Mexican Trypanosoma cruzi isolates: in vitro susceptibility of epimastigotes to anti-trypanosoma cruzi drugs and metacyclic forms to complement-mediated lysis.

Trypanosoma cruzi has a clonal organization with an ample array of genetic and phenotypic features and probably anaploid constitution. Consequently, the biological behavior, biochemistry, and molecular attributes may be distinctive for each parasite strain in different geographical regions. As far as we know, there is no published information on the susceptibility of Mexican T. cruzi stocks to anti-T. cruzi drugs such as benznidazole and gentian violet, or on its resistance to complement-mediated lysis. We studied 10 Mexican T. cruzi isolates from different geographical areas, such as the pacific coast (Oaxaca, Guerrero, and Nayarit States), central part of Mexico (Guanajuato State), Gulf of Mexico (Veracruz State), and the Yucatan Peninsula (Campeche State). We searched for the natural resistance to drugs in in vitro assay against the 10 Mexican isolates using epimastigote forms and the complement-mediated lysis using metacyclic trypomastigotes insect-derived in three of them (one for each geographic region). In general, we observed high resistance to benznidazole in all the Mexican isolates tested, but in the complement-mediated lysis test, they showed moderate to high susceptibility. Although it is necessary to expand this study by using trypomastigotes and the intracellular form to verify its biological role, we suggest that Mexican T. cruzi parasites may have a variable susceptibility to antibody-mediated lysis and high resistance to benznidazole.

Description of inflammation and cytokine profile at the inoculation site and in heart tissue of mice re-infected with Trypanosoma cruzi vector derived-metacyclic trypomastigotes.

We studied the role of Trypanosoma cruzi reinfection in regard to inflammatory and cytokine response at the inoculation site, lymph node and heart. We reinfected Balb/c mice intradermically into the hind foot-pad with natural infective metacyclic trypomastigotes. They were followed from 24 h to 30 days after the last reinfection. At the inoculation site 24 h after the last re-infection, the infiltrating inflammatory cells increased dramatically with respect to baseline inflammation, reaching maximum infiltrates for the third day. In contrast, parasite DNA was undetectable 24 h after inoculation, despite poor cytokine induction, only IFN-gamma, IL-12 and TGF-beta were noticeable on days 7 and 15, whereas in the lymph nodes draining the inoculation site positive expression of IL-2, IL-4, IL-12 and TGF-beta were found to be induced as soon as 24 h after re-entry of parasite. In the heart, the inflammatory response increased immediately 24 h after re-entry of parasites, reaching its maximum on the 7th day and returning to baseline on day 30. In conclusion, although the inflammatory response is triggered in both compartments by re-entry of parasites, the inflammatory process returns almost to baseline after 30 days, leaving a persistent low-grade inflammation.

Seroprevalence of human Trypanosoma cruzi infection in diferent geografic zones of Chiapas, Mexico.

A serologic survey was carried out in four different geographic zones of Chiapas, Mexico. A total of 1,333 samples were collected from residents of thirteen communities located on the Coast, Central Mountain, Lacandon Forest and a zone called Mesochiapas. One hundred and fifty one seropositive individuals (11.3%) were identified. Human Trypanosoma cruzi infection was influenced by geography. In the Lacandon Forest and Central Mountains there was a higher seroprevalence 32.1 and 13.8% respectively, than on the coast (1.2%). In Mesochiapas there were no seropositive individuals among the 137 persons tested. An active transmission is probably continuing because seropositive cases (13.8%) were detected in children under 10 years of age. The vector recognized on the Coast was Triatoma dimidiata while in the Lacandon Forest it was Rhodnius prolixus.

IgG subclass reactivity to Trypanosoma cruzi in chronic chagasic patients.

