Integrated Management of Vector Borne Diseases: Case of Chagas Disease

By Satesh Bidaisee, Associate Professor of Public Health and Preventive Medicine, St. George's University
September 20, 2013

Chagas disease is an infectious illness caused by the protozoan Trypanosoma cruzi (T. cruzi) that is primarily found in Central and South America among poor, indigenous populations located in rural areas (CDC-DPD, 2007). The World Health Organization estimates that approximately 100 million people are at risk of infection, with 16 to 18 million being infected, representing a major public health problem for Latin America (Dumonteil & Gourbiere, 2004). This parasitic protozoan is transmitted by Triatomine vectors (Hemiptera: Reduvidae) more commonly known as the “Reduviid” or “Kissing” bug (Aguilar, et. al., 1999). The reduviid bug is haematophagous in nature, however, unlike the mosquito; the reduviid bug does not infect its prey via feeding. Exposure occurs when the organism’s excreta is deposited after feeding, near the feeding site where T. cruzi enters the host’s bloodstream, resulting in infection (CDC-DPD, 2007). Infection results in the acute stage of Chagas disease which usually occurs immediately after infection and may last for weeks or months. Symptoms include swelling of the inoculation site or mucus membrane in which T. cruzi entered. On rare occasion, severe inflammation of the heart or brain and brain lining occurs (CDC, 2007).
The chronic stage of Chagas disease may occur after a prolonged asymptomatic phase. Development of debilitating and, in some cases, life-threatening medical complications will occur among 30% of those infected with chronic Chagas disease. These complications include cardiac arrhythmias, cardiac dilation resulting in poor cardiac output or dilation of the esophagus or colon resulting in difficulty in eating or passage of stool (CDC, 2007). Chagas disease induced cardiomyopathy is the most prevalent form of cardiac disease in Central and South America. Resulting complications from cardiomyopathy include congestive heart failure, cardiac arrhythmias, thromboembolism, apical aneurysm and sudden cardiac death. The reemergence of Chagas disease has made it the leading cause of cardiovascular death in places where Chagas disease remains endemic (Tarleton, et. al., 2007). Chagas disease and its resulting complications create numerous health burdens for a population as the socio-economic contribution by those infected is greatly reduced and is compounded by the costs of treatment for both acute and chronic stages.
In the past thirty years, Chagas disease has gone from being considered a rare to reemerging infectious disease. This has recently been attributed to the complex interaction between biological and social determinants. The social determinants primarily consist of poverty, mass human immigration from endemic areas into non-endemic locations, as seen in the Amazonian region, dramatic landscape transformation and uninhibited deforestation (Aguilar, et. al, 2007).
The integrated approach is not, in itself, novel. Chagas disease, like virtually all other health issues, is associated with poor socio-economic status and poverty (Rojas-de-Arias, 2001). Issues, such as substandard housing and conditions, inadequate access to prenatal care and unsafe blood-transfusion practices are what allow for vector-borne, blood transfusion related and congenital T. cruzi infection. These issues are directly tied to low socio-economic status (Franco-Paredes, 2007). MDGs, such as Goal 3: Promote Gender Equality and Empower Women, Goal 4: Reduce Child Mortality, Goal 5: Improve Maternal Health and Goal 7: Ensure Environmental Sustainability, are measures to counteract the social determinants for Chagas disease (UN, 2008). Virtually all health issues including Chagas disease are affected by problems the MDGs articulate. With the integration of such methods, it will be possible to address and prevent the socio-cultural determinants of Chagas disease, while establishing prevention measures regarding vector control and clinical application.
Such methods involve promotion of gender equality with empowerment to women, elimination of extreme poverty within communities, reduction of child mortality and improvement of maternal health while guaranteeing environmental and community sustainability. The involvement of such methods would be done by involving international, national and local parties who are already focused on achieving the above mentioned socio-economic goals. Educational programs and other intervention methods focused on the above topics would add to the overall effort to control Chagas disease, while establishing knowledge and measures to come closer to obtaining such overall health goals like the MDGs.
The integrated management approach will serve as a multi-tool, similar to a Swiss-Army knife, consisting of multiple components that will be managed by a Central Managerial Body (CMB). The components consist of a Geographical Information System (GIS), Epidemiological/Sociological Data System (ESDS), Entomological Control (EC), Clinical Studies/Applications (CSA) and a Community Education Initiative (CEI). The gathering of preliminary data for multiple areas will be the primary objective for each component so as to establish baseline indices from which to build upon. CMB would then coordinate all findings, determining the best course of action. Like the Swiss-Army knife, the integrated management program will allow for flexibility once baseline data is collected. CMB will then be able to design specific intervention measures, tailored to that community’s specific needs.
Once intervention measures are designed, CMB will then disperse these newly designed measures and interventions back to each component, excluding GIS, for implementation. As each component begins intervention/education measures, GIS will continue to gather data to establish ongoing assessment and evaluations for the each component, as well as for the program overall.

