Eduardo Massad

Testes neuropsicológicos de aplicação simples para o diagnóstico de demência

Thirty patients with dementia defined by DSM-III-R criteria (Alzheimers disease (22), vascular dementia (3), Parkinsons disease, frontal lobe dementia, possible diffuse Lewy body dementia, normal pressure hydrocephalus and uncertain diagnosis), with scores below 24 points in the Mini-Mental Status Examination and more than 4 years of education were submitted to a neuropsychological evaluation. The scores in the neuropsychological tests were compared to those obtained by thirty normal volunteers paired for age, sex and education. Sensivity, specificity and accuracy of the tests in the distinction of demented and normal volunteers were determined. The accuracies were calculated using ROC curves. Blesseds information-memory-concentration test showed greatest accuracy, followed by copy of simple figures, delayed memory of 10 figures (after 5 minutes), recognition of 10 figures and verbal fluency test (animals). A linear discriminant function, composed by 6 tests: visual perception, incidental memory, delayed memory (after 5 minutes), drawing of a clock, verbal fluency (animals) and calculation tests, was able to discriminate all controls from patients and only one patient was wrongly classified as normal control. These tests were chosen because they can be applied in less than 10 minutes and are very easy to interpret. This discriminant function must be applied in another group of patients and controls in order to demonstrate its value. When associated to the MMSE it may be useful to discriminate patients with dementia from normal people in epidemiological studies.Thirty patients with dementia defined by DSM-III-R criteria (Alzheimers disease (22), vascular dementia (3), Parkinsons disease, frontal lobe dementia, possible diffuse Lewy body dementia, normal pressure hydrocephalus and uncertain diagnosis), with scores below 24 points in the Mini-Mental Status Examination and more than 4 years of education were submitted to a neuropsychological evaluation. The scores in the neuropsychological tests were compared to those obtained by thirty normal volunteers paired for age, sex and education. Sensitivity, specificity and accuracy of the tests in the distinction of demented and normal volunteers were determined. The accuracies were calculated using ROC curves. Blesseds information-memory-concentration test showed greatest accuracy, followed by copy of simple figures, delayed memory of 10 figures (after 5 minutes), recognition of 10 figures and verbal fluency test (animals). A linear discriminant function, composed by 6 tests: visual perception, incidental memory, delayed memory (after 5 minutes), drawing of a clock, verbal fluency (animals) and calculation tests, was able to discriminate all controls from patients and only one patient was wrongly classified as normal control. These tests were chosen because they can be applied in less than 10 minutes and are very easy to interpret. This discriminant function must be applied in another group of patients and controls in order to demonstrate its value. When associated to the MMSE it may be useful to discriminate patients with dementia from normal people in epidemiological studies.

Modelling the control strategies against dengue in Singapore

Notified cases of dengue infections in Singapore reached historical highs in 2004 (9459 cases) and 2005 (13,817 cases) and the reason for such an increase is still to be established. We apply a mathematical model for dengue infection that takes into account the seasonal variation in incidence, characteristic of dengue fever, and which mimics the 2004-2005 epidemics in Singapore. We simulated a set of possible control strategies and confirmed the intuitive belief that killing adult mosquitoes is the most effective strategy to control an ongoing epidemic. On the other hand, the control of immature forms was very efficient in preventing the resurgence of dengue epidemics. Since the control of immature forms allows the reduction of adulticide, it seems that the best strategy is to combine both adulticide and larvicide control measures during an outbreak, followed by the maintenance of larvicide methods after the epidemic has subsided. In addition, the model showed that the mixed strategy of adulticide and larvicide methods introduced by the government seems to be very effective in reducing the number of cases in the first weeks after the start of control.

The risk of yellow fever in a dengue-infested area

Yellow fever and dengue are viral infections that in urban centres are transmitted by the same arthropod vector, a mosquito of the genus Aedes. In order to estimate the risk of an epidemic of urban yellow fever in a dengue-infested area we calculated the threshold in the basic reproduction number, R0, of dengue, above which any single sylvatic yellow fever-infected individual will trigger an urban yellow fever epidemic. Specifically, we analysed the relationship between the extrinsic incubation period and the duration of viraemia, from which it is possible to define the R0 for dengue that would also suggest an outbreak potential for yellow fever. We also calculated the critical proportion of people to vaccinate against yellow fever in order to prevent an epidemic in a dengue-endemic area. The theory proposed is illustrated by the case of São Paulo State in southern Brazil, where dengue is endemic and the risk of urban yellow fever is already imminent.

HIV and infections of similar transmission patterns in a drug injectors community of Santos Brazil.

