Helminths (worms) and protozoa are the two main types of human intestinal parasite and when people speak about parasites, they usually think of worms. Intestinal worms vary a lot in size and can be several meters long, rounded or flat but parasitic protozoa are microscopic and people are generally unaware of them.
There are hundreds of types of worms that infect humans worldwide but the ones most commonly known are roundworms, thread- or pinworms and tapeworms.
Ascaris lumbricoides, a big roundworm that can reach a length of 49cm, is the most common parasitic worm worldwide and some sources estimate that a quarter of the human population is infected by it. Like most parasitic worms, it is thin and whitish in color, with male and female worms able to live in the gut for up to two years.
Threadworm, also known as pinworm, seatworm or Enterobiasis, is one of the most common childhood parasitic worms in the developed world. These worms are small, thin, around one to two mm in length and cause intense itching at night, particularly in the area of the anus.
One of the most feared of the intestinal worms is the long, flat tapeworm with its head full of hooks and suckers that attach to the intestine. The worm is white with a segmented body that reaches lengths of three to five meters and the segments break off and pass out of the body with the feces.
You can see what the some of the worst human intestinal parasites look like by visiting the online gallery at New Scientist magazine.
There are hundreds of types of worms that infect humans worldwide but the ones most commonly known are roundworms, thread- or pinworms and tapeworms.
Ascaris lumbricoides, a big roundworm that can reach a length of 49cm, is the most common parasitic worm worldwide and some sources estimate that a quarter of the human population is infected by it. Like most parasitic worms, it is thin and whitish in color, with male and female worms able to live in the gut for up to two years.
Threadworm, also known as pinworm, seatworm or Enterobiasis, is one of the most common childhood parasitic worms in the developed world. These worms are small, thin, around one to two mm in length and cause intense itching at night, particularly in the area of the anus.
One of the most feared of the intestinal worms is the long, flat tapeworm with its head full of hooks and suckers that attach to the intestine. The worm is white with a segmented body that reaches lengths of three to five meters and the segments break off and pass out of the body with the feces.
You can see what the some of the worst human intestinal parasites look like by visiting the online gallery at New Scientist magazine.
