Intestinal Parasites James Gaensbauer MD, MScPH Fellow, Pediatric Infectious Diseases University of Colorado School of Medicine November 12, 2012
Outline Parasites 101 Global Burden of Disease An Evolutionary Perspective A Societal Perspective Global Public Health Response
Parasites 101
Classification of Macroparasites Protozoa--first animals Platyhelminths--flat worms Nematodes--round Acanthocephala--thorny headed Arthropods--jointed feet
Protozoa Platyhelminths Cestodes Trematodes Nematodes Intestinal Entamoeba Giardia Cryptosporidium Taenia (ingested larvae) Diphyllobothrium Ascaris Hookworms Strongyloides Trichuris Tissue/Blood Malaria Leishmania Naeglaria Toxoplasma Taenia/cysticercosis (ingested eggs) Echinococcus Schistosoma Fasciola Clonorchis Trichonella Druncunculus Angiostrongylus Filaria
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The global burden of intestinal parasitic disease
Adverse Effects: Soil Transmitted Helminths Ascaris Hookworm Acute Effects Pulmonary Hypersensitivity Bile duct obstruction Liver abscess Intestinal obstruction Ground Itch Abdominal Pain Chronic Effects Malabsorption Nutritional deficency Growth Retardation Congnitive delay Anemia Cognitive Delay Trichuris Trichuris Dysentery Nutritional deficiency Growth retardation Cognitive Delay
Burden of Intestinal Parasitic Infection Soil Transmitted Helminths Ascaris 1 billi on Hookworms 740 milli on Trichuris 795 milli on Strongyloides 30-100 milli on Cestodes Taeniasis 2.5 million Cysticercosis 100 milli on (50,000 deaths/year) Protozoa Giardia 2% adult/8% children Entamoeba 50 milli on Cryptococcus >1 billi on World Health Organization, 2012; Hotez 2008, CDC 2012
Global Burden of Parasitic Disease: Disability Adjusted Life Year. DALY s by age and cause (millions) Total 0-4 yr 4-15 yr Tuberculosis 34.2 1.6 1.8 Diarrheal Disease 72.7 61.6 3.5 Malaria 34.0 29.3 3.2 HIV/AIDS 58.5 8.9 1.7 Dengue 0.7 0.1 0.5 Intestinal Nematode infections 4.0 0.5 2.7 World Health Organization, 2004
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Intestinal Parasites: Evolutionary Perspective
Intestinal Parasites: Evolutionary Perspective
Immune Response to Helminth infection Parasite Killing Tissue Damage Parasite IFN-γ IL-17 IL-4 Th2 Th1 x IL-10 Immune Modulation Protective Immunity Tissue Healing
Challenges to Vaccine Development: Hookworm Vaccine Schneider, 2011
Hygiene Hypothesis Yazdanbakhsh, 2002
Impact of intestinal infection on immunity Viral HIV Bacterial Cholera Tuberculosis Parasitic Malaria Vaccine Immunity? Cholera vaccine BCG Tetanus Numerous Animal models
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Intestinal Parasites: Societal Perspective Intrinsic link to poverty: Lack of sanitation/infrastructure Contamination of soil Contamination of food/water supply Inadequate education/awareness
Neglected Tropical Diseases Soil Transmitted Helminths Schistosomiasis Lymphatic filariasis Trachoma Onchocerciasis Leishmaniasis Chagas disease Leprosy Trypanosomiasis Dracunculiasis Buruli Ulcer Cysticercosis Dengue Rabies Yaws Echinococcus Fascioliasis
USAID: NTD treatments 2007-2012
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Global Public Health Response Development Related Interventions Improved sanitation Prevention of fecal contamination of food and water supply Hygeine Education Economic development
Meta-analysis of sanitation to prevent Helmenthiasis. Ziegelbauer, 2012
Deworming Programs Periodic Therapy Universal Targeted Selective Frequency Medication Benzimidazoles Vitamin A supplementation Monitoring QuickTime and a decompressor are needed to see this picture.
Deworming Programs: Effectiveness Universal impact varies Greatest improvements occur when: Hookworm is a predominant parasite and anemia is the primary outcome Iron supplementation complements deworming Treatment begins at early age Doses are given 3 times/year vs. 2 in high prevalence areas Primary intervention is Vitamin A supplementation
Future Directions Vaccination Technology New anti-helminth medications Outside the box strategies (eg. Wolbachia)
Questions