To study the prevalence of HIV and infections with related transmission patterns, we interviewed and obtained blood samples from 220 injecting drug users (IDUs), sampled by snowballing, from the city of Santos in the state of São Paulo, Brazil, where the estimated number of IDUs (10,000) comprises approximately 2% of the entire population. Seroprevalence of HIV, hepatitis B and C, syphilis, and HTLV (1 and 2) was assessed and compared with that in 197 blood donors from the same city, matched for age and gender. Risk behavior related to HIV was assessed by a standard questionnaire applied to the IDU sample. Univariate and multivariate analyses of the risk factors were performed. Seroprevalences found were 62% for HIV, 75% for HCV, 75% for HBV, 34% for syphilis, and 25% for HTLV (1 and 2) among IDUs, which compare with 0.0%, 2%, 23%, 12%, and 1% for blood donors, respectively. The risk for parenterally transmitted infections in this IDU community was higher than that for sexually transmitted infections (odds ratio for syphilis, 3.57; hepatitis B, 10.0; and hepatitis C, 100). The results of the mutivariate risk analysis showed that daily rate of ID use >5 times/day (OR = 6.73), not changing behavior to avoid AIDS (OR= 3.28), ID use >15 days/month (OR = 2.72), and ID use in the last 2 months (OR = 2.23) were the risk behaviors significantly associated with HIV infection.

Positive selection results in frequent reversible amino acid replacements in the G protein gene of human respiratory syncytial virus

Human respiratory syncytial virus (HRSV) is the major cause of lower respiratory tract infections in children under 5 years of age and the elderly, causing annual disease outbreaks during the fall and winter. Multiple lineages of the HRSVA and HRSVB serotypes co-circulate within a single outbreak and display a strongly temporal pattern of genetic variation, with a replacement of dominant genotypes occurring during consecutive years. In the present study we utilized phylogenetic methods to detect and map sites subject to adaptive evolution in the G protein of HRSVA and HRSVB. A total of 29 and 23 amino acid sites were found to be putatively positively selected in HRSVA and HRSVB, respectively. Several of these sites defined genotypes and lineages within genotypes in both groups, and correlated well with epitopes previously described in group A. Remarkably, 18 of these positively selected tended to revert in time to a previous codon state, producing a “flip-flop” phylogenetic pattern. Such frequent evolutionary reversals in HRSV are indicative of a combination of frequent positive selection, reflecting the changing immune status of the human population, and a limited repertoire of functionally viable amino acids at specific amino acid sites.

Uncertainties regarding dengue modeling in Rio de Janeiro, Brazil

Dengue fever is currently the most important arthropod-borne viral disease in Brazil. Mathematical modeling of disease dynamics is a very useful tool for the evaluation of control measures. To be used in decision-making, however, a mathematical model must be carefully parameterized and validated with epidemiological and entomological data. In this work, we developed a simple dengue model to answer three questions: (i) which parameters are worth pursuing in the field in order to develop a dengue transmission model for Brazilian cities; (ii) how vector density spatial heterogeneity influences control efforts; (iii) with a degree of uncertainty, what is the invasion potential of dengue virus type 4 (DEN-4) in Rio de Janeiro city. Our model consists of an expression for the basic reproductive number (R0) that incorporates vector density spatial heterogeneity. To deal with the uncertainty regarding parameter values, we parameterized the model using a priori probability density functions covering a range of plausible values for each parameter. Using the Latin Hypercube Sampling procedure, values for the parameters were generated. We conclude that, even in the presence of vector spatial heterogeneity, the two most important entomological parameters to be estimated in the field are the mortality rate and the extrinsic incubation period. The spatial heterogeneity of the vector population increases the risk of epidemics and makes the control strategies more complex. At last, we conclude that Rio de Janeiro is at risk of a DEN-4 invasion. Finally, we stress the point that epidemiologists, mathematicians, and entomologists need to interact more to find better approaches to the measuring and interpretation of the transmission dynamics of arthropod-borne diseases.

Threat of Dengue to Blood Safety in Dengue-Endemic Countries

Modeling the risk for transmission of this disease is quantified by blood transfusions.

Threshold conditions for a non-autonomous epidemic system describing the population dynamics of dengue.

A non-autonomous dynamical system, in which the seasonal variation of a mosquito vector population is modeled, is proposed to investigate dengue overwintering. A time-dependent threshold, R(t), is deduced such that when its yearly average, denoted by

Studies on mosquitoes (Diptera: Culicidae) and anthropic environment: 9- Synanthropy and epidemiological vector role of Aedes scapularis in South-Eastern Brazil

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