Infection through Blood Transfusions

Blood transfusion is the second most important mechanism of transmission of Chagas’ disease. Blood transfusions have enabled T. cruzi to travel beyond tropical and semitropical zones, where it was environmentally limited by the fact that its triatomine vectors needed the warmth and humidity of these areas. This makes Chagas’ disease a worldwide problem, because Latin American countries have been major exporters of blood, as well as organs, through the years (Moraes‑Souza et al. 1995; WHO 1990, 1991; Docampo et al 1988). In Brazil alone, 10,000 to 20,000 cases of Chagas’ disease occur yearly because of infections through transfusions (Dias and Brener 1984).[17]Bolivia has a high rate of infected blood. The National Secretariat of Health estimated that in 1988 there were five new cases of Chagas’ disease each day (Bryan and Tonn 1990:15). In seven capital departments of Bolivia, 1,298 sera samples from blood banks were examined for T. cruzi (Carrasco et al. 1990). Percentages of infected blood reached 28 percent, with the following distribution: Santa Cruz (at an elevation of 430 m), 51 percent; Tarija (1,951 m), 45 percent; Sucre (2,750 m), 39 percent; Cochabamba (2,570 m), 28 percent; Potosí (4,060 m), 28 percent; Oruro (3,706 m), 6 percent; and La Paz (3,640 m), 4.9 percent. Other studies for contaminated blood range from 56 percent to 70 percent contamination (Valencia 1990a, Bryan and Tonn 1990) to a less alarming 8 percent (Schmuñis 1991). High percentages of infected blood are found in rural migrants and low‑income donors who live in infested dwellings and need money.

Measures to decrease contaminated blood include the screening of donors and the lysing of T. cruzi with gentian violet, a trypanocide (Moraes‑Souza et al. 1995; see Appendix 13: Chemotherapy). Blood needs to be stored with gentian violet for twenty‑four hours at 4°C for the substance to destroy T. cruzi (Nussenzweig et al. 1953, Schmuñis 1991). Gentian violet gives blood a deep violet coloration, and its side effects are unclear.

Bolivians generally have not adopted these screening measures. Blood is rarely stored in Bolivia, except for export. People receive transfusions directly from someone for about twenty dollars or they purchase a blood bag for five dollars and then have someone fill it for a fee (J. Méndez, interview 5/6/97). Bolivians often refuse transfusions of violet blood, and serological and clinical examinations are expensive.

Fortunately, only 14 to 18 percent of people who receive a transfusion of infected blood develop Chagas’ disease. The following factors are important: the quantity of infected blood received in one or a series of transfusions, the general state of the person’s health, and the immunocompetence of the person (Toro Wayar, interview 6/20/91). Patients receiving multiple transfusions are at high risk, and many patients are immunosuppressed from sickness. People at risk are generally from the poorer classes; wealthy patients usually go to private clinics which have access to blood banks. However, there are not many wealthy people in Bolivia; only 2,000 Bolivians receive annual salaries of more than U.S. $10,000 (Presencia, May 11, 1997).

Chagas’ disease is no longer restricted to Latin America. Immigrants from El Salvador and Nicaragua in Washington, D.C., have tested positive for T. cruzi infection. In 1985, estimates were that 100,000 individuals living in the United States were infected with T. cruzi (Kirchhoff, Gam, and Gillian 1987). I now estimate that number to be more than one million people because of increased immigration from Latin America, increased travel back and forth between countries in Latin America, increased numbers of blood transfusions and organ transplants, and transmission of the disease through birth.[18]