Demographic Projection Model Research Articles

Youth Experiencing Parental Death Due to Drug Poisoning and Firearm Violence in the US, 1999-2020

Youth (those aged <18 years) parental death has been associated with negative health outcomes. Understanding the burden of parental death due to drug poisoning (herein, drugs) and firearms is essential for informing interventions. To estimate the incidence of youth parental death due to drugs, firearms, and all other causes. This cross-sectional observational study was conducted using vital registration, including all US decedents, and census data from January 1990 through December 2020. Data were analyzed from May 30, 2023, to March 28, 2024. Parental death due to drug poisoning or firearms. A demographic matrix projection model was used to estimate the number and incidence of youth experiencing parental death, defined as the death of 1 or more parents, per 1000 population aged less than 18 years. Analyses evaluated parental deaths by drugs, firearms, and all other causes from 1999 through 2020 by race and ethnicity. Between 1999 and 2020, there were 931 785 drug poisoning deaths and 736 779 firearm-related deaths with a mean (SD) age of 42.6 (16.3) years. Most deaths occurred among males (73.8%) and White decedents (70.8%) followed by Black (17.5%) and Hispanic (9.5%) decedents. An estimated 759 000 (95% CI, 722 000-800 000) youth experienced parental death due to drugs and an estimated 434 000 (95% CI, 409 000-460 000) youth experienced parental death due to firearms, accounting for 17% of all parental deaths. From 1999 to 2020, the estimated number of youth who experienced parental death increased 345% (95% CI, 334%-361%) due to drugs and 39% (95% CI, 37%-41%) due to firearms compared with 24% (95% CI, 23%-25%) due to all other causes. Black youth experienced a disproportionate burden of parental deaths, based primarily on firearm deaths among fathers. In 2020, drugs and firearms accounted for 23% of all parental deaths, double the proportion in 1999 (12%). Results of this modeling study suggest that US youth are at high and increasing risk of experiencing parental death by drugs or firearms. Efforts to stem this problem should prioritize averting drug overdoses and firearm violence, especially among structurally marginalized groups.

Methods and Assumptions for Estimating Key HIV Indicators in the UNAIDS Annual Estimates Process.

Each year UNAIDS supports national teams to estimate key HIV indicators using their latest data. These estimates are produced using a collection of models and software tools. This paper describes the demographic and HIV projection models used in this process. The demographic model (DemProj) projects the population by sex and single age for each year of the estimate. This information is fed into the HIV model (AIDS Impact Model) to estimate key HIV indicators. The model uses program, survey and surveillance data along with incidence trends produced through 1 of several separate models, to estimate new HIV infections, HIV-related deaths, and the population living with HIV by sex, age, CD4 category, and treatment status. These models allow the annual production of estimates of key HIV indicators including uncertainty intervals. This information is used to track progress toward national and global goals and to develop national strategic plans, Global Fund applications and PEPFAR country operational plans. Under the guidance of the UNAIDS Reference Group on Estimates, Modeling and Projections, these models are updated on a regular basis in response to evolving programmatic needs, new data, and analyses. This process of continuous review and improvement has led to mature models that make the best use of available data to provide estimates of indicators important to monitoring progress and developing future plans.

Estimation of Improvements in Mortality in Spectrum Among Adults With HIV Receiving Antiretroviral Therapy in High-Income Countries.

