Household chagasic endemia detected as a consequence of a case of congenital infection]

During a study on prevalence of parasitic and viral serological markers in pregnant adolescents, a 17-year-old primipara from Polpaico, village near Santiago, gave birth to a normal male newborn in a Santiago hospital. As both of them presented positive an indirect hemagglutination test (IHAT) for Chagas' disease and the corresponding xenodiagnosis (XD), the infection in the infant was considered to be acquired through the placental route. According to recent epidemiological surveys Polpaico is an endemo-enzootic chagasic rural settlement, where 14.7% of dwellings were infested with Triatoma infestans, while triatominae, persons and domestic mammals were found infected with Trypanosoma cruzi. One month later the adolescent mother, her son and other 11 consanguineous members of the family were visited in their homes in order to submit each of them to a physical examination and to IHAT for Chagas' disease, and XD to those whose IHAT resulted positive. Thus, in 7 (53.8%) the IHAT was positive and in 4 (57.1%) out of these 7 presented positive the XD, results that as a whole yielded a household chagasic endemics.     

Chagas disease in the Chilean altiplane. Epidemiological, parasitological, and clinical aspects]

Chagas' disease is endemo-enzootic in periurban and rural sections of the first seven (18 degrees 30'-34 degrees 36' South lat.), out of the thirteen political-administrative regions of Chile. Permanent inhabited localities situated at different altitudes over the sea level (OSL) are classified in: coastal settlement (0-1,499 m OSL), intermediate settlement (1,500-3,000 m OSL) and altiplano settlement (> 3,000 m OSL). A total of 1,558 dwellings and their occupants from regions I and II were surveyed in 1982-1984 for different epidemiological Trypanosoma cruzi infection parameters. Hence, 261 dwellings, 189 domestic mammals and 517 people (ages 5- > or = 60 years) from the Altiplano settlement were studied. The results obtained were: 4(1.5%) and 2(0.8%) of dwellings infested with Triatoma infestans, according to occupants information and by observation of direct evidences respectively; 8(4.2%) animals (1 dog, 4 goats and 3 sheep) with a positive hemagglutination test (IHAT) for Chagas' disease; 21 people (4.1%) with a positive IHAT; 4(19.0%) and 3(14.3%), out of the 21 IHAT positive individuals with all types of electrocardiogram (EKG) abnormalities and EKG abnormalities suggestive of a chagasic etiology respectively, whereas 65(13.1%) and 15(3.0%), out of the 496 IHAT negative ones presented the same kinds of EKG abnormalities.(ABSTRACT TRUNCATED AT 250 WORDS)     

Electrocardiographic alterations in persons with a positive serology for toxoplasmosis]

To each of 11,161 randomly taken people from urban and peri-urban localities of the first seven regions of Chile (geographic area of distribution of Chagas' disease in the country), with negative serology for Chagas' disease, an indirect hemagglutination test (IHAT) for toxoplasmosis and an EKG were practiced. The IHAT for toxoplasmosis resulted positive in 3,519 individuals (31.5%). The EKG showed alterations in 10.9% of the IHAT positive individuals and in 7.9% of the IHAT negative ones. This difference between the proportion of altered EKG in IHAT positive people and altered EKG in those with negative IHAT is statistically significative with p < 0.001. These results suggest the convenience of considering toxoplasmosis as a cause of chronic myocardiopathy in epidemiological studies on Chagas' disease, since not discard the presence of Toxoplasma gondii infection should overvaluete the magnitude of the impact of Trypanosoma cruzi in the genesis of such a myocardiopathy.     

Experimental antitriatomic program in Santiago]

