Non-lactose-fermenting uropathogenic Escherichia coli from dogs: virulence profile characterization.

Non-lactose-fermenting Escherichia coli (NLFEC) has a few descriptive studies restricted to human infections. In the present study, isolates of NLFEC obtained from urine samples of dogs with hyperadrenocorticism were characterized regarding their virulence ability, biofilm formation capacity and antimicrobial susceptibility profile. Escherichia coli lactose-fermenting strains from urinary infection in dogs with the same conditions were analysed to provide comparisons. The non-lactose-fermenting E. coli strains were classified as belonging to clade I E. coli, whereas the lactose-fermenting strains were classified in phylogroup B2. All strains presented virulence markers to adhesion, iron acquisition, toxins, colicin and cytotoxin production, and biofilm regulation. Components of the extracellular matrix in addition to the in vitro biofilm formation ability were observed in the strains. Multidrug resistance (MDR) profiles were observed by in vitro susceptibility tests to all NLFEC strains. In summary, non-lactose-fermenting uropathogenic E. coli from dogs behaves similar to lactose-fermenting E. coli, exhibiting MDR profile, and pathogenic potential of promote animal infections.

Listeria monocytogenes isolates from food and food environment harbouring tetM and ermB resistance genes.

UNLABELLED: Listeria monocytogenes is a foodborne pathogen that has become an important cause of human and animal diseases worldwide. The purpose of this study was to evaluate the serotypes, virulence potential, antimicrobial resistance profile, and genetic relationships of 50 L. monocytogenes isolates from food and food environment in southern Brazil. In this study, the majority of L. monocytogenes isolates belonged to the serotypes 1/2b (42%) and 4b (26%), which are the main serotypes associated with human listeriosis. In addition, all isolates harboured internalin genes (inlA, inlC, inlJ), indicating a virulence potential. The isolates were sensitive to most of the antimicrobial compounds analysed, and five isolates (10%) were multi-resistant. Two isolates harboured antimicrobial resistance genes (tetM and ermB) and in one of them, the gene was present in the plasmid. Moreover, according to the pulsed field gel electrophoresis assay, two multi-resistant isolates were a single clone isolated from food and the processing plant. The isolates were susceptible to the most frequently used antibiotics for listeriosis treatment. However, the presence of multidrug-resistant isolates and antimicrobial resistance genes including in the plasmid could even be transferred between bacterial species, suggesting a potential health risk to consumers and a potential risk of spreading multi-resistance genes to other bacteria. SIGNIFICANCE AND IMPACT OF THE STUDY: Listeria monocytogenes is an important agent of foodborne diseases. The results of this study suggest a potential capacity of L. monocytogenes isolates from food and food environment to cause human infections. Antimicrobial multi-resistance profiles were detected in 10%, and two isolates harboured tetM and ermB resistance genes. Moreover, the present research can help to build up a better knowledge about antimicrobial resistance of L. monocytogenes. Additionally, we found one isolate carrying tetM resistance gene in a plasmid, that suggests a possible transmission between commensal and/or other pathogenic bacteria of food environment, thereby raising up concerns regarding bacterial resistance.

Surface Morphology and Structural Modification Induced by Femtosecond Pulses in Hydrogenated Amorphous Silicon Films.

This work investigates the modification, resulting from fs-laser irradiation (150 fs, 775 nm and 1 kHz), on the structure and surface morphology of hydrogenated amorphous silicon (a-Si:H) thin films. The sample morphology was studied by performing a statistical analyzes of atomic force microscopy images, using a specially developed software that identifies and characterizes the domains (spikes) produced by the laser irradiation. For a fluence of 3.1 MJ/m2, we observed formation of spikes with smaller average height distribution, centered at around 15 nm, while for fluencies higher than 3.7 MJ/m2 aggregation of the produced spikes dominates the sample morphology. On the other hand, Raman spectroscopy revealed that a higher crystalline fraction (73%) is obtained for higher fluences (> 3.1 MJ/m2), which is accompanied by a decrease in the size of the produced crystals. Therefore, such results indicate that there is a trade-off between the spike distribution, crystallization fraction and size of the nanocrystals attained by laser irradiation, which has to be taken into account when using such approach for the development of devices.