BACKGROUND: The anti-Trypanosoma cruzi antibodies isotype profile in Chagas' disease has been studied in relation to different clinical manifestations. A high titer of IgG anti-T. cruzi antibodies is found in patients with cardiac involvement, while a high titer of IgA anti-T. cruzi antibodies is associated with digestive forms. OBJECTIVE: The aim of this work was to analyze the IgG subclass reactivity of anti-T. cruzi antibodies in patients with chronic Chagasic cardiomyopathy. METHODS: Twelve consecutive chagasic patients were analyzed for IgG subclass reactivity to a T. cruzi antigenic extract. They had a complete clinical evaluation, peripheral EKG, echocardiography, left ventriculogram, and coronariography. RESULTS: All patients came from rural areas of Mexico and had lived in endemic zones for over seven years. They presented left ventricular endsystolic dimension above 42 mm in 58% (7/12) and ejection fraction below 50% in 58% (7/12). We found that IgG1 and IgG2 anti-T. cruzi antibodies showed higher titer than IgG3 antibodies, with consistently low titer of IgG4 antibodies. Expression of the four IgG subclasses of anti-T. cruzi antibodies suggest a mixed Th1/Th2-like immune response under a probably continuous chronic antigenic stimulation. On the other hand, high levels of IgG2 anti-T. cruzi antibodies showed a tendency to be associated with severe cardiomegaly. CONCLUSIONS: Our results suggest that a mixed Th1/Th2-like immune response may take place in chronic chagasic patients under a chronic antigenic stimulation.

[Chagasic cardiopathy in Tehuantepec. Preliminary report]. / Cardiopatía chagásica en Tehuantepec. Informe preliminar.

UNLABELLED: American trypanosomosis was described in the state of Oaxaca, Mexico in 1936, and is probably endemic in rural areas. However, there is no information regarding chronic disease in the Isthmus of Tehuantepec, previous to this report. OBJECTIVE: To identify the prevalence of American trypanosomosis and its consequences, such as the chronic chagas cardiomyopathy (CCC) among patients who were evaluated by the cardiology service in two general hospitals in Salina Cruz in the state of Oaxaca which is the main city of the Tehuantepec Region. MATERIAL AND METHODS: Consecutive patients referred to the two cardiology services were identified as primary dilated myocardiopathy after a complete clinical and epidemiological history, chest roengentgram, EKG and echocardiogram. Blood was obtained through venipuncture and samples were studied for anti-Trypanosoma cruzi antibodies using validated indirect immunofluorescence, ELISA and Western blot assays. RESULTS: Over a two period in which 540 cardiologic patients were examined, 16 (2.4% cases) of primary dilated cardiomyopathy were diagnosed and 13 (81%) of these were seropositive for anti-T. cruzi and therefore, fulfilled epidemiological and clinical criteria for chronic chagasic cardiomyopathy (CCC). CONCLUSIONS: American trypanosomosis and CCC were diagnosed in cases of dilated cardiomyopathy within a geographical area where, there is an important distribution of triatomine bugs infected and Trypanosoma cruzi. Infection caused a progressive heart disease in this population exposed to insect vectors due to poor housing and sanitary conditions. The present study points out the need for further epidemiological studies in the Tehuantepec region.

[Rheumatic cardiopathy and Chagas disease]. / Cardiopatía reumática y enfermedad de Chagas.

Rheumatic heart disease is common in the undeveloped world; Chagas disease, a typical rural parasitic condition started to affect urban areas. Both have a relatively high incidence and prevalence in Latin America, however, we could not find a report of patients with coincidental rheumatic heart disease and Chagas disease. Herein we report the first documented case.

Humoral nitric oxide levels and antibody immune response of symptomatic and indeterminate Chagas' disease patients to commercial and autochthonous Trypanosoma cruzi antigen.

We report here the evaluation of chagasic patients for the presence and/or severity of the disease, antibody to Trypanosoma cruzi, and nitric oxide (NO) serum levels. Serum samples tested by ELISA with autochthonous and commercial antigen revealed that 10% and 7.5% of the individuals were anti-T. cruzi antibody-positive, respectively. Ten of 21 seropositive individuals had no clinical signs, the other 11 cases presented cardiomyopathy and/or mega-gastrointestinal syndromes, and three patients presented a combined form. A statistical difference (P < 0.001) in antibody titer between asymptomatic and symptomatic patients with autochthonous antigen was detected, and serum NO levels was found to be three times higher in cases than in controls. These results suggest that it is recommended to use a sole source of antigen (autochthonous) for the serodiagnosis of Chagas' disease, and that the pathogenic role of NO in this disease should be evaluated.

