Cardiac morbidity due to chronic Chagas’ disease is high in rural communities of Bolivia. According to one study in a community in the central Andes, sixty-nine of 104 persons (66 percent) tested positive to T. cruzi by two serological methods (Weinke et al. 1988). Twenty-one of the sixty-nine people (30 percent) showed modest and severe cardiac abnormalities. This community had a high percentage (56 percent) of houses infested with Triatoma infestans infected with T. cruzi. Epidemiologically, there was a significant relationship between substandard housing, infested houses, and cardiac morbidity.
Figure 13.
Areas endemic for T. cruzi in Bolivia. (See Appendices 5 and 7.)
Seven children in Bolivia die each day from the acute phase of Chagas’ disease, which leads to meningoencephalitis (Ault et al. 1992:9). Estimates throughout Latin America are that 10 percent of children with acute infection die from the disease (Manson-Bahr and Bell 1987:80). Treatment of acute Chagas’ disease is important to lessen the severity of symptoms and prevent death. Chemotherapy has decreased the mortality rate from about 50 percent in 1900 to 10 percent currently (see Appendix 13).
The majority of new infections of Chagas’ disease are found in children from only a few weeks of age to two years of age. Bolivian children are more vulnerable than adults to acute forms because they have developing immune systems and often have other diseases and are malnourished. The immaturity of the immune system in the fetus and the child partially explains the appearance of cerebral involvement of the disease almost exclusively at these times (Moya 1994).[14]
With adults, the acute phase occurs in roughly 25 percent of people infected with T. cruzi, and a much lower percentage of that number die than among infants. The lesser occurrence of the acute phase in adults presents a problem for those treating the disease in that the victims are frequently unaware of having Chagas’ disease and go untreated until the incurable chronic phase, when the symptoms frequently are not attributed to T. cruzi. Thus the age of the victim is important in the epidemiology and treatment of Chagas’ disease (WHO 1991:2).
Some generalized symptoms of the acute phase are fever, enlarged liver and spleen, generalized edema, and swollen lymph nodes (WHO 1991). Symptoms can be sudden and dramatic, as a person may suffer from moment to moment with fever, chills, coughing, diarrhea, dysphagia, tachycardia, headaches, excitation, muscle pains, lack of appetite, neuropsychological alternations, exanthematous rash, and general malaise (Borda 1981; Chagas 1911; Katz, Despommier, and Gwadz 1989; Köberle 1968). Fevers range from 99.5 to 102.2 degrees Fahrenheit; temperatures above 104 degrees are rare and not indicative of the severity of infection. The fever may be continuous or recurrent, lasting four to five weeks and then falling gradually towards the normal range. Infants under one year of age frequently have higher temperatures and suffer symptoms of meningeal irritations (rigidness of neck and spinal column), convulsions, ocular seizures, stupor, and coma, which often lead to death. Coughing is caused by bronchial irritation associated with abundant mucus secretion. Diarrhea is frequent, very obstinate, and cannot be explained either by bacterial or by parasitic intestinal infections (see Appendix 9).
One common symptom of acute Chagas’ disease is development of a chagoma, which is a local inflammatory swelling, like a large, hard boil, found frequently below the eye as well as elsewhere on the body, that lasts for weeks (Manson-Bahr and Bell 1987:80). Chagomas differ from the local swelling and edema that follow a bug bite, which resolves quickly. Chagomas result from local inflammatory swelling caused by amastigotes multiplying in fat cells. When the chagoma occurs near the eye, the eyelids become filled with liquid and one eye often becomes inflamed, which is called Romaña’s sign (see Figure 4). Carlos Chagas considered Romaña’s sign the hallmark symptom of Chagas’ disease; however, this is misleading, because it is present only in one-fourth of all acute phases, and only 25 percent of infected people suffer the acute phase. For every one hundred persons infected with T. cruzi, only six manifest Romaña’s sign. Some Bolivians think they are not infected with T. cruzi because they can’t recall having a swollen eye. Others attribute Romaña’s sign to conjunctivitis due to the dusty regions of Bolivia and seldom report it to doctors. They should be advised that if the swollen eye continues for longer than a week they should consult a doctor.