Transrectal endoscopy with three different techniques of rectal suture associate: NOTES survival study with liver biopsy in a swine model / Endoscopia transretal para biópsia hepática associada com três diferentes técnicas de sutura retal: estudo da NOTES em modelo experimental suíno

A cirurgia endoscópica por orifícios naturais (NOTES) representa um novo conceito de cirurgia, caracterizada por ausência de incisões abdominais. Os acessos mais comumente usados são o transvaginal e o transgástrico. Entretanto, as rotas transcolônica e transretal representam alternativas promissoras. O presente estudo objetiva avaliar três diferentes técnicas de sutura retal em três suínos submetidos a NOTES transretal para biópsia hepática, avaliando-se concomitantemente as repercussões clínicas e hematológicas. Sob anestesia geral, foi realizada uma incisão transversal no reto para a passagem do endoscópio até a cavidade abdominal em todos os animais para a realização da biópsia hepática. Cada animal recebeu um tipo de sutura retal: sutura em dois planos; reforço com tela de polipropileno ou reforço com membrana de pericárdio bovino. A NOTES transretal em modelo experimental suíno não apresentou implicações clínicas e hematológicas importantes, o que demonstra um acesso alternativo para biópsia hepática. Nenhum animal apresentou sinais de peritonite, aderências ou deiscência de pontos. O uso de reforço com pericárdio bovino para a sutura retal apresenta um atraso na cicatrização quando comparado com a sutura convencional ou com o uso de tela de polipropileno.(AU)

Detection of antibody responses against Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis proteins in children with community-acquired pneumonia: effects of combining pneumococcal antigens, pre-existing antibody levels, sampling interval, age, and duration of illness.

We evaluated the effects of combining different numbers of pneumococcal antigens, pre-existing antibody levels, sampling interval, age, and duration of illness on the detection of IgG responses against eight Streptococcus pneumoniae proteins, three Haemophilus influenzae proteins, and five Moraxella catarrhalis proteins in 690 children aged <5 years with pneumonia. Serological tests were performed on acute and convalescent serum samples with a multiplexed bead-based immunoassay. The median sampling interval was 19 days, the median age was 26.7 months, and the median duration of illness was 5 days. The rate of antibody responses was 15.4 % for at least one pneumococcal antigen, 5.8 % for H. influenzae, and 2.3 % for M. catarrhalis. The rate of antibody responses against each pneumococcal antigen varied from 3.5 to 7.1 %. By multivariate analysis, pre-existing antibody levels showed a negative association with the detection of antibody responses against pneumococcal and H. influenzae antigens; the sampling interval was positively associated with the detection of antibody responses against pneumococcal and H. influenzae antigens. A sampling interval of 3 weeks was the optimal cut-off for the detection of antibody responses against pneumococcal and H. influenzae proteins. Duration of illness was negatively associated with antibody responses against PspA. Age did not influence antibody responses against the investigated antigens. In conclusion, serological assays using combinations of different pneumococcal proteins detect a higher rate of antibody responses against S. pneumoniae compared to assays using a single pneumococcal protein. Pre-existing antibody levels and sampling interval influence the detection of antibody responses against pneumococcal and H. influenzae proteins. These factors should be considered when determining pneumonia etiology by serological methods in children.

Prevalence and risk factors for wheezing in Salvador, Brazil: a population-based study.

BACKGROUND: Wheezing is one of the most frequent causes of visit to emergency rooms among children. However, data on wheezing burden are mostly provided at healthcare setting, and particularly only for infants. AIMS: We sought to estimate the prevalence of wheezing in children under 4 years and to assess potential risk factors in the community. DESIGN: This was a cross-sectional analysis of a population-based cohort study. METHODS: The sample comprised children aged <4 years living in Salvador, Brazil. Data were collected via home visits when the parents/guardians were interviewed. Data were recorded on standardized forms. RESULTS: Of 1534 children, mean age was 21 ± 14 months (minimum 3 days; maximum 47 months; 6% <2 months); 780 (51%) were males and 501 [33%; 95% confidence interval (95% CI): 30-35%] reported wheezing in the last 12 months. Among wheezers, 321 (64%) had occasional wheezing. Overall, 180 (12%; 95% CI: 10-14%) had recurrent wheezing and 157 (10%; 95% CI: 9-12%) had asthma. For children in the first, second, third and fourth year of life wheezing was reported in 23, 41, 34 and 37%, respectively. Mother atopic-related disease was independently associated with recurrent wheezing (AdjPR[95% CI]: 1.54 [1.12-2.11]) and asthma (AdjPR[95% CI]: 1.54 [1.10-2.16]). Smoker at home (AdjPR[95% CI]: 1.34 [1.07-1.67]) and low birth weight (AdjPR[95%CI]: 1.38 [1.05-1.81]) were independently associated with occasional wheezing. CONCLUSIONS: One-third of under 4 years reported wheezing; history of mother's atopic-related disease was an independent risk factor for recurrent wheezing and asthma; smoker at home and low birth weight were independent risk factors for occasional wheezing.

