Demographic surveillance and health equity in sub-Saharan Africa

The Indian Health and Demographic Surveillance System Network: Opportunity to Generate Evidence for Public Health Policy

The Health and Demographic Surveillance System (HDSS) is a valuable longitudinal cohort study that tracks the health and demographic changes of a geographically defined population, serving as a platform for research and evidence-based policymaking. In India, there are nearly 20 HDSS sites covering diverse areas and populations totaling around two million. To foster collaboration, the Indian HDSS Network (IHN) was formed, comprising 19 sites from 16 institutes, covering a population of 1.5 million. The IHN aims to standardize data collection processes while allowing site-specific autonomy, generating high-quality longitudinal health, and demographic data. To ensure effective coordination, a governance structure with a rotating secretariat and working committee was proposed. The IHN envisions conducting robust multicentric research, supporting data-driven efforts to improve population health, and promoting research-policy synergy. The network's outcomes have the potential to optimize health research funding, generate epidemiological data, and provide evidence for public health policy. Collaboration within the IHN strengthens HDSS sites in newer technologies and community-based research, fostering capacity building. Seed funding is being sought to formalize and support the day-to-day functioning of the network, which holds promise for advancing population health and informing policymaking in India.

Health and demographic surveillance systems in low- and middle-income countries: history, state of the art and future prospects

Health and Demographic Surveillance Systems (HDSS) have been developed in several low- and middle-income countries (LMICs) in Africa and Asia. This paper reviews their history, state of the art and future potential and highlights substantial areas of contribution by the late Professor Peter Byass.Historically, HDSS appeared in the second half of the twentieth century, responding to a dearth of accurate population data in poorly resourced settings to contextualise the study of interventions to improve health and well-being. The progress of the development of this network is described starting with Pholela, and progressing through Gwembe, Balabgarh, Niakhar, Matlab, Navrongo, Agincourt, Farafenni, and Butajira, and the emergence of the INDEPTH Network in the early 1990'sThe paper describes the HDSS methodology, data, strengths, and limitations. The strengths are particularly their temporal coverage, detail, dense linkage, and the fact that they exist in chronically under-documented populations in LMICs where HDSS sites operate. The main limitations are generalisability to a national population and a potential Hawthorne effect, whereby the project itself may have changed characteristics of the population.The future will include advances in HDSS data harmonisation, accessibility, and protection. Key applications of the data are to validate and assess bias in other datasets. A strong collaboration between a national HDSS network and the national statistics office is modelled in South Africa and Sierra Leone, and it is possible that other low- to middle-income countries will see the benefit and take this approach.

Protocol: Leveraging a demographic and health surveillance system for Covid-19 Surveillance in rural KwaZulu-Natal

A coordinated system of disease surveillance will be critical to effectively control the coronavirus disease 2019 (Covid-19) pandemic. Such systems enable rapid detection and mapping of epidemics and inform allocation of scarce prevention and intervention resources. Although many lower- and middle-income settings lack infrastructure for optimal disease surveillance, health and demographic surveillance systems (HDSS) provide a unique opportunity for epidemic monitoring. This protocol describes a surveillance program at the Africa Health Research Institute's Population Intervention Platform site in northern KwaZulu-Natal. The program leverages a longstanding HDSS in a rural, resource-limited setting with very high prevalence of HIV and tuberculosis to perform Covid-19 surveillance. Our primary aims include: describing the epidemiology of the Covid-19 epidemic in rural KwaZulu-Natal; determining the impact of the Covid-19 outbreak and non-pharmaceutical control interventions (NPI) on behaviour and wellbeing; determining the impact of HIV and tuberculosis on Covid-19 susceptibility; and using collected data to support the local public-sector health response. The program involves telephone-based interviews with over 20,000 households every four months, plus a sub-study calling 750 households every two weeks. Each call asks a household representative how the epidemic and NPI are affecting the household and conducts a Covid-19 risk screen for all resident members. Any individuals screening positive are invited to a clinical screen, potential test and referral to necessary care - conducted in-person near their home following careful risk minimization procedures. In this protocol we report the details of our cohort design, questionnaires, data and reporting structures, and standard operating procedures in hopes that our project can inform similar efforts elsewhere.