Mortality rates for people living with HIV (PLHIV) on antiretroviral therapy (ART) in high-income countries continue to decline. We compared mortality rates among PLHIV on ART in Europe for 2016-2020 with Spectrum's estimates. The AIDS Impact Module in Spectrum is a compartmental HIV epidemic model coupled with a demographic population projection model. We used national Spectrum projections developed for the 2022 HIV estimates round to calculate mortality rates among PLHIV on ART, adjusting to the age/country distribution of PLHIV starting ART from 1996 to 2020 in the Antiretroviral Therapy Cohort Collaboration (ART-CC)'s European cohorts. In the ART-CC, 11,504 of 162,835 PLHIV died. Between 1996-1999 and 2016-2020, AIDS-related mortality in the ART-CC decreased from 8.8 (95% CI: 7.6 to 10.1) to 1.0 (0.9-1.2) and from 5.9 (4.4-8.1) to 1.1 (0.9-1.4) deaths per 1000 person-years among men and women, respectively. Non-AIDS-related mortality decreased from 9.1 (7.9-10.5) to 6.1 (5.8-6.5) and from 7.0 (5.2-9.3) to 4.8 (4.3-5.2) deaths per 1000 person-years among men and women, respectively. Adjusted all-cause mortality rates in Spectrum among men were near ART-CC estimates for 2016-2020 (Spectrum: 7.02-7.47 deaths per 1000 person-years) but approximately 20% lower in women (Spectrum: 4.66-4.70). Adjusted excess mortality rates in Spectrum were 2.5-fold higher in women and 3.1-3.4-fold higher in men in comparison to the ART-CC's AIDS-specific mortality rates. Spectrum's all-cause mortality estimates among PLHIV are consistent with age/country-controlled mortality observed in ART-CC, with some underestimation of mortality among women. Comparing results suggest that 60%-70% of excess deaths among PLHIV on ART in Spectrum are from non-AIDS causes.

Rural outmigration in Northeast Brazil: Evidence from shared socioeconomic pathways and climate change scenarios

Climate change negatively impacts agricultural production influencing the rural-to-urban migration options of the population. In this study, we investigate the effects of expected climate change on population distribution and outmigration from rural areas of the Northeast region of Brazil (NEB) over the coming decades under different socioeconomic and climate scenarios. Demographic projection models to 2060 were created based on assumptions of future fertility, mortality, migration, and educational transition. Results reveal that changes in rural population size and composition and rural outmigration may emerge depending on future climatic conditions, agricultural income, and education. The highly-educated population can adapt with changes in climate and avoid income loss while earnings of those with lower education are reduced. The latter's outmigration option is also limited because of lower qualifications. Policies should support economically vulnerable populations especially those dependent on agriculture. Also, policies must accommodate alternative climate change scenarios and their consequences on rural population displacement.

The cost-effectiveness of banning highly hazardous pesticides to prevent suicides due to pesticide self-ingestion across 14 countries: an economic modelling study

SummaryBackgroundReducing suicides is a key Sustainable Development Goal target for improving global health. Highly hazardous pesticides are among the leading causes of death by suicide in low-income and middle-income countries. National bans of acutely toxic highly hazardous pesticides have led to substantial reductions in pesticide-attributable suicides across several countries. This study evaluated the cost-effectiveness of implementing national bans of highly hazardous pesticides to reduce the burden of pesticide suicides.MethodsA Markov model was developed to examine the costs and health effects of implementing a national ban of highly hazardous pesticides to prevent suicides due to pesticide self-poisoning, compared with a null comparator. We used WHO cost-effectiveness and strategic planning (WHO-CHOICE) methods to estimate pesticide-attributable suicide rates for 100 years from 2017. Country-specific costs were obtained from the WHO-CHOICE database and denominated in 2017 international dollars (I$), discounted at a 3% annual rate, and health effects were measured in healthy life-years gained (HLYGs). We used a demographic projection model beginning with the country population in the baseline year (2017), split by 1-year age group and sex. Country-specific data on overall suicide rates were obtained for 2017 by age and sex from the Global Burden of Disease Study 2017 Data Resources. The analysis involved 14 countries spanning low-income to high-income settings, and cost-effectiveness ratios were analysed at the country-specific level and aggregated according to country income group and the proportion of suicides due to pesticides.FindingsBanning highly hazardous pesticides across the 14 countries studied could result in about 28 000 (95% uncertainty interval [UI] 24 000–32 000) fewer suicide deaths each year at an annual cost of I$0·007 per capita (95% UI 0·006–0·008). In the population-standardised results for the base case analysis, national bans produced cost-effectiveness ratios of $94 per HLYG (95% UI 73–123) across low-income and lower-middle-income countries and $237 per HLYG (95% UI 191–303) across upper-middle-income and high-income countries. Bans were more cost-effective in countries where a high proportion of suicides are attributable to pesticide self-poisoning, reaching a cost-effectiveness ratio of $75 per HLYG (95% UI 58–99) in two countries with proportions of more than 30%.InterpretationNational bans of highly hazardous pesticides are a potentially cost-effective and affordable intervention for reducing suicide deaths in countries with a high burden of suicides attributable to pesticides. However, our study findings are limited by imperfect data and assumptions that could be improved upon by future studies.FundingWHO.

