UNderstanding The Causes Of Worms

UNderstanding The Causes Of Worms
Parasitic diseases are much more widespread than many people realize. These diseases

affect not only impoverished peoples in remote countries but they also can be important

health problems for rich and poor throughout the world, including the United States.

As with other parasitic diseases, roundworm infections are more common in warm climates

than in cooler, temperate areas of the world. Many roundworm parasitic diseases result

from human carelessness and a lack of appropriate personal hygiene and sanitation

measures. Thus, the best solution to the problem rests in preventing these infections

rather than in curing them.

Roundworms, or nematodes, are a group of invertebrates (animals having no backbone)

with long, round bodies. They range in size from those plainly visible to the naked eye to

those several hundredths of an inch long and visible only under a microscope. Most

roundworms or their eggs are found in the soil and can be picked up on the hands and

transferred to the mouth or can enter through the skin. With the exception of Trichinella

spiralis, which causes trichinosis, mature roundworms eventually end up or reside in the

intestine and cause a variety of health problems.

Nematodes are the most numerous multicellular animals on earth. A handful of soil will

contain thousands of the microscopic worms, many of them parasites of insects, plants or

animals. Free-living species are abundant, including nematodes that feed on bacteria,

fungi, and other nematodes, yet the vast majority of species encountered are poorly

understood biologically. There are nearly 20,000 described species classified in the

phylum Nemata.

Nematodes are structurally simple organisms. Adult nematodes are comprised of

approximately 1,000 somatic cells, and potentially hundreds of cells associated with the

reproductive system . Nematodes have been characterized as a tube within a tube ;

referring to the alimentary canal which extends from the mouth on the anterior end, to the

anus located near the tail. Nematodes possess digestive , nervous, excretory, and

reproductive systems, but lack a discrete circulatory or respiratory system. In size they

range from 0.3 mm to over 8 meters.

Most nematodes feed on bacteria, fungi, and other soil organisms. Others are parasitic,

obtaining their food from animals (such as the dog heartworm), humans (such as the pinworm)

, and plants.

Some of the most common parasitic roundworms in humans are: Enterobius vermicularis,

the pinworm that causes enterobiasis; Ascaris lumbridoides, the large intestinal roundworm

that causes ascariasis; Necator and Ancylostoma, two types of hookworms cause

ancylostomiasis; Trichuris trichiura, the whipworm that causes trichuriasis; Strongyloides

stercoralis that causes strongyloidiasis; and Trichonella spirae that causes trichinosis.

Nematodes that do not infect human intestines are not discussed in this fact sheet.

Pinworms generally find a home in the colon, or large intestine. At night, they come

through the anus to lay their eggs on the surrounding skin outside of it. Sometimes the

worms migrate to other areas of the body, such as the urethra (the tube that takes urine

from the bladder outside the body), vagina, fallopian tubes (tubes connecting the ovaries

with the uterus) or pelvis, causing inflammation. After leaving the colon to lay eggs or

migrate to other parts of the body, the worms usually die, so the infection can be

self-limiting. Often, though, children, and sometimes adults, reinfect themselves.

An itchy anus is the most common symptom of pinworms. It is caused by the adult worm

migrating out through the anus to lay eggs. This usually occurs at night, which is when

the itching will be most intense.

Presently there is no way to prevent pinworms. Treatment is not usually needed, though

parents are often concerned about the pinworms in their children. One dose of a

combination of the drugs mebendazole and pyrantel pamoate is usually given and repeated

again 2 weeks later.