Effect of ischemic preconditioning on injuries caused by ischemia and reperfusion in rat intestine.

To study whether ischemic preconditioning (IPC) attenuated intestinal dysfunction caused by ischemia (I) and reperfusion (R), rats were underwent 60 minutes of I which was produced by occlusion of the superior mesenteric artery, and/or 120 minutes R. The IPC group had the I procedure previously stimulated for 5 minutes and the R for 10 minutes. IPC and sham groups were injected with saline solution (SS) via the femoral vein 5 minutes before the I and R, and for R. After I or I/R, 2-cm jejunal segments were mounted in an organ bath to study neurogenic contractions stimulated by electrical pulses or KCl using a digital recording system. Thin jejunal slices were stained with hematoxylin and eosin for optical microscopy. Compared with the sham group, jejunal contractions were similar in the IPC + I and the IPC + I/R groups, but reduced in the I + SS and the I/R + SS groups. The jejunal enteric nerves were damaged in the I + SS and the I/R + SS groups, but not in the IPC groups. These results suggested that ischemic preconditioning attenuated intestinal dysfunction caused by I and I/R.

Differences in evolution of children with non-severe acute lower respiratory tract infection with and without radiographically diagnosed pneumonia.

OBJECTIVE: To identify differences in the evolution of children with non-severe acute lower respiratory tract infection between those with and without radiographically diagnosed pneumonia. DESIGN: Prospective cohort study. SETTING: A public university pediatric hospital in Salvador, Northeast Brazil. PATIENTS: Children aged 2-59 months. METHODS: By active surveillance, the pneumonia cases were prospectively identified in a 2-year period. Each case was followed-up for changes in various clinical symptoms and signs. Demographic, clinical and radiographic data were recorded in standardized forms. Exclusion was due to antibiotic use in the previous 48 hours, signs of severe disease, refusal to give informed consent, underlying chronic illness, hospitalization in the previous 7 days or amoxicillin allergy. Chest X-ray (CXR) was later read by at least 2 independent pediatric radiologists. MAIN OUTCOME MEASURES: Radiographic diagnosed pneumonia based on agreed detection of pulmonary infiltrate or pleural effusion in 2 assessments. RESULTS: A total of 382 patients receiving amoxicillin were studied, of whom, 372 (97.4%) had concordant radiographic diagnosis which was pneumonia (52%), normal CXR (41%) and others (7%). By multivariate analysis, age (OR=1.03; 95% CI: 1.02-1.05), disease > 5 days (OR = 1.04; 95% CI: 1.001-1.08), reduced pulmonary expansion (OR = 3.3; 95% CI: 1.4-8.0), absence of wheezing (OR = 0.5; 95% CI: 0.3-0.9), crackles on admission (OR = 2.0; 95% CI: 1.2-3.5), inability to drink on day 1 (OR = 4.2; 95% CI: 1.05-17.3), consolidation percussion sign (OR = 7.0; 95% CI: 1.5-32.3), tachypnea (OR = 2.0; 95% CI: 1.09-3.6) and fever (OR = 3.6; 95% CI: 1.4-9.4) on day 2 were independently associated with pneumonia. The highest positive predictive value was at the 2nd day of evolution for tachypnea (71.0%) and fever (81.1%). CONCLUSION: Persistence of fever or tachypnea up to the second day of amoxicillin treatment is predictive of radiographically diagnosed pneumonia among children with non-severe lower respiratory tract diseases.

Radiographic findings among children hospitalized with severe community-acquired pneumonia.