The rural migration to urban centers occurred since the 40s in many Latin American countries, including Santiago the capital city of Chile, originated a growing belt of premises built with light poor material (the rests of previous rural habitations, mud, pieces of timber, plastic and cardboard for walls, and cane stalks and artificial clinkstones for roofs) giving raise to many types of slums. This situation facilitated the passive transport of the different instars, including eggs, of triatomine bugs. Due to the fact that in the 1959-1960 warm seasons, the Santiago province health institutions had received an increasing reported number of triatomine bugs (Triatoma infestans) in dwellings from different periurban, even urban and rural sections of the province, the central local health authorities with the advise of the University of Chile, Department of Parasitology decided to carry out an experimental program against these vectors of Chagas' disease. The program consisted basically in an spray and thorough application of liquid forms (emulsion, suspension, solution) of 1% lindane (average > or = 500 mg per 1 m2), depending on the material of the constructions, to all the surfaces of walls, ceilings, attics and peridomiciliary structures of all the infested dwellings in a sector and those located less than 100 m around. In order to reach triatomine bugs not affected, for different reasons, in the first spraying, a second application, identical to the first was performed to the total number of premises between 30 and 120 days later. Periodical evaluations were made, and positive dwellings found and neighboring ones were sprayed again. During insecticide applications adequate protection measures for spraying workers, inhabitants, domestic animals, household goods and food were adopted. All the steps of the program were accompanied by health education activities directed to individuals, families, school teachers and community institutions, tending to motivate the people to an active participation, as in the report of the presence or reappearing of triatomines in premises as in cooperating in the sprayings and improving the material conditions of their properties. Thus, in the period 1960-1972 the following goals were achieved: 1) Spraying twice with 1% lindane 32,708 dwellings located in 199 quarters from 26 periurban and rural sections. 2) Protection to 191,090 people against T. infestans bites and the eventual acquired chagasic infection. 3) Percentages of triatomines infested dwellings decreased from to 18.7 to 3.0 according to residents and from 3.0 to 0.3 according insects collection. At present, a significant proportion of the sprayed dwellings has been demolished and replaced by new constructions.(ABSTRACT TRUNCATED AT 400 WORDS)     

Evaluation of Chagas' disease transmission through breast-feeding

One hundred milk or colostrum samples from 78 mothers with chronic Chagas' disease were parasitologically studied for Trypanosoma cruzi infection by means of direct examination and inoculation of mice. The mice were submitted to direct blood examination three times a week. At the end of 45 days, xenodiagnosis and indirect immunofluorescent test (IFAT) for T. cruzi antibodies were carried out in the animals. No parasitized sample was observed even though five mothers had parasitemia at milk collection. In addition, 97 breast-fed children of chronic chagasic mothers, born free of infection, were tested for IgG antibodies to T. cruzi using IFAT. No case of T. cruzi infection was detected. The authors conclude that breast-feeding should not be avoided for children of chronic chagasic women. However, as these mothers had intermittent parasitemia, they should avoid nursing when there is nipple bleeding.     

Isolation of Trypanosoma cruzi samples by xenodiagnosis and hemoculture from patients with chronic Chagas' disease

Fifty nine chronic chagasic patients were simultaneously submitted to xenodiagnosis and hemoculture for Trypanosoma cruzi samples isolations. The xenodiagnosis was done with 40 Panstrongylus megistus, Triatoma infestans and Dipetalogaster maximus nymphs, performing 120 triatomines. Groups of 10 insects per specie were dissecated and the intestinal content pooled and examined, after previous trituration and homogenization. The microscopically negative material was seed into LIT medium and examined after 20 days. Twenty nine patients were parasitologically proved, being 15 only by xenodiagnosis, 4 only by hemoculture and 10 by both methods. It was discussed the parasitological comprovation difficulties in chronic chagasic patients, the value of the simultaneous utilization of different triatomine species in xenodiagnosis and the hemoculture, in a favorable positive association to the sensitivity increase in the diagnosis' disease. The 49.2% of positivity obtained in this group, visualize approaches like clinic-therapeutic assay and or epidemiological (case-control) with the purpose to investigate a possible association with T. cruzi samples and different clinic forms in Chagas' disease.     

Yielding of xenodiagnosis, according to the number of boxes used in 1,181 persons with chronic chagasic infection diagnosed with indirect hemagglutination reaction]

