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Chagas Disease
Tabitha MartelEpidemiology
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
Chagas Disease
AcuteFever
SwellingHeart/brain/lining
death
ChronicHeart abnormalities
Dilated heart/esophagus/colondeath
Months-life
Weeks-monthsWHO?
Residents of north, south & central America and Mexico in poor housing conditions especially un rural areas
DiagnosisObservation via blood smear
(acute)Agent Isolation
TransmissionInsect
TransfusionsOrgan transplantFecal-skin contact
Mother-baby
Why?Underdeveloped technology,
resources
PreventionBug Bombs
New housingBetter screening
WhyFriendly environment for the
insect
Chain of infectionPoorly 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