes a disease.
• The microorganism must be present in every case of the disease but absent from healthy individuals.
• The microorganism must be isolated from the diseased individual and grown in pure culture.
• The cultured microorganism should cause disease when introduced into a healthy individual.
• The microorganism must be re-isolated from the inoculated, diseased experimental host and identified as identical to the original specific causative agent.
• The suspected pathogen must be isolated from the new host, grown again in pure culture, and shown to have the same characteristics as the original pathogen.
• A disease reservoir is a source of the pathogen in the environment
• Humans are the main reservoir pathogens that affect humans
• An individual that is symptom-free but capable of passing the pathogen is called a carrier.
• Other animals also are reservoirs of pathogens that can be passed to humans.
• Direct Contact: Pathogens spread through physical contact with infected individuals, bodily fluids, or contaminated surfaces.
• Indirect Contact by object : In this type of transmission, pathogens are spread indirectly through contact with contaminated surfaces, objects, or vectors
• indirect contact through air some pathogens can be passed through air. when a person with an infectious disease sneeze or coughs, pathogens can be passed along with the tiny mucus droplets.
• Vector: certain diseases can be transmitted by vectors. the most common vectors are arthropods, which include biting insects such as mosquitoes and ticks.
• Endemic diseases are consistently present within a particular geographic area or population group.
• Epidemics occur when there is a sudden and significant increase in the number of cases of a disease within a specific population or region.
• Pandemics are global outbreaks of disease that spread across multiple countries or continents, affecting a large number of people.
• An antibiotic is a substance that can kill or inhibit the growth of other microorganisms
• Chemical agents are substances designed to cause harm through chemical reactions, often used in warfare or terrorism.
• Antiviral drugs are medications designed to inhibit the replication of viruses in the body, helping to treat viral infections.