Germs, or microbes, are found everywhere - in the air, soil, and water. There are also germs on your skin and in your body. Many of them are harmless, and some can even be helpful. But some of them can make you sick. Infectious diseases are diseases that are caused by germs.
There are many different ways that you can get an infectious disease:
- Through direct contact with a person who is sick. This includes kissing, touching, sneezing, coughing, and sexual contact. Pregnant mothers can also pass some germs along to their babies.
- Through indirect contact, when you touch something that has germs on it. For example, you could get germs if someone who is sick touched a door handle, and then you touch it.
- Through insect or animal bites
- Through contaminated food, water, soil, or plants
There are four main kinds of germs:
- Bacteria - one-celled germs that multiply quickly. They may give off toxins, which are harmful chemicals that can make you sick. Strep throat and urinary tract infections are common bacterial infections.
- Viruses - tiny capsules that contain genetic material. They invade your cells so that they can multiply. This can kill, damage, or change the cells and make you sick. Viral infections include HIV/AIDS and the common cold.
- Fungi - primitive plant-like organisms such as mushrooms, mold, mildew, and yeasts. Athlete's foot is a common fungal infection.
- Parasites - animals or plants that survive by living on or in other living things. Malaria is an infection caused by a parasite.
Infectious diseases can cause many different symptoms. Some are so mild that you may not even notice any symptoms, while others can be life-threatening. There are treatments for some infectious diseases, but for others, such as some viruses, you can only treat your symptoms. You can take steps to prevent many infectious diseases:
- Germs: Learn How Germs Work and What You Can Do to Protect Yourself (Mayo Foundation for Medical Education and Research) Also in Spanish
- Infectious Diseases (Mayo Foundation for Medical Education and Research) Also in Spanish
- Coping with Stress during Infectious Disease Outbreaks (Substance Abuse and Mental Health Services Administration) - PDF Also in Spanish
- Taking Care of Your Behavioral Health: Tips for Social Distancing, Quarantine, and Isolation during an Infectious Disease Outbreak (Substance Abuse and Mental Health Services Administration) - PDF Also in Spanish
- Antibiotic Resistance: MedlinePlus Health Topic (National Library of Medicine) Also in Spanish
- Bacterial vs. Viral Infections: How Do They Differ? (Mayo Foundation for Medical Education and Research) Also in Spanish
- Infections in People with Cancer (American Cancer Society) Also in Spanish
- Understand Quarantine and Isolation (Centers for Disease Control and Prevention)
- What's the Difference Between Infectious and Contagious? (Nemours Foundation) Also in Spanish
- From A to Zika: Understanding Emerging Diseases (National Institutes of Health) Also in Spanish
- Recurrent Infections May Signal Immunodeficiencies (American Academy of Allergy, Asthma, and Immunology) Also in Spanish
- Types of Neglected Tropical Diseases (National Institute of Allergy and Infectious Diseases)
Statistics and Research
- FastStats: Infectious Disease (National Center for Health Statistics)
- ClinicalTrials.gov: Communicable Diseases (National Institutes of Health)
Journal Articles References and abstracts from MEDLINE/PubMed (National Library of Medicine)
- Childhood Contagious Diseases (Logical Images)
- Overview of Infectious Diseases (American Academy of Pediatrics) Also in Spanish
- Repeated Infections in Children (American Academy of Family Physicians) Also in Spanish
- What Is a Pediatric Infectious Diseases Specialist? (American Academy of Pediatrics) Also in Spanish