Pathogens can cause a variety of different diseases, with some being more severe than others. Human bodies are nutrient-rich and can provide a pathogen with an ideal environment in which to grow and multiply.
The severity of infections that pathogens cause will vary. Some infections may be mild, while others can be life threatening. For example, the common cold is a mild viral infection compared with the lethal Ebola virus disease.
Diseases resulting from bacterial pathogens include:
- tuberculosis
- meningitis
- food poisoning
- gonorrhea
- typhoid
- chlamydia
Some scientists believe that viruses are not living organisms. Some reasons for this include:
- they do not have cells
- they cannot reproduce without invading a living cell
- they do not actively respond to changes in their environment
Viral infections include:
- influenza
- rotaviruses
- measles
- mumps
- HIV
- coronaviruses that cause the common cold
- SARS-CoV-2Trusted Source, which causes COVID-19
About 300 species of fungiTrusted Source are pathogenic to humans. As with bacteria and viruses, they can have a significant effect on human health.
Fungi cause many different types of illness, including:
- asthma
- skin and nail infections
- lung infections, such as pneumonia
- bloodstream infections
- meningitis
Protozoa are responsible for most protist diseases. Protozoa are single cell microorganisms that feed on other microorganisms, organic tissues, and debris. Protist diseases include:
- dysentery
- malaria
- African trypanosomiasis, or sleeping sickness
Parasitic worms cause many diseases, which includeTrusted Source:
- lymphatic filariasis
- onchocerciasis
- schistosomiasis