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.     

Overview of the epidemiology of Chagas' disease in Chile]

Chile is a long and narrow country located in the south western coast of South America. Chagas' disease exists in the seven first (18 degrees 30'-34 degrees 36' South lat.) of the total of thirteen administrative regions of the country. In the 1982-1990 period a series of studies considering different epidemiological aspects of this parasitic zoonosis has been carried out with the following results: 5,601 rural of periurban dwellings were surveyed for the presence of Triatoma infestans (the most important and almost exclusive vector of Trypanosoma cruzi in Chile). 37.4% of the dwellings were infested according to the inhabitants and 29.4% were found infested according to the presence of tracks or insects captured. In 659 (17.2%) out of 3,822 T. infestans captured and examined T. cruzi was found in their abdominal contents. The most common sources of T. infestans feeding were mammals (89.0%), including man, and birds (9.5%). An indirect hemagglutination test (IHAT) for Chagas' disease, a very sensitive and specific reaction, was performed to 5,050 domestic mammals, resulting positive 7.9% of cats, 7.0% of dogs, 7.0% of goats, 4.9% of sheep and 4.1% of rabbits. 2,579 (16.9%) out of 15,418 persons were positive for the IAHT for Chagas' disease. The rates of infection were rather similar in males (17.5%) and females (16.2%) with an increase in infection rates in accordance with increase of age of individuals. The overall frequency of ECG abnormalities in positive IHAT persons was 18.7% against 8.8% in those with negative IHAT, whereas ECG abnormalities considered as suggestive of a chagasic etiology were 6.8% and 2.2% respectively. The esophageal motility in 311 persons with a positive IHAT and in 150 with a negative IHAT was found altered in 42.8% and 18.7% respectively. In the corresponding urban sectors of the 7 regions mentioned 2.7% of blood donors, 2.3% of delivering mothers, 2.6% of newborns and 0.6% of school children had positive IHAT. 646 chagasic women and 709 non-chagasic women in their reproductive span of life, and the products of the pregnancies that they had in a 6-year period were followed-up. No significant differences were found neither in the number nor in the evolution of pregnancies in both groups of mothers. Xenodiagnosis of children from chagasic mothers resulted positive in 6.3-8.9%, showing the transmission of T. cruzi by the placental route. Recently, 3 cases of congenital Chagas' disease of second generation have been demonstrated.(ABSTRACT TRUNCATED AT 400 WORDS)     

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.     

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.     

Seroepidemiological survey of human toxoplasmosis in Osorno, Region X, Chile, 1998]

A serological survey was carried out in Osorno X Region, Chile (40 degrees 21'-40 degrees 46' South lat, and 73 degrees 26' -72 degrees-46' West long.). An indirect hemagglutination test (IHAT) for toxoplasmosis was performed to 305 persons--160 blood donors and 145 with sexually transmitted disease (STD). The age of the surveyed persons (167 males and 138 females) varied between 10 and 72 years. IHAT titers > 16 were considered as positive. The general prevalence was 20.3%--21.2% in blood donors and 19.3% in persons with some STD--with no differences between males and females. However, significant differences between males and females with STD were found (35.6% and 8.1% respectively). No differences between urban and rural inhabitants were found with a slight higher prevalence in the urban ones. No antibodies against Toxoplasma gondii were detected in six AIDS patients. The importance of performing toxoplasmosis immunodiagnosis and individual prophylaxis to avoid the infection in high risk group are recommended.     

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.     

