Urban transmission of Chagas disease in Cochabamba, Bolivia.

Chagas disease is a major public health problem in Bolivia. In the city of Cochabamba, 58% of the population lives in peripheral urban districts ("popular zones") where the infection prevalence is extremely high. From 1995 to 1999, we studied the demographics of Chagas infections in children from five to 13 years old (n = 2218) from the South zone (SZ) and North zone (NZ) districts, which differ in social, environmental, and agricultural conditions. Information gathered from these districts demonstrates qualitative and quantitative evidence for the active transmission of Trypanosoma cruzi in urban Cochabamba. Seropositivity was high in both zones (25% in SZ and 19% in NZ). We observed a high risk of infection in children from five to nine years old in SZ, but in NZ, a higher risk occurred in children aged 10-13, with odds ratio for infection three times higher in NZ than in SZ. This difference was not due to triatomine density, since more than 1,000 Triatoma infestans were captured in both zones, but was possibly secondary to the vector infection rate (79% in SZ and 37% in NZ). Electrocardiogram abnormalities were found to be prevalent in children and pre-adolescents (SZ = 40%, NZ = 17%), indicating that under continuous exposure to infection and re-infection, a severe form of the disease may develop early in life. This work demonstrates that T. cruzi infection should also be considered an urban health problem and is not restricted to the rural areas and small villages of Bolivia.

Urban transmission of Chagas disease in Cochabamba, Bolivia

Chagas disease is a major public health problem in Bolivia. In the city of Cochabamba, 58 percent of the population lives in peripheral urban districts ("popular zones") where the infection prevalence is extremely high. From 1995 to 1999, we studied the demographics of Chagas infections in children from five to 13 years old (n = 2218) from the South zone (SZ) and North zone (NZ) districts, which differ in social, environmental, and agricultural conditions. Information gathered from these districts demonstrates qualitative and quantitative evidence for the active transmission of Trypanosoma cruzi in urban Cochabamba. Seropositivity was high in both zones (25 percent in SZ and 19 percent in NZ). We observed a high risk of infection in children from five to nine years old in SZ, but in NZ, a higher risk occurred in children aged 10-13, with odds ratio for infection three times higher in NZ than in SZ. This difference was not due to triatomine density, since more than 1,000 Triatoma infestans were captured in both zones, but was possibly secondary to the vector infection rate (79 percent in SZ and 37 percent in NZ). Electrocardiogram abnormalities were found to be prevalent in children and pre-adolescents (SZ = 40 percent, NZ = 17 percent), indicating that under continuous exposure to infection and re-infection, a severe form of the disease may develop early in life. This work demonstrates that T. cruzi infection should also be considered an urban health problem and is not restricted to the rural areas and small villages of Bolivia.

The Bambuí health and aging study (BHAS). Prevalence of intermittent claudication in the aged population of the community of Bambuí and its associated factors.

OBJECTIVE: To assess the prevalence of intermittent claudication in the aged population of Bambuí, Brazil, and to identify the factors associated with this disease. METHODS: Population-based cross-sectional study of the aged population (>/= 60 years of age) of Bambuí. Participants were interviewed and examined, after written consent. Intermittent claudication was defined based on a standardized questionnaire. Analysis was performed using multiple logistic regression. RESULTS: Of the 1,742 elderly living in Bambuí, 1,485 (85.2%) were enrolled in the study. Thirty-seven individuals (2.5%) with intermittent claudication were identified: 28 (1.9%) males and 9 (0.6%) females. Their age brackets were: 16 (1.08%) individuals between 60 and 69 years of age, 17 (1.15%) between 70 and 79 years, and 4 (0.27%) >/= 80 years. A significant association between intermittent claudication and the following characteristics was found: male sex (OR=5.1; CI 2.4-11.0), smokers (OR=3.1; CI 1.2-8.5), ex-smokers (OR=3.4; CI 1.3-8.7), and more than 2 hospital admissions in the last 12 months (OR=2.8; CI 1.1-7.2). CONCLUSION: Disease prevalence was similar to that of other countries. The association between intermittent claudication and smoking strengthens the significance of tobacco in peripheral artery disease pathogenesis. The association of intermittent claudication and a higher number of hospital admissions suggests greater morbidity in the elderly affected.