Children also suffer painful subcutaneous nodules (lipochagomas) on the body. The chagoma stage is followed by fever and the appearance of trypanosomes in the blood about fourteen days after infection. Amastigotes remain in the lymph glands, causing generalized pathology in lymphatic tissue (see Figures 15 and 16). A rash may appear on the chest or abdomen, with precise red spots the size of pinheads. These spots are painless and disappear after ten days. Acute patients may suffer more serious pathologies of enlarged colon, spleen, or liver, irregular heartbeat, and cardiac deficiency and failure. It is important to recognize that there is no clearly defined set of symptoms that characterizes either acute or chronic Chagas’ disease and that many of the above symptoms can refer to other diseases. Clinical diagnosis of Chagas’ disease is difficult without testing for the parasite, and frequently it goes undetected in Bolivia.
Treatment of Chagas’ Disease
Dr. Ciro Figaroa, a medical doctor in Tarija, Bolivia, administers the following dosages of nifurtimox for acute Chagas’ disease: for children, 15 to 20 milligrams per kilo of weight in four doses per day for 90 days; for adults, 8 to 10 milligrams per kilo of weight for 120 days. Figaroa claims that he has cured Chagas’ disease in the acute phase but is unable to do this once patients have passed the acute stage. In Sucre, doctors recommend Radanil (Roche’s benznidazole product) in the following dosage: 7 milligrams per kilo of weight three times a day for four weeks. The cost for Radanil for an average-size adult for one month is $340 Bolivian (or U.S. $70), a month’s wage for the average Bolivian.
An advantage of the acute phase of Chagas’ disease is that its symptoms signal a point when it can be treated. Asymptomatic patients may realize they are infected only at the chronic stage, when cardiac and gastrointestinal damage is pronounced. There currently is no adequate treatment for the chronic phase (for future possibilities see Urbina et al. 1996). Since the trypanocidal drugs currently available are effective during the acute period of the disease, it is important to diagnose earlier infections as well as to distinguish recent infections from older infections. New tools for the serodiagnosis of Chagas’ disease have proven to have great diagnostic potential in distinguishing different stages of the disease (see Frasch and Reyes 1990: 137-41).
Chemotherapy treatment of the disease is not completely satisfactory for reasons already discussed in Chapter 3. Nifurtimox and benznidazole have serious adverse effects and yet do not destroy all the parasites, which soon repopulate the body. Their therapeutic efficacy depends upon variations in parasite virulence and variations in the human response to infection as they relate to a particular chemotherapeutic strategy.
In Bolivia and other Andean countries, the inadequacy of chemotherapy is related to the fact that trypanosomiasis generally is a disease of rural subsistence farmers in developing areas. Here, medical service is usually inadequate because of the inequitable distribution of health resources in favor of urban centers. To be useful in this environment, a drug must be inexpensive, have a long shelf-life without refrigeration, and be able to be administered by paramedics orally without side effects.[15]
Infestation with T. infestans
A major reason for the spread of Chagas’ disease throughout Bolivia and Latin America is the domestication of T. infestans (see Appendices 5 and 6). In endemic areas of the disease in Bolivia, T. infestans has invaded domestic areas to a staggering degree. The percentages of infestation for houses in the departments of Bolivia are as follows: Cochabamba, 38.2 percent; Chuquisaca, 78.4 percent; Tarija, 78.2 percent; La Paz, 42.2 percent; Potosi, 62.5 percent; and Santa Cruz, 96.5 percent (SOH/CCH 1994:20; Valencia 1990a:44). Thus, 70 percent of houses in the most populated departm
ents of Bolivia are infested with T. infestans.
Once they are inside domestic areas, triatomines hide in a variety of places. Of 1,090 vinchucas gathered from 191 houses, 529 were in the walls, 46 in the roof, 48 in the beds, 324 in the peridomicile area, and 143 in surrounding corrals (Valencia 1990a:42-65). All vinchucas were identified as T. infestans: 581 (53 percent) were nymphs and 509 (47 percent) were adults. The infestation rate for homes in the study area was 92 percent (Valencia 1990a:44).