BACKGROUND: Community-acquired pneumonia (CAP) is a leading cause of childhood death. There are few published reports of radiographic findings among children with severe CAP. OBJECTIVE: To describe chest X-ray (CXR) findings and assess association between these radiographic findings and pneumococcal isolation in children with severe CAP. METHODS: A prospective, multicenter, observational study was conducted in 12 centers in Argentina, Brazil, and the Dominican Republic. Children aged 3-59 months, hospitalized with severe pneumonia, were included. On admission, blood and pleural effusion cultures were performed. Streptococcus pneumoniae was identified according to standard procedures in the respective national reference laboratory. Chest X-rays were taken on admission and read before the culture results were reported. RESULTS: Out of 2,536 enrolled patients, 283 (11.2%) had S. pneumoniae isolated, in 181 cases (7.1%) from blood. The follow radiographic patterns were observed: alveolar infiltrate (75.2%), pleural effusion (15.6%), and interstitial infiltrate (9.2%). Overall, pleural effusion was associated with pneumococcal isolation and pneumococcal bacteremia (P < 0.001). Infiltrates were unilateral (78.7%) or bilateral (21.3%), right-sided (76%) or left-sided (24%), in the lower lobe (53.6%) or the upper lobe (46.4%). Multivariate analysis including patients with affection of only one lobe showed that upper lobe affection and pleural effusion were associated with pneumococcal isolation (OR 1.8, 95% CI, 1.3-2.7; OR 11.0, 95% CI, 4.6-26.8, respectively) and with pneumococcal bacteremia (OR 1.7, 95% CI, 1.2-2.6; OR 3.1, 95% CI, 1.2-8.0, respectively). CONCLUSIONS: Three-quarters of the patients studied had alveolar infiltrates. Upper lobe compromising and pleural effusion were associated with pneumococcal invasive disease.

Antimicrobial resistance and subtyping of Salmonella enterica subspecies enterica serovar Enteritidis isolated from human outbreaks and poultry in southern Brazil.

To investigate antimicrobial resistance, 96 Salmonella enterica subspecies enterica serovar Enteritidis strains isolated from salmonellosis outbreaks and poultry-related products obtained in southern Brazil were analyzed. Macrorestriction patterns, obtained by pulsed-field gel electrophoresis and phage types, were assessed. Although 43.75% of samples were sensitive to all drugs tested, resistance to sulfonamide (34.37%), trimethoprim-sulfamethoxazole (25.00%), nalidixic acid (14.58%), streptomycin (2.08%), gentamicin, and tetracycline (1.04%) was identified. Furthermore, 89.60% of strains belonged to phage type 4, and a predominant pulsed-field gel electrophoresis genotype represented by 82.29% of the strains was identified, suggesting that a clonal group was distributed in poultry, food, and human isolates. Although it was not possible to associate strains from different sources, the occurrence of antimicrobial-resistant Salmonella Enteritidis strains supports the need to establish monitoring programs to identify the emergence of potential resistance patterns and to direct policies for use of these drugs in food-producing animals.

Evaluation of thermal simulation of households in the metropolitan region of São Paulo, Brazil.

This paper aims at assessing the performance of a program of thermal simulation (Arquitrop) in different households in the city of Sao Paulo, Brazil. The households were selected for the Wheezing Project which followed up children under 2 years old to monitor the occurrence of respiratory diseases. The results show that in all three study households there is a good approximation between the observed and the simulated indoor temperatures. It was also observed a fairly consistent and realistic behavior between the simulated indoor and the outdoor temperatures, describing the Arquitrop model as an efficient estimator and good representative of the thermal behavior of households in the city of Sao Paulo. The worst simulation is linked to the poorest type of construction. This may be explained by the bad quality of the construction, which the Architrop could not simulate adequately.

Phase I trial of DNA-hsp65 immunotherapy for advanced squamous cell carcinoma of the head and neck.

Considering that mycobacterial heat-shock protein 65 (hsp65) gene transfer can elicit a profound antitumoral effect, this study aimed to establish the safety, maximum-tolerated dose (MTD) and preliminary efficacy of DNA-hsp65 immunotherapy in patients with advanced head and neck squamous cell carcinoma (HNSCC). For this purpose, 21 patients with unresectable and recurrent HNSCC were studied. Each patient received three ultrasound-guided injections at 21-day intervals of: 150, 600 or 400 microg of DNA-hsp65. Toxicity was graded according to CTCAE directions. Tumor volume was measured before and after treatment using computed tomography scan. The evaluation included tumor mass variation, delayed-type hypersensitivity response and spontaneous peripheral blood mononuclear cell proliferation before and after treatment. The MTD was 400 microg per dose. DNA-hsp65 immunotherapy was well tolerated with moderate pain, edema and infections as the most frequent adverse effects. None of the patients showed clinical or laboratory alterations compatible with autoimmune reactions. Partial response was observed in 4 out of 14 patients who completed treatment, 2 of which are still alive more than 3 years after the completion of the trial. Therefore, DNA-hsp65 immunotherapy is a feasible and safe approach at the dose of 400 microg per injection in patients with HNSCC refractory to standard treatment. Further studies in a larger number of patients are needed to confirm the efficacy of this novel strategy.