In vitro study on thiabendazole action on viability of Ascaris lumbricoides (Lineu, 1758) eggs.

The in vitro activity of thiabendazole on Ascaris lumbricoides eggs, which were recovered from uteri of worm excreted after chemotherapeutic treatment, was studied. Four concentrations of the drug were used: 1 - 2.5 - 5 - and 10 ppm during 24, 48 and 72 hours of exposure. Subsequently, the eggs were centrifuged, washed three times and H(2)SO(4)0.1N was added. The eggs were maintained in an incubator for 20 days at 28 degrees C. Finally, the percentage of embryonated eggs was determined under a lightmicroscope at a 100X magnification. After 48 and 72 hours of thiabendazole exposure, at a concentration of 10ppm, the drug showed complete inhibition of egg embryonation.

Ageing with Trypanosoma cruzi infection in a community where the transmission has been interrupted: the Bambuí Health and Ageing Study (BHAS).

BACKGROUND: The prevalence of Chagas' disease is decreasing in Brazil. Due to cohort effect, the disease might remain a public health problem for some time among older individuals. The present burden of Trypanosoma cruzi infection for the elderly living in areas where the transmission has been interrupted has not been studied. METHODS: The prevalence of T. cruzi infection and its association with indicators of health status and health services use were assessed among the elderly living in one of the oldest endemic areas in Brazil (Bambuí, MG). Seropositivity was determined by blood tests (IHA and ELISA) performed in 85.6% of all residents aged 60+ (1496/1742) and in 83.1% of sampled residents aged 5-59 years (1212/1458). RESULTS: Seropositivity showed a cohort effect, with no cases below 20 years and high prevalence among those aged 60+ years (37.7%). After adjustment for confounders, seropositivity was associated with self-rated health reasonable (OR = 1.43; 95% CI : 1.03-1.98) and bad/very bad (OR = 1.89; 95% CI : 1.30-2.75), staying in bed in past 2 weeks (OR = 1.88; 95% CI : 1.21-2.92), hospitalization in past 12 months (OR = 1.41; 95% CI : 1.05-1.89) and use of 5+ prescribed medications in past 3 months (OR = 1.75; 95% CI : 1.15-2.59). IMPLICATIONS: Our results are an example of how survival of individuals with past exposure to infectious disease may lead to a different picture of ageing in the developing world. Policy makers need to consider the extra burden imposed by increasing rates of non-infectious disease among the elderly (as observed in Brazil) including the consequences of T. cruzi infection in areas where the infection was widespread in the past.

In vitro study on thiabendazole action on viability of Ascaris lumbricoides (Lineu, 1758) eggs

The in vitro activity of thiabendazole on Ascaris lumbricoides eggs, which were recovered from uteri of worm excreted after chemotherapeutic treatment, was studied. Four concentrations of the drug were used: 1 - 2.5 - 5 - and 10 ppm during 24, 48 and 72 hours of exposure. Subsequently, the eggs were centrifuged, washed three times and H(2)SO(4)0.1N was added. The eggs were maintained in an incubator for 20 days at 28 degrees C. Finally, the percentage of embryonated eggs was determined under a lightmicroscope at a 100X magnification. After 48 and 72 hours of thiabendazole exposure, at a concentration of 10ppm, the drug showed complete inhibition of egg embryonation.

Foi estudada, in vitro, a ação do tiabendazol, contra ovos de Ascaris lumbricoides , retirados de úteros de vermes eliminados após tratamento. Foram utilizadas quatro concentrações da droga: 1 ¾ 2,5 - 5 e 10 ppm em três diferentes períodos de tempo: 24, 48 e 72 horas. Decorridos estes tempos a suspensão com os ovos foi centrifugada, lavada por três vezes com água destilada, adicionada de solução de H2SO4, 0,1N e mantida em estufa a 28°C por 20 dias. Em seguida, os ovos foram levados ao microscópio óptico, no aumento de 100X, para observação do percentual de embrionamento. Na concentração de 10ppm, nos tempos de 48 e 72 horas de exposição à droga, verificou-se completa inibição do embrionamento dos ovos.

