Is it a COLD or is it an ALLERGY? David L. Stewart, MD, MPH Department of Family & Community Medicine University of Maryland School of Medicine

Overview Anatomy Physiology Comparisons – Colds vs. Allergies Myths Immune Response Inflammatory Response Comparisons – Colds vs. Allergies Myths

Anatomy of Nose and Sinuses

Anatomy of Nose & Sinuses, cont.

Definitions Immune System Antigen Allergen Antibody White Blood Cells Immune Response Mast Cell Inflammation

Immune System A collection of mechanisms within an organism that protects against disease by identifying and killing pathogens. Pathogen, from the Greek “pathos”… that which produces suffering.

Immune System A surveillance system which detects a wide variety of agents and must distinguish them as harmful or not harmful to the body. Subsequently neutralize or kill agents which are harmful.

Antigen Triggers Immune System Seen by Body as Foreign Usually a Protein or Polysaccharide May be Environmental

Allergen Triggers an allergic response Usually dust, pollen and pet dander

White Blood Cells Different Classes Make Antibodies Neutralize and Kill Antigen Inflammatory Response

Immune Responses Carried out by the body in order to remove an invader. Harmful Allergen Other

Antibodies Prepare the immune system to act Found in the blood and other body fluids Purpose is to recognize an antigen

Mast Cell Type of white blood cell Boundary between the outside world & the inside of the body Skin, mouth, eye, nose, digestive tract & lungs Plays role in inflammatory response

Inflammation Latin – Inflammatro – To set on fire Response of organism to harmful stimuli such as pathogens, damaged cells or irritation.

Inflammation Biological response of vascular tissue Acute or chronic Swelling, redness, warmth & pain Involves immune system

Inflammation One of the first responses of immune system to infection. Increases blood flow to tissue. Protection attempt by an organism to remove injurious stimuli (pathogen, damaged cells or irritant).

Infection Response Click black box to play

How The Infection Occurs* *www.commoncold.org/ undrstn3.htm

How the Virus Spreads* *www.commoncold.org/ undrstn3.htm

Allergic Response Click black box to play

Cold Virus & Allergens Activate Inflammatory and Immune Response

Cold Symptoms Inflammatory Mediators: Cause dilation and leakage of blood vessels and mucus gland secretion Activation of sneeze and cough reflexes

Colds vs. Allergy: How do I know the difference? Symptoms Allergy Cold Runny Nose Often Sneezing Sometimes Itchy Eyes Rarely Fever Never Aches & Pains Headache Cough Dizziness Hoarseness Recur at a certain time of the year Need for antibiotics No Warning time Symptoms occur after exposure to allergen Gets worse over several days How long does it last? As long as you are exposed to allergen Usually 7 to 10 days

Treatment Antihistamine Decongestants

Allergy Myths Allergies are no big deal… I’m too old to have allergies… I’ll grow out of allergies… If I move they’ll go away… There is not much I can do about allergies…

Cold Myths To be susceptible to a cold, you must have a weakened immune system.

Cold Myths Central heating dries out the mucus membrane of the nose making a person more susceptible to catching a cold. ¹

Cold Myths Becoming cold or chilled leads to catching a cold.

Cold Myths Having cold symptoms is good for you because they help you get over a cold; therefore you should not treat a cold.

Cold Myths Drinking milk causes increased nasal mucus during a cold. ¹

Cold Myths Starve a fever, feed a cold.

References http://www.commoncold.org http://www.virtualneurocentre.com/diseases.asp?did=10 David L. Stewart, MD, MPH Chair, Family & Community Medicine, 29 S. Paca Street, Baltimore, MD 21201, (410) 328-2580