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Biomedical subjects

S A Silva

Publications and source records attributed to S A Silva.

15 recordsLinked to original sources
PubMed1998

[Eradication of leprosy in the Americas: current status and perspectives].

Leprosy, a disease that used to be shrouded in darkness and fear, can now be cured thanks to a multidrug treatment schedule with rifampicin, clofazimine, and dapsone which has been in use since 1981. In 1991 the World Health Assembly, encouraged by the efficacy of this treatment regimen, established the goal of eliminating the disease as a public health problem globally and nationally by the year 2000. This goal, which calls for reducing disease prevalence to less than one case per 10,000 inhabitants, should not be confused with the goal of eradicating the disease, which implies a complete interruption of its transmission. Eliminating leprosy is an attainable goal which will depend on the forceful and massive use of the multidrug treatment regimen. This paper describes and discusses the various initiatives that have been launched in Latin America for the purpose of achieving this goal and the results obtained so far. It also explores the factors that impact on the feasibility of eradicating the disease.

Brazil↗
PubMed1998

Early electrocardiographic abnormalities in Trypanosoma cruzi-seropositive children.

As part of a major epidemiologic study on Chagas' disease, we compared the prevalence of electrocardiographic (ECG) abnormalities among 141 school children 7-12 years of age and seropositive for Trypanosoma cruzi, and 282 age-, sex-, and school-matched seronegative children in an endemic area in Brazil. The prevalence of ECG abnormalities was 11.3% among seropositive children and 3.5% among seronegative children (odds ratio = 3.5, 95% confidence interval [CI] = 1.5-8.4). The prevalence rate of ECG alterations was 10.7% for seropositive males versus 8.9% for seropositive females. Complete right bundle branch block (CRBBB), which is highly suggestive of Chagas' disease cardiopathy, was diagnosed in nine (6.4%) seropositive children and in only one (0.3%) seronegative child (odds ratio = 18.5, 95% CI = 2.3-146.5, attributable fraction = 58.3%). Five incident new cases of CRBBB were diagnosed after a 36-month follow-up of seropositive children who were enrolled in an independent clinical field trial. No case of frequent and/or multifocal ventricular premature beats was found in the cohort of children. The surprisingly high frequency of early ECG abnormalities, which indicates a rapid evolution from infection to disease, suggests the existence of endemic areas with a particular accelerated disease progression that was not described before. Under such conditions, a public health chemotherapy program focusing on the treatment of young seropositive children would be recommended.

Chagas Disease↗
PubMed1995

Evaluation of risk factors for house infestation by Triatoma infestans in Brazil.

An active entomologic survey was conducted by a team of trained health workers in a rural area endemic for Chagas' disease in central Brazil. They used pyrethrum as a flushing agent and 4,232 houses were inspected for triatomine bugs both inside and in the immediate environs. Houses with Triatoma infestans or evidence of an established colony were identified and defined as infested houses (cases). The building and environmental characteristics of 161 randomly selected infested houses were compared with 161 matched, noninfested houses (controls) that were the shortest distance from the infested house. Domestic and peridomestic potential risk factors associated with house infestation by Triatoma infestans were assessed by logistic regression analysis. Incomplete house construction (odds ratio [OR] = 2.5, 95% confidence interval [CI] = 1.5-4.1) was confirmed as a risk factor related to the presence or evidence of Triatoma infestans in the dwellings. The study also disclosed a statistically significant association between the presence of rats (OR = 1.6, 95% CI = 1.1-2.6) and indoor crop storage (OR = 2.3, 95% CI = 1.1-5.2) and house infestation. Further experimental field studies using tagged rodents should be conducted to assess their epidemiologic role in the domestic chain of Trypanosoma cruzi transmission.

Analysis of Variance↗
PubMed1995

Spatial patterns of leprosy in an urban area of central Brazil.

