Infectious Diseases

Infectious diseases are caused by microorganisms, with four germs being the most common in causing health problems: bacteria, viruses, fungi, and parasites. These microorganisms most commonly affect plants and animals, but all living things can be infected. Many of these microorganisms exist both inside and outside the host. Often they are harmless, or even helpful. Other times, the living thing only serves as a carrier. But, under certain circumstances, some microorganisms can cause disease.

These diseases can be transmitted in different ways: from species to species, e.g., from person to person; between different species, e.g., from insects to people; by consuming spoiled food or water; or by indirect contact, by touching something with microorganisms. It is possible to contract the disease through blood transfusion or organ transplant.

Symptoms vary depending on the microorganism, but every infectious disease goes through three stages: incubation, symptom development, and recovery. Some microorganisms can cause mild symptoms, while others can be fatal.

There are treatments for some infectious diseases, but for others, only the symptoms can be treated. Some of the measures to prevent these diseases include vaccination, handwashing, food safety, avoiding contact with wild animals, safe sex, and not sharing objects that could be put in the mouth.

Whether for treatment or prevention, diagnosis is vitally important to curbing infectious diseases. To identify the microorganism causing the disease, a sample of blood, urine, sputum, or other tissue or body fluid is taken and analyzed. To do this, the sample can be analyzed microscopically, cultured, or the presence of antibodies, antigens, or genetic material (DNA or RNA) of the microorganism can be detected.