Here's why:

* Pathogen: A pathogen is any organism that can cause disease.

* Parasite: A parasite is an organism that lives in or on another organism (the host) and benefits by deriving nutrients at the host's expense.

Many parasites cause disease in their hosts, making them pathogens. Here are some examples:

* Malaria: Caused by a parasitic protozoan called *Plasmodium*.

* Tapeworms: Parasitic worms that live in the intestines of animals and humans.

* Roundworms: Another type of parasitic worm that can infect various organs.

* Ticks: Parasites that can transmit diseases like Lyme disease.

However, not all parasites are pathogens. Some parasites can live in their hosts without causing any harm or even provide benefits. For example, certain gut bacteria are considered parasites but play an essential role in digestion.

In conclusion, while all pathogens are by definition disease-causing organisms, not all parasites are pathogens. But many parasites are capable of causing diseases, making them fall under the category of pathogens.