Infectious diseases are caused by microscopic germs (or organisms) found in our air, water, food and other animals. Once you come into contact with one of these organisms, and your body isn’t able to fight it off, you can get sick. These organisms are:
- Viruses — which use your own cells to multiply; responsible for the common cold, flu, and AIDS}
- Bacteria — release chemicals that may make you sick; strep throat, tuberculosis, urinary tract infections
- Fungi — primitive plants; can affect your lungs, nervous system and skin (athlete’s food, for example)
- Parasites — animals that live off of other living things; can cause malaria, West Nile
Emerging infectious diseases are those that are new to humans, they’ve been known for some time but becoming more common, or are making a comeback (like tuberculosis).
Examples of emerging infectious diseases include:
- Ebola — virus was discovered in 1977
- HIV/AIDS — virus isolated in 1983
- Hepatitis C — first identified in 1989
- Influenza A (H5N1) — isolated in humans in 1997
- West Nile — virus first identified in 1937
E. coli— first detected in 1982
- Borrelia burgdorferi (causes Lyme disease) — identified in 1982
How infectious diseases spread
People, animals, insects or objects can spread infectious diseases:
- Person to person — touching, sneezing or coughing, kissing, having sexual contact, through a blood transfusion.
- Animal or insect to person — disease spread from the bite or scratch of an infected animal or insect (e.g. lice, ticks, mosquitoes, fleas).
- Pregnant mother to unborn/newborn baby — some germs can be passed via the placenta or vagina during childbirth.
- Food and water — a germ in a single contaminated source can spread to many people this way (e.g. the
- Object touched by an infected person — germs can linger on such things as a drinking straw, shower floor, doorknob or faucet (for example, if you use a doorknob that has germs from someone with a bad cold, and then touch your mouth or eyes).
Symptoms and protection
Anyone can get an infectious disease, but it’s easier to get sick if your immune system isn’t strong enough to fight it off. And it can affect one part of your body (like one organ) or all of it.
Symptoms depend on the infectious disease but there are some common ones, including fever and fatigue, muscle aches and diarrhea.
Here are some simple steps you can take to help protect yourself and others:
- Wash your hands — especially after using the bathroom and before handling food.
- Keep kitchen countertops, utensils and gadget clean, and cook and store food properly.
- Limit the amount of times you touch your eyes, nose or mouth.
- Stay home when you’re sick.
- Use condoms when having sex.
- Get vaccinated.
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