Infectious and infectious diseases.

Although the words infectious and contagious are often used synonymously to describe diseases, they actually mean two very different things.

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Simply put, an infectious disease is an infection. That is, when a microorganism enters your body and you feel comfortable. For bacteria or fungi, this means dividing and growing new cells at an exponential rate.

Viruses, for their part, have an additional obstacle: they invade human cells and take over their control centers in order to earn more money for themselves.

Infectious and non-infectious

While all infectious diseases are infectious, not all infections are infectious. Tetanus , for example, can cause an infection, but a person with tetanus cannot pass it on to other people .

Bacteria live in dirt and dust and enter your body through abrasions such as cuts, scrapes, or punctures. Although the pathogen can cause very serious infections and diseases in humans, it will almost certainly never cause a global pandemic.

Invisible infections

Infectious disease

An infectious disease is contagious. The effect is external.

If someone gets sick, they can get sick and pass the pathogen, be it a cold, virus, or other disease-causing agent, to the next person. This can lead to small isolated outbreaks or full- blown pandemics .

An example of this occurs every year in the United States from approximately October to May: the flu . Because influenza viruses are spread from person to person and through infected objects, the virus spreads everywhere.

For every person who gets the flu, one or two more people are likely to become infected if they are not immune.

The rate at which a pathogen spreads is called the basic reproductive number, or R0 (pronounced R-zero ), and it depends on many factors, including how the microbe reaches new people.

Transmission methods

Nature has no shortage of creativity in how pathogens can move through a population. These are just a few of the most common methods for spreading germs.

In a personal meeting

Pathogens that are transmitted from one person to another can be transmitted in different ways, for example, through respiratory droplets such as coughing or sneezing, sexual activity, contact with blood, or from mother to baby during pregnancy, childbirth or breastfeeding. .

An active disease in which you sneeze or cough a lot can give the germ more room to spread, but you don't have to have symptoms to be contagious. You don't even have to be around.

For example, measles can be transmitted four days before the characteristic rash develops, and the virus can remain airborne for two hours after leaving the room .

Cartoon vector

Some microbes are not spread from person to person, but rather through a more indirect route from person to carrier. Mosquitoes cause millions of diseases each year and are one of the most common vectors of infection in the world.

For example, malaria is transmitted by mosquitoes, which become infected after a sick person bites and then transmit the parasite to the next person who is bitten .

The presence of mosquitoes is not enough to spread disease. They are just a passage. If there are no people with malaria nearby, mosquitoes cannot spread the disease.


Some diseases don't even need a living thing to infect new people, just a surface to hold onto.

One of the reasons hand washing is so important to prevent illness is because we touch so many objects every day that are full of germs that can make you sick.

During cold and flu season, absentmindedly wiping your runny nose and then touching the doorknob is a common way for viruses to jump to the next person.

When you walk up to them to open the same door, viruses enter your skin and wait for a chance to enter your body, often when you touch your nose or rub your eyes.

Fecal-oral and alimentary

One particularly dangerous route for the spread of microbes is called fecal-oral, that is, through something contaminated with feces.

For example, a doorknob is contaminated by a person who has not washed their hands after using the bathroom. It could infect another person who could touch the same doorknob and then put their hand in their mouth.

Another method of infection is food poisoning , caused by ingesting toxins, usually from spoiled food. Spoiled food can contain toxins, parasites, and bacteria.

The most common bacteria that spoil food and cause illness in humans include coli, Staphylococcus aureus, Salmonella, botulism, Campylobacter, cholera, and listeria .

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