A study for evaluation of the yielding of xenodiagnosis (XD) in 1,181 persons with a previous positive indirect hemagglutination test (IHAT) for Trypanosoma cruzi infection was carried out. The infection of these people was detected during epidemiological surveys performed in rural-periurban and urban sections of the endemo-enzootic area of Chagas' disease in Chile, which involves the first seven, out of the thirteen political-administrative regions of the country. The sex distribution was 75.0% females and 25.0% males, varying the ages between 2 and 80 years. According to individual and geographical possibilities each person was submitted to 1-8 XD, which consisted in cylindrical wooden boxes containing seven third instar nymphs, laboratory reared, of Triatoma infestans. The boxes, covered with a piece of tulle fixed with a rubber band were applied on the skin of the posterior side of the arm of the subject to be examined, held with a linen bracelet during 25-30 min. After the insects were fed the boxes were maintained in the laboratory at 27 degrees C and 85% relative environmental humidity. Posteriorly, all the nymphs of each box were examined at 30, 60 and 90 days after the application. A drop of abdominal content of each of them, homogenized with a drop of saline, was examined at the microscope looking for T. cruzi. XD resulted positive in 503 (42.6%) people. The positiveness of XD showed a trend of increasing according to the number of boxes used, from 11.4% with one to 51.6% with six. Under a practical point of view, the simultaneous application of four XD boxes seems to be advisable.(ABSTRACT TRUNCATED AT 250 WORDS)     

Epidemiological status of Chagas disease in the endemic area from Region II of Antofagasta]

During 1997 a seroepidemiological study on Chagas' disease was carried out in 18 localities of three provinces (Tocopilla, El Loa and Antofagasta) of Region II (20 degrees 56'-26 degrees South Lat.; 70 degrees 38'-67 degrees West Long.), in order to assess the impact of the control program against Triatoma infestans launched in 1988, based on insecticide spraying of dwellings. By means of ELISA and an indirect hemagglutination test for Chagas' disease blood samples from 1,034 children under 10 years of age were examined, arising a 0.5% (3 cases) positivity. Test resulted positive in 2 (0.9%) children from the locality of San Pedro de Atacama and 1 (0.4%) from Calama city, all in the age group 6-10 year-old. However, none of their dwellings were found infested with T. infestants. These results indicate that the control program has a good possibility to prevent new human infections. It is advisable to continue the seroepidemiological and entomological vigilance and remark the necessity of increasing the effort in the study of transmission through other routes, to adopt or reinforce the pertinent preventive measures.     

Pragmatic data and observations related to the epidemiology of Chagas disease

Chagas' disease or American trypanosomiasis is a parasitic zoonosis which constitutes and important public health problem in most of the Latin American countries. According to the development of socio-political events in the world, it is possible at present to speak of rural-periurban Chagas' disease and urban Chagas' disease. Rural-periurban Chagas' disease. In its endemo-enzootic condition it is distributed in vast areas from Mexico in the north and Argentina and Chile in the south. It is calculated that the population at risk is about 90 million persons, not less than 16-18 million are Trypanosoma cruzi infected and approximately 38% of these present or have presented pathology caused by the parasite. Organs most frequently affected: heart, esophagus and colon. The corresponding biological vectors are hematophagus triatomid bugs, with greater than 100 species synantropic (st) or sylvatic (sv), existing between parallels 41 N. and 46 S., but only about 36, which have been found infected, have some relationship with man because their adaptation to human dwelling. The human parasitose is less extended due to the fact that the vectors of the region are predominantly sv. The known reservoirs are more than 180 species of terrestrial mammals: domestic, st and sv. Man is possibly the most important. Some available relevant epidemiological information is summarized as follows: Additionally, some autochthonous cases of T. cruzi human infection have been registered in the United States, Trinidad-Tobago, Guyana and Belize. Moreover, infected vectors and/or sv reservoirs have been observed in almost a dozen of Caribbean countries. Urban Chagas' disease. As a consequence of possible better salaries and many other motivations, in the last decades there have been significant and constant migrations from rural to urban areas in many Latin American countries. This situation has facilitated the dissemination of T. cruzi infection through infected reservoirs--mostly humans--and/or passively transported infected vectors. In most of the cases these rural-urban migrations occur in chagasic endemic areas within a same country or in neighbouring ones; in others, the migration can involve countries where Chagas' disease does not exist, transmission being via blood transfusion or placental. According to some estimates, with a mean rate of 1.5% chagasic infected blood donors the minimum risk of T. cruzi transmission is nearly 12.5-25.0% when the volumen of transfused blood is 500 ml.(ABSTRACT TRUNCATED AT 400 WORDS)     

Vertical transmission of Trypanosoma cruzi in the Province of Choapa, IV Region, Chile: Preliminary Report (2005-2008)