[The Bambuí Project: a population-based study of factors associated with regular utilization of dental services in adults]. / Projeto Bambuí: estudo de base populacional dos fatores associados com o uso regular de serviços odontológicos em adultos.

A cross-sectional study was conducted in Bambuí, Minas Gerais, to identify factors associated with regular use of dental services. Participants were interviewed with a structured questionnaire and previously validated questions. 999/1,221 (81.8%) randomly selected individuals aged > 18 years participated in the Bambuí dental survey. Of these, 654 out of 656 individuals who had at least one natural tooth and had visited a dentist during their lifetime participated in the study. Results adjusted by multiple logistic regression showed that regular use of dental services was significantly related to having > 8 and 4-7 years of schooling (OR = 9.90; 95% CI = 2.90-33.77 and OR = 3.87; 95% CI = 1.11-13.51, respectively), having a preference for restorative treatment rather than extraction (OR = 4.91; 95% CI = 2.23-10.79), having no present need of dental treatment (OR = 4.87; 95% CI = 3.17-7.49), and belief that visiting the dentist prevents tooth decay and gum disease (OR = 1.73; 95% CI = 1.13-2.65). The results show that regular use of dental services was related to factors distributed in the Andersen and Newman model (1973) explaining use of dentistry services.

The Bambuí Health and Aging Study (BHAS): prevalence of risk factors and use of preventive health care services.

OBJECTIVE: To describe, for the first time in Brazil, the prevalence of risk factors and the use of preventive health care services among adults 60 years and older. METHODS: This population-based study was conducted during 1996-1997 in the state of Minas Gerais, in the town of Bambuí, which is located in the municipality of the same name. In 1996 the town had 14,950 inhabitants. For the study, all the town's residents aged > or = 60 years were selected, along with a comparison sample of persons aged 18-59 years. Data were gathered using interviews and physical examinations. RESULTS: Of the 1,742 inhabitants of the town of Bambuí aged > or = 60 years, 1,606 (92.2%) participated in the interview and 1,495 (85.8%) were examined (blood pressure, anthropometric measurements, and blood tests). Among the 1,020 younger adults selected for the survey, 909 of them (89.1%) participated in the interview, and 820 of them (80.4%) underwent the physical examination. The prevalence of the following risk factors was higher among older adults than among younger adults: physical inactivity (47.7% vs. 28.0%); blood pressure 140-159 mmHg (systolic) or 90-99 mmHg (diastolic) (25.8% vs. 8.7%); blood pressure > or = 160 mmHg (systolic) or > or = 100 mmHg (diastolic) (19.1% vs. 4.1%); total cholesterol > or = 240 mg/dL (40.6% vs. 9.8%); and blood glucose > or = 126 mg/dL (12.4% vs. 2.2%). The daily consumption of fruits and vegetables was similar among the older adults and the younger ones (51.9% and 51.7%), as was also body mass index > or = 25 kg/m2 (51.6% and 56.2%). Smoking was lower among the older adults (18.7%) than among the younger ones (31.1%). The proportion of participants whose blood pressure had been checked in the preceding year was high (86.8% among the older adults and 61.2% among the younger ones), suggesting that the high prevalence of uncontrolled hypertension was not due to limited access to health care. CONCLUSIONS: For a long time it was believed that the kinds of risk factors that we found in the urban section of the municipality of Bambuí were public health problems only in large Brazilian cities. Around 72% of the municipalities in Brazil have < or = 20,000 inhabitants, and these smaller municipalities contain some 19% of the country's entire population. The high prevalence of various risk factors among the older and younger adults in Bambuí indicates a great need for health promotion and disease prevention actions. More research is needed to find out whether our results in Bambuí reflect the reality of other small towns in Brazil.

[Search of antimeasles antibodies in HIV-infected children after basic immunization] / Pesquisa de anticorpos contra o sarampo em crianças infectadas pelo HIV, após a imunização básica.

