Chapter 23 Communicable Diseases

Lesson 1 What causes infectious diseases? Microscopic organisms- pathogens Microscopic organisms- pathogens Parasites- organisms that live in or on another organism and derive nourishment from it Parasites- organisms that live in or on another organism and derive nourishment from it

Forms of Pathogens- Bacteria Bacteria- single-cell microorganism. Can live almost anywhere Bacteria- single-cell microorganism. Can live almost anywhere Some bacteria produce poisons. If a person is not immune- disease results Some bacteria produce poisons. If a person is not immune- disease results Bacteria multiply at a rapid rate through cell division- every 20 minutes Bacteria multiply at a rapid rate through cell division- every 20 minutes

Forms of Pathogens- Viruses Virus- smallest known type of infectious agent Virus- smallest known type of infectious agent Not living cells Not living cells Highly specific in the kinds of cells that they invade Highly specific in the kinds of cells that they invade When a virus invades a cell it attaches itself to a cell- host cell When a virus invades a cell it attaches itself to a cell- host cell

Viruses prey upon all living organisms, turning them into Virus Xerox machines

Forms of Pathogens- Rickettsias Resemble small bacteria Resemble small bacteria Most are found in the intestinal tract of insects- notably fleas as well as in mice, ticks and mites Most are found in the intestinal tract of insects- notably fleas as well as in mice, ticks and mites Typhus and Rocky Mountain Spotted fever Typhus and Rocky Mountain Spotted fever Passed on to humans by bites or by feces being deposited on the skin. Passed on to humans by bites or by feces being deposited on the skin.

Forms of Pathogens- Protozoan Single celled organisms that are larger than bacteria and have more complex cell structure. Single celled organisms that are larger than bacteria and have more complex cell structure. Most are harmless, but more than 30 types cause disease in humans. Most are harmless, but more than 30 types cause disease in humans. Disease-producing protozoan are most common in tropical areas that have poor sanitation. Disease-producing protozoan are most common in tropical areas that have poor sanitation.

Forms of Pathogens- Fungi Simple organisms Simple organisms Sarophytes- feed off of dead animals, insects and leaves Sarophytes- feed off of dead animals, insects and leaves Prefer dark damp areas Prefer dark damp areas

Fungi The most common disease-causing fungi invade mainly deep tissues of the hair, nails, and skin. The most common disease-causing fungi invade mainly deep tissues of the hair, nails, and skin. Cause infections of the scalp or feet Cause infections of the scalp or feet Examples- athlete's feet and ringworm Examples- athlete's feet and ringworm

Athlete’s Feet

Ring worm

How infectious diseases are spread- People Direct Contact- uninfected person comes into physical contact with an infected person. STDs are spread this way. Human bite is another (dangerous) mode of transmission. A pregnant woman may also infect her unborn child Direct Contact- uninfected person comes into physical contact with an infected person. STDs are spread this way. Human bite is another (dangerous) mode of transmission. A pregnant woman may also infect her unborn child Indirect Contact- Bacteria and viruses can enter the body through the lungs if droplets-exhaled, coughed or sneezed out by an infected person- are inhaled. The common cold, influenza, and tuberculosis are spread this way. Indirect Contact- Bacteria and viruses can enter the body through the lungs if droplets-exhaled, coughed or sneezed out by an infected person- are inhaled. The common cold, influenza, and tuberculosis are spread this way.

How infectious diseases are spread- Animals Bite of dog or another animal can spread rabies Bite of dog or another animal can spread rabies Bloodsucking mosquitoes can pass on malaria and dengue fever Bloodsucking mosquitoes can pass on malaria and dengue fever

How infectious diseases are spread- Contaminated Objects Eating utensils Eating utensils Glasses/bottles Glasses/bottles Toothbrushes Toothbrushes needles needles

Did You Know? Your toothbrush should be discarded after a cold sore or sore throat. Your toothbrush should be discarded after a cold sore or sore throat.

