Infectious Infectious DiseaseDisease

Disease UnitDisease Unit

Lecture 1Lecture 1

What Causes Infectious What Causes Infectious Diseases?Diseases?

Infectious diseasesInfectious diseases are diseases are diseases caused by agents invading the body.caused by agents invading the body.

BacteriaBacteria are single-celled are single-celled organisms, some of which cause organisms, some of which cause disease. Other kinds of bacteria are disease. Other kinds of bacteria are harmless or even helpful to the body. harmless or even helpful to the body. Tetanus, tuberculosis, and sinus Tetanus, tuberculosis, and sinus infections are bacterial diseases.infections are bacterial diseases.

What Causes Infectious What Causes Infectious Diseases?Diseases?

VirusesViruses are tiny disease-causing particles are tiny disease-causing particles made up of genetic material and a protein made up of genetic material and a protein coat. Viruses survive and replicate inside coat. Viruses survive and replicate inside living cells. Colds, the flu, measles, living cells. Colds, the flu, measles, chicken pox, and AIDS are viral diseases.chicken pox, and AIDS are viral diseases.

Fungi Fungi are organisms that absorb and use are organisms that absorb and use the nutrients of living or dead organisms. the nutrients of living or dead organisms. Some fungi cause diseases, such as Some fungi cause diseases, such as athlete’s foot and ringworm.athlete’s foot and ringworm.

What Causes Infectious What Causes Infectious Diseases?Diseases?

ProtozoanProtozoan are single-celled organisms are single-celled organisms that are larger and more complex than that are larger and more complex than bacteria. They account for some of the bacteria. They account for some of the leading causes of death worldwide, leading causes of death worldwide, including malaria.including malaria.

ParasitesParasites get their energy and nutrients get their energy and nutrients by feeding on other living things. Head by feeding on other living things. Head lice, tapeworms, and some roundworms lice, tapeworms, and some roundworms are parasites.are parasites.

How Are Infectious Diseases How Are Infectious Diseases Treated?Treated?

AntibioticsAntibiotics are medicines used to kill or are medicines used to kill or slow the growth of bacteria. Examples slow the growth of bacteria. Examples include penicillin, tetracycline, and include penicillin, tetracycline, and streptomycin.streptomycin.

Antibiotic resistanceAntibiotic resistance is a condition in is a condition in which bacteria can no longer be killed by a which bacteria can no longer be killed by a particular antibiotic.particular antibiotic.

Improper use of antibiotics contributes to Improper use of antibiotics contributes to the growth of antibiotic-resistant bacteria.the growth of antibiotic-resistant bacteria.

How Are Infectious Diseases How Are Infectious Diseases Treated?Treated?

Treating Viral DiseasesTreating Viral Diseases - Viral diseases - Viral diseases are hard to treat. Most antiviral are hard to treat. Most antiviral medications focus on relieving symptoms. medications focus on relieving symptoms. Viruses are not affected by antibiotics.Viruses are not affected by antibiotics.

Treating Fungal InfectionsTreating Fungal Infections - Some - Some fungal infections can be treated with fungal infections can be treated with over-the-counter antifungal medications. over-the-counter antifungal medications. Others require prescription medications.Others require prescription medications.

How Are Infectious Diseases How Are Infectious Diseases Treated?Treated?

Treating Protozoan InfectionsTreating Protozoan Infections - - The best protection is prevention The best protection is prevention through good hygiene and sanitation.through good hygiene and sanitation.

Treating ParasitesTreating Parasites - Head lice can - Head lice can be treated with medicated be treated with medicated shampoos.shampoos.

How Your Body Fights How Your Body Fights DiseaseDisease

Physical barriersPhysical barriers to pathogens to pathogens include:include:

- Skin- Skin

- Mucous membranes- Mucous membranes

- Chemicals- Chemicals InflammationInflammation is a reaction to injury is a reaction to injury

or infection characterized by pain, or infection characterized by pain, redness, and swelling.redness, and swelling.

How Your Body Fights How Your Body Fights DiseaseDisease

The immune system is the body’s system for fighting disease once it is in the body.

White blood cells are cells in the blood that defend the body against disease.

Antibodies are proteins that mark pathogens to be destroyed by white blood cells.

The lymphatic system is a network of vessels that carry lymph throughout the body, carrying viruses and bacteria back to the lymph nodes.

