How to Know if a Bacterial Infection Is Contagious

Bacteria are single-celled organisms that strive throughout our environment. Many are helpful, like those that help treat wastewater and that are used in the manufacture of chemicals, including the antibiotics we use to control them. Bacteria are present in the yeast we use to make bread and the yogurt that we use to help our digestive tracts work better. Less than one percent of bacteria are infectious but they can create problems when they attack our bodies' systems and our systems begin producing antibodies to fight them. Bacteria live by cell division and it is the rate and character of this process as well as the system that is infected help determines whether or not a bacterial infection can be passed from one person to another.

Instructions

• 1

  Check to see how the infection begins. Some bacterial infections, like gingivitis and periodontal disease are not communicable. They spread slowly and their activity is firmly anchored to the affected area, in this case the teeth. They literally have to be chopped and scraped away to eliminate the infection. This bacterial infection is caused not by transmission from person to person but by existing, opportunistic bacteria and dental environmental factors like poor hygiene, smoking and genetic factors.

• 2

  Find out what system the bacteria affects. A bacteria that resides in the respiratory system, like streptococcus is present in exhaled air and sputum. A bacteria that resides in the immune system, like the one that causes leprosy is not particularly transmittable because the skin condition is a result of the body's defense against the infection, not a symptom of the infection itself. Strep is one of the most common bacterial infections because of its rapid growth rate and its ability to transmute into disease-resistant varieties. Mycobacterium leprae, the root cause of leprosy causes the immune system to set off reactions in the nervous system and skin that cause the outward symptoms of the infection, symptoms which have nothing to do with transmission of the condition.

• 3

  Determine whether the illness is a primary infection, like staphylococcus or is actually a secondary result of a bacterial infection like Legionellosis, or Legionnaire's Disease, which is actually a pneumonia resulting from infection of the legonnella bacteria. Staph is an aggressive grower that can be carried on the skin and is easily transmittable from one person to another by touch or in environments like swimming pools. Legonella, on the other hand, grows only in specific conditions like heating and cooling systems and the lungs. It is not easily transmitted between humans.

• 4

  Find out how fast the disease progresses. Some bacteria grow very fast. If they find a vulnerable environment and are destructive, the results can be disastrous. Yersinia pestis, the bacteria known as bubonic plague, attacks the lymph nodes and, within 24 hours, the infection can develop into pneumonic and septicemic plagues, resulting in death. Outbreaks of the plague have wracked Asia and Europe since the 14th century. Investigation of the diseases known collectively as plague and the bacteria that cause them provided the basis for the science of bacteriology and the study of hygiene and immunology.

• 5

  Check with your health care professional to find out whether and when a bacterial infection is contagious. Red, blotchy skin or blotchiness in the mouth or throat may be a virus or it may be strep. Itchiness, sensitivity or soreness may indicate a "yeast" infection. Vomiting, diarrhea or nausea may indicate a bacterium like salmonella or e. coli is at work. Your doctor can tell you whether they are contagious, when and for how long.