Eggs of different species of<unk> .<unk> s, also known as helminths, are large macroparasites; adults can generally be seen with the naked eye. Many are intestinal<unk> s that are soil-transmitted and infect the gastrointestinal tract. Other<unk> s such as schistosomes reside in blood vessels. Some<unk> s, including leeches and monogeneans, are ectoparasites thus, they are not classified as helminths, which are endoparasites.<unk> s live in and feed in living hosts. They receive nourishment and protection while disrupting their hosts' ability to absorb nutrients. This can cause weakness and disease in the host, and poses a global health and economic problem.<unk> s cannot reproduce entirely within their host's body; they have a life cycle that includes some stages that need to take place outside of the host. Helminths are able to survive in their mammalian hosts for many years due to their ability to manipulate the host's immune response by secreting immunomodulatory products. All<unk> s produce eggs during reproduction. These eggs have a strong shell that protects them against a range of environmental conditions. The eggs can therefore survive in the environment for many months or years. Many of the<unk> s referred to as helminths are intestinal parasites. An infection by a helminth is known as helminthiasis, helminth infection, or intestinal<unk>  infection. There is a naming convention which applies to all helminths: the ending "-asis" (or in veterinary science: "-osis") is added at the end of the name of the<unk>  to denote the infection with that particular<unk> . For example, Ascaris is the name of a type of helminth, and ascariasis is the name of the infection caused by that helminth.
Parasitic worm
Human parasite
Intracellular parasite
Virus
Disease vector
Pathogenic fungus
Microorganism
Human pathogen