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)     

Epidemiology of toxoplasmosis in Chile. V. Prevalence of the infection in humans and domestic and wild animals, studied by indirect hemagglutination reaction, in the Juan Fernández Archipelago. V Region

A serological study utilizing an indirect hemagglutination test (IHAT) for toxoplasmosis was carried out in 222 humans and in 58 domestic animals (31 dogs, Canis familiaris; 27 cats, Felis catus), and in 62 wild mammals distributed into 50 rabbits, Oryctolagus cuniculus and 12 goats, Capra hircus. This survey was performed in the Juan Fernández Archipelago, formed by three islands: Robinson Crusoe, Santa Clara and Alejandro Selkirk (80 degrees 47'-78 degrees 47' west long., and 33 degrees 36'-33 degrees 47' south lat.). Blood samples were collected in filter paper and IHAT with titres greater than or equal to 1:16 were considered positive. This survey showed a prevalence of 42.3% in humans with no difference between men (43.0%) and women (41.5%). A high prevalence was found within groups of young individuals (0 to 19 years old), men and women. Regarding the domestic animal population, 44.8% resulted positive, distributed as follows: dogs 9.7% and cats 85.2%. Twenty one percent of wild animals were positive, distributed as follows: rabbits 8.0% and goats 75.0%. The global prevalence of toxoplasmosis in animals (domestic and wild) was 32.5%. All titres in humans and animals were less than or equal to 1:512. Toxoplasmosis is well extended among the human and animal population of the Juan Fernández Archipelago.     

Seroepidemiological study of human hydatidosis and trichinosis, with the indirect hemagglutination reaction, in San Juan de la Costa County. Osorno, X Region, Chile. 1990-1991]

San Juan de la Costa County (40 degrees 45' South lat., 73 degrees 19' West long.) is located in the Osorno province, South of Chile. Its population is 8,486 inhabitants. The basic economic activities are agriculture, cattle raising, timber production and manufacture of wood and coal. According to official reports, the incidence of human hydatidosis and trichinosis in this locality in 1989 were 24 and 59 per 100,000 respectively. In order to contribute to a better knowledge of the epidemiology of human hydatidosis and trichinosis in San Juan de la Costa County, an indirect hemagglutination test (IHAT) for these parasitoses was performed to 511 randomized people. Nine (1.8%) individuals resulted positive for hydatidosis and twenty four (4.7%) were positive for trichinosis. Some considerations on the corresponding prophylactic measures are proposed.     

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)     

Comparison of the yield of indirect hemagglutination reaction and complement fixation reaction in the diagnosis of neurocysticercosis

Two variations of an indirect hemagglutination test (IHAT) and a complement fixation test (CFT) for the diagnosis of human cysticercosis were compared and evaluated. For the IHAT, a cysticerci crude total saline extract (SE) and a cysticerci lyophylized and delipidized veronal bicarbonate saline buffer (VBS) extract were used, comparing their diagnosis yieldings with that of a CFT in 57 confirmed cysticercosis patients: 45 serum samples and 32 cerebrospinal fluid (CSF). Sera and CSF from 29 patients with other neurological diseases and 25 sera from healthy volunteers were also compared. Both types of methods presented an overall average concordance of 91.5% and 97.0% with CSF and sera respectively. With respect to the sensitivity observed with CFT was 85.2% and 93.3% for CSF and sera, whereas that of IHAT was 96.9% in CSF and 97.8% in sera, when SE antigen was used; with the VBS antigen for IHAT 96.9% and 95.6% were detected in CSF and sera respectively. In order to determine the specificity of the IHAT, besides the study in healthy volunteers, in patients with other neurological diseases and in 156 serum samples from individuals with other parasitoses, such as hydatidosis (43), trichinosis (56), fascioliasis (31) and Chagas' disease (26) were also tested. A high reactivity with the hydatidosis group was found. The specificity, using a titre > or = 1:16 as a diagnostic value and without considering hydatidic sera was 99.4% for RHAI (SE), 100.0% for RHAI (VBS). The use of IHAT and CFT in diagnosis of human cysticercosis is discussed.     

Seroepidemiological study of human hydatidosis, by means of an indirect hemagglutination test in Rio Negro County, X Region, Chile, 1989-1990

Rio Negro Country (40 degrees 48'-40 degrees 50' South lat.; 73 degrees 12'-73 degrees 13' West long.), is located in the province of Osorno, South of Chile. It has a population of 18,031 inhabitants, with 39% in rural areas. The basic economic activity is cattle raising (cows, pigs). According to reports, prevalence of human hydatidosis in 1988 was 11.1 per 100,000. In order to contribute to a better knowledge of human hydatidosis in Rio Negro County, an indirect hemagglutination test (IHAT) was performed to 509 randomized persons. Five (1.0%) individuals resulted positive.     

