A pathogen is any organism — such as a virus, a fungus, or a bacterium — that causes a disease in another organism. Diseases caused by organisms can range from the common cold to food poisoning to meningitis. They can be spread in many ways, such as by coming in contact with bodily fluids, ingesting undercooked food, or swimming in contaminated water. In some countries, measures have been taken in order to reduce the amount of disease caused by waterborne pathogens. There are also other steps people can take to protect themselves these disease-causing agents.
One of the most common ways a pathogen is spread is through personal contact. Some, such as the virus that causes the common cold, are spread through saliva. Others, such as the Human Immunodeficiency Virus (HIV), can be spread through intercourse or through sharing needles. Disease-causing organisms can also be spread through contact with feces or through unsanitary practices. Keeping up sanitary practices can go a long way to keep you from getting sick and spreading disease.
Water can also be host. Different types of disease-causing organisms can take up residence in fresh water and cause problems in people who drink it. In some countries, the water supply is treated in order to effectively eliminate many of the different organisms that may be present. Even in these countries, should a storm or other disaster interrupt the water treatment processes, contaminated water can be an issue. Boiling water often kills off most pathogens, which is why this is commonly advised if there has been an interruption in water treatment processes.
Viruses and bacteria can cause a wide range of diseases. Chicken pox, for instance, is caused by a virus, and some types of the E. coli bacteria cause food poisoning. Many times, fungi that cause disease affect plants, but there are some that can affect humans, such as ringworm, athlete’s foot, and oral thrush.
Another interesting organism that acts as a pathogen is an amoeba called Naegleria fowleri, which can be found in many areas, including fresh water supplies. It can travel up the nose of a person swimming in contaminated water and eventually make its way to the brain. There, it starts to destroy brain cells and causes primary amoebic meningoencephalitis (PAM). It is fatal to most victims, but infections are very rare.