OBJECTIVE: To determine the presence of antimeasles antibodies in children perinatally infected with HIV and properly immunized. METHODS: A retrospective cohort study conducted in Belo Horizonte by the Universidade Federal de Minas Gerais, between 1995 and 1996. Twenty one children perinatally infected with HIV and 29 immunocompetent noninfected children were included in the study. Information about measles vaccination was obtained from patients immunization charts. The presence of neutralizing antibodies against the measles was determined by the plaque reduction neutralization test and IgM was measured by ELISA. The level of significance was set at 5% in all the performed statistical analyses. RESULTS: Median age was 44.5 months for HIV-infected patients and 62.0 months for noninfected children (P=0.64). Both groups received on average two doses of antimeasles vaccine. All HIV-seronegative patients presented antimeasles antibody titers greater than 50 mIU/ml, whereas 57.1% of infected children presented titers above this value (P=0.0001). The geometric mean titer of neutralizing antibodies was significantly lower in the group of HIV-infected children (433.5 mIU/ml) than in noninfected children (1,668.1 mIU/ml), P=0.001. All patients in both groups were negative for antimeasles IgM. CONCLUSION: In the present study, HIV-infected children showed a lower seroprevalence of antimeasles antibody after immunization than noninfected children. These results emphasize the risk of acquisition of measles virus and the need to evaluate alternatives to the vaccination of HIV-infected children in an attempt to maximize the protection against the measles in this group of patients.

Hypertension and clustering of cardiovascular risk factors in a community in Southeast Brazil--The Bambuí Health and Ageing Study.

OBJECTIVE: A population-based prospective study was analysed to: a) determine the prevalence of hypertension; b) investigate the clustering of other cardiovascular risk factors and c) verify whether older differed from younger adults in the pattern of clustering. METHODS: The data comprised a representative sample of the population of Bambuí, Brazil. Multiple logistic regression was used to investigate the independent association between hypertension and selected factors. RESULTS: A total of 820 younger adults (82.5%) and 1494 older adults (85.9%) participated in this study. The overall prevalence of hypertension was 24.8% (SE=1.4 %), being higher in women (26.9+/-1.5%) than in men (22.0+/- 1.7%) (p=0.033). Hypertension was positively and significantly associated with physical inactivity, overweight, hypercholesterolemia hyperglycemia and hypertriglyceridemia. The coexistence of hypertension with 4 or more of these risk factors occurred 6 times more than expected by chance, after adjusting for age and sex (OR=6.3; 95%CI: 3.4-11.9). The pattern of risk factor clustering in hypertensive individuals differed with age. CONCLUSION: Our results reinforce the need to increase detection and treatment of hypertension and to approach patients' global risk profiles.

The Bambuí Health and Aging Study (BHAS): factors associated with hospitalization of the elderly.

This study aimed to identify factors associated with hospital admissions of the elderly. All residents of Bambuí, Minas Gerais State >/= 60 years (n = 1,742) were selected. Some 1,606 of these (92.2%) participated in the study. The dependent variable was the number of hospital admissions (none, one, and two or more) during the previous 12 months. Independent variables were grouped as enabling, predisposing, and need-related factors. The strongest associations with multiple hospital admissions were: living alone; financial constraints to purchase of medication; and various indicators of need (worse self-perceived health, more visits to physician, greater use of prescription medications, and history of coronary heart disease). Such variables could help identify older adults at greatest risk and thus prevent hospitalization.

Predicting the community prevalence of schistosomiasis mansoni from the prevalence among 7- to 14-year-olds.

The World Health Organization suggested that the prevalence of Schistosoma mansoni among 7- to 14-year-olds be used to guide treatment strategies in endemic areas. This study explores how well the prevalence in that age group predicted the overall prevalence in the community in data from stool examinations (Kato-Katz method) from 180,000 people in 3 municipalities in Brazil in 1984 and 1985. The median prevalence was higher in 1984, before community treatment was introduced. There was a strong relationship between the prevalence among 7- to 14-year-olds and the overall prevalence in the community. We present sensitivities and positive predictive values for the use of prevalence in the indicator group to select communities for mass treatment as recommended by WHO. For a range of assumptions sensitivity and positive predictive value were never both above 80 %. We suggest that the estimates of validity presented in this paper inform future evaluations of strategies for S. mansoni control.