Geographical Information System
Gathering of demographic data such as a census of the population, geographical positioning/dispersion of the population, ascertainment of available infrastructure, database management and geo-spatial analysis are key items of information. As mentioned above, this data is needed to determine the specific needs and disparities for each community to implement interventions uniquely tailored for that community. Even after implementation of interventions and education programs, GIS will continue to ascertain what progress has been made in particular areas. The data will provide CMB with interim assessments that will be used for interim evaluations for each component. This will allow for flexibility regarding unforeseen hindrances or issues of which were not previously considered. Along with ongoing assessment, GIS will compile the ongoing assessment data for a final assessment at program’s end, enabling CMB to measure whether or not program-end objectives were met.

Epidemiological/Sociological Data System
The Epidemiological/Sociological Data System will serve as the component responsible for the gathering of data pertaining to health status and socio-cultural factors (i.e. current knowledge, attitudes and beliefs) regarding Chagas disease. Domicile construction practices, status of domestic animals in domiciles, sanitation practices, etc. are just some of the information to be gathered by ESDS. The health status data, collected via epidemiological practices, will be used to determine community specific risk factors and behaviors for Chagas disease. This will be aided by the establishment of the sociological factors mentioned above. ESDS will then confer this information to CMB where, with the data collected by GIS, it will be used to begin the designing of community specific interventions. Information on the population levels of knowledge, attitudes and beliefs towards Chagas disease will also be collected by testing on knowledge of disease transmission, symptoms, treatment as well as prevention and control strategies. Attitudes and beliefs of the disease will include the population’s awareness of the disease including their specific practices towards treatment, prevention and control.

Entomological Control
The Entomological Control (EC) component will be responsible for assessing the environmental load of the vector. Along with this, EC will also demonstrate and assess the environmental load of the parasite via isolation of the organism in the feces of the vector. Once the vector and parasite loads are determined, EC will then be responsible for control of the vector. This will be done with biological, as well as, chemical control methods. Biological control will include the employment of the entomopathpgenic fungi, Beauveria bassiana based on data of environmental vector load. Chemical control will be conducted via judicious use of pyrethroids throughout the immediate environment in conjunction with the biological approach.

Clinical Studies /Applications
Clinical Studies and Applications (CSA) will have the task of identifying and obtaining positive infections throughout the community using serological surveillance. Among those individuals found serologically positive, a cardiac assessment will be conducted to ascertain any involvement of cardiomyopathy. This will be done among the at risk socio-demographic determinants within the study population who are serologically positive. The aforementioned group will then be managed on a case basis using treatment including follow-up to determine response and referral if indicated.

Community Education Initiative
Immediate education will be provided to those seropositive individuals and household members on case management and treatment as well as information on transmission and symptoms of the disease. Secondary intervention will involve participation of targeted groups such as mothers, children and community leaders. Information dissemination will be designed to address and deficiencies in the population’s knowledge, attitudes and beliefs regarding Chagas disease.

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