Infectious Diseases and Robert Koch's Experiment

• An infectious disease occurs when a pathogen transmits from one organism to another
• Pathogens are responsible for infectious diseases
• Examples of pathogens include viruses, bacteria, protozoans, fungi, and parasites

Robert Koch's Experiment

• Robert Koch experimented on bacteria
• Robert Koch studied anthrax, a deadly disease affecting cattle, sheep, and humans
• Koch isolated bacteria from the blood of cattle that had died from anthrax
• He then grew the bacteria in a laboratory

Koch's Postulates

• Robert Koch developed guidelines used to identify pathogens that cause specific diseases
• The pathogen must be found in sick organisms, not healthy ones
• The pathogen must be isolated and grown in a pure culture in a lab
• Purified pathogens placed in a new host should cause the same disease as the original host
• An injected pathogen isolated from the second host should be identical to the original pathogen

Human Infectious Diseases

• Bacterial Cause:

  • Tetanus is caused by a bacterium, affecting the nervous system, and spreads through soil in deep puncture wounds
  • Strep Throat is caused by a bacterium, affecting the respiratory system, and spreads through droplets and direct contact
  • Lyme Disease is caused by a bacterium, affecting skeletal and nervous systems, and is spread by a vector (tick)

• Viral Cause:

  • Chicken Pox is caused by a virus, affecting the skin, and spreads through droplets/direct contact
  • Rabies is caused by a virus, affecting the nervous system and spreads through animal bites
  • Influenza is caused by a virus, affecting the respiratory system, and spreads through droplets/direct contact
  • Hepatitis B is caused by a virus, affecting the liver, and spreads through direct contact with exchange of body fluids

• Protozoan Cause:

  • Giardia is caused by a protozoan, affecting the digestive tract, and spreads through contaminated water
  • Malaria is caused by a protozoan, affecting the blood and liver, spread by a vector (mosquito)

• Fungal Cause:

  • Athlete's Foot is caused by a fungus, affecting the skin, and spreads through direct contact or contaminated objects

• Bacterium cause tetanus

• Chicken Pox is not transmitted by vector

• Malaria affects the blood and liver

• Athlete's foot is caused by a fungus

• A carrier is symptom-free but capable of passing a pathogen

• Lyme disease, malaria and west nile virus are passed to humans via organisms called vectors that carry pathogens

Disease Transmission

• Direct contact refers to physical contact to spread disease
• Vectors are organisms which transmit disease

Symptoms of Disease

• Symptoms of disease are received when a pathogenic has invaded the host cells
• Viruses: Multiply in the host cells, then leave the host cells via exocytosis or by causing the cell to burst, which damage tissues or kills cells
• Bacteria: Produce harmful chemicals and toxins carried throughout the body via the bloodstream, damaging various parts of the body

Disease Patterns

• Bacteria that cause skeletal muscle spasm: Tetanus bacteria
• Bacteria that cause Paralyzes nerves: Botulism bacteria
• A large outbreak in an area and afflict many people: epidemic
• Widespread throughout a large region such as country ,continent and the entire globe: pandemic
• Outbreaks of diseases spread, which leads to observation of certain patterns
• It's important to monitor disease patterns for helping to control the spread of diseases
• Type agencies observe the spread of disease patterns, such as CDC (Centers for Disease Control and Prevention), and the WHO (World Health Organization)
• The role of these agencies is to publish reports about the incidence of specific disease, which helps to control the spread of diseases patterns
• Endemic diseases are continually found in small amounts within the population, such as the common cold

Treating and Fighting Diseases

• Penicillin is a chemical substance secreted by the fungus Penicillium
• Penicillin kills competing bacteria that grow on fungal food sources
• Antibiotics are a substance that can kill or inhibit the growth of microorganisms
• Chemical agents treat protozoan and fungal diseases
• Antiviral drugs treat infections and influenza in the elderly
• The body’s immune system usually handles viral diseases

Antibiotic Resistance

• Widespread usage can cause bacteria to resit particular antibiotics
• Natural selection is a process where better adapted microorganisms survive and produce more offspring
• Bacteria in a population might have a trait that enables them to survive when a particular antibiotic is present
• Bacteria reproduce quickly and pass trait on the variation
• Antibiotic-resistant bacteria in a population can increase quickly

Staphylococcal Disease

• Antibiotic resistance of bacteria has presented the medical community with some problems with treating certain diseases

• Penicillin was used effectively for many years to treat some diseases

• Staphylococcal disease is acquired in a high-density living condition

• Staphylococcal disease is an infection in skin, pneumonia, or meningitis

• Difficult to treat because the organism has become resistant to many antibiotics

• Penicillin is secreted by the Penicillium fungus

• Gonorrhea bacteria became more resistant to penicillin in 1990

• Bacteria develop antibiotic resistance

• Rabies is transmitted from an animal reservoir

• A carrier is symptom free but contagious

• Lyme disease, malaria and west nile virus are passed to humans via organisms called vectors that carry pathogens

• Pathogen transmission can occur through direct contact, indirectly through the air, through contaminated objects, or via vectors

• Toxin production is one way by which pathogenic bacteria is harmful to humans

• Botulism bacteria can cause disease even when no bacteria are present

• Not all bacteria, protozoa and viruses invade and cause damage to cells

• Diseases that are continually in small amounts are referred to as Endemic

• Immune system handles viral diseases

• Influenza in the elderly is treated by some antiviral drugs

• Skin is not a chemical barrier

• Lysozyme enzyme break down bacterial cell WALL

• Hydrochloric acid is mostly found in the stomach

• Neutrophils and macrophage are the cellular defenses

• Macrophage ingest bacteria

• Virus infected cells secrete a protein called interferon

• Inflammatory response example is an inflammatory response

• Skin is a physical barrier

• Inflammatory response is nonspecific response example

-Lymph is the watery part of the blood that exits the capillaries to bathe the cells -Spleen is one of the lymphatic systems

• Spleen is part of lymphitic system located above heart

Antibodies attack proteins in autoimmune disorder