Ch. 13

Infectious Diseases

Define Infectious (Communicable) Disease

Examples?

Collaborative Questions

• What is a pathogen?

• What is a virus?

• What are some ways diseases can be spread?

• What is happening in the body when an infection is present in a living organism?

• What is a vaccines• How do they work?

Any disease that is caused by an agent that has invaded the body

Can be passed from one person to another person, from food or water, from animals, or from something in the environment

Examples:Colds, flu, tuberculosis, MRSA, Ebola

Infectious (Communicable) Diseases

PATHOGENSAny agent that causes disease

Bacteria, viruses, fungi, protists, parasites

All infectious diseases are caused by:

Bacteria: Tiny, single-celled organisms that live almost everywhere

on Earth Most bacteria are harmless and help with bodily functions Bacteria in mouth, intestines

Harmful bacteria make you sick when they grow on or in your body

Example: Some give off poisons (tetanus/toxins) that damage cells Sinus infections

Most harmful bacteria are killed by our immune system, others need antibiotics to treat and cure infections

Pathogens

Viruses:Smaller than bacteriaDisease-causing particles made up of

genetic material surrounded by a coat of protein

the virus finds a living “host cell” and forces it to reproduce and “attack” more cellsColds, flu, measles, AIDS

Pathogens

Fungi (fungus) Organisms that absorb and use nutrients from other living or dead

organisms Mushrooms Athlete’s foot, ringworm

Protists Larger and more complex than bacteria

Malaria

Parasites Animals—get their energy and nutrients by feeding on other living

organisms Lice, tape worms, etc.

Rickettsia Pathogens that resemble bacteria

Invade cells of other organisms Enter humans through bites from fleas, ticks, or lice

typhus

Pathogens

Person to person Airborne (sneezing, coughing, touching anything drops landed on)

kissing, drinking from same glass, direct contact (tetanus)

Dirty Hands Suck

Food and water Contaminated food (from humans, from infected animal)

Examples? Water from streams or lakes, sewage,

Typhoid, cholera, dysentery

Environment Pathogens are all around you—few can cause disease

Tetanus present in soil

Animals Pathogens live on/in animals Ringworm from pets, mosquitos carry malaria, yellow fever,

encephalitis, ticks carry Lyme disease

How are they transmitted (spread)?

Bacterial diseases Antibiotics-medicines used to kill or slow the growth of bacteria

Penicillin CANNOT be used to treat colds or viral diseases

Antibiotic resistance: bacteria are no longer killed by a particular antibiotic

Improper use=build up of antibiotic resistant bacteria

Viral Diseases Not much is known, so most concentrate on relieving symptoms and

stopping production of viruses inside cells

Fungal Infections Over-the-counter or prescription medicine

Protistan, parasitic Infections Prevention—good hygiene, sanitation

How to treat…

Immune System- general and specific

Network of cells, tissues, organs, and chemicals that fight off pathogens

Physical and Chemical BarriersFirst line of defensePhysical—skin (sweat and oil) and mucous

membranes (mucus and cilia)block pathogens from entering the body

Chemical—enzymes (stomach acid, tears)

Protection Against Diseasesread pgs. 638-644

Inflammatory Response-2nd line of defense A reaction to tissue damage caused by injury or

infections Prevents further tissue injury and stops invading

pathogens

Immune System- general

Made up of different types of blood cells and proteins called antibodies-(act against a specific pathogen)

Cells move through bloodstream and lymphatic system

A network of vessels that carry a clear fluid called lymph throughout the body—pick up bacteria and viruses and delivers them to the lymph nodes

Collection of WBCs in lymph nodes while fighting infection

Protection

Antigen-a substance capable of triggering an immune response Found on the surface of pathogens and in toxins

Immune System White Blood Cells

Primary job=defend against disease

Phagocytes (to eat) A specific white blood cell that attacks invading pathogens Engulfs pathogens and then destroys them with chemicals (enzymes) Creates pus

A collection of dead white blood cells and damaged tissue—may collect at the site of inflammation as a response to harmful bacteria