The control of schistosomiasis in Brazil: an ethnoepidemiological study of the effectiveness of a community mobilization program for health education.

This study combined anthropological and epidemiological approaches to assess the effectiveness of community mobilization for health education, developed as part of the Brazilian program for the control of schistosomiasis. The study was carried out in two villages in the state of Minas Gerais, SE Brazil, exposed to the same established schistosomiaisis control strategies. Residents of one village were also exposed to the community mobilization for health education (study area) while those from the other community were not exposed to this program (control area). Schistosoma mansoni prevalence rates for the study and control villages were compared over time. A population-based survey was carried out in the two villages to obtain information on socio-demographic factors, water contact patterns and knowledge of S. mansoni transmission. Intensive ethnographic interviews with key informants in each locality were employed to determine the knowledge, attitudes and practices of the communities regarding schistosomiasis. Ethnographic data were analysed using the model of systems of signs, meanings and actions. Differences were observed in prevalence trends between the study and control areas but they could not be explained by the existence of the community mobilization program in the former. It was also found that educational actions carried out by the Brazilian Ministry of Health transmitted information on schistosomiasis but were ineffective in transforming the information received into preventive behaviour related to water contact. With regard to disease, the population studied tended to distinguish minor symptoms, which they associated with water contact, from major symptoms, which they attributed to lack of medical treatment. This distinction mediated perceptions of the severity of "xistose" and reduced the importance of avoiding contact with potentially infested waters. The perception of protection conferred by treatment observed in the present study might also apply to other communities where access to treatment is readily available and free. The extent to which this perception exists in endemic areas needs to be determined so that apparent contradictions of this type can be addressed in future educational programs.

The Bambuí health and ageing study (BHAS): methodological approach and preliminary results of a population-based cohort study of the elderly in Brazil.

OBJECTIVE: A cohort study has been designed to identify predictors of adverse health events in the elderly. The methodology of the study and preliminary descriptive results are presented. METHODS: The study population comprises all residents of Bambuí (Minas Gerais, Brazil), aged 60 or more years (n=1.742). From these, 92.2% were interviewed and 85.9% underwent clinical examination, consisting of haematological and biochemical tests, serology for Trypanosoma cruzi, anthropometric and blood pressure measures and electrocardiogram. Aliquots of serum, plasma and DNA were stored for future investigations. The baseline interview included sociodemographic characteristics, self-referred health condition and history of selected diseases, medication use, health service use, source of medical care, physical activities, smoking, drinking and eating habits, reproductive history, physical functioning, life events, social support and mental health. Individuals are being followed up annually. RESULTS: The following characteristics predominated among participants: women (60,0%), married (48.9%) or widowed (35.4%), people living in households with up to 2 residents (73.8%), heads of family (76.7%), people with monthly income between 1.00 and 2.99 Brazilian minimum wages (62.0%) and people with up to 4 years of schooling (89.1%). The median age was 68 years. Among the cohort members, only 1.7% were lost in the first follow-up. CONCLUSIONS: In general, the characteristics of the study population were very similar to those from other epidemiological studies of the elderly based on large Brazilian cities. The small number of losses to follow-up indicates that the choice of Bambuí was adequate, assuring the feasibility of a long term cohort study.

[Death of elderly patients in the Santa Genoveva Clinic in Rio de Janeiro: excess mortality that the public health system could have prevented]. / A morte de idosos na Clínica Santa Genoveva, Rio de Janeiro: um excesso de mortalidade que o sistema público de saúde poderia ter evitado.