Congenital Chagas disease acquired special importance in Chile after the certification of the control of Triatoma infestans and transmission by blood donors affected with Trypanosoma cruzi. In order to establish adequate protocols for intervention and control in infected mother-neonate pairs in endemic zones of Chagas disease, we present partial results (2005-2008) of a pilot project which is being carried out in the Province of Choapa, IV Region, Chile, whose objectives are: determine the current prevalence of the disease in pregnant women, estimate the incidence of vertical transmission of T. cruzi to newborns, determine the lineages of the parasite present in mothers who do and do not transmit the disease, determine the prevalence of Chagas disease in maternal grandmothers of neonates and study placental histopathology. Preliminary results indicated that in this study period, 3.7% of the women who gave birth in the Province have Chagas disease and 2.5% of their newborns were infected. The most frequent T. cruzi genotypes found in mothers studied during pregnancy were TCI and TCIId, either alone or in mixed infections. A high percentage (74.3%) of the grandmothers studied was infected with the parasite. In 29 placentas from mothers with Chagas disease we observed edema, necrosis, fibrinoid deposits and slight lymphoplasmocyte infiltration. In three placentas we found erythroblastosis and in one of them amastigote forms of T. cruzi; this was one of the cases of congenital infection. The evaluation of the diagnostic and control protocols generated will allow us to determine if it has been possible to modify the natural history of vertical transmission of T. cruzi in Chile.     

Trypanosoma cruzi (Kinetoplastida Trypanosomatidae): ecology of the transmission cycle in the wild environment of the Andean valley of Cochabamba, Bolivia

An active Trypanosoma cruzi transmission cycle maintained by wild rodents in the Andean valleys of Cochabamba Bolivia is described. Wild and domestic Triatoma infestans with 60% infection with T. cruzi were found and was evidenced in 47.5% (rodents) and 26.7% (marsupial) by parasitological and/or serologycal methods. Phyllotis ocilae and the marsupial species Thylamys elegans, are the most important reservoirs followed by Bolomys lactens and Akodon boliviensis. In spite of both genotypes (TCI and TCII) being prevalent in Bolivia, in our study area only T. cruzi I is being transmitted. Our data suggest that wild T. infestans and wild small mammals play an important role in the maintenance of the transmission cycle of T. cruzi. Furthermore, the finding of high prevalence of T. cruzi infection in wild T. infestans point to the risk of the dispersion of Chagas' disease.     

Morbidity in Chagas' disease. IV. Longitudinal study of 10 years in Pains and Iguatama, Minas Gerais, Brazil

An evolutive study of the "case-control" type was carried out in an endemic area of Chagas' disease in Minas Gerais State, Brazil, using two cross-section evaluations with an interval of ten years between them (1974-1984). Patients were paired for sex and age. In the first cross-section study 264 pairs one with a positive serology and the other with a negative serology for T. cruzi antibodies were included. In the second evaluation, ten years later, 235 patients among those with previous positive serology and 216 with negative serology were located, but only 110 pairs could be recomposed and reexamined (clinical examination, ECG and Rx of the heart and esophagus). The incidence of chagasic cardiopathy in the cases with positive serology but previously assymptomatic was 38.3% during the ten year period. On the other hand there was a deterioration in 24% of the patients with chagasic cardiopathy since the first examination. Considering all clinical forms of the disease in 34.5% of the patients the clinical situation deteriorated, in 57.3% there was no change and in 8.2% the situation improved. The general mortality in the period was 23% in the chagasic group and 10.6% in the control group, but the lethality by cardiopathy was 17% in chagasic group and only 23.3% in the control group. The mortality was twice as high in males than in females, mainly in the age group from 30 to 59 years.     

Trypanosoma cruzi: description of a highly purified surface antigen defined by human antibodies

A glycoprotein of 25,000 daltons (G25) purified from T. cruzi extracts is recognized by serum antibodies of Chagas' disease patients. These human antibodies were isolated by affinity chromatography and were used to demonstrate that G25 antigenic determinants are i) represented at the parasite surface, and ii) are expressed in all developmental stages of the parasite's life cycle, as well as in several T. cruzi strains. This antigen-antibody system may be useful for the diagnosis of Chagas' disease because antibodies to radiolabeled G25 are found in the serum of 96.5% of 173 chagasic patients from different endemic areas, but are not found in the serum from other individuals. Taken collectively, the data suggest that antibodies to G25 define highly conserved determinants of the species T. cruzi. Moreover, its remarkable immunogenicity to infected humans offers an opportunity to investigate the role of specific immunologic responses in the pathogenicity of Chagas' disease.     