The indirect hemagglutination reaction in the diagnosis of trichinosis

An indirect hemagglutination test (IHAT) for trichinosis using a Melcher's antigen was evaluated and compared with a precipitin test (PT) and a bentonite flocculation test (BFT). One hundred and forty eight serum samples from patients from the whole country confirmed or suspected to have trichinosis by clinical or epidemiological evidences were studied: 117 (79.1%) samples resulted positive by IHAT, 138 (93.2%) by PT and 65 (43.9%) by BFT. Sixty three serum samples from patients with strong clinical suspect of trichinosis presented the PT and the BFT positive and were compared with the IHAT for sensitivity study. IHAT was positive in 60 (95.2%) serum samples. In order to determine the specificity of IHAT 25 serum samples from healthy volunteers and 124 serum samples from individuals with other parasitoses, such as cysticercosis (48), hydatidosis (45) and fascioliasis (31) were studied. The specificity, using a titre > or = 1:16 as a possible diagnostic value was 96%. The use of IHAT with RP and BFT in the diagnosis of human trichinosis is discussed.     

Health Risk Assessment of Inhalation Exposure to Formaldehyde and Benzene in Newly Remodeled Buildings,Beijing

Objective

To assess health risks associated with inhalation exposure to formaldehyde and benzene mainly emitted from building and decoration materials in newly remodeled indoor spaces in Beijing.

Methods

We tested the formaldehyde and benzene concentrations in indoor air of 410 dwellings and 451 offices remodeled within the past year, in which the occupants had health concerns about indoor air quality. To assess non-carcinogenic health risks, we compared the data to the health guidelines in China and USA, respectively. To assess carcinogenic health risks, we first modeled indoor personal exposure to formaldehyde and benzene using the concentration data, and then estimated the associated cancer risks by multiplying the indoor personal exposure by the Inhalation Unit Risk values (IURs) provided by the U.S. EPA Integrated Risk Information System (U.S. EPA IRIS) and the California Office of Environmental Health Hazard Assessment (OEHHA), respectively.

Results

(1) The indoor formaldehyde concentrations of 85% dwellings and 67% offices were above the acute Reference Exposure Level (REL) recommended by the OEHHA and the concentrations of all tested buildings were above the chronic REL recommended by the OEHHA; (2) The indoor benzene concentrations of 12% dwellings and 32% offices exceeded the reference concentration (RfC) recommended by the U.S. EPA IRIS; (3) The median cancer risks from indoor exposure to formaldehyde and benzene were 1,150 and 106 per million (based on U.S. EPA IRIS IURs), 531 and 394 per million (based on OEHHA IURs).

Conclusions

In the tested buildings, formaldehyde exposure may pose acute and chronic non-carcinogenic health risks to the occupants, whereas benzene exposure may pose chronic non-carcinogenic risks to the occupants. Exposure to both compounds is associated with significant carcinogenic risks. Improvement in ventilation, establishment of volatile organic compounds (VOCs) emission labeling systems for decorating and refurbishing materials are recommended to reduce indoor VOCs exposure.     

Results of serological reactions in patients with presumptive diagnosis of toxoplasmosis]