Serodiagnosis of American trypanosomosis by using nonpathogenic trypanosomatid antigen.

Crithidia luciliae, a nonpathogenic trypanosomatid, could provide a good alternative source of antigen for serodiagnosis of Chagas' disease. An enzyme-linked immunosorbent assay showed 100% sensitivity and 83% specificity when 91 human serum samples from Chagas' disease patients and 127 human serum samples from people suffering from toxoplasmosis (21 samples), leishmaniasis (32 samples), systemic rheumatic diseases (33 samples), and heart diseases (41 samples) were tested simultaneously with Trypanosoma cruzi and C. luciliae crude extracts. By Western blotting, an immunodominant band (30 kDa) was recognized by chagasic sera on the C. luciliae crude extract; specificity reached 97% with respect to this protein band. The carbohydrate moieties were not antigenic.

American trypanosomosis: in situ and generalized features of parasitism and inflammation kinetics in a murine model.

American trypanosomiasis: In situ and generalized features of parasitism and inflammation kinetics in a murine model. Experimental Parasitology 83, 267-274. Mimicking the natural conditions of mammalian infection, metacyclic trypomastigote forms of a Mexican isolate (Ninoa) of Trypanosoma cruzi were inoculated into mice in order to study inflammation kinetics and parasite clearance at the inoculation site, parasite tropism to different organs, and local inflammatory cell infiltrates. Polymorphonuclear cells were detected at the inoculation site as early as 1 hr after inoculation. Peak cell infiltrate was observed at 24 hr; at 96 hr polymorphonuclear cells had disappeared. Mononuclear cell infiltrates began at 24 hr, peaking at Day 15, and then stared disappearing by Day 30. Antigens and parasites were detected by conventional techniques up to 15 min and thereafter became undetectable. Amplification of the hypervariable region of kinetoplast minicircle DNA by polymerase chain reaction was positive from 24 hr to Day 15, and the reaction became negative on Day 30. Myositis was observed in skeletal muscle from Days 7 to 180, it progressed from slight to severe, with an inflammation process which included macrophages, plasmatic cells, and a few eosinophils, the phenotype of the infiltrating cells included LyT2+ and LyT1+ on Day 30, and both cell populations decreased in parallel on Day 180. Antigen and parasite nests were present from Day 15 to 180; in muscle the earliest time at which minicircle DNA was detected was Day 7 and it was present until Day 180. Myocarditis was also observed; it developed from slight to severe in between Days 7 and 30, then gradually decreased, and cleared up. Mononuclear cell infiltrates in the myocardium were present from Days 7 to 180. Antigen and parasite nests were detected at Days 15 and 30 and disappeared at Day 180, although minicircle DNA was detected until the last day of observation. Both skeletal and heart muscles showed inflammatory reaction foci containing T. cruzi antigen. There was twice the number of foci in heart as in skeletal muscle. This ratio was maintained by Day 30; later skeletal muscle showed persistent inflammation which was practically cleared up in the heart. Parasites or antigen were not detected by Day 180 in both skeletal and cardiac muscle; however, minicircle DNA was amplified, indicating that an small proportion of parasites evaded immune response. According to these data, Mexican Ninoa Strain has a classification as biodeme 3.

[Serological diagnosis of Chagas disease: self-sufficiency and interlaboratory concordance]. / Diagnóstico serológico de la enfermedad de Chagas: autosuficiencia y concordancia interlaboratorios.

