Spatial distribution of the Human T-Lymphotropic Virus types I and II (HTLV-I/II) infection among blood donors of Hemominas Foundation, Belo Horizonte, Minas Gerais State, Brazil, 1994-1996.

We conducted a cross-sectional study of the spatial distribution of HTLV-I/II infection among blood donors of Hemominas Foundation, living in Belo Horizonte, from 1994 to 1996. Study population (1,022) was composed by 533 cases (positive Western Blot (WB), indeterminate WB and ELISA positive without WB result) and a random sample of 489 non-cases (HTLV-I/II serum negative). Cases and non-cases were georeferenced using the exact or an approximation of the household address reported at the blood donation interview. Using multivariate analysis, cases with WB result are less likely to be reposition blood donors compared to voluntary ones (OR = 0.70; CI 95%: 0.50-0.99). Using the difference between univariate K functions, we found no evidence that cases and non-cases differ in their spatial distribution. We found no evidence that cases with and without WB result differ in the distance between their residence and Hemominas Foundation. No donors without WB result were georeferenced by the exact address. These donors could not have received the Hemominas letter inviting them to return to collect the second blood sample.

Spatial distribution of human and canine visceral leishmaniasis in Belo Horizonte, Minas Gerais State, Brasil, 1994-1997.

In this paper, we present spatial analysis of the association between all incidents cases of human Visceral Leishmaniasis and seropositive dogs, from 1994 to 1997 in Belo Horizonte, a large Brazilian city. We geocoded 158 human cases and 11,048 seropositive dogs and compared canine prevalence rates with Human Bayesian Incidence rates in the same areas. We also used Knox's test to evaluate the hypothesis of space-time clustering of human cases in the period. Additionally, we used Kernel's maps for seropositive dogs distribution and located the human cases in the resulting smooth maps. We concluded that human and dog rates are correlated. Also, the Visceral Leishmaniasis in Belo Horizonte spread quickly, but apart from the rates' magnitude, it has kept the same spatial pattern through time. We believe it is possible to use this technique to choose areas to implement control measures against Visceral Leishmaniasis in a more efficient way.

[Homicide clusters and drug traffic in Belo Horizonte, Minas Gerais State, Brazil from 1995 to 1999]. / Conglomerados de homicídios e o tráfico de drogas em Belo Horizonte, Minas Gerais, Brasil, de 1995 a 1999.

The article presents a spatial analysis of homicides in Belo Horizonte according to the Minas Gerais Military Police records from 1995 to 1999. The authors identify clusters of high mortality risk and relate them to areas with drug traffic and associated violence. SaTScan software is used to locate the clusters.

Diffusion and prediction of Leishmaniasis in a large metropolitan area in Brazil with a Bayesian space-time model.

We present results from an analysis of human visceral Leishmaniasis cases based on public health records of Belo Horizonte, Brazil, from 1994 to 1997. The main emphasis in this study is on the development of a spatial statistical model to map and project the rates of visceral Leishmaniasis in Belo Horizonte. The model allows for space-time interaction and it is based on a hierarchical Bayesian approach. We assume that the underlying rates evolve in time according to a polynomial trend specific to each small area in the region. The parameters of these polynomials receive a spatial distribution in the form of an autonormal distribution. While the raw rates are extremely noisy and inadequate to support decisions, the resulting smoothed rates estimates are considerably less affected by small area issues and provide very clear directions to implement public health actions.

A new proposal to adjust Moran's I for population density.

We analyse the effect of using prevalence rates based on populations with different sizes in the power of spatial independence tests. We compare the well known spatial correlation Moran's index to three indexes obtained after adjusting for population density, one proposed by Oden, another proposed by Waldhör, and a third proposed by us in this paper. We find an effect of spatially correlated populations in the type I error probability on the test based on Moran's and Waldhör's indexes. We conclude also that the test proposed by Oden is powerful to test risk heterogeneity, but it has disadvantages when the interest is solely on the spatial correlation of morbidity risks. In this latter case, we recommend using our proposed test which is more powerful than the usual Moran's index applied directly to the rates.

[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.

Lifetime cost of human immunodeficiency virus-related health care.

Estimates of the lifetime cost of illnesses are needed for temporal and international comparisons and for assessment of the efficiency of prevention strategies. The goal of the present study was to estimate the average present value, at both the time of diagnosis and the time of seroconversion, of the lifetime cost of health care for HIV infection. Australian data on the monthly cost of HIV-related health care for homosexual men were linked with published data on disease progression using survival analysis methods. Future costs were discounted at 5% per annum. For a patient diagnosed when his CD4+ count fell below 500 x 10(6)/L, the average present value in 1992-1993 of lifetime cost was approximately $93,000, of which 49% was for drugs and 32% was for hospital bed-days. For a man infected in 1992-1993 and diagnosed when his CD4+ count falls below 500 x 10(6)/L, the average present value of lifetime cost at the time of seroconversion is approximately $70,000. These estimates are lower than the lifetime cost of $119,000 reported recently in the United States. However, when the U.S. figure was adjusted to make discounting of future costs consistent between the two studies, lifetime costs were approximately 17% lower in the United States. The lower American costs appear to be due to lower rates of hospitalization and drug prescribing, possibly because of reduced access to health services, but underestimation of costs due to study methodology might also explain the difference.