The medium index of vinchucas with T. cruzi parasites was 31 percent, with the index reaching as high as 53 percent in one community (Valencia 1990a: 44). Some 46 percent of the infected vinchucas were found in dormitories, which indicates that they transmit T. cruzi best among sleeping humans. Infection rates within the nymph stages was 25 percent; within the adult stage it was 37 percent. The vector was infected incrementally with T. cruzi from its initial nymph stages to adult stages.[16]
T. infestans is accountable for 97 percent of the cases of Chagas’ disease in Bolivia; twelve other species account for the remaining 3 percent. The most prominent of these species are T. guasyana, T. melanocephala, T. oswaldoi, and T. venosa, which are primarily sylvatic, prey on wild animals, and spread Chagas’ disease among such animals. This becomes another threat to the threatened and depleted species of wild animals in the Andes and Amazon. Large numbers of Triatoma infestans and lesser numbers of Triatoma sordida are found in every department of Bolivia except Oruro, which is located at an elevation of 3,500 meters.
Triatoma infestans usually inhabits areas at elevations from 1,100 to 11,200 feet (330 to 3,450 m.) above sea level; nevertheless, it has been found at higher elevations, such as Llallagua, Potosi, at 13,300 feet (4,100 m.) (Borda 1981:16). Sylvatic triatomine vectors of T. cruzi are primarily found within forested areas of the departments of Beni, Pando, and Santa Cruz and within the Yungas area of the Department of La Paz. Sylvatic triatomines spread Chagas’ disease more in animals than in humans within the departments of Santa Cruz, Beni, and Pando, although they do infect some forest dwellers.
Although T. infestans are found throughout Bolivia, the insects prefer warm and humid conditions, being found more in the lower elevations and warmer climates of the central regions and the lowlands rather than in the highlands such as La Paz and the Altiplano. Chagas’ disease occurs primarily in the valleys, plains, and forests lying between elevations of 1,000 to 11,400 feet (300 and 3,500 m.) above sea level. Roughly 84 percent of Bolivian territory lies within this zone. Some 47 percent of Bolivia’s populace reside in endemic areas of the disease, thereby placing approximately 3 million people at risk for Chagas’ disease. Many more Bolivians are also at risk because of possible infection through blood transfusions in non-endemic urban areas (Ault 1992, Schmuñis 1991, Valencia 1990a).
Rates of household infestation of T. infestans are higher in rural and periurban areas of Bolivia; but urban infestation has increased significantly with increased urban migration and rapid transportation between rural and urban areas. Infestation rates presently are 70-100 percent for rural areas, 40-60 percent for peri-urban areas, and 20-40 percent for urban areas (SOH/CCH 1994). A general average is that 50 percent of vinchucas found anywhere in Bolivia are infected with T. cruzi parasites. This percentage increases proportionally as more people become infected with these parasites and pass them on to uninfected vinchucas. In endemic areas, T. cruzi passes rapidly from sick persons to healthy persons, because vinchucas prey on different people, many of them sleeping together, until virtually all the hosts are infected with Chagas’ disease.
Adaptation of Bolivians and Bugs
The spread of T. cruzi throughout Bolivia is accomplished by certain selective and adaptive mechanisms of vinchucas. A combination of nocturnal predation, crawling and gliding, and transformation through nymph stages, means that there are bugs with different sizes, air and land mobility, and the cover of darkness in which to hide, move, and draw blood from humans, easily targeting those sleeping in run-down adobe houses with thatched roofs.
Vinchucas are sensitive to light, and, at the laboratory for Proyecto Chagas at the National University at Cochabamba, biologist J. Delgado keeps them in loosely covered jars during the day. As he explained to me, “as long as there’s light in the room, they stay as still as sleeping sloths.” Reaching into the jar with pinchers, he grabbed a vinchuca around the thorax and held it. It remained motionless, occasionally wiggling its antennae, while I photographed it (see Figure 14). He then replaced the vinchuca in a tightly covered jar and draped a dark cloth over its top and sides; within seconds you could hear this vinchuca moving about inside the jar.
Figure 14.
