What makes diseases contagious

If they do, is it because they're contagious? Or because they're infectious? What exactly is the difference? The crux of the distinction is this: contagious diseases are spread by contact, while infectious diseases are spread by infectious agents.

So, if contact with your sniffling coworker results in your developing the sniffles, your coworker's sniffles are contagious.

If your coworker's sniffles are caused by allergies, you can't catch them because allergy symptoms aren't contagious. Infectious sniffles are sniffles that are spread by infectious agents; an infectious agent is the thing that gets you sick, usually a virus or a bacteria.

Anything contagious is always automatically infectious: if you can catch it from someone, it's being passed to you via an infectious agent. But the reverse isn't true. Just because something is infectious does not mean it's contagious. Food poisoning is a good example of something infectious but not contagious: food can be contaminated with a bacteria that makes you sick, but you can't give your food poisoning to someone else just by shaking their hand or even giving them a kiss. Both these words are also used figuratively, often in much happier contexts.

In addition, some infectious diseases may become silent, only to appear again in the future — sometimes even decades later. For example, someone who's had chickenpox may develop shingles much later in life. Prepare food safely. Keep counters and other kitchen surfaces clean when preparing meals. Cook foods to the proper temperature, using a food thermometer to check for doneness. For ground meats, that means at least F 71 C ; for poultry, F 74 C ; and for most other meats, at least F 63 C.

Also promptly refrigerate leftovers — don't let cooked foods remain at room temperature for long periods of time. Mayo Clinic does not endorse companies or products. Advertising revenue supports our not-for-profit mission. This content does not have an English version. This content does not have an Arabic version. Overview Infectious diseases are disorders caused by organisms — such as bacteria, viruses, fungi or parasites. Request an Appointment at Mayo Clinic. What are superbugs and how can I protect myself from infection?

Share on: Facebook Twitter. Show references Facts about infectious disease. Infectious Disease Society of America. Accessed May 29, Jameson JL, et al.

Approach to the patient with an infectious disease. In: Harrison's Principles of Internal Medicine. New York, N. Clean hands count for safe health care. Centers for Disease Control and Prevention. Kumar P, et al. Infectious diseases and tropical medicine. In: Kumar and Clark's Clinical Medicine. Philadelphia, Pa. Infected children have a few days of high fever fol.

Measles rubeola is a highly contagious infection of the respiratory system, which is caused by a virus. It does not occur often in the United States, since immunizations have been required since the s.

Chickenpox varicella is an infectious disease caused by the varicella zoster virus that goes away on its own. Infection spreads among humans through fluids from the airways, such as from coughing and sneezing, with non-infected household members at high. Scarlet fever is an infection with a type of bacteria called Streptococcus , which not only causes a throat infection "strep throat" , but also produces a poison toxin causing the distinctive rash of scarlet fever.

Some people are more sensitive. German measles rubella is caused by the rubella virus and spreads among humans through contact with fluids in the respiratory tract.

The development incubation period of German measles is 14—21 days before starting to feel ill, and a rash accomp. Scabies is an itchy skin condition caused by a tiny parasite mite called Sarcoptes scabiei that can live and multiply infest on skin.

They are passed between people by prolonged skin-to-skin contact. Scalp ringworm tinea capitis is a common mild infection of the scalp and hair that appears as scaly spots and patches of broken hair on the head. Caused by a fungus, it is most commonly seen in children. Hand-foot-and-mouth disease is a suddenly appearing acute , self-limited viral disease caused by viruses of the enterovirus group, particularly Coxsackievirus A