Transcript Set 10 Parasite Diseases

Emerging Diseases
Lecture 10:
Parasite Diseases-on the Way Out
or Making a Comeback?
10.1: Overview
10.2: “Pork” Tapeworm
10.3: Guinea Worm Disease
10.4: Parasites as Medicine?
10.5: Relevance
10.6: Summary
10.1: Most Multicellular Parasitic
Diseases Provide Examples of
Gastrointestinal Transmission
• Internal parasitic infections
frequently caused by animals that
are classified as worms.
• The adult animals can be quite
large.
• A heavy “worm load” debilitates
the victim.
• These diseases have been known
since antiquity.
Supposedly this child passed all of these parasites upon receiving worm-killing
medicine. True story or legend? No one knows.
10.2: Pork Tapeworms Were Once Very
Common
• Human infection named as a pig parasite
• Very widespread infection in developing countries but
now rare in industrialized nations.
• May be acquired through undercooked (measly) pork
or via unsanitary conditions.
Life Cycle of “Pork” Tapeworm
Humans are usually the primary or definitive host. Pigs are secondary or intermediate
hosts
Usually found where pigs live close to people
With poor sanitation
And pork is a dietary favorite
Then how did this happen?
Neurocysticercosis in an Orthodox Jewish Community
in New York City
Peter M. Schantz, V.M.D., Ph.D., Anne C. Moore, M.D., Ph.D., José L. Muñoz,
M.D., Barry J. Hartman, M.D., John A. Schaefer, M.D., Alan M. Aron, M.D.,
Deborah Persaud, M.D., Elsa Sarti, M.D., Marianna Wilson, M.S., and Ana
Flisser, D.Sc. N Engl J Med 1992; 327:692-695September 3, 1992DOI:
10.1056/NEJM199209033271004
3 Key points:
Primary host: host in which sexual reproduction
of parasite occurs
Secondary host: parasite grows but does not
sexually reproduce
Parasites can move back and forth between host
species
10.3: Dracunculiasis is Another Parasite
Disease
• Caused by another type of worm: roundworm.
• Dracunculus medinensis: little dragons
because infection is so painful.
• First described in antiquity
• Once widespread-now restricted to some
regions of Africa
• Named “Guinea Worm Disease” by explorers
from Europe
Life Cycle of Dracunculus
Larvae are the
Juvenile forms
Of the animal
Aquatic
Crustaceans
Are the
Intermediate
Hosts.
Humans infected via
contaminated water
Parasites reach
Sexual maturity
In human host.
Grow to large size in
body then crawl to
surface
The exiting parasite has to be removed
manually and carefully.
If the worm gets broken during removal severe burning
and itching result.
Disease Prevention
Contaminated water can be treated to kill
crustaceans-
Or just filtered through panty hose mesh.
Eradication of Another Disease?
• Since 1986, The Carter Center has led the international
campaign to eradicate Guinea worm disease, working closely
with ministries of health and local communities, the U.S.
Centers for Disease Control and Prevention, the World Health
Organization, UNICEF, and many others.
• Guinea worm disease is set to become the second human
disease in history, after smallpox, to be eradicated. It will be
the first parasitic disease to be eradicated and the first disease
to be eradicated without the use of a vaccine or medicine.
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http://www.youtube.com/watch?v=nu3z7mRyLRc
http://www.youtube.com/watch?v=Hn4jNqzGsbo&feature=related
http://www.youtube.com/watch?v=kwdS6rho0yE
http://www.youtube.com/watch?v=u4kQWvUv_Ns
http://www.goldbamboo.com/video-t2086.html
https://www.cartercenter.org/health/guinea_worm/case-totals.html
10.4: Parasites as Medicine?
by Krissi Maarx, eHow Contributor
The tapeworm, a parasite that lives in the intestine, can
grow up to 30 feet in length, according to the
Merck Manual. Tapeworm infection in humans can
cause diarrhea, abdominal pain and release of
tapeworm egg sacs in excrement; but because it
can also lead to weight loss, dieters purchase and
ingest tapeworm cysts in an effort to shed extra
pounds.
History
In 2007, the Los Angeles Times reported that rumors of
tapeworm's weight loss power have persisted for a
century and that druggists supposedly sold them in
pill form during the 1910s. Tapeworm pills were
sold and advertised throughout the early 20th
century, but according to Snopes.com, there's no
verifiable evidence that the pills actually contained
tapeworms. The "poster girl" of the tapeworm diet,
opera singer Maria Callas, supposedly lost 66
pounds from intentional ingestion of tapeworms,
though it's more likely that she was infected from
her love of eating raw meat.
Helminthic Therapy (worm therapy)
Helminthic therapy, or less accurately worm therapy, is an idea derived
from the Hygiene Hypothesis. It is impossible to understand helminthic
therapy without first understanding the hygiene hypothesis. What the
hygiene hypothesis suggests us is that a lack of early childhood exposure
to infectious agents and parasites increases susceptibility to allergic
diseases by preventing the natural modulation of immune reactions.
Does deliberate infection with worms cause the immune system to calm down?
10.5: Relevance
Why are you reading about worm
diseases when they are so rare in
the United States?
Answer One: Watch “Monsters Inside Me” on
Animal Planet and be careful when you travel.
Answer Two: See Next Slide
Raccoon Roundworm-an emerging disease in
the US
Humans are intermediate hosts.
The larvae are very stable in the environment.
Humans may acquire disease from contact with
raccoon feces or with contaminated materials or
from other secondary hosts.
Larvae cause serious symptoms or death in
intermediate hosts.
Your pets can
be carriers.
10.6: Summary:
Pathogens that cause parasitic
diseases (e.g. worms) have
complex life cycles that include
alternate hosts.