How infectious diseases are spread- The Environment Food Food Water Water Soil Soil Air Air Some forms of infectious diseases are a direct result of human negligence- careless disposal of waste materials, pollution, handling of foods

How Your Body Defends Against Infections Immunity- body’s natural defense against infection Immunity- body’s natural defense against infection

The Immune Response Your body is exposed each day to pathogens Your body is exposed each day to pathogens Your body is constantly fighting pathogens that enter it Your body is constantly fighting pathogens that enter it Most of the time your body fights off an infection without you even knowing it because of your immune system. Most of the time your body fights off an infection without you even knowing it because of your immune system.

Nonspecific Resistance Physical barriers- skin, mucous membranes and cilia Physical barriers- skin, mucous membranes and cilia Chemical barriers- tears, saliva, acid juices Chemical barriers- tears, saliva, acid juices Body Cells- White blood cells (phagocytes) Body Cells- White blood cells (phagocytes) Inflammatory Response Inflammatory Response

Specific Resistance The general response of your nonspecific defenses is not always enough to protect your body from disease. The general response of your nonspecific defenses is not always enough to protect your body from disease. The adaptive immune system mounts specific attacks against particular types of pathogens. The adaptive immune system mounts specific attacks against particular types of pathogens. When this happens another body defense goes to work in the form of cells called lymphocytes When this happens another body defense goes to work in the form of cells called lymphocytes

Lymphocytes Type of white blood cell that fight pathogens Type of white blood cell that fight pathogens Travel through body in 2 networks -blood vessels and lymph vessels Travel through body in 2 networks -blood vessels and lymph vessels

2 types of lymphocytes B cells- when B cells encounter pathogens, they are stimulated to enlarge and multiply. They then turn into plasma cells which in turn produce antibodies- proteins that destroy or neutralize pathogens B cells- when B cells encounter pathogens, they are stimulated to enlarge and multiply. They then turn into plasma cells which in turn produce antibodies- proteins that destroy or neutralize pathogens Antibodies remember the pathogens and become active again when the same pathogens re-enter the body (memory T-cells and B-cells) Antibodies remember the pathogens and become active again when the same pathogens re-enter the body (memory T-cells and B-cells)

2 types of lymphocytes T-cells T-cells Killer T- cells- are stimulated to multiply by the presence of abnormal cells. They attach themselves to the cells and release toxins to destroy. Killer T- cells- are stimulated to multiply by the presence of abnormal cells. They attach themselves to the cells and release toxins to destroy. Helper T-cells- aid in the activity of B- cells and Killer T-cells Helper T-cells- aid in the activity of B- cells and Killer T-cells

Immune Response

Lesson 2 Common Infectious Diseases Respiratory infections Respiratory infections Common cold- viral infection that causes inflammation of the mucous membranes lining the nose and throat. Common cold- viral infection that causes inflammation of the mucous membranes lining the nose and throat. Symptoms- stuffy runny nose, sneezing and sometimes sore throat and head ach. Symptoms- stuffy runny nose, sneezing and sometimes sore throat and head ach. Transmission -by breathing in a virus-containing droplets that have been sneezed or coughed out by an infected person- rubbing nose or eyes with fingers that have handled a contaminated object Transmission -by breathing in a virus-containing droplets that have been sneezed or coughed out by an infected person- rubbing nose or eyes with fingers that have handled a contaminated object

Did You Know? Water particles expelled through a sneeze can travel at speeds up to 100 miles an hour Water particles expelled through a sneeze can travel at speeds up to 100 miles an hour

Common Infectious Diseases Respiratory infections Respiratory infections Influenza- viral infection of the respiratory tract Influenza- viral infection of the respiratory tract Symptoms include chills, fever, headache muscle ache and weakness Symptoms include chills, fever, headache muscle ache and weakness Transmission- virus infected droplets coughed or sneezed into the air Transmission- virus infected droplets coughed or sneezed into the air Treatment- rest, proper nutrition, drinking plenty of fluids Treatment- rest, proper nutrition, drinking plenty of fluids

