Parasites are life forms that subsist wholly off of other organisms. The most widely known parasite across the globe is the regular, uni-cellular virus, undetectable by the human eye. In order to survive and reproduce, viruses need a host, and they can spread from person to person through close contact or exposure to the infected. No one is exempt from infection.
The most common of all viruses is the flu virus, which has probably been existence as long as there has been mankind. The flu has transformed considerably over generations, and changes further each flu season.
Other types of Human parasites
Lesser known types of parasites are listed here:
Protozoa – these single-celled life forms are the most dangerous type of parasite in terms of causing misery and death. Intestinal protozoa are commonly found in water in which there are human and animal feces. The protozoa contaminate the host while a cyst, which is encased in an outer layer.
This protective layer ensures the integrity of the cyst as it makes its way along the digestive system.When it settles in the intestines, it takes up lodging here, feeds and multiplies, causing the condition called amoebic dysentery, common to the tropics, and causing vomiting, diarrhea and dehydration.
Other kinds of protozoa affect the blood or tissue of the host. The best known source of transmission of these is the tsetse fly, which causes sleeping sickness and malaria.
Helminths – roundworms, tapeworms, leeches and flukes belong to this species of parasite and all invade muscle tissue. These can be contracted by consuming improperly cooked pork or beef.
Flukes are flat roundish-shaped worms whose musculature facilitates their movement. Their sucker lets them latch on to the host who is usually swimming in water where the parasites live. One type of fluke enters the bloodstream and travels through the human body until it reaches the liver.
Tapeworm and roundworms reside in the intestines and may actually be seen in the stool. Symptoms of this type of parasite include grinding teeth during sleep and anal itching.
Arthropods – these are parasites may bear viral illnesses and have exoskeletons. Some include crustaceans, insects and arachnids. Mosquitoes, flies, lice, fleas are all arthropods. Certain types of flies cause river blindness and sleeping sickness. Mosquitoes infect humans with yellow fever, elephantiasis and malaria.
Lice and fleas actually subsist on human and animal blood and cause skin irritations, rashes and sores. Some lice cause typhoid fever. Mites are a type of parasite that can plague both plant and animal life. Ticks trigger Lyme Disease tick fever and spotted fever.