Reported is the spatial variation of leprosy in an urban area of Brazil and its correlation with socioeconomic indicators. From November 1991 to October 1992 a total of 752 newly diagnosed leprosy patients who were attending all outpatient clinics in Goiânia city, central Brazil, were identified. A database o leprosy cases was set up linking patients' addresses to 64 urban districts. Leprosy cases were detected in 86% of the districts and three risk strata were identified. The highest-risk area for leprosy was in the outskirts of the city and detection rates increased on moving from more developed to poorer areas. The risk of detecting leprosy cases was 5.3-fold greater (95% CI: 3.8-7.4) in the outskirts of the town than in the central zone. Discussed are the methodological issues related to leprosy case ascertainment, completeness and reliability of information, and the interpretation of the spatial distribution of leprosy per unit area. Highlighted also are the lack of leprosy control activities in primary health care units and the usefulness of geographical analysis in planning health services.

Adolescent↗
PubMed1992

Surveillance of Trypanosoma cruzi transmission by serological screening of schoolchildren.

The seroprevalence of Trypanosoma cruzi infection among children is a sensitive indicator for assessing the effectiveness of programmes for control of Chagas disease. In this study we report the result of a cross-sectional serological survey carried out among schoolchildren living in a poor rural area in central Brazil. Eluates of blood collected on filter-paper were tested for anti-T. cruzi antibodies using immunofluorescence, haemagglutination, and enzyme-linked immunosorbent assays. The overall seroprevalence of T. cruzi infection was 7.9%, which compared with the findings of the national survey carried out in 1975-80 indicates that a twofold-to-threefold reduction in prevalence has occurred over the last 10 years. This is consistent with a reduction of transmission in the area, probably related to vector control efforts. Based on our results, the incidence of new cases was estimated to be 44 per annum in the study region. In rural areas with a scattered population, surveillance of T. cruzi transmission by serological screening of children at school entry is more practical and economical than entomological evaluation for assessing both the risk of transmission in the community and the efficacy of vector control measures. A sample size of around 1000 schoolchildren is sufficient to detect prevalences as low as 2%, and such an approach would be practical and applicable to most areas where Chagas disease is endemic.

Antibodies, Protozoan↗
PubMed1992

Protective effect of intradermal BCG against leprosy; a case-control study in central Brazil.

A case-control study was undertaken to evaluate the protective efficacy of intradermal BCG against leprosy in a high-endemic area of leprosy in central Brazil. Sixty-two cases and 186 controls were included in the study. Cases were all newly diagnosed leprosy patients under 16 years of age attending an outpatient health service, and all of them were schoolchildren. Three controls under 16 years old, frequency matched by sex and age group, were selected from schools geographically located in the area from which the cases came. The presence of BCG was negatively associated with leprosy, indicating a 5.3 risk of leprosy for those nonvaccinated and protective efficacy of 81%. Paucibacillary patients were more likely to have a BCG scar than multibacillary patients.

Adolescent↗
PubMed1989

Endoscopic ultrasonography in leiomyoma of gastric cardia.

Gastric submucosal tumors are relatively common. Using the current diagnostic techniques, however, differentiating these tumors from external gastric compression may sometimes be difficult. The nature of submucosal tumors, which may have therapeutic implications, may also be quite difficult to elucidate using current techniques, such as bore biopsy, high-frequency-wave scalpel biopsy, topical infusion of pure ethanol, and submucosography. We report a case of a sumucosal tumor of the gastric cardia and discuss the usefulness of endoscopic ultrasonography (EUS) in determining the internal structure of these tumors. After endoscopic ultrasonography, the tumor was diagnosed as a myoma of the gastric cardia, whose bulk had grown out the gastric cavity.

Adult↗
PubMed1986

Removal of intestinal nematode eggs in tropical waste stabilization ponds.

The removal of intestinal nematode eggs in waste stabilization ponds treating domestic waste-water was studied in northeast Brazil. Anaerobic and primary facultative ponds achieved Ascaris spp. removals of 88-98% and 99-100%, and hookworm removals of 91-97% and 98-100%, respectively. Egg-free effluents were produced by a single primary facultative pond with a retention time of 18.9 days, and by an anaerobic and a secondary facultative pond in series with retention times of 6.8 and 5.5 days. It is concluded that effluents with less than or equal to 1 egg per litre can be produced by a 1 day anaerobic pond followed by a 5 day secondary facultative and a 5 day maturation pond.

Ascaris↗
PubMedDate not supplied

Endoscopic ultrasonography of esophageal tumors and compressions.