Common Infectious Diseases Respiratory infections Tuberculosis (TB)- highly contagious bacterial infection that most often infects the lungs. Tuberculosis (TB)- highly contagious bacterial infection that most often infects the lungs. Symptoms, coughing (sometimes with blood), chest pain, shortness of breath, fever, sweating, poor appetite and weight loss Symptoms, coughing (sometimes with blood), chest pain, shortness of breath, fever, sweating, poor appetite and weight loss Transmission- Air borne droplets Transmission- Air borne droplets Treatment-antibiotics Treatment-antibiotics

Common Infectious Diseases Respiratory infections Strep Throat- bacterial infection of the throat Strep Throat- bacterial infection of the throat Symptoms- sore throat, fever, a general feeling of illness, and enlarged lymph nodes Symptoms- sore throat, fever, a general feeling of illness, and enlarged lymph nodes Transmission- air borne droplets Transmission- air borne droplets Treatment- antibiotics Treatment- antibiotics

Infectious Diseases of the Nervous System Encephalitis- Encephalitis- Inflammation of the brain Inflammation of the brain Caused by a virus carried in mosquitoes Caused by a virus carried in mosquitoes Starts off with a headache and fever- if left untreated it can progress to hallucinations, confusion, paralysis, and disturbances of speech, memory, behavior and eye movement Starts off with a headache and fever- if left untreated it can progress to hallucinations, confusion, paralysis, and disturbances of speech, memory, behavior and eye movement

Infectious Diseases of the Nervous System Meningitis-inflammation of the meninges- the membranes that cover the brain and spinal cord Meningitis-inflammation of the meninges- the membranes that cover the brain and spinal cord Viral meningitis-mild caused by virus- no treatment Viral meningitis-mild caused by virus- no treatment Bacterial meningitis- bacterial infection that can be life-threatening- treated with antibiotics. Bacterial meningitis- bacterial infection that can be life-threatening- treated with antibiotics.

Infectious Diseases of the Nervous System Polio- disease of the central nervous system caused by a virus Polio- disease of the central nervous system caused by a virus -Can lead to extensive paralysis including paralysis of the muscles used in breathing and can result in death

Vaccine Vaccine- a preparation based on a weakened or dead pathogen that provides immunity by causing the body to produce antibodies to the pathogen. Vaccine- a preparation based on a weakened or dead pathogen that provides immunity by causing the body to produce antibodies to the pathogen.

Measles Measles- highly contagious viral disease characterized by fever and rash that covers the entire body. Measles- highly contagious viral disease characterized by fever and rash that covers the entire body. Rubella-German Measles Rubella-German Measles

Mononucleosis Mono- viral infection common among teenagers. Mono- viral infection common among teenagers. “Kissing Disease” “Kissing Disease”

Hepatitis Hepatitis A- results in eating foods or drinking water that has been contaminated with a virus from an infected person’s feces. Many cases occur among people who have traveled to areas where standards of hygiene are low. Hepatitis A- results in eating foods or drinking water that has been contaminated with a virus from an infected person’s feces. Many cases occur among people who have traveled to areas where standards of hygiene are low. Hepatitis B- is found in all body fluids of an infected person especially blood. Spread through blood transfusions and blood products. Contaminated needles and sexual contact with infected person. More serious than hepatitis A. Can lead to chronic infection especially in the liver. Hepatitis B- is found in all body fluids of an infected person especially blood. Spread through blood transfusions and blood products. Contaminated needles and sexual contact with infected person. More serious than hepatitis A. Can lead to chronic infection especially in the liver.

Hepatitis Hepatitis C- is spread through infected blood. Can cause liver cancer. Hepatitis C- is spread through infected blood. Can cause liver cancer.