Protocol: Leveraging a demographic and health surveillance system for Covid-19 Surveillance in rural KwaZulu-Natal

A coordinated system of disease surveillance will be critical to effectively control the coronavirus disease 2019 (Covid-19) pandemic. Such systems enable rapid detection and mapping of epidemics and inform allocation of scarce prevention and intervention resources. Although many lower- and middle-income settings lack infrastructure for optimal disease surveillance, health and demographic surveillance systems (HDSS) provide a unique opportunity for epidemic monitoring. This protocol describes a surveillance program at the Africa Health Research Institute's Population Intervention Platform site in northern KwaZulu-Natal. The program leverages a longstanding HDSS in a rural, resource-limited setting with very high prevalence of HIV and tuberculosis to perform Covid-19 surveillance. Our primary aims include: describing the epidemiology of the Covid-19 epidemic in rural KwaZulu-Natal; determining the impact of the Covid-19 outbreak and non-pharmaceutical control interventions (NPI) on behaviour and wellbeing; determining the impact of HIV and tuberculosis on Covid-19 susceptibility; and using collected data to support the local public-sector health response. The program involves telephone-based interviews with over 20,000 households every four months, plus a sub-study calling 750 households every two weeks. Each call asks a household representative how the epidemic and NPI are affecting the household and conducts a Covid-19 risk screen for all resident members. Any individuals screening positive are invited to a clinical screen, potential test and referral to necessary care - conducted in-person near their home following careful risk minimization procedures. In this protocol we report the details of our cohort design, questionnaires, data and reporting structures, and standard operating procedures in hopes that our project can inform similar efforts elsewhere.

Health and socio-demographic profile of women of reproductive age in rural communities of southern Mozambique

Reliable statistics on maternal morbidity and mortality are scarce in low and middle-income countries, especially in rural areas. This is the case in Mozambique where many births happen at home. Furthermore, a sizeable number of facility births have inadequate registration. Such information is crucial for developing effective national and global health policies for maternal and child health. The aim of this study was to generate reliable baseline socio-demographic information on women of reproductive age as well as to establish a demographic surveillance platform to support the planning and implementation of the Community Level Intervention for Pre-eclampsia (CLIP) study, a cluster randomized controlled trial. This study represents a census of all women of reproductive age (12–49 years) in twelve rural communities in Maputo and Gaza provinces of Mozambique. The data were collected through electronic forms implemented in Open Data Kit (ODK) (an app for android based tablets) and household and individual characteristics. Verbal autopsies were conducted on all reported maternal deaths to determine the underlying cause of death. Between March and October 2014, 50,493 households and 80,483 women of reproductive age (mean age 26.9 years) were surveyed. A total of 14,617 pregnancies were reported in the twelve months prior to the census, resulting in 9,029 completed pregnancies. Of completed pregnancies, 8,796 resulted in live births, 466 resulted in stillbirths and 288 resulted in miscarriages. The remaining pregnancies had not yet been completed during the time of the survey (5,588 pregnancies). The age specific fertility indicates that highest rate (188 live births per 1,000 women) occurs in the age 20–24 years old. The estimated stillbirth rate was 50.3/1,000 live and stillbirths; neonatal mortality rate was 13.3/1,000 live births and maternal mortality ratio was 204.6/100,000 live births. The most common direct cause of maternal death was eclampsia and tuberculosis was the most common indirect cause of death. This study found that fertility rate is high at age 20–24 years old. Pregnancy in the advanced age (>35 years of age) in this study was associated with higher poor outcomes such as miscarriage and stillbirth. The study also found high stillbirth rate indicating a need for increased attention to maternal health in southern Mozambique. Tuberculosis and HIV/AIDS are prominent indirect causes of maternal death, while eclampsia represents the number one direct obstetric cause of maternal deaths in these communities. Additional efforts to promote safe motherhood and improve child survival are crucial in these communities.

