Project Activities

Chagas disease (American trypanosomiasis) is a parasitic infection in which the causative agent, a flagellate protozoan Trypanosoma cruzi, is transmitted to humans mainly through blood-sucking species of Triatominae (Hemiptera Reduviidae), blood transfusion, and congenital transmission. Among these transmission pathways, vector-born transmission accounts for more than 80% of all transmission to humans. T. cruzi is present in the feces of triatomine vectors, and enters the human body through bites, cuts or scratches on the skin. In 2006, WHO estimated that 7.5 million people were infected by Chagas disease.

Chagas disease is known for its difficulty in diagnosis and treatment. Chagas disease has two stages  an acute phase and a chronic phase. The disease has a 5-15% mortality rate in the acute phase, especially among young children. Acute cases are recognized only in an estimated 1-2% of all individuals acquiring the infection, and the infection is detected only by serological or parasitological tests, to which many of the population in high-risk areas do not have access. Vaccines against T. cruzi are not available, and curative treatment of the infection is possible only during the early acute phase using one of two drugs  nifurtimox and benznidazole. Ten to 40% of infected individuals will develop severely debilitating lesions of organs such as the heart and digestive system.

(For details on Chagas disease, please see section "Information on Chagas Disease" for related links.)

Triatoma dimidiata (right) and Rhodnius prolixus (left)

Typical houses infested with R. prolixus

Typical houses infested with T. dimidiata

Over 100 species of triatomines are present in the Americas. While the majority of them have only sylvatic habitats, there are five main species which have adapted to the human environment and transmit Chagas disease: Triatoma infestans, Rhodnius prolixus, Triatoma dimidiata, Panstrongylus megistus, and Triatoma brasiliensis. In Central America, R. prolixus and T. dimidiata are the principle vectors to transmit Chagas disease.

With its high natural infection rate and capacity to reach high densities, R. prolixus is a much more efficient vector than T. dimidiata in transmitting T. cruzi. The prevalence of human infection with T. cruzi is three to four times higher in villages infested with R. prolixus than in areas infested with T. dimidiata. R. prolixus is an exclusively domestic species in Central America, and is almost exclusively found in thatched-roof houses, thus its elimination is feasible. T. dimidiata, a native species of Central America, mainly infests crevices in the mud-walls of houses and peri-domestic mud-walled structures such as chicken pens, and to a lesser degree infests houses with other structures such as wood or concrete walls. T. dimidiata is known to have domestic, peri-domestic, and sylvatic populations, and cannot be eradicated from the region, thus the reduction of the domestic infestation rate is a feasible goal.

* Geographic distribution of R. prolixus and T. dimidiata in Central America in 2008(PDF/61KB).

In 1997, Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua, and Panama launched the Central American Initiative (Iniciativa de los países de Centroamérica: IPCA). In 1998, the 51st World Health Assembly acknowledged IPCA, and resolved to eliminate Chagas disease transmission in the Americas by the end of 2010. IPCA set three objectives: (1) elimination of Rhodnius prolixus; (2) decreased house infestation by T. dimidiata; and (3) elimination of transfusional transmission of T. cruzi.

Elimination of an introduced triatomine species, R. prolixus, and reduction of domestic infestation of a native species, T. dimidiata, have been the two main strategies to interrupt vector transmission of Chagas disease in Central America.

* Central American Initiative and other regional initiatives to combat Chagas disease(PDF/44KB).

International cooperation agencies and NGOs joined to support IPCA and the control of Chagas disease. Among them, JICA has so far the largest contribution in Central America. JICA launched a vector control project in Guatemala in 2000, and sent Japanese long-term and short-term experts and Japan Overseas Cooperation Volunteers (JOCVs) as well as materials (insecticide, spray pumps and vehicles) to the project site. Pan American Health Organization (PAHO), the secretariat of IPCA, provided technical support to the project via regional meetings, seminars, and the dispatch of evaluation missions. Phase 1 of the JICA project was launched in Honduras and El Salvador in 2003. IPCA and PAHO acknowledged the rapid progress of the JICA project. JICA launched phase 2 of the project in El Salvador and Honduras in 2008. JOCVs are currently working on Chagas disease control in El Salvador, Honduras and Panama.