A demographic projection model to support conservation decision making for an endangered snake with limited monitoring data

AbstractConservation planning for rare and threatened species is often made more difficult by a lack of research and monitoring data. In such cases, managers may rely on qualitative assessments of species risk that lack explicit acknowledgement of uncertainty. Snakes are a group of conservation concern that are also notoriously difficult to monitor. Here, we demonstrate a quantitative population projection for a data‐deficient species, the Puerto Rican boa (Chilabothrus inornatus) using expert knowledge and published information about species life history and threats to persistence. Using this model, we simulated population dynamics over 30 years under four scenarios of future urbanization and found that there was an increased probability of population decline as urbanization rates increased. We conduct a sensitivity analysis to evaluate the sensitivity of outcomes to model inputs, a practice that may also be useful in recovery planning. The sensitivity analyses also provide insight into how the future trajectories would change if the elicited demographic rates are incorrect. Even when data are sparse, quantitative methods can often be used to produce rigorous and reproducible estimates of future status with quantifiable uncertainty.

POPULATION PROJECTION OF INDIA: AN APPLICATION OF DYNAMIC DEMOGRAPHIC PROJECTION MODEL

The objective of this paper is to forecast Indian population till the end of the present century and also an attempt has been made to explore the year in which youth population of India is maximum. Authors have also seen the pattern of age wise distribution of population and compare age structure of population in 2001 with 2096. In this study the most popular method of projection of population i.e. known as cohort component method is used to forecast the population of India. For this purpose a population at every five year interval is utilized with the valid assumptions of certain level of fertility and mortality, therefore this method is named as Dynamic Demographic Projection Model. Age Specific Fertility Rate (ASFR) for various years is taken from the NFHS-3 and 4 to forecast new arrivals. The study shows that the population of India will start decreasing nearby middle of the present century. However, it is observed that the total population in year 2101 is nearly same as the total population in year 2001, but interesting point is that the age structure of both the population found to be contradictory. Study shows that in future the number of higher age (70+) female will be more than the number of higher age (70+) male.

Projecting Monterey Pine (Pinus radiata) Populations over Time in the Presence of Various Representations of Pitch Canker Disease, Caused by Fusarium circinatum

Monterey pine (Pinus radiata D. Don) is native to California and widely planted in Mediterranean climates around the world. Pitch canker, a disease caused by Fusarium circinatum Nirenberg and O’Donnell, is a serious threat to P. radiata in native forests and in plantations. Because of its economic importance worldwide, conservation of P. radiata native populations is a high priority. We developed a demographic matrix projection model to simulate dynamics of naturally occurring P. radiata populations in California in the presence of the disease. Tree demography data for the model were collected from seven sites in a native forest on the Monterey Peninsula. Height and stem diameter were recorded for all trees, which were divided into five size classes based on these data. Transition probabilities were calculated for each size class; cone production, seed release, and seed transition probability were estimated using an iterative search process. In the model, pitch canker influences state-specific fecundity and survival probabilities. Five different approaches to include these effects were compared. Populations were projected over 50 decades from three specified initial population sizes. Elasticity analysis indicated that facilitating survival of all size classes is vital to maintaining the structure of the forest.