Laboratory assistant at Chagas Project at the Universidad San Simon in Cochabamba holding a vinchuca bug that will be used to diagnose victims of Chagas’ disease. Uninfected vinchucas are placed under the armpit for thirty minutes to draw blood; thirty days later their feces are examined for T. cruzi. This diagnostic test is called xenodiagnosis and is commonly used throughout Bolivia to determine parasite population and zydomenes. Indirect ELISA tests are frequently used first to determine antibodies to T. cruzi. (Photograph by Joseph W. Bastien)
When vinchucas are caught in the light of day, they appear to be friendly domesticated bugs, neither biting, kicking, or trying to get away. Not surprisingly, many Bolivian children play with them. Boys race the bugs, and some put them in girls’ lunch boxes. Girls gather their rice-shaped eggs in tiny wicker baskets, pretending they are chicken eggs. Even some adults consider the insects’ eggs to be good omens predicting fertility or a bountiful harvest. They are referred to as “harbingers of good luck,” “kissing bugs,” “friends,” and “toys.” Their perceived personalities disassociate these bugs from their disease-carrying capability.
Attitudes about vinchucas were revealed in the following conversation I had with Sarah Arredondo outside of Tarija, Bolivia, in 1997 (see Figure 15). Sarah was seven years old at the time and had been bitten while she was sleeping by a vinchuca, which her mother removed from under her nightie. Her mother squashed it against the floor and blood squeezed out. Sarah said that she didn’t mind vinchucas and was unaware that they caused sickness. Sarah wants to be a hairdresser because she likes to dress up dolls. She coyly expressed herself, slightly twisting her head to purse her lips to hide shyness, which eventually turned into a smile. She then told me how her ducks ate vinchucas. Sarah’s mother hated vinchucas and had grown up in a house filled with them. She said that they were inside the house and that she had removed unnecessary items from the sleeping areas, but that they needed to plaster the walls. She feared that Sarah had Chagas’ disease and asked me to examine the wound from the bite. I explained that I couldn’t tell by looking at the wound, and informed her to watch for a high fever; if that occurred, she should take Sarah to a doctor for testing and treatment. Talking with a child bitten by a vinchuca whose future as a hairdresser was threatened by a parasite made the statistics of Chagas’ disease more meaningful and alarming to me.
Public health educators, in efforts to dispel friendly attitudes towards vinchucas, in a rather bizarre fashion have sponsored contests for schoolchildren to see who could bring the most bugs to school (somewhat akin to a campaign to collect discarded drug needles). Children captured vinchucas, put them in matchboxes, and brought them to the school, where they were later examined for T. cruzi infection. Obviously, this technique encouraged children to handle vinchucas despite the fact that contamination is the major route of infection and thus this campaign put them at risk. Posters and videos are a much safer pedagogical method to educate Bolivians about vinchucas as vectors of Chagas’ disease.
Figure 15.
Sarah Arredondo showing where she had been bitten by a vinchuca and possibly infected with Chagas’ disease. Several thousand children die each year in Bolivia from acute Chagas’ disease. (Photograph by Joseph W. Bastien)
The insect world fascinates children in part perhaps because tiny creatures
are more proportionate to their size. José Beltrán, health educator, observed that children are much quicker than adults to learn about the different species of vinchucas, many of which are beneficial. Many Bolivian children also love to see parasites through microscopes and learn about Chagas’ disease.
On the other hand, Quechua peasants in Choromoro hate vinchucas because they suffer from their annoying bites at night. These peasants in the Department of Chuquisaca, Bolivia, are accustomed to having vinchucas in their beds, with sometimes as many as thirty to forty housed within their mattresses. One complained, “All night we are taking off their heads and destroying them. We have to sleep outside the huts to escape them. Sometimes we don’t sleep all night because we have to kill vinchucas, and when they bite us, we scratch it.”
Some Bolivians are allergic to vinchuca bites, which then result in festering sores (see Figure 16). Others vigorously scratch the itching bite, opening the skin and rubbing infected fecal matter into the wound. T. cruzi travel to the opening or are aided when the victim scratches the wound, frequently damaging the skin or pushing the parasites into the wound.
The Kiss of Death Page 9