Chagasic infection in blood donors from hospitals in endemic regions of Chile (1982-1987). Epidemiological impact of the problem]

Chagas' disease, produced by Trypanosoma cruzi and transmitted by hematophagous triatomine bugs, exists in the Western Hemisphere from the south-western United States to central Chile and Argentina. It exists in rural and periurban sections of the northern half of Chile, with a prevalence of 16.9%. Constant rural-urban migrations have contributed to its spreading to urban sections. In order to investigate the impact of these migrations on the population susceptible of being blood donors and the probable increasing of the risk of T. cruzi transmission by blood transfusion, epidemiological surveys were carried out in donors from 22 hospitals located in the northern half of Chile. By means of an indirect hemagglutination test for Chagas' disease 16,841 blood donors were examined, arising a 2.7% of positivity, percentage that permitted to estimate that 126,477 potential blood donors infected with T. cruzi should be in the urban sections studied. These facts strengthen the need that serology for Chagas' disease must be routinely performed in endemic regions of the country, to adopt or reinforce the pertinent preventive measures.     

Cell mediated immunity in Chagas' disease. Trypanosoma cruzi antigens induce suppression of the in vitro proliferative response of mononuclear cells.

The partial suppression of the cell-mediated immune response by Trypanosoma cruzi antigens in patients with Chagas' disease is demonstrated in a costimulation assay with T. cruzi antigens and Mycobacterium tuberculosis purified protein derivative (PPD) or Tetanus toxoid (TT). Mononuclear cells from 13 patients with chagasic infection without evidence of heart disease, 10 patients with chagasic cardiomyopathy and 7 healthy blood bank donors were stimulated with antigen A (autoclaved epimastigotes), PPD, TT, PPD + A, PPD + TT and TT + A. The average percentage of suppression induced by costimulation of mononuclear cells with PPD and antigen A was 47.1% in patients with chagasic infection without heart disease (INF), 38.8% in patients with chagasic cardiomyopathy (CDM) and 23.3% in healthy controls. Similar values were observed when living trypomastigotes were used. A costimulatory study with PPD and TT, PPD and A and TT and A was carried out in 8 patients with chagasic infection, in order to evaluate the possibility that this difference could be due to a nonspecific inhibitory effect. The mean suppression induced by TT + PPD was -8.9, with TT + A was 52.7 and with PPD + A was 50.1. The data reported show that T. cruzi antigens induce a specific suppression of the proliferative response of mononuclear cells, that might be relevant to the persistence of the parasite in the host.     

Identification of trypanosomes isolated from reduviidae from north Chile

Examination of 54 Triatoma infestans from a village near the European Southern Observatory La Silla in Chile and of 9 Triatoma spinolai from the territory of the observatory showed that 10 T. infestans were infected with trypanosomatids. Mice were infected with in vitro cultures initiated with five different trypanosomatid isolates and treated with the immunosuppressive drug cyclophosphamide to increase the parasitemia of the flagellates. Evidence of the presence of T. cruzi was provided by a comparative biometrical analysis of blood trypomastigotes and the occurrence of intracellular amastigotes. Three methods for further identification were used: examination of kDNA ultrastructure, disc electrophoresis of soluble proteins and the Aaptos papillata II lectin induced agglutination. We obtained the following results for all isolates: (1) presence of a central band of the kDNA; (2) T. cruzi specific double bands of the protein patterns; (3) positive reaction with Aaptos papillata II. No differences between the five isolates from Chile and T. cruzi or T. cruzi-like strains from other countries could be observed. Based on these results an infection of the bugs with T. rangeli and T. conorhini could be excluded.     