Infecção por Salmonella enterica em suínos criados em um sistema integrado de produção do sul do Brasil / Salmonella infection in pigs raised in a multiple-site swine production system from southern Brazil

Avaliou-se a difusão da infecção em um rebanho com prévio isolamento de Salmonella sp, em que leitões, individualmente identificados, foram amostrados para excreção fecal de Salmonella sp e sorologia do nascimento ao abate. Da mesma forma, amostras de ração e suabes do ambiente foram coletados durante o estudo para pesquisa de Salmonella sp A pesquisa de anticorpos foi realizada pela utilização de ELISA-LPS de Salmonella Typhimurium. Os leitões foram negativos na análise bacteriológica e na sorologia até a fase de creche, tornando-se positivos para Salmonella sp no início da terminação. Nessa amostragem, 28,6 por cento dos animais foram soropositivos e 75 por cento estavam excretando Salmonella sp nas fezes. Ao abate, a percentagem de animais soropositivos (76,9 por cento) aumentou, enquanto o isolamento de Salmonella sp ocorreu em 19,2 por cento dos suínos. Foi isolada Salmonella sp de duas das 26 amostras de ração. A contaminação do ambiente da terminação ocorreu apenas após o alojamento dos animais. Concluiu-se que a terminação foi o ponto crítico de contaminação desse lote, sendo a ração uma fonte de contaminação.

Salmonella diffusion in a swine production system, previously identified as Salmonella-positive, was evaluated. A cohort of pigs was followed from farrowing to slaughtering. Samples of feces, intestinal content, mesenteric lymph nodes and blood were taken from the animals throughout the study. In addition, feed samples and environmental swabs were done for the isolation of Salmonella sp. Serum was submitted to a Salmonella Typhimurium LPS-ELISA. Piglets were negative in bacteriological and serological tests until the nursery phase, but became Salmonella positive in the early finishing. On this phase, 28.6 percent of finishers were seropositive and 75 percent were shedding Salmonella in feces. At slaughtering, the seropositivity (76.9 percent) was higher than in the early finishing, but Salmonella was isolated only from 19.2 percent of the sampled pigs. Two out of 26 feed samples were Salmonella positive. Contamination of the finishing site environment was detected only when the animals were housed. It was concluded that the termination phase was critical for the contamination of this cohort of pigs, being the feed a source of contamination.

The benefit of influenza vaccination after bone marrow transplantation.

Influenza vaccine is recommended yearly for recipients after the sixth month of BMT. Although a higher risk of complications of influenza is expected to occur in BMT patients, no study has addressed the clinical efficacy of influenza vaccination in this setting. Focusing on the clinical benefits of influenza vaccination, we evaluated the risk factors for influenza infection in a cohort of 177 BMT recipients followed up for 1 year. Influenza was diagnosed in 39 patients. Multivariate analyses showed that seasonal exposure and more aggressive conditioning regimens were independently associated with increased risk for influenza. Influenza vaccination and steroid use showed a protective role. Of the 43 patients who had received BMT longer than 6 months, 19 were vaccinated (compliance rate = 44.2%) and vaccine efficacy was 80%. We conclude that influenza vaccination plays an important role in protecting BMT recipients against influenza and all efforts should be made to ensure good compliance with vaccination.

Diagnosis and prognosis of wheezing disorders in young children in the city of São Paulo, Southeast Brazil.

UNLABELLED: Three-hundred-and-ninety-seven children aged 2-59 mo presenting to the paediatric emergency departments of five public hospitals in São Paulo, Brazil, with an acute episode of lower respiratory disease were examined. The children were classified into the following diagnostic categories: acute bronchitis, acute bronchiolitis, pneumonia, asthma, post-bronchiolitis wheezing and wheezing of uncertain aetiology. Three years after the initial study, the homes of the children diagnosed as asthmatic or as having wheezing of uncertain aetiology were visited to collect information on subsequent episodes of lower respiratory disease. This paper reports the proportional incidence of different categories of lower respiratory disease and the results of an analysis to investigate clinical features that might distinguish wheezing children between those with asthma and those with an infectious disease. The predictions made for children with wheezing of uncertain aetiology were then compared with the follow-up data. Recurrent wheezing disorders (asthma, post-bronchiolitis wheezing) were common in the study sample (47% of children). Thirty-six percent of children with an initial diagnosis of wheezing of uncertain aetiology were diagnosed as asthmatic by another doctor over the next 3 y. We were unable to identify any clinical features that were useful in identifying those children likely to be diagnosed subsequently as asthmatic. CONCLUSIONS: The use of a diagnostic category similar to that which we have called "wheezing of uncertain aetiology" might help to alert physicians early to the possibility of asthma without interfering in the management of the illness. Such a classification might also be useful in epidemiological investigations of the aetiology of lower respiratory diseases.