American trypanosomiasis (Chagas' disease) is becoming a relatively common condition in North America. Diagnosis at the chronic stage depends on demonstration of specific antibodies in body fluids, since parasitologic or pathologic diagnosis is uncertain at this stage. Therefore, standardization of immunodiagnostic techniques is mandatory, and it depends on antigen quality. Locally prepared antigens and crude extracts obtained from Mexican isolates, -both from infected vector and human cases-were compared using three different immunodiagnostic assays-indirect immunofluorescence, hemagglutination and enzyme linked immunosorbent assay (ELISA)-at two different laboratories from the Instituto Nacional de Cardiología and the Instituto Nacional de Diagnóstico y Referencia Epidemiológicos. Concordance between laboratories reached a significant Kappa value (0.8) and sensitivity, specificity and predictive values of individual diagnostic assays were adequate to use these tests in clinical diagnoses. This is the first attempt to standardize immunodiagnostic techniques in Mexico.

[Ventricular aneurysm in chronic Chagas' disease. The experience of the Instituto Nacional de Cardiología Ignacio Chávez]. / Aneurisma ventricular en la cardiopatía chagásica crónica. Experiencia del Instituto Nacional de Cardiología "Ignacio Chávez".

This work describes the incidence of ventricular aneurysms in patients with angiographically normal epicardial coronary arteries, who have epidemiological, clinical and serologic features suggesting chronic Chagasic cardiomyopathy (C.C.C). Eight out of 22 patients (36%) with such features had ventricular aneurysm. Three were located on the apex, 3 anteroapical and 2 basal. All patients had arrhythmia. In a case it was necessary a surgical approach to control a medically intractable life threatening ventricular tachyarrhythmia. In regard of the incidence of ventricular aneurysms in C.C.C., our results are in agreement with published experiences in South America. Surgical treatment of chagasic aneurysm should be considered when medical treatment is unable to control dangerous arrhythmia and an electrophysiological study supports this approach.

[Reactivity of sera from Chagas patients to extracts of mexican Trypanosoma cruzi isolates]. / Reactividad de sueros de pacientes chagásicos crónicos con extractos de aislamientos mexicanos de Trypanosoma cruzi.

An antigenic extract prepared from four different Mexican isolates of Trypanosoma cruzi cultured on BHI (three came from human cases-Agripina, Fidelfa and Ninoa, and other from triatoma-Cocula) were assayed with human sera. ELISA results always were consistent with clinical diagnosis. Sera from patients with a diagnosis of Chagas disease were reactive and non-chagasic sera were negative. Western blot of chagasic sera recognized antigens of molecular weight > 81 kd, 81 kd, 54 kd, 42 kd, and 26 kd. Sera with high OD in ELISA reacted with more peptide bands. The soluble extract antigens prepared from Mexican isolates of T. cruzi and from the Brazilian Y strain have an homogenous and similar reactivity.

[American trypanosomiasis (Chagas' disease). A clinico-serological survey in a rural community of Oaxaca]. / Tripanosomiasis americana (enfermedad de Chagas). Encuesta clínico-serológica en un municipio rural oaxaqueño.

A survey at a rural community in Oaxaca, Mexico revealed 30 (29%) out of 104 people tested are carriers of anti-Trypanosoma cruzi antibodies. This high prevalence of seropositivity signals an important parasite circulation. We did not studied people under 15 years of age, therefore we can not identify transmission in this area. A concomitant study of 12 lead showed that those who are seropositive had more EKG abnormalities as a group. Such findings could indicate the parasitic disease impact on community health.

[The incidence of Trypanosoma cruzi antibodies in patients with dilated myocardiopathy at the Instituto Nacional de Cardiología Ignacio Chávez]. / La incidencia de anticuerpos anti Tripanosoma cruzi en pacientes con miocardiopatía dilatada en el Instituto Nacional de Cardiología "Ignacio Chávez".

Our objective was to measure the incidence of humoral immune response against Trypanosoma cruzi among patients with a definitive diagnosis of dilated cardiomyopathy at the Instituto Nacional de Cardiología "I. Chávez" over a year. Thirty seven patients were collected, 15 of them (40%) had antibodies against T. cruzi in two different tests, indirect immunofluorescence and ELISA, the presence of IgG antibody was confirmed through Western blot. There was not differences in clinical picture of cardiomyopathy nor on paraclinical studies. However, there was a significant difference in regard socio economical indexes between the group with positive anti T. cruzi antibodies. They had a predominant rural origin, poor housing and were aware of the vector bug. Also they recalled primary infection in their childhood--American trypanosomiasis could be on important etiologic factor for dilated cardiomyopathy in our country.

