What are the types of organisms that can cause parasitic diseases in the human being? Explain at least four such organisms.
What are the different routes that pathogenic protozoans can use to enter the host cells?
What are three methods for establishing a laboratory diagnosis of an intestinal parasitic infection? Explain.
A parasite is an organism lives in and off of a host organism. There are several kinds of parasitic organisms which include protozoans, helminths, ectoparasites, and parasitic infection.
Protozoans are one cell organisms that are free living and multiply within the host in which they are residing. They live in the human intestines, blood or tissue and can be transmitted from one host to another through fecal matter, blood or via insects.
Helminths is a larger multicellular organism that can be seen with the human eye (you need a microscope to see a protozoa). Also unlike protozoans they cannot multiple inside humans.
Ectoparasites are blood sucking artopod (like a mosquito) and are dependent upon animal blood for food. These are often the causes of parasitic infections.
Parasitic diseases are generally transmitted by parasites. Parasites are defined as organisms (both plants and animals) that exist in a non-mutual relationship with another organism, called the host. The parasite benefits from this relationship, while the host is harmed by it. Transmission of parasitic diseases is one way in which the host is harmed.
Parasites do not affect all organisms equally. Some parasites prefer, or are confined to, specific hosts; for example, the plant mistletoe is considered a parasite, but is unable to parasitize humans or any other animal. Thus, organisms which may transmit parasitic diseases to humans are, most likely, going to be parasites that can take a human host.
Organisms that can parasitize humans include nematodes, arthropods, bacteria and protozoa.
Routes that protozoa can use to enter a cell are complex and varied. Two routes that are detailed in one of my sources below include active penetration of the cell membrane under the protozoa's own power, as well as tricking the immune system into engulfing the protozoa and releasing it inside the cell.
Methods of detecting intestinal parasitic infection include
- antibody and serum tests to check for immune response
- the "scotch tape" test (dab a tape-covered microscope slide against the perianal region, and inspect)
- inspection of fecal samples