Foreign cells can cause harm to a host organism, but not all colonization is harmful. Antibiotics can disturb the balance of colonies, causing fungal or yeast infections. Parasites can harm humans gradually, and infections often require medical attention. The body can fight off some infections, but others require antiviral drugs.
An infection is caused by the invasion of foreign cells, such as bacteria in humans that cause damage to the host organism. Generally the host organism is considered “colonized” by cells that do not belong to it. These foreign cells must be harmful to the host organism for colonization to be considered an infection.
There are many cases of living creatures benefiting from colonization by other cells. Two distinct organisms can have a symbiotic relationship with each other, which harms neither. Alternatively, a colony of cells (or parasites) may have no effect on the host organism, but may benefit the colony. For example, staph and strep bacteria are commonly found on the skin of humans and most mammals. Unless the bacteria is making the person or animal sick, this is not an infection.
There are many different types of infectious agents. Not only bacteria, but also viruses, parasites and fungi can cause problems for a host organism. Sometimes these non-host cells actually work together to prevent the infection from occurring. For example, if you have a sore throat, you are often given antibiotics. This is great for killing strep cells. The problem is that humans also have a certain amount of fungal cells, called yeasts, on their bodies.
When normal skin bacteria and yeast are present together, they tend not to pose a problem for people. They fight each other instead of fighting the human body, so the levels of each colony remain balanced. When antibiotics are suddenly introduced into the mix, you can kill the good bacteria, which keep yeast levels in check, as well as the infectious bacteria. This can result in a fungal or yeast infection, as the colony balance has been disturbed. Antibiotics can also cause stomach upset or diarrhea, as beneficial bacteria also live in the intestinal tract and can be killed by them.
Other infections occur when a foreign colony is suddenly introduced. People who travel to countries where drinking water contains a high level of parasites can introduce specific parasites into their body. Traveler’s diarrhea tends to be caused by the body receiving parasitic or bacterial agents. Alternatively, parasitic agents such as tapeworms can harm humans gradually by growing inside the body. This would be considered a parasitic infection.
Occasionally, an initial colonization of other organisms causes little harm to the host. Tapeworms can live for years in humans without humans showing any kind of symptoms. However, tapeworms eventually cause harm, so when they are discovered, people usually take special medications to kill the worms so that the tapeworms are eliminated.
In most cases, the key to understanding infection is the concept of “harm to the host”. Whether the damage is currently induced by the colony or an eventual cause of colonization, infections often require medical attention. The only exception to this occurs in situations where people are colonized with transient viral colonies. Generally, in healthy people, the body works to fight off infection, such as the common cold, and is often successful. Some viruses such as HIV are not fought off successfully by the body and require large doses of antiviral drugs to prevent or delay the virus from causing significant damage. Some viruses remain resistant to treatment, such as West Nile virus and Ebola virus.
Protect your devices with Threat Protection by NordVPN
