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Chagas Disease. Tabitha Martel Epidemiology November 15, 2007. The Basics. Chagas disease is a parasite contracted through fecal matter from an insect ( “kissing bug”) and the insect bite. Transferred to both animals and humans.
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Chagas Disease Tabitha Martel Epidemiology November 15, 2007
The Basics • Chagas disease is a parasite contracted through fecal matter from an insect ( “kissing bug”) and the insect bite. • Transferred to both animals and humans. • This disease is most commonly found within North, South, and Central America. • It occurs in two phases, acute and chronic. http://www.cdc.gov/chagas/epi.html
Transmission • There are multiple methods of transmission. • Agent -> host via broken skin • Through blood transfusion • Organ transplant • Fecal to skin • Mother to baby (congenital) http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Signs and Symptoms • Acute Phase (a few weeks to a few months) • Sight swelling • Visible sore • Fever • Swollen Lymph nodes • Death (in children) • Swelling of the heart and brain cavity (rare) http://www.cdc.gov/chagas/disease.html
Signs and Symptoms • Chronic Phase • Heart rhythm abnormalities • Dilated heart • Dilated esophagus • Dilated colon • People with compromised immune systems are more susceptible to the reoccurring, chronic, life threatening symptoms. http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Statistical Analysis • As reported by the World Health Organization • 210,000 deaths annually • At risk population:120 Million, 300,000new cases each year • Of the at risk population, 16-18 million people are currently infected. http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Contributing Factors • Poorly made houses • Mud houses, cracks and crevices provide adequate housing for the insect. • Underdeveloped countries do not have the screening processes in place to screen out infected organs and blood http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Web of Causation Why Friendly environment for the insect WHO? Residents of north, south & central America and Mexico in poor housing conditions especially un rural areas Weeks-months Acute Fever Swelling Heart/brain/lining death Diagnosis Observation via blood smear (acute) Agent Isolation Chagas Disease Transmission Insect Transfusions Organ transplant Fecal-skin contact Mother-baby Chronic Heart abnormalities Dilated heart/esophagus/colon death Prevention Bug BombsNew housingBetter screening Months-life Why? Underdeveloped technology, resources
Chain of infection Poorly constructed housing unit provides shelter for insect Insect bites human/House not treated with insecticide Individual becomes infected Individual spreads disease through a blood transfusion/organ transplant
Focus Region • Geographical region of interest • Central America • In an attempt to remain as close to “home” as possible while still maintaining a large number of infected people as well as those at risk. http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Hypothesis • Educate on the importance of “bug bombing” residences. • Break the cycle by eliminating the insects from the housing areas, by creating an unsuitable environment with the help of the insecticide. • By applying insecticide once a month to each at-risk housing unit in rural central America for two years there will be a decrease in Chagas Disease. http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Break it Down… • Exposure: Monthly “bug bombs” • Health-Outcome: Significant decrease of disease after two years of exposure • Dose: One application every month for two years • Time-response: There will be a decrease after two years from the start of the program • Population: People living in Central America, in rural areas in houses less than satisfactory. http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf
Causation Evaluation • Strong correlation between the exposure and outcome. • Chain of infection is broken with the removal of the insect • Similar programs in place currently to urge communities to use insecticide • Once a month applications for two years is adequate time to see a response. • This program is an analytical intervention community trial.
Final Thought • Designated by WHO to be eradicated by 2010
References Chagas Disease. (n.d.). Center for Disease Control. Retrieved November 15, 2007, from http://www.cdc.gov/chagas/ Tropical Disease Resources. (n.d.). World Health Organization. Retrieved November 15, 2007, from http://www.who.int/tdr/diseases/chagas/files/chagas-poster.pdf