The diagnostic value of endoscopic ultrasonography to determine the nature of submucosal tumors and external compressions of the esophagus was assessed in 14 patients using endoscopic linear array ultrasonography. For submucosal tumors this new approach not only provided an accurate diagnosis but also enabled us to determine the layer of origin, the direction of growth, and the consistency of the tumor--information not obtainable through other diagnostic methods. The structure from which the external compression comes could also be detected through this new technique. Endoscopic ultrasonography is a very helpful diagnostic procedure in determining the nature of these "tumorlike" lesions.

Adult↗
PubMedDate not supplied

The accumulation, distribution and viability of human parasitic nematode eggs in the sludge of a primary facultative waste stabilization pond.

Investigations into the enumeration, distribution and viability of nematode eggs in the sludge from a primary facultative waste stabilization pond showed that pond sludges are not nematologically safe for immediate land application. Up to 12% of Ascaris lumbricoides eggs were viable after the pond had been in operation for 2.5 years. Eggs were recovered from the sludge along the full length of the pond, although there were significant decreases in egg concentration and viability with increasing distance from the inlet.

Animals↗
PubMedDate not supplied

Trypanosoma cruzi stocks isolated from acute Chagas disease patients lead to lethal murine infection.

Ten Trypanosoma cruzi stocks recently isolated from patients in acute and chronic phases of Chagas disease were inoculated to susceptible (A/Sn) mice. The mice were inoculated with 10(4) trypomastigotes intraperitoneally and monitored for parasitaemia and mortality for up to 300 d. The results demonstrated that (i) T. cruzi stocks isolated from patients in the acute phase killed animals, while stocks from patients in the chronic phase did not; (ii) survival curves differed statistically among mice infected with lethal stocks, and (iii) parasite burden did not affect the mortality rate of mice.

Acute Disease↗
PubMedDate not supplied

A randomized clinical trial with high dose of chloroquine for treatment of Plasmodium falciparum malaria in Brazil.

This clinical trial compared parasitological efficacy, levels of in vivo resistance and side effects of oral chloroquine 25 mg/Kg and 50 mg/Kg in 3 days treatment in Plasmodium falciparum malaria with an extended followed-up of 30 days. The study enrolled 58 patients in the 25 mg/Kg group and 66 in the 50 mg/Kg group. All eligible subjects were over 14 years of age and came from Amazon Basin and Central Brazil during the period of August 1989 to April 1991. The cure rate in the 50 mg/Kg group was 89.4% on day 7 and 71.2% on day 14 compared to 44.8% and 24.1% in the 25 mg/Kg group. 74.1% of the patients in the 25 mg/Kg group and 48.4% of the patients in the 50 mg/Kg group had detectable parasitaemia at the day 30. However, there was a decrease of the geometric mean parasite density in both groups specially in the 50 mg/Kg group. There was 24.1% of RIII and 13.8% of RII in the 25 mg/Kg group. Side effects were found to be minimum in both groups. The present data support that there was a high level resistance to chloroquine in both groups, and the high dose regimen only delayed the development of resistance and its administration should not be recommended as first choice in malaria P. falciparum therapy in Brazil.

Adult↗
PubMedDate not supplied

Risk factors for Trypanosoma cruzi infection among blood donors in central Brazil.

Characteristics and possible risk factors associated with Trypanosoma cruzi infection among blood donors were assessed within a routine screening programme in blood banks in an endemic area of Chagas disease. 6,172 voluntary blood donors were interviewed and tested for anti-T. cruzi antibodies by Haemagglutination and Complement Fixation tests in six blood banks in Goiânia-Central Brazil from October 1988 to April 1989. An overall prevalence of 2.3% for T. cruzi infection was obtained, being 3.3% for first-time blood donors and 1.9% for regular ones (p < 0.01). Considering this seropositivity among regular blood donors, selection of candidates relying only on the history of previous donation was found to be inadequate. The risk of infection increased inversely with the degrees of education and monthly income. There was a 9.2 risk of infection (95% CI 3.8-22.6) for those who had lived more than 21 years in an endemic area compared to subjects who had never lived in rural settings, after multivariate analysis. These informations may help to review the criteria of selection of donors in order to improve quality of blood products in endemic areas.

Adolescent↗