* Current (2008) geographic coverage of JICA cooperation for Chagas disease control(PDF/62KB).

Chagas disease is one of the most serious parasitic diseases in El Salvador. PAHO estimated that about 232,000 persons are infected with Chagas disease, and about 2,500 persons became infected in 2005. The seroprevalence of Chagas disease among blood donors was 2.1-3.3% between 2004 and 2007, which is the highest in Central America, and also higher than other screened diseases such as HIV, Hepatitis B and C, and Syphilis. Around 100 acute cases of Chagas were reported annually between 2005 and 2007.

* Seroprevalence of Trypanosoma cruzi among blood donors in Central America 1998-2006(PDF/35KB).

* Seroprevalence of Trypanosoma cruzi among blood donors in El Salvador 1998-2007(PDF/35KB).

The Chagas disease vector, T. dimidiata is present in all 14 departments, and a baseline survey between 2003 and 2008 demonstrated an average of 14.1% of houses were infested with T. dimidiata. Phase 1 of the JICA project initiated vector control activities, and over 200,000 houses were treated with pyrethroid insecticide.

* Infestation index (percentage of infested houses) of Triatoma dimidiata in El Salvador 2003-2006(PDF/49KB).

* Infestation and dispersion index of Triatoma dimidiata, and number of sprayed houses in 14 departments of El Salvador 2003 – 2008(PDF/15KB).

Phase 2 of the JICA project will further advance Chagas disease control in El Salvador. The first phase of the JICA project targeted three western departments (Ahuachapán, Santa Ana, and Sonsonate), and implemented a baseline survey and vector control activities between 2003 and 2007. The second phase, which was launched in March, 2008, aims at maintaining a low level of infestation in the western departments, via establishing an effective surveillance and control system, and to expand Chagas disease vector control activities in the Central and Eastern regions. Phase 2 targets seven departments, which includes four newly added departments (La Libertad, Morazán, San Miguel, and Usulután).

* Map of the project Areas of the JICA phase 2 project in El Salvador(PDF/78KB).

One of the key strategies of phase 2 is the establishment of the Participatory Chagas Disease Monitoring (PCDM) system in areas where significant reduction of risk in the Chagas disease transmission is attained. The PCDM system includes three principal functions: (1) detection and reporting of bug infestation as well as acute cases; (2) stratification of high-risk areas and resource mobilization, and; (3) response to the re-infestation and treatment of the detected cases (see the figure below). The information on bug infestation and acute disease cases should be reported to the closest health centers or posts. The local health centers can detect high-risk areas based on the reporting, obtain necessary resources, and organize an institutional response such as insecticide spraying of positive houses, treatment of patients, and health promotion. The phase 2 project aims at, as an initial step, establishing the PCDM system in the six pilot areas in three departments (Ahuachapán, Santa Ana, and Sonsonate) in the Western Region. Then the PCDM system will be introduced in high-risk areas outside of the pilot areas in the Western Region under an initiative by the Ministry of Health of El Salvador.

* Concept of Participatory Chagas Disease Monitoring System(PDF/18KB).

* Pilot Areas to introduce PCDM system(PDF/209KB).

As part of the establishment of the PCDM system, the project activity includes the implementation of a combined entomological and serological study to identify the possible threshold of T. dimidiata domestic infestation rate. The threshold below which the domestic infestation rate of T. dimidiata should be controlled has not been scientifically identified. This situation makes it very difficult to correctly determine whether or not transmission of Chagas disease through T. dimidiata is eliminated. This study analyzes the relationship between the domestic infestation rate of T. dimidiata and seroprevalence of children under 16 years-old.

(For detail, please see the "3. PROJECT NEWS")

* Map of study areas to determine threshold of the domestic infestation rate of Triatoma dimidiata(PDF/545KB).

The other key strategy is strengthening of education and health-promotion activities for Chagas disease control. The phase 1 project developed a variety of educational materials such as animated and educational videos. The phase 2 project further strengthens the educational activities via collaboration with the Ministry of Education of El Salvador, development of educational materials, as well as continues utilizing fully the educational products of phase 1.

(For detail on the educational materials, please see the section "Educational Materials Produced by the Project").