A microbe is a single-celled organism that is too small to see without a microscope. Most microbes are harmless, and some are even beneficial to the human body, but other strains have caused problems since antiquity; evidence of smallpox has been found on Egyptian mummies.
A list of microbes and microbial diseases includes everything from the common cold virus to the human immunodeficiency virus (HIV/Aids).
Where Do Microbes Live?
Microbes live virtually everywhere, including hot springs and lava beds. Some reside in human and animal bodies, working behind the scenes to support metabolic functions. Intestinal microflora aid human digestion, for example.
Bacteria have been around for about 4 billion years.
What Are Microbial Diseases?
Microbial diseases in humans and animals are health problems caused by microbes, usually bacteria, virus, fungi and protists.
Typically, symptoms include a fever, which is an immune response triggered by rogue microbes. Epidemiologists study how microbes relate to the onset of chronic illness.
List of Microbial Diseases
A long list of pathogenic microbes can raise havoc in the human body and cause death. Microscopic invaders stealthily target the brain, central nervous system and peripheral nervous system. Serious mental and physical problems result when bacterial or viral infections attack vital organs that control control voluntary movement, cognitive processing and automatic responses like breathing.
Another vulnerable target is the respiratory system comprised of the lungs, trachea, nose, throat and other organs that help with breathing. Nose hairs and mucosal lining filter out most airborne invaders. However, a weakened immunity can increase susceptibility to viral infections caused by the rhinovirus.
Many types of microbial diseases upset the digestive system comprised of the gastrointestinal tract, including the mouth, esophagus, stomach and intestines, along with accessory organs like the liver and gall bladder. Most digestive disorders are caused by ingesting infectious agents. Certain bacteria and viruses spread through person-to-person contact, too.
Causes of Serious Microbial Diseases
Botulism: This potentially fatal illness is caused by toxins produced by Clostridium bolulinum bacteria. Paralysis starts in the face and then spreads to other parts of the body.
Meningitis: Viruses, fungi, bacteria and protozoa can inflame the membranes protecting the spinal cord and brain. Common symptoms include a stiff neck, headache and light sensitivity.
Pneumonia is a lower respiratory illness often caused by S_treptococcus_ pneumoniae bacteria. Other forms of the disease may be viral, rather than bacterial. Some studies show that pneumonia can increase the risk of developing microbial diseases of the cardiovascular system, leading to heart attacks.
Cholera: The bacteria Vibrio cholerae infects the intestine with toxins, resulting in cramping and watery diarrhea. Dehydration must be treated immediately or the patient can die.
Leprosy is caused by Mycobacteria. Leprosy can lead to blindness and severe, unsightly damage to skin and appendages. Before modern treatment, those with leprosy, then called lepers, were banished to leper colonies. Leprosy is now called Hansen's disease.
Common Microbial Diseases
The common cold is caused by many viruses. Symptoms can include runny nose, sore throat, low fever, congestion, cough and sneezing. Upper respiratory illnesses further include bronchitis, pneumonia, whooping cough and laryngitis, for instance.
Escherichia coli (E. coli) bacteria are found in contaminated food and water. Symptoms of the disease may include diarrhea, bloody stool, vomiting, cramps and fever.
Norovirus is highly contagious. Vomiting and diarrhea are common indicators. The Centers for Disease Control and Prevention indicates that norovirus is the leading cause of foodborne gastrointestinal illness.
Common skin and eye microbial conditions include athlete’s foot and conjunctivitis (pink eye). Depending on the strain, herpes simplex virus causes cold sores on the on the mouth or genitals. Other body parts, including the eyes, may also be affected.
Microbial Diseases Carried by Vectors
Microbial diseases may be transmitted by a vector. For instance, ticks can carry Borrelia burgdorferi, which causes Lyme disease. Rocky Mountain spotted fever can be passed by ticks carrying Rickettsia rickettsii.
Mosquitos can harbor West Nile virus, yellow fever and dengue fever. Hemorrhagic fevers can be transmitted by ticks, mosquitos, rodents or bats.
Microbial Diseases With Antibiotic Resistance
According the Centers for Disease Control, around 23,000 people die each year after contracting an antibiotic-resistant infections. Some antibiotics have no effect on certain types of pathogens. Mutations in a population can make microbes resistant to antibiotics.
Choice of an antibiotic depends on whether the infectious bacteria is classified as gram-positive or gram-negative. For instance, bacteria such as Staphylococcus aureus (MRSA) are gram-positive. Like many other gram-positive bacteria, MRSA bacteria are penicillin-resistant.
- Centers for Disease Control and Prevention: Antibiotic/Antimicrobial Resistance
- Medical News Today: What Are Bacteria and What Do They Do?
- Medical News Today: Infections Could Trigger Cardiovascular Disease
- Centers for Disease Control and Prevention: Norovirus
- Centers for Disease Control and Prevention: History of Smallpox
- Centers for Disease Control and Prevention: Cholera
- A.T. Still University: Introduction to Upper Respiratory Tract Diseases
- Biology LibreTexts: Microbial Diseases of the Nervous System
- Biology LibreTexts: Microbial Diseases of the Digestive System
- Biology LibreTexts: Microbial Diseases of the Skin
About the Author
Dr. Mary Dowd studied biology in college where she worked as a lab assistant and tutored grateful students who didn't share her love of science. Her work history includes working as a naturalist in Minnesota and Wisconsin and presenting interactive science programs to groups of all ages. She enjoys writing online articles sharing information about science and education. Currently, Dr. Dowd is a dean of students at a mid-sized university.