Macrophages-a type of phagocyte that destroys pathogens by making antigens (recognized my WBCs) to trigger an immune response

Result=IMMUNITY The stat of being protected against a particular disease

Protection- specific

LymphocyteA specialized white blood cell that coordinates and performs

many of the functions of specific immunity

T cells, B cells, NK cellsRecognize antigens not made by the body (non-self)

B cells- produce antibodies to neutralize the pathogen

T cells- produce powerful enzymes to kill the infecting pathogenHelper T cells trigger production of B cells and NK cellsNK Cells- attack and destroy infected cells

**attack only infected cell—NOT pathogen

Protection- specific

VaccinesSubstances made of killed or weakened

pathogens or from genetic material introduced into the body to create immunity

The body begins to make WBCs called memory cells

If the specific pathogen enters the body , the memory cells and their antibodies fight the pathogen before it can cause disease

May need boosters for vaccinesFlu?

Protection

With a partner, answer questions #1 and #3 on page 644

Then, write a story with a phagocyte as the main character.

This story should be an imaginative description of a phagocyte joining the inflammatory response to stop invading pathogens after some kind of injury to the body. Your stories can be funny or sad, but all should accurately describe the strategy against disease.

Questions

A next-gen cure for killer infections

TED Talks

Tetanus Symptoms- Severe muscle spasms

Transmission- Tetanus causing bacteria found in soil Prevention- vaccine and boosters

Treatment- antibiotics

Strep Throat Symptoms- sore throat, fever, yellow or white specks on tonsils

Transmission- contact with mucus from infected person Prevention- avoid contact

Treatment- antibiotics

Meningitis-inflammation of membranes covering brain and spinal chord

Symptoms- severe headache, fever, stiff neck, sensitivity to light, nausea Transmission- contact with saliva or mucus from infected person

Prevention- vaccine, avoid contact Treatment- antibiotics—if caught early enough

Common Infectious DiseasesBacterial

Sinus Infection Symptoms- headache, tenderness of sinuses, thick

greenish mucus, pressure in head Transmission- contact with mucus Prevention- avoid contact and allergens Treatment- ??

Salmonellosis- an infection of the digestive system Symptoms- headache, cramps, diarrhea, nausea, vomiting Transmission- eating contaminated food Prevention- thorough cooking, hand washing,

refrigeration Treatment- OTC meds for symptoms, sometimes

antibiotics

Bacterial cont.

Flu Symptoms- headache, sore muscles and throat, fever, vomiting, ect.

Transmission- contact with saliva or mucus Prevention- vaccine and avoid contact

Treatment- rest, fluids

Cold Symptoms- sore throat, sneezing, runny nose, mild cough

Transmission- contact with saliva or mucus Prevention- wash hands, avoid contact

Treatment- rest, fluids

Mumps Symptoms- pain and swelling of glands in throat, fever, headache

Transmission- contact with infected airborne droplets and infected person

Prevention- vaccine Treatment- see doc. Rest, fluids

Common Infectious DiseasesViral

Measles Symptoms- fatigue, runny nose, cough, fever, small white dots in

mouth, rash on body Transmission- contact with saliva or mucus

Prevention- vaccine Treatment- see doc. Rest, fluids

Mononucleosis Symptoms- fever, swollen lymph nodes, sore throat, weakness

Transmission- contact with saliva or mucus Prevention- avoid eating/drinking after infected person

Treatment- see doc. Rest, fluids

Hepatitis Symptoms- inflammation of liver, jaundice, fever, darkening of urine

Transmission- contact with bodily fluids, contaminated food or water Prevention- vaccine for A and B, wash hands, avoid contact

Treatment- see doc. Rest, meds, no cure for Hep. B and C

Viral cont.

You are a scientist for the CDC and have just discovered a recent outbreak of a new disease. As the head scientist, it is now you responsibility to describe this disease, how it is spread, and how to prevent it.

The following must be provided in your document:

• Name of disease

• Cause of disease

• Symptoms of disease

• Transmission of disease

• Prevention methods

• Treatment