1. 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

2. 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.

3. 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.

4. Life Cycle of “Pork” Tapeworm
Humans are usually the primary or definitive host. Pigs are secondary or intermediate hosts

5. Then how did this happen?
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: September 3, 1992DOI: /NEJM

6. 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

7. 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

8. 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

9. The exiting parasite has to be removed manually and carefully.
If the worm gets broken during removal severe burning
and itching result.

10. Disease Prevention Contaminated water can be treated to kill
crustaceans-
Or just filtered through panty hose mesh.

11. 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.        

12. 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.

13. 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?

14. 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

15. 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.

16. 10. 6: Summary: Pathogens that cause parasitic diseases (e. g
10.6: Summary: Pathogens that cause parasitic diseases (e.g. worms) have complex life cycles that include alternate hosts.