Kissing the Assassin Bug Goodbye
By Debbie K. Becht
The insect crawls out at night from behind pictures, cracks in adobe walls, or thatched rooftops to bite its victims and suck their blood while they sleep. It crawls into a baby's crib with no netting, or under a couple's sheets, bites, and leaves a tiny dose of its feces on the sleeper's skin. The sleeper unwittingly scratches the skin and the feces enter the bloodstream. If the feces are infected with the parasite T. cruzi, this quiet, unnoticed event can later cause the victim severe health problems or an early death.
Chagas disease is the fourth leading cause of illness in Bolivia and is responsible for 13 percent of the deaths of people between 15 and 75 years old. The Ministry of Health says that 3.5 million peoplealmost half of Bolivias populationare at risk of contracting the disease; 300,000 children under 12 are already infected. Besides the significant health effects, Bolivia is suffering economically because of the disease. Dr. Hugo Flórez, a social sector expert at the Inter-American Development Bank, says, "The annual economic loss due to illness by Chagas disease reaches approximately US$189 million."
In 1909, Carlos Chagas, a Brazilian physician, discovered the parasite Trypanosoma cruzi and its carrier Triatoma infestansknown as the "vinchuca" in Boliviaand des-cribed the illness in humans. The parasite T. cruzi multiplies in the body's internal tissue and causes problems in the heart, esophagus, colon, and peripheral nervous system. The disease can go undetected for years unless infected feces are rubbed into the eye and it swells up to produce what is called the sign of Romaña. Although 80 percent of all cases are transmitted by the vinchuca, sometimes called the "kissing bug" or "assassin bug," transmission also occurs during pregnancy, when an infected mother passes the infection to her baby, and through transfusions of infected blood.
Equally implicated in the spread of Chagas disease are the conditions of poverty, especially houses with dirt walls. The poorest populations, who live largely in rural areas and urban outskirts, are the most affected. "We all know about the vinchuca," say women and men from Poroma and Tarabuco, rural communities in the Department of Chu-quisaca, Bolivia. They say the vin-chucas lay their eggs in cracked walls and multiply; they are in the roofs, in dirty, cluttered homes, in animal pens and shelters. People go to the campo and bring back wood with vinchucas in it. "There are vinchucas all year round," say women from Irupana and La Asunta in the Department of La Paz.
The tools for effectively controlling the transmission of Chagas disease by vinchucas in and around living quarters have been available for decades. Mr. Abraham Jemio, who is responsible for a Chagas control program in Bolivia, says, "Unfortunately, in most endemic countries, the political decision capable of transforming knowledge and experience into actions of control was lacking."
Three actions can effectively control Chagas disease spread by the vinchuca: fumigate infected areas, improve housing, and educate the population about the disease. Two actions can prevent transmission by blood transfusions: educate the population and improve blood safety, which is a priority program of the Pan American Health Organization (PAHO).
The National Effort to Eliminate Chagas Disease
Responding to national and regional demands, the Bolivian government created the 20002005 National Program for the Prevention and Control of Chagas Disease, which is due to receive about US$54 million from now until 2005, including US$45 million from the Inter-American Development Bank and US$9 million from the Ministry of Health.
"The program's objectives are to eliminate the transmission of Chagas disease by vector and blood transfusion, and thereby to reduce the incidence of Chagas disease 100 percent by 2004," according to Dr. Flórez. Besides funding the program, the Inter-American Deve-lopment Bank oversees the programs implementation and provides technical assistance to the Ministry of Health.
The Ministry of Health is working to implement the program at the local level along with PAHO, the Ministry of Housing and Basic Services, and the United States Agency for International Development through PROCOSI, a consortium of organizations.
PAHO buys the medicine and insecticides and provides training, supervision, monitoring, and evaluation. It also works on the surveillance system, conducts operational research, and develops communication plans.