Even though Toxoplasma gondii is an ubiquitous parasite that can effect most of human structures and organs, not all clinical manifestations suggestive of being produced by it are caused by this protozoon. For these reasons sera samples of patients suspected of having toxoplasmosis are sent to the laboratory for detecting specific antibodies which would facilitate the differential diagnosis. Thus, 716 sera from suspected patients, mainly from the Metropolitan Region of Chile, were sent to the Parasitology Laboratory of Chile University in order to carry out in them, specific serological tests for toxoplasmosis: indirect hemagglutination test (IHAT), Sabin Feldman reaction (SFT) and complement fixation test (CFT). Were considered positive: IHAT and/or SFT with titers > or = 1:16 and CFT with titer > or = 1:5. The pathologies for demanding these serological tests were obstetrical problems 210 (29.3%), congenital problems 193 (27.0%), ophthalmopathies 81 (11.3%), adenopathies 77 (10.8%), AIDS 67 (9.4%), myocardiopathies 46 (6.4%) and miscellaneous 42 (5.9%). The positivity found in these sera was higher in ophthalmopathies (61.7%), followed by obstetrical problems, miscellaneous problems, myocardiopathies and AIDS (50.7-52.4%), less frequent was the positivity in adenopathies (35.1%) and congenital problems (23.1%). In general, the 43.7% of positivity for toxoplasmosis found in these patients is higher than the 37.0% found in the general population. High titers of IHAT and SFT plus positive CFT was found in 13-fold higher proportion than in the general population.     

Effect of temperature on the settlement choice and photophysiology of larvae from the reef coral Stylophora pistillata

To better understand the consequences of climate change for scleractinian corals, Stylophora pistillata was used to test the effects of temperature on the settlement and physiology of coral larvae. Freshly released larvae were exposed to temperatures of 23 degrees C, 25 degrees C (ambient), and 29 degrees C at light intensities of approximately 150 micromol photons m(-2) s(-1). The effects were assessed after 12 h as settlement to various substrata (including a choice between crustose coralline algae [CCA] and limestone) and as maximum quantum yield of PSII (F(v)/F(m)) in the larvae versus in their parents. Regardless of temperature, 50%-73% of the larvae metamorphosed onto the plastic of the incubation trays or in a few cases were drifting in the water, and 14% settled on limestone. However, elevated temperature (29 degrees C) reduced the percentage of larvae swimming by 81%, and increased the percentage choosing CCA nearly 7-fold, both relative to the outcomes at 23 degrees C. Because temperature did not affect settlement on limestone or plastic, increased settlement on CCA reflected temperature-mediated choices by larvae that otherwise would have remained swimming. Interestingly, F(v)/F(m) was unaffected by temperature, but it was 4% lower in the larvae than in the parents. These results are important because they show that temperature can affect the settlement of coral larvae and because they reveal photophysiological differences between life stages that might provide insights into the events associated with larval development.     

Taeniosis-cysticercosis complex in individuals of a peasants' settlement (Teodoro Sampaio, Pontal of Paranapanema, SP, Brazil)

In order to evaluate the taeniosis-cysticercosis complex in a population of a peasants' settlement, located at Teodoro Sampaio, state of S?o Paulo, Brazil (longitude 52 degrees 36'12 ", latitude 22 degrees 17'12 ") a series of laboratory markers were determined. After signing an informed consent, participants answered a standardized questionnaire. To determine anti-Taenia solium cysticercus antibodies, the samples were tested by enzyme linked immunoabsorbent assay using 18-and 14-kDa antigen proteins from vesicular fluid of Taenia crassiceps (VF-Tcra). The reactive and inconclusive ELISA samples were tested by immunoblotting. Total IgE levels were determined by chemmiluminescence's assay and hemogram by flow cytometer flux counter. A total of 84 individuals, 5.9% presented anti-T. solium cysticercus antibodies in ELISA and 3.6% were strongly reactive in the 18/14 kDa immunoblotting confirmatory test. All of the individuals with positive antibodies showed elevated Total IgE levels. We conclude that the frequency of anti-T. solium cysticercus antibodies in this population is higher than other regions considered endemic in S?o Paulo. Thus, it is important to carry out surveys in Peasants' settlement areas with the objective of establishing public health measures for prevention and control of infectious diseases such as taeniosis-cysticercosis.     

