Treating Chagas Disease in the Southern Cone of South America

Chagas Disease in the Southern Cone of South America

Goal (What is the Purpose of the Intervention)

The overarching goal of the initiative outlined by the Center for Global Development was the elimination of the insect vector in infested homes in the Southern cone of South America in order to reduce the incidence of Chagas disease.

The issue of interest in this study was the epidemic of Chagas disease in the seven countries (Argentina, Bolivia, Brazil, Chile, Paraguay, Uruguay and Peru) that comprise the southern cone of South America during the last decade of the 20th century.

Facts:

Facts Researched or Known Before Intervention

Epidemiological and biological (disease burden, biological characteristics of disease. If a risk factor is involved, what is the connection of the risk factor to the burden of disease)

Researchers determined early on that people who lived in impoverished rural areas were at greatest risk of acquiring Chagas disease. The impact of Chagas disease in these regions was severe, with an estimated 16 to 18 million people in the Southern cone being infected during the 1990s, resulting in more than 50,000 fatalities each year. Beyond the human toll exacted by the disease, the economic consequences of Chagas disease in these regions was also staggering, totaling nearly three-quarters of a billion dollars in Brazil between 1979 and 1981 alone.

2. Known effective interventions for prevention, control, and treatment

The parasite that causes Chagas disease is well-known and the Southern Cone Initiative to Control/Eliminate Chagas Disease Intervention was launched by the Pan-American Health Organization in 1999 to deploy spray teams throughout the region to treat the homes of more than two-and-a-half million people using pyrethroid insecticides which have long-term efficacy. In addition, blood samples from residents in treated areas are screened for the presence of Chagas disease.

3. History. Previous actions, if any, to address the problem and outcome

Chagas disease and its cause were first described in 1909 by a Brazilian physician, Carlos Chagas, who also determined how the parasite is transmitted. The initial efforts to address the problem were based on these findings and focused on treating affected homes in a truly drastic fashion that included the use of kerosene on the walls of homes and even the use of flamethrowers to treat infected homes. Other early attempts included entirely containing houses in a canvas enclosure and then filling the enclosure with cyanide gas. By the 1940s, more viable interventions were introduced that used synthetic pesticides; although DDT was found to be ineffective against the parasites that causes Chagas disease, two organochlorine insecticides (dieldrin and lindane) were found to be effective in destroying them and several countries in the Southern cone initiated spraying campaigns using these pesticides during the 1950s and 1960s.

4. Relevant environmental facts (geography, urban, rural population)

As noted above, one of the major risk factors for Chagas disease is living in an impoverished, rural region of the Southern cone of South America, but other regions in Latin America are also affected, including northern South America, Central America and Mexico where the parasite is hardier and more difficult to eradicate.

5. Relevant Socio-economic facts (i.e. income, social status, education level,

employment of target population)

Although millions of homes in the Southern cone were treated with pyrethroid insecticides, the overwhelming majority of these residences were occupied by low-income families living in rural regions where agriculture predominates.

6. Relevant cultural facts (i.e. belief systems and informal social norms such as beliefs and norms related to family, illness, religion, etc.)

There are no relevant cultural facts discussed in the case study.

7. Structure and strength of public health and health care delivery system

As discussed further below, the multinational approach used by the Pan-American Health Organization was an effective approach for the delivery of this public health initiative.

8. Relevant political facts

By the 1980s, it became increasingly clear to the political leadership of the nations of the Southern cone that unilateral efforts to combat Chagas disease were ineffective because the disease vectors were capable of crossing national borders with ease, making the need for a coordinated, multinational intervention all the more important. Indeed, the case study emphasizes that "political commitment has been vital to sustained success and has ensured continued vigilance" (p. 6).

9. Relevant facts related to financing the intervention. Known costs of intervention and sources of financing

The money needed to finance the Southern Cone Initiative to Control/Eliminate Chagas Disease Intervention was provided by the individual member states of the Southern cone to treat the homes of more than two-and-a-half million people using pyrethroid insecticides. The initiative has been widely regarded as being among the most cost-effective public health interventions in recent years.

10. Details of intervention (i.e. initial plan, how initially financed and supported, responsibility for implementation. Final cost of implementation if known

All told, more than $400 million was provided by the members states of the Southern cone to finance the Southern Cone Initiative to Control/Eliminate Chagas Disease Intervention

11. Problems encountered during implementation (Technological and logistic? Political? Cultural? Economic? How, if at all were problems overcome

As noted above, unilateral efforts by countries such as Brazil to eradicate the disease vector were ineffective without coordinated actions between Southern cone member states, and "peer pressure" from countries that signed onto the initiative early on was an important factor in compelling the others to cooperate in the intervention.

12. Missing facts, if any, that you feel would be relevant to understand and evaluate efficacy of intervention, Indicate why these facts are relevant

The case study was silent concerning the reactions by the local populaces to the intervention, and did not describe or discuss any relevant cultural factors that may have facilitated or hampered the implementation of the intervention.

4. Discussion and Evaluation

a. Was the intervention discussed in the case a success? Why? Why not? (In evaluating the success of an intervention you should consider questions such as the following: Did the intervention accomplish its goals? Was it cost effective? Did it have any unintended consequences? If there was a favorable outcome, can the outcome be sustained? Is monitoring in place? Was the intervention ethical?

The outcome of this initiative was highly successful. The incidence of Chagas disease in the seven countries that comprise the Southern cone decreased by a staggering 94% overall in just one year. Furthermore, the number of new cases of Chagas disease decrased from a high in 200,000 in 1983 to less than 200,000 by 2000. In addition, the number of fatalities due to Chagas disease was more than cut in half (from 45,000 to 22,000) during this same period.