Fumigating Infested Areas. The "Southern Cone Initiative to Eliminate Triatoma infestans in and Around Living Quarters," an agreement signed by Brazil, Uruguay, Argentina, Paraguay, Chile, and Bolivia, calls for elimination of the vinchuca by 2010.
"Excellent progress has been made in three Southern Cone countries," says PAHO's Dr. Gabriel Schmunis, a leader in the fight against Chagas disease. Uruguay interrupted transmission of T. cruzi in 1997, Chile in 1999, and 10 of the 12 endemic states of Brazil were certified free of transmission in 2000. Dr. Schmunis attributes their success to "resources for spraying, well-trained and committed staff, community participation for surveillance, and reasonable but sustained political support."
So far, about 230,000 houses of the 700,000 in Bolivias endemic area have undergone the first round of fumigation with the help of soldiers, community leaders, international organizations, and local and international nongovernment organizations. At this rate, Dr. Julio Alfred, director general of health at the Ministry of Health, estimates that Bolivia can begin the solicitation process at the end of this year to be certified for interruption of the transmission by the vector in at least three departmentsChuquisaca, Potosi, and Tarija. "Bolivia has with fumigation done in one year what it had previously done in 20," says Mr. Enrique Gil, consultant in epidemiology and communicable diseases at the Pan American Health Organization. The pesticides used in the program have been approved by PAHO and are being used in other Southern Cone countries.
This years goal is to reach 300,000 households with fumigation, housing improvement, control of blood transfusions, diagnosis and treatment of children, and information and education. Community mapping is being used so residents can visually follow the progress of fumigation and housing improvements in their community.
"We have been working with 13 municipalities," says Dr. Amadeo Rojas, coordinator of the Chagas program in the Department of Cochabamba, "but the social problems in the region made it difficult to train soldiers some homes are closed homes in rural areas are more dispersed and we have zero insecticide." Dr. Rojas says several isolated projects are being implemented in the region, but information and implementation of the programs activities should be consolidated.
"Efforts in Tupiza are coordinated and have made a difference in that region," says Dr. Alfred, who was in charge of the program in Tupiza from 1987 to 1993. Vinchuca elimination was coordinated with the International Fund for Agricultural Development, health officials in the bordering town of Jujuy, Argentina, and the World Food Program. In 12 years, the 70-percent infestation rate of the vinchuca was lowered to 0.1 percent, and health officials are now engaged primarily in epidemiologic surveillance. "However," says Mr. Erik Villena, coordinator of the Chagas program in Tupiza, "there is an infestation rate of 80 percent outside the community."
Improving Housing Conditions. Fumigation kills the vinchucas that currently infest homes and other community buildings, but the structures themselves must be made inhospitable to the vinchuca. Thatched roofs and cracks in walls invite nesting. Inhabitants of Mecapaca, a community in the Rio Abajo region near the capital, La Paz, say that the quality of their houses varies according to the income of the community members. Some walls are made of adobe with a metal alloy roof; others are made out of straw. The Ministry of Housing helps residents improve the structure of walls and roofs in living quarters. When local materials to improve homes, such as cement and lime, cannot be found in the community, the ministry provides them.
Community members help improve the homes of widows and the elderly, homes that are closed because people have migrated, and community buildings such as churches and schools. The program is part of the national housing policys Pillar of Equity, which, according to Dr. Maria Bolivia at the Ministry of Housing, "believes people should live in dignified, healthy, and secure homes."
Using Uncontaminated Blood. Dr. Xavier Castro, hematologist and director of the Regional Blood Bank in Santa Cruz, tells the story of a 25-year-old man who had gone to the blood bank to donate blood for a relative. The blood bank found that he was positive for Chagas disease. He said he had never been in an endemic area and therefore could not possibly have been bitten by the vinchuca. It turned out that he had been in an accident a few years back, underwent surgery, and received a blood transfusion from his father, who was infected with Chagas disease.