Trends in Between-Country Health Equity in Sub-Saharan Africa from 1990 to 2011: Improvement, Convergence and Reversal

It is not clear whether between-country health inequity in Sub-Saharan Africa has been reduced over time due to economic development and increased foreign investments. We used the World Health Organization's data about 46 nations in Sub-Saharan Africa to test if under-5 mortality rate (U5MR) and life expectancy (LE) converged or diverged from 1990 to 2011. We explored whether the standard deviation of selected health indicators decreased over time (i.e., sigma convergence), and whether the less developed countries moved toward the average level in the group (i.e., beta convergence). The variation of U5MR between countries became smaller from 1990 to 2001. Yet this sigma convergence trend did not continue after 2002. Life expectancy in Africa from 1990-2011 demonstrated a consistent convergence trend, even after controlling for initial differences of country-level factors. The lack of consistent convergence in U5MR partially resulted from the fact that countries with higher U5MR in 1990 eventually performed better than those countries with lower U5MRs in 1990, constituting a reversal in between-country health inequity. Thus, international aid agencies might consider to reassess the funding priority about which countries to invest in, especially in the field of early childhood health.

Resource Effective Strategies to Prevent and Treat Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of global deaths, with the majority occurring in low- and middle-income countries. The primary and secondary prevention of CVD is suboptimal throughout the world, but the evidence-practice gaps are much more pronounced in low- and middle-income countries. Barriers at the patient, healthcare provider, and health system level prevent the implementation of optimal primary and secondary prevention. Identification of the particular barriers that exist in resource-constrained settings is necessary to inform effective strategies to reduce the identified evidence-practice gaps. Furthermore, targeting modifiable factors that contribute most significantly to the global burden of CVD, including tobacco use, hypertension, and secondary prevention for CVD, will lead to the biggest gains in mortality reduction. We review a select number of novel, resource-efficient strategies to reduce premature mortality from CVD, including (1) effective measures for tobacco control, (2) implementation of simplified screening and management algorithms for those with or at risk of CVD, (3) increasing the availability and affordability of simplified and cost-effective treatment regimens including combination CVD preventive drug therapy, and (4) simplified delivery of healthcare through task-sharing (nonphysician health workers) and optimizing self-management (treatment supporters). Developing and deploying systems of care that address barriers related to the above will lead to substantial reductions in CVD and related mortality.

Measuring population health: costs of alternative survey approaches in the Nouna Health and Demographic Surveillance System in rural Burkina Faso

BACKGROUND

There are more than 40 Health and Demographic Surveillance System (HDSS) sites in 19 different countries. The running costs of HDSS sites are high. The financing of HDSS activities is of major importance, and adding external health surveys to the HDSS is challenging. To investigate the ways of improving data quality and collection efficiency in the Nouna HDSS in Burkina Faso, the stand-alone data collection activities of the HDSS and the Household Morbidity Survey (HMS) were integrated, and the paper-based questionnaires were consolidated into a single tablet-based questionnaire, the Comprehensive Disease Assessment (CDA).

OBJECTIVE

The aims of this study are to estimate and compare the implementation costs of the two different survey approaches for measuring population health.

DESIGN

All financial costs of stand-alone (HDSS and HMS) and integrated (CDA) surveys were estimated from the perspective of the implementing agency. Fixed and variable costs of survey implementation and key cost drivers were identified. The costs per household visit were calculated for both survey approaches.

RESULTS

While fixed costs of survey implementation were similar for the two survey approaches, there were considerable variations in variable costs, resulting in an estimated annual cost saving of about US$45,000 under the integrated survey approach. This was primarily because the costs of data management for the tablet-based CDA survey were considerably lower than for the paper-based stand-alone surveys. The cost per household visit from the integrated survey approach was US$21 compared with US$25 from the stand-alone surveys for collecting the same amount of information from 10,000 HDSS households.

CONCLUSIONS

The CDA tablet-based survey method appears to be feasible and efficient for collecting health and demographic data in the Nouna HDSS in rural Burkina Faso. The possibility of using the tablet-based data collection platform to improve the quality of population health data requires further exploration.