[Interaction of a mixture of epimastigotes and tripomastigotes from a culture of a Mexican isolate of Trypanosoma cruzi with mouse macrophages]. / Interacción de una mezcla de epimastigotes y tripomastigotes de cultivo de un aislamiento mexicano de Trypanosoma cruzi con macrófagos murinos.

Chagas disease, a cause of important morbo-lethality in Latinamerica, is produced by a protozoan which has a circulating and tissular phase the Trypanosoma cruzi. Adhesion between T. cruzi and phagocytes is the first step in cellular parasitism, which has a central role in pathogenesis. Although there are studies on parasite phagocyte interaction with some strains of T. cruzi, and it is known that biological variation does exist. We now report the first studies with a mexican isolate using a mix of different phases of T. cruzi obtained from acellular culture resembling the natural conditions. Murine macrophages adheres to epimastigotes, transitional trypomastigotes and metacyclic trypomastigotes since the first minutes of observation, progression on cell-cell interaction was demonstrated, there were no differences among parasite faces however, in some cases there was a failed adhesion, this suggest a possible parasite evasion mechanism. These studies limited only to morphologic aspects the adhesion phenomena, should be pursued.

[American trypanosomiasis and chronic Chagas cardiopathy at the "Ignacio Chaves" National Institute of Cardiology]. / Tripanosomiasis americana y cardiopatia chagásica crónica en el Instituto Nacional de Cardiologia Ignacio Chavez.

The cumulated experience at the Instituto Nacional de Cardiolog ía Ignacio Chavez during the period from 1977 to 1988 in regard of American Trypanosomiasis (AT) and its sequelae, chronic Chagasic Cardiopathy (CHC) was reviewed. There are 39 cases. One was an acute myocarditis in a child 16 months old. Three, subacute diseases among young patients and 35 cases of chronic disease with severe heart compromise. Heart failure was the most important manifestation in 19 patients. Arrhythmia was the dominant one in 8 cases. Both conditions did occur in 8, 2 had Stokes Adams syndrome as presenting complaint and one had pulmonary embolism. The surface EKG was always abnormal and heart enlargement was noted in 36 cases on chest X rays. All patients had serologic evidence of antitrypanosoma antibodies, 28 had heart reactive antibodies in their serum, 24 had polyclonal hypergammaglobulinemia and the same proportion had rheumatoid factor. Only the acute case showed another non-organ specific autoantibody. Echocardiography was useful to show dilatation of all cavities, left ones were more severely affected, abnormal movement was also detected with lower frequency, apical aneurysm and left ventricular hypertrophy were rarely detected. Fifteen out of 16 cases studied by angiogram did show normal coronary arteries, abnormal movement was demonstrated in 62% and apical aneurysm was present in 4 cases. Studies with EKG monitoring (Holter) and electrophysiology confirmed electrical abnormalities. Although once considered an exotic disease, CHC is probably underdiagnosed because the lack of methodic studies looking for epidemiologic, clinical and seroimmunologic features in patients with dilated myocardiopathy. Cardiologist practicing in south and southeast states in Mexico should be aware of this heart ailment.(ABSTRACT TRUNCATED AT 250 WORDS)

[Mechanisms of innate and acquired resistance to Trypanosoma cruzicruzi]. / Mecanismos de resistencia innata y adquirida al Tripanosoma cruzi.

Defense mechanisms against the parasite Trypanosoma cruzi, the etiologic agent for dilated myocardiopathy and Chagas disease are reviewed, in vitro studies and experimental models are described and commented. Applying new techniques derived from Molecular Biology for the study of Chagas disease, both at experimental and clinical level could be rewarding and maybe useful to design effective treatment for this irreversible heart disease in humans.