What You Can to Do Stay What You Can to Do Stay WellWell

Protect yourself.Protect yourself. Eat a healthy, balanced diet.Eat a healthy, balanced diet. Drink plenty of water.Drink plenty of water. Reduce your stress levels.Reduce your stress levels. Exercise regularly.Exercise regularly. Get regular medical checkups.Get regular medical checkups. Avoid close contact with sick people.Avoid close contact with sick people. Get enough sleep.Get enough sleep. Stay up to date on all available vaccines.Stay up to date on all available vaccines.

What to Do When You Are What to Do When You Are SickSick

Stay home and rest.Stay home and rest. Drink plenty of fluids.Drink plenty of fluids. Throw away tissues you use right Throw away tissues you use right

away.away. Follow all the directions your doctor Follow all the directions your doctor

gives.gives.

How to Prevent the Spread How to Prevent the Spread of Diseaseof Disease

Get vaccinated.Get vaccinated. Keep clean by washing with soap Keep clean by washing with soap

frequently.frequently. Don’t share food, drinks, or personal Don’t share food, drinks, or personal

items such as toothbrushes.items such as toothbrushes. Cover your mouth when you sneeze Cover your mouth when you sneeze

or cough.or cough.

How to Prevent the Spread How to Prevent the Spread of Diseaseof Disease

When you are outdoors:When you are outdoors: - wear long-sleeved shirts and pants - wear long-sleeved shirts and pants

in long grassin long grass - use insect repellant when necessary- use insect repellant when necessary - avoid contact with animals that - avoid contact with animals that

behave strangelybehave strangely - avoid drinking and swimming in - avoid drinking and swimming in

remote watersremote waters

Diseases Affect EverybodyDiseases Affect Everybody

No matter how healthy we are, we all No matter how healthy we are, we all become ill from diseases sometimes.become ill from diseases sometimes.

There are so many pathogens in so There are so many pathogens in so many places it is impossible to avoid many places it is impossible to avoid them.them.

The best defense against pathogens The best defense against pathogens is avoiding behaviors that increase is avoiding behaviors that increase our chances of infection.our chances of infection.

Common Bacterial DiseasesCommon Bacterial Diseases

Tetanus causes severe muscle spasms. It can enter the body through cuts or wounds. Vaccinations are the best form of prevention.

Strep throat causes a sore throat and spots on the tonsils. It is spread by contact with mucus. The best prevention is avoiding contact with infected people.

Common Bacterial DiseasesCommon Bacterial Diseases

Meningitis causes inflammation of membranes around the brain and spinal cord. It is spread by contact with mucus or saliva. There are some vaccines for meningitis.

Sinus infections cause headaches, mucus, and pressure in the head. They are spread by contact with mucus. Prevention includes avoiding infected people and avoiding irritants and allergens in the air.

Common Bacterial DiseasesCommon Bacterial Diseases

Salmonellosis causes headaches, stomach cramps, diarrhea, and nausea. It is spread by eating food from an infected animal or food contaminated by an infected person. Prevention involves proper refrigeration, cooking, and handling of food.

Other Common DiseasesOther Common Diseases

Fungal infectionsFungal infections include Athlete’s foot, include Athlete’s foot, jock itch, and ringworm. These often occur jock itch, and ringworm. These often occur when the fungus contacts warm, moist when the fungus contacts warm, moist skin. Prevention involves good personal skin. Prevention involves good personal hygiene and keeping clothes dry.hygiene and keeping clothes dry.

MalariaMalaria is the most widespread and is the most widespread and serious protozoan disease. It is spread serious protozoan disease. It is spread from person to person via mosquitoes. from person to person via mosquitoes. Malaria can be prevented and treated with Malaria can be prevented and treated with antimalarial medicines.antimalarial medicines.

Other Common InfectionsOther Common Infections

Parasitic infectionsParasitic infections include include hookworms and tapeworms inside the hookworms and tapeworms inside the body, and lice, leeches, ticks, and body, and lice, leeches, ticks, and fleas on the body.fleas on the body.

A person can contract parasites by A person can contract parasites by eating infected food, drinking infected eating infected food, drinking infected water, contacting infected soil, and by water, contacting infected soil, and by being bitten by infected insects.being bitten by infected insects.

Working Toward a Healthy Working Toward a Healthy FutureFuture

International air travel has made it easier for International air travel has made it easier for diseases to spread from country to country.diseases to spread from country to country.

The National Institute of Health (NIH) and The National Institute of Health (NIH) and Centers for Disease Control (CDC) track the Centers for Disease Control (CDC) track the spread of diseases and watch for new spread of diseases and watch for new diseases entering the country.diseases entering the country.

Public health organizations throughout the Public health organizations throughout the world fight diseases through vaccinations world fight diseases through vaccinations and treatments.and treatments.