[Secular trends in respiratory diseases of childhood in the city of São Paulo, Brazil (1984-1996)]. / Tendência secular da doença respiratória na infância na cidade de São Paulo (1984-1996).

OBJECTIVE: Data from two consecutive household surveys undertaken in mid-80s and mid-90s allow to characterize and analyse secular trends in infant and child respiratory diseases in the city of S. Paulo, Brazil. METHODS: The two surveys included random population samples aged from zero to 59 months (1,016 in the period of 1984-85 and 1,280 in 1995-96). In both surveys the instant prevalence of high respiratory diseases (above the epiglottis) and low respiratory diseases with or without wheezing were calculated. All sampled children were examined in their household at a random day by trained pediatricians using standardized procedures. The examinations included medical history, past respiratory diseases and a complete physical examination. In both surveys the examinations were distributed throughout a period of almost 12 months to assure a uniform coverage of the various areas of the city along the four seasons of the year. For each survey, the study of the social distribution of the diseases took into account tertiles of the per capita family income. For the study of the determinants of secular trends, hierarchical causal models, multivariate regression analyses and calculations analogous to the ones used to assess population attributable risks were applied. RESULTS/CONCLUSIONS: In the time span from the first to the second survey, there was a substantial increase in the prevalence of both low (from 22.2% to 38.8%) and high respiratory diseases (from 6.0% to 10.0% and from 0.8% to 2.8%, without and with wheezing, respectively). In the case of high respiratory disease and low respiratory disease without wheezing, an increase in prevalence was observed among all social strata, which did not interfere with the slightly less favourable situation of the lower income groups. In the case of low respiratory disease with wheezing, the increase was only observed among middle and low-income groups, being particularly high among the lower income group, yielding a significant inverse gradient between income and respiratory disease. Positive changes in distal (family income and maternal schooling) and in intermediate determinants related to housing characteristics would have resulted in a decline, not an increase, in the prevalence of respiratory diseases in the city. The duplication in the attendance rate to day care nurseries seen in the period could have counterbalanced the positive effect due to socioeconomic and housing variables but would not be enough to explain an increase in the disease.

[Referred morbidity and the utilization of health services in Brazilian urban areas: methodology]. / Morbidade referida e utilização de serviços de saúde em localidades urbanas brasileiras: metodologia.

The reorganization of the Brazilian health system in the last few years has been based on the decentralization of the services and the integration of preventive and curative medicine, then creating new needs in term of the health information needed for health planning. The planning and administration of a regionalized and integrated health system calls for information about the population's morbidity profile, and the description of the pattern of the utilization of the health services, which can be obtained by means of household health surveys. The methodology utilized in a household health survey carried out in the Metropolitan Area of S. Paulo, Brazil, from July 1989 to June 1990, is described. This survey has some distinct methodological characteristics, such as the sampling process that defined the domains by age and sex, allowing an analysis of populational groups less well represented in the general population, as that of less than one year of age and that of aged people, as well as the use of the results of the latest Brazilian Census in 1991 for adjusting the sample.

Rubella seroepidemiology in a non-immunized population of São Paulo State, Brazil.

A rubella serological survey of 476 individuals selected by cluster sampling technique from Caieiras, a small town located in the outskirts of São Paulo city, southeastern Brazil, was carried out over the period November 1990-January 1991. The aim of the study was to characterize rubella epidemiology in a representative non-immunized community in south east Brazil. The survey comprised a seroprevalence study, stratified by age (0-40 years) and a seroconversion study of rubella vaccine in non-infected children below 2 years of age. Mathematical techniques were applied to resultant data sets to determine the age dependent rates of decay in the proportion of individuals with maternally derived antibodies, vaccine seroconversion, and infection of susceptibles, termed the force of infection, and to estimate the average age at first infection.