There are three main classes of parasites that can cause disease in humans: protozoa, helminths, and ectoparasites.
Nematodes (roundworms), cestodes (tapeworms), and trematodes (flatworms) are among the most common helminths that inhabit the human gut. Usually, helminths cannot multiply in the human body. Protozoan parasites that have only one cell can multiply inside the human body.
Giardia is arguably the most common parasite infection of humans worldwide, and the second most common in the United States after pin-worm.
Three types of parasites can cause disease in humans. They are protozoa, carried by mosquitos, helminths, such as roundworm, and ectoparasites, for instance lice and bed bugs. Parasites are organisms that live in or on a living host of another species.
Antiparasitic drugs are a group of medications used in the management and treatment of infections by parasites, including protozoa, helminths, and ectoparasites. Antiparasitic drugs include several classes of drugs that cover a broad range of diseases caused by parasites.
Diphyllobothrium latum (the fish or broad tapeworm).
They are the largest parasite known to infect humans, as the adults can reach up to 15 meters in length, with more than 3,000 proglottids.
Blood parasites are malaria plasmodia, microfilaria species, trypanosomes (the causative agents of African sleeping sickness and South American Changas disease) and the causative agents of schistosomiasis of the bladder and the intestine.
Nonpathogenic intestinal protozoa are single-celled parasites commonly found in the intestinal tract but never associated with illness.
Rather than spraying expensive and damaging pesticides on their fields, some farmers turn to parasitoids for help. Parasitoid is the name given to insects that behave like parasites but always kill their host. Farmers take advantage of the fact that certain parasitoids naturally prey on particular species of crop pest.
Parasites that may be found in urinary sediments include Trichomonas vaginalis, Enterobius vermicularis, and Schistosoma haematobium. Parasites and parasitic ova are usually present in urine sediment as a result of vaginal or fecal contamination.
Some common parasites are Giardia duodenalis, Cryptosporidium parvum, Cyclospora cayetanensis, Toxoplasma gondii, Trichinella spiralis, Taenia saginata (beef tapeworm), and Taenia solium (pork tapeworm).
Parasitic organisms are found almost everywhere, from tropical and sub-tropical regions to freezing places like Antarctica. Yet, what every parasite needs is an organism that provides food, shelter, and a place to reproduce. This organism is called a host.
(The infection caused by cysts is called cysticercosis or, when the cysts form in the brain, neurocysticercosis.) These cysts cause few symptoms until the cysts degenerate and the larvae die, triggering inflammation, swelling, and symptoms such as headaches, seizures, personality changes, and mental impairment.
Parasitic infections are one of the most common causes of persistent fever in adults. Prolonged fever caused by parasites causes the patient to have sudden high fevers, lasting in episodes.
People become infected with these diseases when they swallow or have contact with water that has been contaminated by certain parasites. For example, individuals drinking water contaminated with fecal matter containing the ameba Entamoeba histolytica can get amebic dysentery (amebiasis).
The smallest parasitic animals comprise various unicellular, protozoan parasites, some of which are only a few micrometres long. Leishmania donovani and L. tropica, responsible for leishmaniasis in humans, are intracellular parasites, measuring a mere 2 mm (0.08 in) long.
Once infected, a person carries Toxoplasma for life. So far, we don't have a drug that can eradicate the parasite from the body. And there is no vaccine approved for use in humans. Across the world, it's estimated 30–50 percent of people are infected with Toxoplasma – and infections may be increasing in Australia.
Trichinella species, the smallest nematode parasite of humans, has an unusual lifecycle, and are one of the most widespread and clinically important parasites in the world.
Parasites live in other host organisms and depend on them for survival. Parasites that can affect humans include ticks, lice, and hookworms. Without a host, a parasite cannot live, grow, and multiply. For this reason, a parasite rarely kills its host, but it can spread diseases, some of which may be fatal.
Five tiny parasites cause some of the most devastating diseases including malaria, schistosomiasis, leishmaniasis, sleeping sickness and guinea worm disease. These diseases affect 1 in every 18 people in the world.
Gastroenterologist. Diseases of the stomach and intestine. Infectious Disease Specialist. Illnesses caused by infections with bacteria, viruses, or parasites.