A parasite is known as an organism, which derives nourishment by feeding on or within another animal. Human parasites types are separated into intestinal and blood borne parasites.

All parasites types can be transmitted in the following different ways:

1.from animals to humans,

2. from humans to humans,

3. from humans to animals.

These organisms are able to live and reproduce within the organs and tissues of infected human and animal hosts. They are often excreted in feces.

Some parasites may be present in food or in water that's why they have emerged as significant causes of waterborne and foodborne diseases. Thus, nowadays parasites are frequently identified as causes of foodborne illnesses ranging from mild discomfort to debilitating disease and possibly death (in the most severe cases).

Parasites are known to be transmitted from host to host through the intake of contaminated water and food and, or by putting into the mouth anything, which has touched the feces of the infected individual or animal.

All parasites types range in size from single-celled and tiny organisms (called protozoa) to the larger, multi-cellular worms (called helminths) which can be visible with naked eye. According to modern medical practice helminths cannot multiply in the human body and are known eventually to clear up without infecting the person one more time. Protozoa have only one cell and can multiply inside the human body. Such parasites are also known as endoparasites ("endo" meaning within) - the organisms living inside their hosts. At the same time other distinguishing parasites types belong to ectoparasites ("ecto" meaning outside) - the organisms living on but not inside their hosts (for example the ones attached to their skin).

Parasites can also be divided into the following parasites types:

1) Obligatory parasites which can survive only in a host and that's why move directly from one host to another. The mentioned process may involve complicated life cycles. This type of parasites includes Trichomonas, Taenia and Trichinella.

2) Temporary parasites which spend only one part of their lives being a parasite and another one - as free-living organisms. This parasites type includes Fasciola hepatica (Liver fluke), Schistosoma, Ascaris and Haemonchus.

3) Facultative parasites which are normally free-living organisms able to infect a host just by an accident. This group of parasites includes some free-living amoeba including Naegleria, Acanthamoeba and Fungi (Candida).

It's necessary to admit that there is a number of distinct symptoms experienced by individuals affected by parasites. They include gas and bloating, constipation, diarrhea, irritable bowel syndrome, sleeping problems, skin conditions, allergies, joint and muscle aches, nervousness, granulomas, chronic fatigue anemia, teeth grinding and other problems of the immune system.

According to the recent North American and European research studies, different parasites types have been found in the bodies of all of those people suffering from various chronic conditions.