There are countless pathogens that differ in name, structure, disease-causing mechanism and malignancy. Against many of these evildoers, there are drugs - either to treat sick people or to protect large populations. Bacteria, viruses and fungi are the first to be mentioned when we list pathogens, but there are more - prions that cause BSE, worms (like the fox tapeworm) and parasites. In addition, there are fleas, mosquitoes and ticks that can be infected with pathogens and transmitted to humans.
Infectious diseases by bacteria
Bacteria are the smallest creatures that are not necessarily harmful. On our skin and in the intestine, there are species that even help us - they make the acid mantle of the skin or decompose the porridge. Others, such as meningococci or pneumococci, are very dangerous for the brain and lungs. Helicobacter, Campylobacter and Salmonella are bacteria that like to upset the gastrointestinal tract. It is also known that tubercle bacteria cause tuberculosis and borreliosis bacteria via ticks as carriers of Lyme disease.
Infectious diseases due to viruses
Viruses depend on other creatures because they can not live alone. Once a virus has lodged in a body cell and replicates, the host cell breaks down. While many viruses cause annoying but not life-threatening diseases: cold viruses and diarrhea viruses such as rotavirus or noroviruses are examples. Other viruses cause glandular fever, influenza, TBE or hepatitis - all diseases that humans can handle most. More threatening are SARS or bird flu - because without a vaccine, humans are pretty helpless.
Infectious diseases caused by fungi
There are also differences in mushrooms: many are harmless, edible or can be used as a remedy. On the other hand, a mold fungus is probably responsible for the legend formation "the curse of the pharaoh". In addition to typical infectious diseases, pathogens can also have a carcinogenic effect - Helicobacter is suspected of causing stomach cancer, molds are said to promote the development of liver cancer, and the association between papillomavirus and uterine cancer is assured.
One of the most common causes of death: infectious diseases
Infectious diseases are among the most common causes of death worldwide, with AIDS, tuberculosis and malaria accounting for the largest number of deaths. Our immune system is always concerned with pathogens, with whom we have contact with the skin, respiration and food - because it usually works well, we get nothing from it.
Only when our immune system is weakened - because of a congenital immune deficiency, stress or other illnesses such as diabetes - pathogens have a chance. If our immune system underestimates a pathogen, a life-threatening sepsis threatens. Rare, very malignant agents are also important as biofuels: anthrax and smallpox are at the center of terrorist interest.