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