From January to May 1996, 156 inpatients died in a clinic for elderly people in Rio de Janeiro, Brazil. The highest mortality rate was observed in May: 143/1,000 inpatients. As a result, the clinic was closed by the Ministry of Health. This study investigated whether the excessive number of deaths observed in the clinic in early 1996 was unexpected or reflected prevailing conditions. The investigation used the Public Health System database (SIH-SUS). The study period was 01/1993 to 05/1996. The investigation was based on: 1) a time-series analysis of the number of deaths and crude mortality rates and 2) comparison of the mortality rates observed in that clinic with those calculated for 15 area hospitals, defined as the reference rates. Risk of death in the clinic was higher than expected in 28 of the 41 months considered in the study. Highest risks were observed in January 1993 (RRcrude = 2.23; 95% CI 1.56-3. 14) and May 1996 (RRadjusted = 2.73; 95% CI 1.88-3.95). The high mortality rates observed in the clinic in 1996 were already present in 1993. Thus, adequate use of the SIH-SUS could have anticipated and avoided the excess mortality identified in early 1996.

Trypanosoma cruzi: parasitaemia produced in mice does not seem to be related to in vitro parasite-cell interaction.

The interaction of Trypanosoma cruzi strains producing subpatent or high parasitaemia in mice with mouse macrophages, Vero and L929 cells was evaluated using tissue culture trypomastigotes. Macrophages were the cells most readily infected while Vero cells presented the highest parasite intracellular multiplication rates. Subpatent strains were equal or more infective than the high parasitaemia. Due to the small number of strains, no correlation could be established between the zymodemes and parasitaemia or parasite-cell interaction in vitro. However parasitaemia in mice does not seem to be related to in vitro parasite-cell interaction.

Questionnaires in the screening for Schistosoma mansoni infection: a study of socio demographic and water contact variables in four communities in Brazil.

The use of questionnaires has been recommended for identifying, at a lower cost, individuals at risk for schistosomiasis. In this study, validity of information obtained by questionnaire in the screening for Schistosoma mansoni infection was assessed in four communities in the State of Minas Gerais, Brazil. Explanatory variables were water contact activities, sociodemographic characteristics and previous treatment for schistosomiasis. From 677, 1474, 766 and 3290 individuals eligible for stool examination in the communities, 89 to 97% participated in the study. The estimated probability of individuals to be infected, if they have all characteristics identified as independently associated with S.mansoni infection, varied from 15% in Canabrava, to 42% in Belo Horizonte, 48% in Comercinho and 80% in São José do Acácio. Our results do not support the hypothesis that a same questionnaire on risk factors could be used in screening for S.mansoni infection in different communities.

[Maps of epidemiological rates: a Bayesian approach]. / Mapas de taxas epidemiológicas: uma abordagem Bayesiana.

This article presents statistical methods recently developed for the analysis of maps of disease rates when the geographic units have small populations at risk. They adopt the Bayesian approach and use intensive computational methods for estimating risk in each area. The objective of the methods is to separate the variability of rates due to differences between regions from the background risk due to pure random fluctuation. Risk estimates have a total mean quadratic error smaller than usual estimates. We apply these new methods to estimate infant mortality risk in the municipalities of the State of Minas Gerais in 1994.

Re-evaluation of schistosomiasis mansoni in Minas Gerais, Brazil. III. "Noroeste de Minas" mesoregion.

This study was conducted to assess the presence of schistosomiasis mansoni in the "Noroeste de Minas" mesoregion, an area considered non-endemic. A malacologic survey and parasitologic stool examinations were undertaken in 13 municipalities of the mesoregion. A sample of 3,283 primary school students was submitted to fecal examination by the Kato-Katz method. A total of 3,627 planorbids was collected and examined. The molluscs were identified as Biomphalaria straminea in seven municipalities (Unaí, Bonfinópolis de Minas, Paracatu, Jaão Pinheiro, Vazante, Lagamar and Lagoa Grande) and as Biomphalaria peregrina in one (Presidente Olegário). All planorbids were negative for Schistosoma mansoni. Four students were diagnosed with schistosomiasis in the municipalities of Buritis, Formoso, Paracatu and Unaí, but none of these cases was considered autochthonous. The data obtained indicate that the "Noroeste de Minas" mesoregion continues to be non-endemic for schistosomiasis mansoni, although the presence of intermediate hosts associated with parasitized individuals emphasizes the need for epidemiological surveillance of schistosomiasis in this mesoregion.