Estimating the future health and aged care expenditure in Australia with changes in morbidity

AimsWe estimate the pure effect of ageing on total health and aged care expenditure in Australia in the next 20 years.MethodsWe use a simple demographic projection model for the number of people in older age groups along with a needs based estimate of changes in the public and private cost of care per person in each group adjusted for expected changes in morbidity.ResultsA pure ageing model of expenditure growth predicts an increase in health expenditure per elderly person from $7439 in 2015 to $9594 in 2035 and an increase in total expenditure from $166 billion to $320 billion (an average annual growth of 3.33%). If people live longer without additional morbidity, then total health expenditure only grows at an average annual rate of 0.48%. If only some of those additional years are in good health, then the average year on year growth is 1.87%.ConclusionAgeing will have a direct effect on the growth of health spending but is likely to be dwarfed by other demand and supply factors. A focus on greater efficiency in health production and finance is likely to be more effective in delivering high quality care than trying to restrain the demand for health and aged care among the elderly.

Will peak car observed in the North occur in the South? A demographic approach with case studies of Montreal, Lille, Juarez and Puebla

In most developed countries, total car driving has stagnated in the 2000s. This trend can be attributed primarily to people living in the largest urban areas: trips have become less frequent (with unbroken workdays) and less exclusively taken by car (as more young adults adopt multimodal behaviours). A review of the literature shows that demography is an important factor explaining peak car. It is examined through case studies from cities of different level of development. To represent developed economies, we chose Lille in the North of France, and Montreal in Canada. For the emerging economies, we chose two Mexican cities, Juarez, on the northern border of Mexico where the level of motorization is quite high, and Puebla more traditional, where car ownership is lower. A straightforward combination of fixed mobility by age group with the evolving number of inhabitants suggests that the demographic transition (i.e. a slower growth of the number of inhabitants with population ageing) shows a peak in the total amount of car travel. Then, considering travel behaviour in terms of distance travelled per person per day, an age-cohort demographic projection model is implemented for each case-study in order to consider the extent to which, and in what time frame, the trends observed in developed cities could spread southward to the emerging economies.

Temporal variation in reproductive costs and payoffs shapes the flowering strategy of a neotropical milkweed, Asclepias curassavica

AbstractA central goal of evolutionary ecology is to understand the factors that select for particular life history strategies, such as delaying reproduction. For example, environmental variation and reproductive costs to survival and growth often select for reproductive delays in semelparous and iteroparous species. In this study, we examine how variation in reproductive cost, which we define as a reduction to growth, survival, or future reproduction after a reproductive event, may select for reproductive delay in an iteroparous Neotropical milkweed with no obvious reproductive season. We analyzed demographic data collected every 3 months for 3 years from four populations of Asclepias curassavica in Monteverde, Costa Rica. We detected costs of flowering to survival and growth that varied in magnitude between our 12 transition periods without a seasonal pattern. The populations also exhibited temporal variation in reproductive payoffs measured as seedling establishment. We incorporated these reproductive costs into demographic projection models, which predicted a delayed flowering strategy only when we included temporal variation in costs and payoffs. Temporal variation in reproductive costs and payoffs is an important selective force in the evolution of delayed flowering in iteroparous species. Further, a lack of predictable seasonal pattern to reproductive costs and payoffs may contribute to the lack of seasonal reproductive patterns observed in our study species and other Neotropical species.

Effect of drought on demography of Pileated Finch (Coryphospingus pileatus: Thraupidae) in northeastern Brazil

Information on the effects of stochastic weather events on the survival of tropical birds can improve the knowledge of life history adaptations, allowing better demographic projection models to examine species persistence in light of global climate change forecasts. With this in mind, we conducted a mark-recapture study on Coryphospingus pileatus in the Brazilian Caatinga. We applied Cormack-Jolly-Seber and Robust Design models to test the influence of sex, precipitation, drought and vegetation on demographic parameters. We found that the apparent annual survival of residents ranged from 31 to 49% in the first year and 65–77% in the second, depending on the area, sex and structure of the models used. Controlling for an effect of time since marking, survival was substantially lower in a year affected by a severe drought, and was higher at a site with more open vegetation structure. The results showed little variation in survival of the species during the regular annual dry season and a decline greater than 50% in apparent survival caused by severe drought. This suggest that in prolonged drought the drastic reduction of food directly affects the productivity, reducing in survival observed over time and projecting a critical perspective for endangered species that may disappear due to climate change.