Epidemiology of toxoplasmosis in Chile. VI. Prevalence of human infection, investigated by means of an indirect hemagglutination test, in regions VII, VIII and IX

In presecuting the investigations on the epidemiology of toxoplasmosis in Chile, a new series of serological surveys has been performed during 1982-1989 in 10 urban and 25 periurban-rural localities from the regions VII, VIII and IX of the country (34 degrees 41'-39 degrees 38' South lat.). In 9,758, randomly selected apparently healthy persons, and indirect hemagglutination test (IHAT) for toxoplasmosis was carried out. The age of these individuals (4,203 males and 5,555 females) varied between 4 and 84 years. The examined persons represent a 0.33% of the total population of the three studied regions. IHAT titers of 1: > or = 16 were regarded as positive. The global prevalence for positive IHAT was 45.5% (50.5% in men and 41.7% in women). A higher proportion of positive tests was observed in urban areas (47.0%) than in periurban-rural sections (33.3%). An increasing prevalence with age was also observed. Only 5 (0.05%) persons had IHAT titers higher than 1:1000.     

Usefulness of the ELISA-IgG test in sera and filter paper blood eluates in the Chagas disease immunodiagnosis]

An ELISA-IgG test using a soluble extract of Trypanosoma cruzi antigen has been developed. One hundred and seventy eight sera (74 healthy people, 44 chagasic patients with positive xenodiagnosis and 60 with clinical symptoms), and 64 paper filter blood eluates (35 healthy people, 10 chagasic patients and 19 with clinical symptoms) were tested by ELISA-IgG and an indirect hemagglutination test. Both types of methods presented an overall average concordance of 98.3% and 100.0% with sera and filter paper blood eluates respectively. A cut off (average of optical density plus 3 standard deviations) of 0.365 and 0.379 for sera and eluates was found. The use of ELISA-IgG in Chagas' disease clinical diagnosis and seroepidemiological studies is discussed.     

Prevalence of anti-R-13 antibodies in human Trypanosoma cruzi infection

Abstract Infection with Trypanosoma cruzi develops in three phases: acute, indeterminate or asymptomatic, and chronic phase (with cardiac or digestive manifestations). Moreover, transmission may occur from infected mothers to newborn, the so-called congenital form. In the present study, humoral responses against T. cruzi total extract and against the 13 amino acid peptide named R-13 derived from the parasite ribosomal P protein, previously described as a possible marker of chronic Chagas heart disease, were determined pateints and in blood bank donors from endemic areas. While in sera from acute phase, only IgM anti- T.cruzi response was observed, both IgM and IgG anti- T. cruzi antibodies were detected in sera from congenitally infected newborns. The percentage of positive response in sera from blood bank donors was relatively high in endemic regions. Antibodies against the R-13 peptide were present in a large proportion of cardiac chagasic patients but were totally lacking in patients with digestive form of Chagas disease. Furthermore, anti-R-13 positive responses were detected in congenitally infected newborns.     

Longitudinal study, by xenodiagnosis, of parasitemia in patients with chronic Trypanosoma cruzi infection]

A 2-5 years follow-up of parasitemia, by the use of xenodiagnosis (XD) was carried out in nine patients with chronic T. cruzi infection who proceeded from chagasic endemic areas of Chile. The patients (mean age 55 years) were hospitalized in the chronic section of a psychiatry institution sited in a permanent triatomines free urban area. Clinical examination, X-rays images (cardiovascular, esophagus and colon) and electrocardiogram resulted normal in all the patients. Basic study unit of parasitemia was a XD box which contained 7 nymphs III of Triatoma infestans which was used in a serial XD consisting in the simultaneous application of a pair of boxes a day during three consecutive days, making a total of six boxes (42 nymphs). The minimal time of duration of infection (M.D.I.) for each patient was estimated that this was adquired close to hospitalization. The M.D.I. varied between 6 and 45 years. The global positivity of XD boxes ranged between 6.3 and 84.7%, being in three patients lower than 12% and in six patients higher than 52%. In considering the yield of XD it is important to stress that during all the study of the nine patients with chronic chagasic infection 1282 XD boxes were applied resulting positive 582 (45.4%). At the end of the follow-up all patients received specific treatment for chagasic infection with nifurtimox at the daily dose of 10 mg/kg of body weight during 60 days. According to the result, two main conclusions arise: 1.--Serial XD has a high efficiency for detecting, evaluate and evolve parasitemia in patients with chronic chagasic infection. 2.--Parasitemia may present low, medium or high levels in different individuals and has a variable and fluctuating character.