Watch out for dangerous microorganisms around us

Donya Betancourt, Pediatrician, drdonya@hotmail.com

Organisms that invade our body live everywhere -- in the air, plants, on and in animals, in the soil and water and every other surface.

They're kept under control by our immune system. But if this system is weakened or you encounter any substance that you have not built resistance to, illness may result.

Bacteria: one-celled organisms visible only with a microscope. Many bacteria prefer the mild environment of a healthy body. Not all bacteria are harmful. Less than 1 percent cause disease, and some bacteria that live in your body are actually of benefit.

For example, Lactobacillus acidophilus is a harmless bacterium that lives in your intestines and helps you digest food, destroys some disease-causing organisms and provides nutrients for your body.

But when infectious bacteria enter your body, they can cause illness by rapidly reproducing, and many produce toxins, powerful chemicals that damage specific cells in the tissue they have invaded. That is what makes you ill.

A virus is a capsule that contains genetic material known as DNA (deoxyribonucleic acid) or RNA (ribonucleic acid). Viruses are even tinier than bacteria.

The main mission of a virus is to reproduce. Unlike bacteria, viruses are not self-sufficient: They need a suitable host to reproduce.

When a virus invades your body, it enters some of your cells and takes over, instructing these host cells to manufacture the parts it needs for reproduction. Host cells are eventually destroyed during this process. Polio, AIDS and the common cold are all viral illnesses.

Fungi, molds, yeasts and mushrooms: are types of fungi. Mushrooms aren't infectious, but certain yeasts and molds can be.

Fungi live in the air, water, soil and on plants. They can live in your body, usually without causing illness. Some fungi have beneficial uses. For example, penicillin, an antibiotic that kills harmful bacteria in your body, is derived from fungi. Fungi are also essential in making certain foods, such as bread, cheese and yogurt.

Other fungi are not as beneficial and can cause illness. One example is candida, yeast that can cause infection. Candida can cause thrush, which is an infection of the mouth and throat in infants, in people taking antibiotics and in people with impaired immune systems. It is responsible for most types of infection- induced diaper rash.

Protozoa: are single-celled organisms that behave like tiny animals by hunting and gathering other microbes for food. Protozoa can live within your body as a parasite. Many protozoa inhabit your intestinal tract and are harmless.

Some protozoa invade your body through the food you eat or the water you drink. Others can be transmitted through sexual contact. Still others are vector-borne, relying on another organism to transmit from person to person. Malaria is an example of a disease caused by a vector-borne protozoan. Mosquitoes are the vector that transmits the deadly parasite, plasmodium, which causes the disease.

Helminths: are among the larger parasites. The word helminth means worm. If this parasite or its eggs enter your body, they take up residence in your intestinal tract, lungs, liver, skin or brain, where they live off the nutrients in your body. The most common helminths are tapeworms and roundworms.

Most of these organisms are not harmful to you. But others can cause infection. Your immune system works to fight off an abundance of infectious agents, and it is a tough task.

Viruses and bacteria are cunning adversaries, constantly seeking new ways to breach your immune system's defenses.

Although some infectious diseases, such as the common cold, might not require a visit to the doctor, others might call for the expertise of a trained professional.

Your doctor or health care provider can perform diagnostic tests to find out if you are infected, the seriousness of the infection, and how best to treat that infection, especially if you have these symptoms or signs: an animal bite, breathing difficulty, a cough lasting longer than a week, a fever of 38.0 degrees Celsius or more, periods of rapid heartbeat, a rash -- especially if it is accompanied by a fever -- swelling, blurred vision or other difficulty seeing, vomiting or unusual or severe headache.

If you think you have contacted an infectious disease, contact your doctor.

Dr. Donya