Demography and population growth rate of the tree Prosopis flexuosa with contrasting grazing regimes in the Central Monte Desert

One of the most important current challenges for ecologists is to evaluate how human-induced changes in ecosystems would impact viability of populations. Demographic response to anthropogenic impact could help us to understand how to manage those impacts. Using demographic techniques and population projection models, here we assess if demography and population dynamics of the tree Prosopis flexuosa change in cattle grazed areas compared to ungrazed areas in the Central Monte desert, Mendoza, Argentina. To this end, we quantified vital rates and constructed a population projection matrix model to compare the deterministic population growth rate (λ) between grazed and ungrazed areas. We also estimated elasticities of vital rates to evaluate their potential importance for future changes in λ and performed a life table response experiment (LTRE) to identify the life cycle transitions that contribute the most to the observed differences in λ between the two treatments. Although we found differences in demographic processes, such as lower seed production and higher probability of reversion to smaller size classes in young individuals when cattle were present, our results indicate that cattle grazing had no significant effect on λ for this species. According to the elasticity analysis, survival of large trees is the main driver of the population growth rate (λ) of P. flexuosa, and the vital rates related to tree reproduction, such as seed production and germination, have a poor contribution to λ. Therefore, limitations of activities that can affect survival of large trees should be considered as part of the conservation strategy for this species. Our study provides a compilation of demographic information that can be useful to set policies connecting the conservation objectives for this woodlands with that of ranch managers of the area.

Population Viability and Vital Rate Sensitivity of an Endangered Avian Cooperative Breeder, the White-Breasted Thrasher (Ramphocinclus brachyurus).

Social behaviors can significantly affect population viability, and some behaviors might reduce extinction risk. We used population viability analysis to evaluate effects of past and proposed habitat loss on the White-breasted Thrasher (Ramphocinclus brachyurus), a cooperatively breeding songbird with a global population size of <2000 individuals. We used an individual-based approach to build the first demographic population projection model for this endangered species, parameterizing the model with data from eight years of field study before and after habitat loss within the stronghold of the species’ distribution. The recent habitat loss resulted in an approximately 18% predicted decline in population size; this estimate was mirrored by a separate assessment using occupancy data. When mortality rates remained close to the pre-habitat loss estimate, quasi-extinction probability was low under extant habitat area, but increased with habitat loss expected after current plans for resort construction are completed. Post-habitat loss mortality rate estimates were too high for projected populations to persist. Vital rate sensitivity analyses indicated that population growth rate and population persistence were most sensitive to juvenile mortality. However, observed values for adult mortality were closest to the threshold value above which populations would crash. Adult mortality, already relatively low, may have the least capacity to change compared to other vital rates, whereas juvenile mortality may have the most capacity for improvement. Results suggest that improving mortality estimates and determining the cause(s) of juvenile mortality should be research priorities. Despite predictions that aspects of cooperative systems may result in variation in reproduction or juvenile mortality being the most sensitive vital rates, adult mortality was the most sensitive in half of the demographic models of other avian cooperative breeders. Interestingly, vital rate sensitivity differed by model type. However, studies that explicitly modeled the species’ cooperative breeding system found reproduction to be the most sensitive rate.

Flowering schedule in a perennial plant; life-history trade-offs, seed predation, and total offspring fitness.

