A Review of Human Parasites

Human parasites can be found in every part of the world including developed countries like the United States.  In fact, there are a few that are exclusive to the United States.  Understanding and knowing about human parasites can save a person a lot of grief down the road.

E. vermicularis or the pinworm is a nematode.  It is the most prevalent nematode in the United States and has the widest range of population.  With humans being the only known host, there are millions of people affected world wide.  Nearly 30% of all children are infected with pinworm, the most highly reported of all intestinal human parasites in the United States.

The life cycle of the pinworm begins at the anus.  What a way to start life!  You see, the host’s cecum is the predominant living quarters for the pinworms, but at night, the queen wanders down to the perineum and deposits around 15,000 eggs.

It is this aspect of these human parasites that causes the main presenting symptom:  itching!  Irritated areas can be the perineum, perianal region and the vulvar region.  Children who are infected with human parasites can have such irritation that sleep disturbances are common.

Spreading of human parasites of this nature is usually by oral fecal contact due to the constant scratching of the affected region as well as poor hygiene.

Another one of the human parasites you may come into contact with is G. lamblia or giardia.  Many folks have heard of this pear-shaped protozoan and sometimes refer to it as “back-packer’s diarrhea” or “beaver fever.”  This is because of giardia’s water borne nature and its resistance to chlorination as well as its ability to survive in cold mountain waters.

Human parasites like giardia are spread by fecal-oral contamination and are prevalent in poorly sanitized areas and or areas with oral-anal sexual practices.  Cysts  in the host’s feces can remain viable for months.  When the host ingests a cyst, the cyst produces trophozoites which then eventually attach to the intestinal wall.

At this time, dyspepsia, malabsorption and diarrhea occur.  The whole process may take up to four weeks which is a classic sign of giardia.  At this time, nausea, vomiting, malaise, flatulence, cramping, diarrhea, steatorrhea (fat malapsorption) and weight loss may occur.

Prevention of these types of human parasites is to drink bottled water and/or treat non-bottled water through boiling or iodine tablets.  Campers may benefit from using a portable camping filter.  Proper hand sanitation is important to prevent spreading.

Another type of human parasites is the hookworm or N. americanus.  Though human parasites such as the hookworm are less prevalent in developed countries, infection can still take place.

The hookworm has quite an intricate life cycle as human parasites go.  The eggs in soil hatch into larvae and feed on the bacteria in the soil.  At this time, they become the infective form of larvae and can in the right conditions, enter their hosts body via pores, hair follicles and intact skin.

The larvae travel through the circulatory system until they reach the alveoli in the lungs.  They then climb the bronchial tree.  You’re probably wondering how in the heck they end up as intestinal human parasites.  You swallow them with secretions at the end of the bronchial tree.

So, six weeks after the hookworm larvae has penetrated the skin, the mature worms finally end up attached to the intestinal wall where they can take in up to .25 ml of blood per day per worm.  After time, anemia can result.

Human parasites are definitely something one should avoid!  By following good hygiene practices and keeping a healthy colon, you might be able to prevent these human parasites from affecting you!