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However, not all parasites want to keep their hosts alive, and there are parasites with multistage life cycles who go to some trouble to kill their host. For example, some tapeworms make some fish behave in such a way that a predatory bird can catch it. The predatory bird is the next host for the parasite in the next stage of its life cycle. [12]
A parasite may evolve to become less harmful for its host or a host may evolve to cope with the unavoidable presence of a parasite—to the point that the parasite's absence causes the host harm. For example, although animals parasitised by worms are often clearly harmed, such infections may also reduce the prevalence and effects of autoimmune ...
Entamoeba histolytica is a pathogenic parasite known to cause amoebiasis, which is the third leading cause of parasitic deaths. [20] It is diagnosed by the assessment of stool samples. [ 21 ] Amoebiasis is caused by the ingestion of food or water contaminated with feces or other bodily wastes of an infected person, which contain cysts, the ...
G. salaris requires fresh water, [2] but can survive in brackish water for up to 18 hours. [5] The parasite is 0.5 mm (0.02 in) long, [2] and cannot be seen with the naked eye, but it can be seen with a magnifying glass. [6] On its posterior end is a haptor, a specialized organ for attaching to the host fish, which has sixteen hooks around its ...
The parasite then replaces the fish's tongue by attaching its own body to the muscles of the tongue stub. [7] The parasite apparently does not cause much other damage to the host fish, [2] but Lanzing and O'Connor (1975) reported that infested fish with two or more of the parasites are usually underweight. [8]
Parasites are organisms which derive sustenance from its host while causing it harm. [2] The study of parasites and parasitic diseases is known as parasitology. [3] Medical parasitology is concerned with three major groups of parasites: parasitic protozoa, helminths, and parasitic arthropods. [2]
A perspective on the evolutionary options can be gained by considering four questions: the effect on the reproductive fitness of a parasite's hosts; the number of hosts they have per life stage; whether the host is prevented from reproducing; and whether the effect depends on intensity (number of parasites per host). From this analysis ...
Trematodiases can be transmitted through food or water that contains larval forms of the parasite. [1] [5] Infections can be transmitted through aquatic organisms which act as a host for the maturity of the parasite. [5] Foodborne trematodiasis is transmitted when organisms ingest contaminated undercooked food including aquatic plants and ...