Optimal timing of reproduction within a season may be influenced by several abiotic and biotic factors. These factors sometimes affect different components of fitness, making assessments of net selection difficult. We used estimates of offspring fitness to examine how pre-dispersal seed predation influences selection on flowering schedule in an herb with a bimodal flowering pattern, Actaea spicata. Within individuals, seeds from flowers on early terminal inflorescences had a higher germination rate and produced larger seedlings than seeds from flowers on late basal inflorescences. Reproductive value, estimated using demographic integral projection models and accounting for size-dependent differences in future performance, was two times higher for intact seeds from early flowers than for seeds from late flowers. Fruits from late flowers were, however, much more likely to escape seed predation than fruits from early flowers. Reproductive values of early and late flowers balanced at a predation intensity of 63%. Across 15 natural populations, the strength of selection for allocation to late flowers was positively correlated with mean seed predation intensity. Our results suggest that the optimal shape of the flowering schedule, in terms of the allocation between early and late flowers, is determined by the trade-off between offspring number and quality, and that variation in antagonistic interactions among populations influences the balancing of this trade-off. At the same time they illustrate that phenotypic selection analyses that fail to account for differences in offspring fitness might be misleading.

Access to antiretroviral treatment in South Africa, 2004 - 2011

Background. South Africa’s National Strategic Plan (NSP) for 2007 - 2011 aimed to achieve new antiretroviral treatment (ART) enrolment numbers equal to 80% of the number of newly eligible individuals in each year, by 2011. &#x0D; Objectives. To estimate ART coverage in South Africa and assess whether NSP targets have been met.&#x0D; Methods. ART data were collected from public and private providers of ART. Estimates of HIV incidence rates were obtained from independent demographic projection models. Adult ART data and incidence estimates were entered into a separate model that estimated rates of progression through CD4 stages, and the model was fitted to South African CD4 data and HIV prevalence data.&#x0D; Results. By the middle of 2011, the number of patients receiving ART in South Africa had increased to 1.79 million (95% CI 1.65 - 1.93 million). Adult ART coverage, at the previous ART eligibility criterion of CD4

Application of Estimation and Projection Package and Spectrum to the Context of Australia’s HIV Epidemic

Objectives: Understanding and monitoring the HIV epidemic is essential for developing and evaluating public health responses. The Joint United Nations Programme on AIDS (UNAIDS) Estimation and Projection Package (EPP) and Spectrum have become a standard tool to interpret HIV surveillance systems in many settings, particularly in low- and middle-income countries where surveillance data is often based on serial cross-sectional prevalence studies and not on notifications. EPP has not previously been used to evaluate the HIV epidemic in Australia. We derived best HIV estimates using EPP and assumptions that reflect the current understanding of HIV epidemiology in Australia and compared derived estimates with independent estimates and estimates from mathematical models using backprojections method. Methods: The epidemic curves for different population groups (i.e., men who have sex with men, injecting drug users, and low-risk population) generated by EPP were combined with antiretroviral therapy (ART) data into a demographic projection model, Spectrum to determine the consequences of the HIV epidemic in Australia. Results: The overall pattern of the HIV epidemic was consistent with both independent estimates and backprojection modelling estimates. However, the number of HIV-infected females, AIDS-related deaths, and the number in need of ART estimated by EPP were approximately 3.7 times, 20 times, and 6.3 times, respectively higher than independent estimates based on our current surveillance system. EPP estimates of new HIV infections were, however, half the number of independent and back-projection estimates. Conclusions: These findings suggest that customized tools that are tailored to the unique epidemiology and surveillance mechanisms in each setting are required to enable effective programmatic response and policy.

Predicting survival, reproduction and abundance of polar bears under climate change