The geographical distribution of human T. cruzi infection extends from the southern United States to Argentina, with Chagas disease being endemic in 21 countries. Migration from rural, vinchuca-infested areas to the cities in the 1960s and 1970s increased transmission of Chagas' disease by blood transfusions. Between 1960 and 1989, the prevalence of infected blood in blood banks ranged widely, from 1.7 percent in São Paulo, Brazil, to 53 percent in Santa Cruz, Bolivia, according to the World Health Organization, a percentage far higher than that of hepatitis or HIV infection.
Because of this high rate, the Chagas program is working with laboratories and blood banks throughout the country. Like others, the Regional Blood Bank of Santa Cruz has been working "to ensure the quality of the bloodthat it be 100 percent screened, free of communicable diseases, and exempt of external contamination," says Dr. Castro.
"In 1999, 40 percent of donors tested positive for Chagas disease; this year it was 37 percent," says Dr. Castro. He attrib-utes the decrease to the blood banks outreach for donors from public and private universities. The students come from wealthy and middle-class families and are less likely to be exposed to the vinchuca. In the last blood drive, according to Dr. Castro, only 9 percent of student donors tested positive for Chagas disease.
The Regional Blood Bank of Santa Cruz works closely with the National Center for Tropical Diseases (CENETROP), located in Santa Cruz, to reconfirm the results of patients who test positive for Chagas disease.
Testing People for Chagas Disease. CENETROP recommends testing all family members and trains health care students and workers. "When a woman who has children under 14 years old tests positive for Chagas, we suggest that the children also get tested," says Dr. Alberto Gianella, director of CENETROP. "If the child is diagnosed, he or she may be curable."
So far treatment is only possible for acute, not chronic, Chagas disease. According to the Control of Commu-nicable Diseases Manual (2000), edited by Dr. James Chin of the Centers for Disease Control and Prevention, "Nifurtimox, a nitrofurfurylidene derivative, is most useful in treatment of acute cases and is available from the CDC Drug Service, Atlanta, on an investigational basis and from major hospitals in endemic areas. Benznidazole, a 2-nitroimidazole derivative, has also proven to be effective in acute cases." Dr. Gianella says that after taking this medicine for two years, children in Brazil tested negative for Chagas disease.
Currently, the World Food Program is doing research on treatment for Chagas disease in children under 12 years old in Tupiza.
Informing the Population. "Above all," Dr. Alfred says, "the program must increase knowledge about the disease, its risks, means of transmission, and mechanisms of prevention. People in endemic areas need to know the implications of the disease and should correctly internalize that they are the fundamental link in its definitive control.
"We have had to work almost 10 years in Tupiza to achieve behavioral change. In some regions people do not associate the presence of the vinchuca with the disease; in some cases they believe it is good luck to have some vinchucas around," he adds.
Ms. Nilda Cuentas, who is responsible for the information component of the Chagas program, says information strategies must take into account differences in gender, age, location, and lifestyle issues, such as whether families stay in their community or migrate to sell their products during the year. She adds that strategies must also be local, reach municipal governments because of their close ties with communities, and take advantage of existing social networks.
In the Country's Best Interest
Chagas disease is directly related to poverty, but the entire population is also at risk if proper precautions are not taken. The first cases of Chagas disease were detected in 1945. Today, Chagas disease transmitted by vinchucas is endemic to 60 percent of Bolivia. The vinchuca is found in towns located at 300 to 3,500 meters above sea level and is adapting to areas up to 4,000 meters.
"The situation is critical the problem has been around for generations," says Ms. Gloria Carrasco, correspondent for CNNenEspañol in La Paz and producer of a television report on Chagas disease that won a PAHO journalism award in 1999. "The biggest issue is extreme poverty; people are living in a center of infection they are living it everyday," she says. Dr. Castro says, "When the social level is improved, that will lower the transmission of Chagas disease."
Debbie K. Becht is a freelance writer based in La Paz, Bolivia, and a previous contributor to Perspectives in Health.