Schistosoma Spp ( Blood Fluke )
There are three
primary species of blood flukes that cause disease. Schistosomiasis
mansoni occurs in Africa, Eastern Mediterranean, the Caribbean, and
South America; Schistosomiasis japonicum is found in Asia; and
Schistosomiasis haematobium is found in Egypt. The disease caused by
these blood flukes infect over 200 million people worldwide, in 71
countries. The widespread distribution and damage caused by this worm makes
it the single most important worm infection in the world today. What keeps
this blood fluke out of the continental United States is only the lack of a
suitable snail host
When eggs are deposited in fresh water, the larvae
hatch quickly and find a snail host particular to their species. After they
invade the snail, this parasite is transformed over the next 1-2 months into
thousands of forked-tail organisms. After leaving the snail, the infectious
larvae swim about vigorously for a few days until they come into contact
with human skin. Now they can attach themselves, discard their tails, and
penetrate the skin.
After burrowing into the skin of humans, these flukes
move through the bloodstream until the male attaches to the wall of a blood
vessel by a sucker on his body. These tiny flatworms (1-2 centimeter long)
typically stay in pairs of a male and a female. The male holds the longer
and more slender female in a deep groove on his body for a life-long
copulatory embrace. Each mating pair produces 300 to 3,000 eggs daily for
the remainder of their 4-35 year life span. After mating, they use their
suckers to move through the bloodstream eventually reaching their site of
attack. Some attack the lining of the intestine or liver, others attack the
bladder, urinary tract, or other pelvic organs. This parasite is increasing,
especially in the rural tropics where there are irrigation farmers.
is usually a self-limiting, but very itchy skin rash immediately after the
parasite penetrates human skin. As the worms migrate to the liver, the rash
disappears and the infected person experiences fever, headache, and
abdominal pain for 1-2 weeks. One to two months after the first exposure,
people with severe infections develop a fever and symptoms that looks very
similar to serum sickness. Other symptoms could include a cough,
arthritis-like symptoms, swollen lymph glands, and diarrhea.
of the illness correlates with the amount of worms invading the body. The
signs and symptoms vary with infecting species, but complications of chronic
disease can be most serious.
There could be a thickening of the intestinal
or bladder wall, blood in the urine, incontinence, dysentery, and
hypertension. Adults could also have blood clots.
The blood fluke produces
an enzyme that destroys the protein in blood. They consume certain amino
acids, especially arginine, from the host's blood, causing a protein
imbalance. Overall, a person infected with blood flukes feels toxic. Where
this worm deposits its eggs, hemorrhage of the intestines, urinary bladder,
or lung can occur, as well as considerable trauma to these tissues, such as
the formation of abscesses. The body's immune defenses will be activated to
destroy this parasite, but by doing so it also causes tissue proliferation
and repair that can lead to cancer. This is the theory that Dr. Hulda Clark,
Ph.D., N.D., discusses in her book, The Cure For All Cancers.
sure of a diagnosis, a laboratory looks for eggs in the urine and stool.
Sometimes, a biopsy needs to be performed. All varieties can cause elevated
eosinophils (a type of white blood cell) on blood tests. A sigmoidoscopic
examination reveals an inflamed colon and signs of hemorrhages. Because dead
eggs may persist in the tissues for a long time after the death of the adult
worms, active infection is confirmed only if the eggs are alive. There may
be available skin and blood tests to detect the presence of an active
It is expensive and difficult to control this deadly disease.
More modern construction of sanitation and water purification facilities
would break this cycle of transmission. There needs to be health education
to keep infected urine and feces out of the water supplies. Often
antihistamines and corticosteroids may be helpful in stopping the more
severe manifestations. The drug praziquantel is effective against all three
species of schistosomes; metrifonate and oxamniquine may be useful for some
species. Many of the drugs effective to kill this parasite are also very
toxic to humans and the environment.