Final answer:
The statement that all pathogens known to infect humans have been identified is false, as new pathogens are continually being discovered. Different types of pathogens, including bacteria and viruses, cause various human diseases, and vaccines are crucial in preventing the spread of some viral infections.
Step-by-step explanation:
The statement that all pathogens known to infect humans have been identified is false. Despite significant scientific advancements, new pathogens continue to be discovered, and there are likely many that remain unidentified due to limitations in detection technologies, undiscovered reservoirs, and the constant evolution of microorganisms. Diseases caused by unknown pathogens can emerge at any time, as seen with recent outbreaks of diseases caused by novel viruses. This underscores the importance of ongoing research in pathogen identification and infectious disease surveillance.
Several types of pathogens such as bacteria, viruses, fungi, and protozoa can cause diseases in humans. For example, the common cold is caused by rhinoviruses, which are a type of virus, and athlete's foot is caused by dermatophytes, which are a type of fungus. Immunization can sometimes prevent transmission of viral pathogens, highlighting the role of vaccines in controlling infectious diseases.