четверг, 13 ноября 2008 г.


Google searches track flu spread

Google flu map
The site maps the state-by-state prevalence of flu

Google's philanthropic arm Google.org has released a new site that tracks the incidence of flu in the US based on terms used in Google searches.

The system uses aggregated, anonymous results from searches for flu-related terms and plots their locations.

The approach, validated against Centers for Disease Control (CDC) flu records, provides timely data that could be two weeks ahead of government figures.

The site, which is free to use, will pass the early-warning data to the CDC.

Hundreds of billions of Google searches from 2003 onwards were used to develop the model, which was then compared with CDC data on outbreaks.

"Our team found that certain aggregated search queries tend to be very common during flu season each year," Google said in their official blog on the topic.

"We compared these aggregated queries against data provided by the US Centers for Disease Control and Prevention, and we found that there's a very close relationship between the frequency of these search queries and the number of people who are experiencing flu-like symptoms each week."

Traditional survey techniques employed by the CDC take about two weeks to precisely identify outbreaks, and Google hopes that its data, based on a stream of current searches, will serve as an early warning system that the CDC can then act upon.

Housing is HIV Prevention and Care

The US National AIDS Housing Coalition (NAHC), working in collaboration with the Ontario HIV Treatment Network (OHTN) and the Department of Health, Behavior and Society of the Johns Hopkins Bloomberg School of Public Health, announces the fourth Housing and HIV/AIDS Research Summit, a meeting of leading health, housing and social service researchers and policy makers. The Housing and HIV/AIDS Research Summit series is an interdisciplinary, interactive forum for the presentation of research findings on the relationship of housing status and HIV prevention and care, coupled with dialogue on public policy implications and strategies among researchers, policy makers, and providers and consumers of HIV housing and services. The theme of Summit IV is Examining the Evidence: The Impact of Housing on HIV Prevention and Care, and the conveners invite abstracts presenting the results of scientific research, program evaluation, community-based interventions, and public policy strategies that reflect this theme. Both research and policy abstracts are encouraged, and abstracts may be submitted for oral or poster presentations.

North America Housing and HIV/AIDS Research Summit Mobilizing Knowledge: Housing is HIV Prevention and Care

For more information contact NAHC, E-mail: nahc@nationalaidshousing.org; Phone: (202) 347-0333; Fax: (202) 347-3411; or access the Web site: http://nationalaidshousing.org/2008/08/save-the-date/

понедельник, 3 ноября 2008 г.

Evaluating HIV Estimates from National Population-Based Surveys

Evaluating HIV Estimates from National Population-Based Surveys for Bias Resulting from Non-Response (English)

Reliable data on HIV prevalence are essential for assessing the scope of and effectively managing the response to the epidemic. Antenatal clinic-based surveillance is commonly used to monitor trends in HIV in developing countries that have generalized epidemics. Recently, HIV seroprevalence data have been also collected in national population-based surveys, such as the Demographic and Health Surveys (DHS) and AIDS Indicators Surveys (AIS). Such surveys enable direct estimation of population HIV prevalence. A major challenge for population-based surveys is bias resulting from non-response, both from refusal and absence. In this study, we evaluate national HIV prevalence estimates from DHS and AIS surveys for bias resulting from non-response in the surveys. Data are from 17 recent national DHS and AIS surveys with HIV testing – Burkina Faso, Cambodia, Cameroon, Cote d’Ivoire, the Dominican Republic, Ethiopia, Ghana, India, Kenya, Lesotho, Malawi, Mali, Rwanda, Tanzania, Uganda, Zambia, and Zimbabwe – conducted during 2001 and 2006. Blood samples were collected and tested for HIV using standard laboratory and quality-control procedures. In the first three surveys, in Mali, Zambia, and the Dominican Republic, HIV status could not be linked to the characteristics and behaviors of the survey respondents. For each of the other 14 countries with HIV serostatus data linked to individual characteristics and behaviors, we predict HIV prevalence among non-responding adults on the basis of multivariate statistical models of HIV for those who were interviewed and tested, using a common set of predictor variables. Predictions are made separately for two groups of non-respondents: not interviewed/not tested and interviewed/not tested. Adjusted HIV prevalence is calculated as a weighted average of observed prevalence in the interviewed/tested group and predicted prevalence in the two non-tested groups. Predictions are made separately for adult males and females. In the 14 countries with linked data, the HIV testing rate varied from a low of 63 percent among men in Malawi and Zimbabwe to a high of 97 percent among women in Rwanda. Non-response rate was higher among urban, more educated, and wealthier men and women but had no clear association with various risk and protective behavioral factors. Non-tested men had significantly higher predicted HIV prevalence than those tested in 8 of the 14 countries, and non-tested women had significantly higher predicted prevalence than those tested in 7 of the 14 countries. Although non-tested men and women tend to have higher predicted HIV prevalence than those tested, the overall effect of non-response bias on observed prevalence estimates was small and not significant in all countries. In the 14 countries, HIV prevalence estimates adjusted for non-response bias were on average only 3 percent and 2 percent higher than the observed, non-adjusted estimates for men and women, respectively. The study finds that non-response for HIV testing tends to have small, non-significant effects on national HIV seroprevalence estimates obtained from national household surveys. National population-based surveys are an important source of reliable data on HIV prevalence that can enhance surveillance-based estimates in generalized epidemics.

full text in pdf about 3 mb