The seven main causes of infection are:
- Viruses: These tiny organisms can replicate only inside the cells of a living host. Examples include the common cold, influenza, HIV, and COVID-19.
- Bacteria: These single-celled organisms can cause a wide range of infections, from skin infections to pneumonia. Examples include E. coli, Staphylococcus aureus, and Streptococcus pneumoniae.
- Fungi: These microscopic organisms can cause infections in the skin, lungs, and other organs. Examples include Candida albicans (yeast infections) and Aspergillus fumigatus (aspergillosis).
- Parasites: These organisms live inside or on other organisms, feeding off their host. Examples include malaria, tapeworms, and hookworms.
- Prions: These are infectious proteins that can cause serious brain diseases, like Creutzfeldt-Jakob disease. They are very rare, and the exact mechanism by which they cause disease is still being studied.
- Protozoa: These single-celled organisms can cause a variety of infections, including giardiasis and toxoplasmosis.
- Helminths: These are parasitic worms that can infect the intestines, lungs, and other organs. Examples include roundworms, tapeworms, and hookworms.
These pathogens can enter the body through various routes, including:
- Contact with an infected person: This can happen through direct contact, such as shaking hands, or indirect contact, such as touching a contaminated surface.
- Contact with contaminated food or water: This is a common way to get food poisoning, which is caused by bacteria, viruses, or parasites.
- Insect bites: Mosquitoes, ticks, and other insects can transmit pathogens to humans.
- Exposure to contaminated soil: This can happen through contact with soil that contains bacteria, fungi, or parasites.
Knowing the different causes of infection can help us better understand how to prevent and treat these diseases.
