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Testing
and Treatment of Chagas Disease
Trypanosomes
of T. cruzi can be found in patients during the
acute phase of Chagas' disease by direct examination
of the blood and later by centrifugation of clotted
blood, xenodiagnosis, and animal inoculation. One problem
is the possible misidentification of parasites in examination
of the blood - for example, the spirochete of syphilis
has been confused with T. cruzi. If T. cruzi
is reported in blood samples, retesting is recommended.
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Xenodiagnosis
Xenodiagnosis
is an effective technique that is akin to the technique
of bloodletting with leeches that dates back to the
Middle Ages. In this test, uninfected vinchucas
are placed in a jar and tucked under the armpit of a
patient suspected of being infected. The vinchucas
are allowed to consume blood for thirty minutes, and
their feces are examined for T. cruzi thirty
and sixty days afterward. One problem with this test
method is obtaining uninfected bugs. This technique
is rarely used
on children, and many adults have are hesitant in being
willfully bitten by vinchucas. However, medical
examinations can be as painful as the symptoms themselves.
Xenodiagnosis can be an excellent examination for determining
strains and populations of parasites.
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ELISA
testing
Indirect
tests that look for T. cruzi antibodies have recently
been devised. However, these tests aren't typically
used during the acute phase of chagas because the immune
system is producing chagasic antibodies. An ELISA test
is similar to that used for AIDS and has been designed
to to detect the presence of T. cruzi antibodies,
though it sometimes does not differentiate T. cruzi
antibodies from those produced in response to other
less harmful or harmless parasites. Chronic patients
should be tested by xenodiagnosis as well as ELISA,
even when ELISA comes out negative, to ensure that the
rate of infection is determined. People without noticeable
signs of chagas who live in chagasic areas should be
encouraged to have an ELISA test. If it comes out positive,
xenodiagnosis is encouraged to help in determining the
nature of the infection and form of treatment. ELISA
testing is offered at a reasonable cost by the Ministry
of Public Health and IBBA in Bolivia.
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Nifurtimox
and Benznidazole
The first
chemical solutions against Chagas' disease with sufficient
activity to justify clinical trials, the bisquinaldines,
were not discovered until 1937. In 1972, the first drug
to combat the disease, nifurtimox, was released for
use in Latin America. Production of the drug was discontinued
in 1997. Nifurtimox is administered as a yellow powder
that a patient is to dissolve in water and drink three
times a day after meals for sixty to ninety days at
a dose of 8-10 mg/kg for adults, 15-20 mg/kg for children
aged one to ten years, and 12.5-15 mg/kg for children
aged eleven to sixteen years. Nifurtimox is readily
absorbed and rapidly metabolize d,
with a peak plasma concentration at one to three hours,
which declines to zero by twenty-four hours. The earlier
the diagnosis is made and treatment initiated, the greater
is the chance that the patient will be parasitologically
cured. Good results can be seen in early treatment,
circulating trypanosomes may disappear, and there may
be a remission of chagasic symptoms. There may be occasional
reversion to a serologically negative state. Negative
side effects include nausea, skin rashes, peripheral
neuritis, bone-marrow depression, weight loss, loss
of memory, and sleeping disorders. Some patients discontinue
this treatment if the side effects are too severe to
tolerate.
Benznidazole
was announced in 1974 and released in Latin America
in 1978. Also a yellow powder, benznidazole, it is taken
in water and is rapidly absorbed and distributed through
the body tissues. Recommended dosage is 5 mg/kg/day
for adults, 10 mg/kg/day for children for sixty days.
It is claimed to be mo re
than eighty percent effective in curing acute and chronic
chagas patients. There is no clear evidence that it
has any advantage over nifurtimox. The efficacy of the
two drugs are similar, though it has been claimed that
benznidazole has less geographic variation in cure rates.
Diverse side effects of benznidazole include vomiting,
peripheral neuropathy, and skin reactions that may include
erythematous light-sensitive skin rashes which can be
severe.
None of
these drugs is ideal, and our ability to control and
treat, let alone eradicate, Chagas' disease is severely
curtailed. The obstacles are formidable on the scientific
side and relate not only to finding trypanosomes that
lyse the parasites in their different stages and differing
strains. There are problems getting the drug to the
vicinity of the in vivo sites of trypanosomes
without destroying human cells.
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Natural
treatments
Therapy
for chagas comes in varying degrees - from controlling
the parasite population in the body to completely eliminating
it. Patients can be treated with Sangre de Drago
(Croton roborensis HBK) which is sold in small
bottles by herbal vendors throughout Bolivia. Though
it is most effective against the symptoms, its parasiticide
properties have not been
verified in the laboratory. Chagasic heart disease can
be treated with three flowers of retama (Spartum
junceum) in maze (steeped in hot water), with
two leaves of of cedron (Lippia triphylla
Kunth). Ingredients may serve as a tranquilizer for
heart attacks. Toronjil (Melissa officinalis
L.) is also used for heart problems.
Restoration
to complete health is an impossible dream for many peasants
who lack the resources to pay for cures. They adapt
through the use of household remedies, herbs, and rituals,
which provide some level of relief and renewal. Until
the problem is addressed by wealthier nations, the simple
products of Mother Earth (Pachamama) remain their
primary source.
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