67. Improved housing to fight the spread of chagas’ disease

Chagas’ disease is one of the more serious diseases in Latin America, with some 15 to 20 million people infected, 10% of whom will develop chronic Chagas’ disease. The disease has an asymptomatic acute phase right after infection, and a chronic phase that only appears 15 to 20 years later. The chronic phase affects the heart, oesophagus, lower intestine, and peripheral nervous system.

The disease occurs mainly in rural areas, but is spreading to the cities through rural migration and through blood transfusions. The loss of work productivity is important, and rural migrants to cities can be refused employment if they are infected.

The disease is caused by a parasite (Trypanosoma cruzi), which is transmitted by the blood-sucking insect Triatoma infestans. The insects infest and breed in cracks in the walls of homes, in thatched roofs, and in cracks and spaces between wooden boards. They thrive in dark, poorly ventilated, humid environments. They also live behind furniture and wall hangings as well as in chicken coops and other animal shelters. Animal reservoirs of the vector are also common.

Because of the absence of effective drugs or vaccines, the disease must be controlled through preventive measures, such as controlling the vector insects inside people’s houses. In Paraguay, a research team has studied the effects of two types of intervention in rural areas:

· Spraying, using the insecticide Deltametrine; and
· Housing improvements to create a hostile environment for the insects.

The housing improvements consist of modifying the existing structures in each house using improved materials to ensure smooth, flat, crack-free inside and outside walls and ceilings. Four main methods are used:

· Plastering the walls and filling the joints between wood boards;
· Smoothing the roof and ceiling;
· Using light-coloured paint on the walls to help in the detection of insects;
· Improving ventilation and light through better doors and windows.

Some examples of effective techniques used for housing improvement include:

Plastering and painting brick walls; plastering adobe and wattle walls using nails or small twigs to hold the plaster;

· Using bamboo cane as supports for the ceiling, which is then plastered with a cement and soil mixture;

· Finding the best natural locally-available additives to add to paint (such as cactus juice) to prevent cracking;

· Finding the best plaster combinations and proportions (cement, sand and lime) to prevent cracking;

· Incorporating a window in the kitchen for the smoke to escape; bamboo canes in a netlike structure in the window can keep insects out while letting smoke escape;

· Mosquito netting can be used to keep insects out of the house.

Most of the modifications can be done using locally available, low-cost materials.

The use of insecticides is a helpful and fast solution, but it can be too costly for rural people and is not permanent. However, it does provide 2-3 years of protection for the family while other interventions are being implemented.

The advantages of the housing improvements over building new houses are:

· The improvements respect the original home, lifestyle, materials, and techniques of the inhabitants;

· Beauty and variety are maintained, and changes are more easily accepted;

· The value of the house increases; pride in their work increases the self-esteem of the inhabitants;

· New houses are often not adapted to the needs of the inhabitants.

These interventions adapt and combine known technologies to solve a problem affecting both health and housing quality. Results of the research show that although the interventions can help reduce the incidence of Chagas’ disease, they do not provide total control of the insect vectors. The key to their success is community involvement and cooperation from the outset. Because of the late onset of symptoms, Chagas’ disease is not taken seriously by rural communities, who are more concerned with day-today survival than with a problem that will only emerge 15 to 20 years later. Strategies to combat the disease must be part of a holistic approach to community health, including interventions on such immediate concerns as maternal and child health and treatment of diarrhea and other infections. They must be an integrated part of general development initiatives undertaken by the community and incorporate other community goals and cultural values.

Potential users

Communities and organizations working in the areas of health and housing throughout Latin America. In Paraguay, the idea has been “bought” by the Ministry of Health and the Council on Housing.

Cost and availability

During the course of the study, costs for housing improvements averaged US $12 per square metre, or about US $400 per house (not including the owner’s labour). This is well below the national average cost for improved housing in Paraguay.

Contact

Dr Luis Rios Centro de TecnologApropriada Facultad de Ciencia y Tecnologia Universidad Cata de Paraguay AsunciParaguay Tel.: 913865

Dr Antonieta Arias Instituto de Investigaciones en Ciencias de la Salud Rio de la Plata y la Gerenza AsunciParaguay Tel.: 81312/82069/83618