Polar bear ( Ursus maritimus) populations are predicted to be negatively affected by climate warming, but the timeframe and manner in which change to polar bear populations will occur remains unclear. Predictions incorporating climate change effects are necessary for proactive population management, the setting of optimal harvest quotas, and conservation status decisions. Such predictions are difficult to obtain from historic data directly because past and predicted environmental conditions differ substantially. Here, we explore how models can be used to predict polar bear population responses under climate change. We suggest the development of mechanistic models aimed at predicting reproduction and survival as a function of the environment. Such models can often be developed, parameterized, and tested under current environmental conditions. Model predictions for reproduction and survival under future conditions could then be input into demographic projection models to improve abundance predictions under climate change. We illustrate the approach using two examples. First, using an individual-based dynamic energy budget model, we estimate that 3–6% of adult males in Western Hudson Bay would die of starvation before the end of a 120 day summer fasting period but 28–48% would die if climate warming increases the fasting period to 180 days. Expected changes in survival are non-linear (sigmoid) as a function of fasting period length. Second, we use an encounter rate model to predict changes in female mating probability under sea ice area declines and declines in mate-searching efficiency due to habitat fragmentation. The model predicts that mating success will decline non-linearly if searching efficiency declines faster than habitat area, and increase non-linearly otherwise. Specifically for the Lancaster Sound population, we predict that female mating success would decline from 99% to 91% if searching efficiency declined twice as fast as sea ice area, and to 72% if searching efficiency declined four times as fast as area. Sea ice is a complex and dynamic habitat that is rapidly changing. Failure to incorporate climate change effects into population projections can result in flawed conservation assessments and management decisions.

On the Use of Published Demographic Data for Population-Level Risk Assessment in Birds

ABSTRACT As the practice of using population models for wildlife risk assessment has become more common, so has the practice of using surrogate data, typically taken from the published scientific literature, as inputs for demographic models. This practice clearly exposes the user to inferential errors. However, it is likely to continue because demographic data are expensive to gather. We review potential errors associated with the use of previously published demographic data and how those errors propagate into the endpoints of demographic projection models. We suggest methods for inferring bias in model endpoints when multiple and opposing biases are present in the demographic input data. We provide an example using Eastern Meadowlarks (Sturnella magna), a common songbird in Midwestern grasslands and agro-ecosystems. We conclude with a brief review of methods that could improve inference made using published demographic data, including methods from life-history theory, meta-analysis, and Bayesian statistics.

Estimating and projecting HIV prevalence and AIDS deaths in Tanzania using antenatal surveillance data

BackgroundThe Estimations and Projections Package (EPP 2005) for HIV/AIDS estimates and projects HIV prevalence, number of people living with HIV and new HIV infections and AIDS cases using antenatal clinic (ANC) surveillance data. The prevalence projection produced by EPP can be transferred to SPECTRUM, a demographic projectionmodel, to calculate the number of AIDS deaths. This paper presents estimates and projections of HIV prevalence, new cases of HIV infections and AIDS deaths in Tanzania between 2001 and 2010 using the EPP 2005 and SPECTRUM soft-wares on ANC data.MethodsFor this study we used; the 1985 – 2004 ANC data set, the 2005 UN population estimates for urban and rural adults, which is based on the 2002 population census, and results of the 2003 Tanzania HIV Indicator Survey. The ANC surveillance sites were categorized into urban and rural areas on the basis of the standard national definitions of urban and rural areas, which led to 40 urban and 35 rural clinic sites. The rural and urban epidemics were run independently by fitting the model to all data and on level fits.ResultsThe national HIV prevalence increased from 0% in 1981 to a peak of 8.1% in 1995, and gradually decreased to 6.5% in 2004 which stabilized until 2010. The urban HIV epidemic increased from 0% in 1981 peaking at 12.6% in 1992 and leveled to between 10.9% and 11.8% from 2003 to 2010. The rural epidemic peaked in 1995 at 7.0% and gradually declined to 5.2% in 2004, and then stabilized at between 5.1% and 5.3% from 2005 to 2010. New infections are projected to rise steadily, resulting in 250,000 new cases in 2010. Deaths due to AIDS started in 1985 and rose steadily to reach 120,000 deaths in 2010, with more females dying than men.ConclusionThe fact that the number of new infections is projected to increase steadily to reach 250,000 per year in 2010 calls for more concerted efforts to combat the spread of HIV infection particularly in the rural areas where the infrastructure needed for prevention programmes such as counseling and testing, condom accessibility and AIDS information is less developed.