The Kiss of Death

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; Potosi (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 (Schmunis 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, Schmunis 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. Mendez, 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]

Transmission through Birth

T. cruzi can travel through the placenta, birth canal, and maternal milk. Infected mothers pass Chagas’ disease to their children, but in lesser percentages than might be expected. Some unknown immunologic process often protects the infant (Calvo et al. 1978:80). In general, the incidence of congenital T. cruzi transmission is under 10 percent, although this rate is much higher in endemic areas such as Bolivia (Mufioz and Acevedo 1994). In Punata, Bolivia, the mortality rate for children infected congenitally was 47 percent (SOH/CCH 1994). Rates of congenital transmission have increased over the years (Azogue, La Fuente, and Darras 1985:176).[19]

In Bolivia, congenital transmission rates were 7 percent in La Paz and 43 percent in Cochabamba (Breniere et al. 1983). Antibodies were detected in the serum of the mother and in the umbilical cord, with the concentration and quality of the antibodies similar. In Santa Cruz, Bolivia, 329 newborn babies were examined from 1979 to 1980; T. cruzi was found in twenty-five cases (Azogue, La Fuente, and Darras 1985:176 -80).[20] Some 51 percent of the mothers and 13 percent of the infants tested positive for Chagas’ disease. Twenty-one (80 percent) of the infected infants weighed less than 2,500 grams (5.5 pounds). It is not clear whether nutrition is an independent or dependent variable; that is, whether the immune system of nutritionally healthy babies resists Chagas’ disease or whether babies infected with Chagas’ disease lose weight. Also, not one case was found before the sixth month of gestation. Although the mother is infected from conception, transmission of T. cruzi from her to the fetus takes time.[21]

The delayed infection of fetuses raises the possibility of treating infected mothers during pregnancy to reduce transmission of the disease to the fetus. The high toxicity levels of nifurtimox and benznidazole used pose serious threats to unborn infants. Moreover, congenitally infected fetuses have been delivered from mothers both positive and negative for parasitemia, and infants have been born uninfected from pregnant women with acute infections and positive parasitemia. Intrauterine T. cruzi infection can cause abortions and premature births (WHO 1991:5).

Mechanisms of transmission of the disease from mother to fetus have not been determined. Possibilities include through the extra-embryonic membranes by diffusion of the parasites, or through progressive migration of the parasite throughout the stroma of the umbilical cord towards the blood vessels, provoking fetal infection by way of the blood (Azogue, La Fuente, and Darras 1985:180).[22]

The chances of getting Chagas’ disease from contaminated blood in Bolivia are higher (14 to 18 percent) than they are of contracting the disease by being born from a Bolivian mother infected with T. cruzi (5 to 10 percent). Even though these percentages vary greatly and are in part guess-estimates, the figures are perplexing in that rates of infected blood and infected mothers are roughly the samefrom 40 to 50 percent. One explanation for the lower rates of congenitally transmitted disease is that it is difficult to diagnose, especially in endemic areas, unless the tests are conducted at birth, since the possibility also exists of infection, or reinfection, by the vector (Mufioz and Acevedo 1994). Secondly, parasites are difficult to detect in the placenta, and, even if they are present, they may not infect the fetus (Thiermann et al. 1985; Munoz 1990).

Significantly, Chagas’ disease in newborns correlates highly with low weight: in one study, 13 percent of babies weighing less than 2,500 grams (5.5 pounds) were infected with Chagas’ disease in Bolivia (Azogue, La Fuente, and Darras 1985:176-80). Prenatal and postnatal nutrition helps babies resist T. cruzi.

Oral and Organ Transmission

Some less-frequent forms of transmission are by direct ingestion, organ transplant, and skin contact with infected material (Bittencourt 1975; Katz, Despommier, and Gwadz 1989; Schofield, Apt, and Miles 1982). Oral transmission to humans is not well documented, although it is easy to infect animals by this route (Marsden 1967).[23] Because vinchucas defecate in domiciliary and peridomiciliary areas, the possibility of contamination through contact with the insect’s feces and subsequent ingestion of the parasite exists but is not likely.

Three microepidemics in Brazil are attributed to oral transmission (NeryGuimaraes et al. 1968). Schoolchildren became infected with T. cruzi from drinking contaminated milk in Estrella, Rio Grande do Sul, Brazil, an area where triatomines were not found (Calvo et al. 1978:80). The milk had been transported from an endemic area.

In an agricultural school in Rio Grande do Sul, seventeen people were infected and six died from T. cruzi transmitted through food contaminated with opossum urine infected with T. cruzi. The initial misdiagnosis of the illness and the patients’ treatment with steroids