内蒙古哈民忙哈遗址废弃情境观察与分析

哈民忙哈遗址位于科尔沁沙地腹心地带,是迄今在西辽河以北地区发现的最重要的史前聚落遗址。本文全面考察2010~2014年发掘的44座房址的废弃情境,将它们分为三种类型。不同类型房址体现的不同废弃行为方式,分别对应灾难性、不预期返回和预期返回三种废弃模式。科尔沁沙地脆弱的生态环境促使人们采取流动性居住方式、依赖多元化的生计方式,从而形成了不预期返回和预期返回废弃模式。但这种人地关系的短暂平衡仍然潜伏着危机,当一系列因素耦合作用时,酿成了一场可怕的灾难,导致聚落形成最后阶段的灾难性废弃模式。     

Cholinesterase activity during embryonic development in the blood-feeding bug Triatoma patagonica

Triatoma patagonica Del Ponte (Hemiptera: Reduviidae), a vector of Chagas' disease, is widely distributed in Argentina and is found in sylvatic and peridomiciliary ecotopes, as well as occasionally in human dwellings after the chemical control of Triatoma infestans. Anti-cholinesteratic products can be applied in peridomiciliary areas and thus knowledge of cholinesterase activity during embryonic development in this species might contribute further information relevant to effective chemical control. Cholinesterase activity was characterized by reactions to eserine 10(-5) m, to increasing concentrations of substrate and to varying centrifugal speeds. Acetylcholinesterase activity was detected on day 4 and was significant from day 5. A reduction in cholinesterase activity towards acetylthiocholine (ATC) was observed on days 9 and 10 of development. Cholinesterase activity towards ATC and butyrylthiocholine (BTC) in homogenates of eggs was inhibited by eserine 10(-5) m. The shape of the curve indicating levels of inhibition at different concentrations of ATC was typical of acetylcholinesterase. Activity towards BTC did not appear to be inhibited by excess substrate, which parallels the behaviour of butyrylcholinesterases. Cholinesterase activity towards ATC was reduced in supernatant centrifuged at 15 000 g compared with supernatant centrifuged at 1100 g. The cholinesterase system that hydrolyzes mainly ATC seems to belong to the nervous system, as indicated by its behaviour towards the substrates assayed, its greater insolubility and the fact that it evolves parallel to the development of the nervous system. Knowledge of biochemical changes associated with the development and maturation of the nervous system during embryonic development would contribute to the better understanding of anti-cholinesteratic compounds with ovicidal action that might be used in control campaigns against vectors of Chagas' disease.     

The Syrian hamster as a model for the dilated cardiomyopathy of Chagas' disease: a quantitative echocardiographical and histopathological analysis

Chronic Chagas' disease cardiomyopathy (CCC) is caused by the protozoan Trypanosoma cruzi, and it affects 30% of the 16-18 million people infected in Latin America. A good rodent model that develops a dilated cardiomyopathy closely resembling human CCC after T. cruzi infection is still needed. We compared the cardiomyopathy developed by T. cruzi-infected Syrian hamsters with human Chagas' disease cardiomyopathy using quantitative methods. Female hamsters were infected with 3.5 x 10(4) (G1, n = 10) or 10(5) (G2, n = 10) T. cruzi Y strain blood trypomastigotes. Control animals (C, n = 10) were injected with saline solution. Cardiac function was assessed by echocardiography at 4, 8 and 12 months post-infection. Heart sections were submitted to histopathological/morphometric analysis 12 months post-infection. At this time, ventricular dysfunction and diffuse or multi-focal myocarditis were observed in 91% and 100% of G1 and G2 infected groups, respectively. Median interstitial collagen volumes in groups C, G1 and G2 were 1.2%, 1.9% and 3.9%, respectively, and were significantly higher in group G2 than in group C. Among infected animals, myocarditis showed a positive correlation with interstitial fibrosis. Deaths in the chronic phase (8-12 months post-infection) were more frequent among G2 than G1, and were associated with macroscopic ventricular dilation, severe myocarditis and increased fibrosis values, along with an earlier onset of ventricular dysfunction. The T. cruzi chronically infected Syrian hamster develops a cardiomyopathy which resembles human Chagas' disease cardiomyopathy, and might be an adequate tool to investigate pathogenic mechanisms of this disease and to search for novel therapeutic strategies.