Inequalities in child mortality in ten major African cities

BACKGROUND

The existence of socio-economic inequalities in child mortality is well documented. African cities grow faster than cities in most other regions of the world; and inequalities in African cities are thought to be particularly large. Revealing health-related inequalities is essential in order for governments to be able to act against them. This study aimed to systematically compare inequalities in child mortality across 10 major African cities (Cairo, Lagos, Kinshasa, Luanda, Abidjan, Dar es Salaam, Nairobi, Dakar, Addis Ababa, Accra), and to investigate trends in such inequalities over time.

METHODS

Data from two rounds of demographic and health surveys (DHS) were used for this study (if available): one from around the year 2000 and one from between 2007 and 2011. Child mortality rates within cities were calculated by population wealth quintiles. Inequality in child mortality was assessed by computing two measures of relative inequality (the rate ratio and the concentration index) and two measures of absolute inequality (the difference and the Erreyger's index).

RESULTS

Mean child mortality rates ranged from about 39 deaths per 1,000 live births in Cairo (2008) to about 107 deaths per 1,000 live births in Dar es Salaam (2010). Significant inequalities were found in Kinshasa, Luanda, Abidjan, and Addis Ababa in the most recent survey. The difference between the poorest quintile and the richest quintile was as much as 108 deaths per 1,000 live births (95% confidence interval 55 to 166) in Abidjan in 2011-2012. When comparing inequalities across cities or over time, confidence intervals of all measures almost always overlap. Nevertheless, inequalities appear to have increased in Abidjan, while they appear to have decreased in Cairo, Lagos, Dar es Salaam, Nairobi and Dakar.

CONCLUSIONS

Considerable inequalities exist in almost all cities but the level of inequalities and their development over time appear to differ across cities. This implies that inequalities are amenable to policy interventions and that it is worth investigating why inequalities are higher in one city than in another. However, larger samples are needed in order to improve the certainty of our results. Currently available data samples from DHS are too small to reliably quantify the level of inequalities within cities.

Trends in child immunization across geographical regions in India: focus on urban-rural and gender differentials

BACKGROUND

Although child immunization is regarded as a highly cost-effective lifesaver, about fifty percent of the eligible children aged 12-23 months in India are without essential immunization coverage. Despite several programmatic initiatives, urban-rural and gender difference in child immunization pose an intimidating challenge to India's public health agenda. This study assesses the urban-rural and gender difference in child immunization coverage during 1992-2006 across six major geographical regions in India.

DATA AND METHODS

Three rounds of the National Family Health Survey (NFHS) conducted during 1992-93, 1998-99 and 2005-06 were analyzed. Bivariate analyses, urban-rural and gender inequality ratios, and the multivariate-pooled logistic regression model were applied to examine the trends and patterns of inequalities over time.

KEY FINDINGS

The analysis of change over one and half decades (1992-2006) shows considerable variations in child immunization coverage across six geographical regions in India. Despite a decline in urban-rural and gender differences over time, children residing in rural areas and girls remained disadvantaged. Moreover, northeast, west and south regions, which had the lowest gender inequality in 1992 observed an increase in gender difference over time. Similarly, urban-rural inequality increased in the west region during 1992-2006.

CONCLUSION

This study suggests periodic evaluation of the health care system is vital to assess the between and within group difference beyond average improvement. It is essential to integrate strong immunization systems with broad health systems and coordinate with other primary health care delivery programs to augment immunization coverage.

Trends in child immunization across geographical regions in India: focus on urban-rural and gender differentials

BACKGROUND

Although child immunization is regarded as a highly cost-effective lifesaver, about fifty percent of the eligible children aged 12-23 months in India are without essential immunization coverage. Despite several programmatic initiatives, urban-rural and gender difference in child immunization pose an intimidating challenge to India's public health agenda. This study assesses the urban-rural and gender difference in child immunization coverage during 1992-2006 across six major geographical regions in India.

DATA AND METHODS

Three rounds of the National Family Health Survey (NFHS) conducted during 1992-93, 1998-99 and 2005-06 were analyzed. Bivariate analyses, urban-rural and gender inequality ratios, and the multivariate-pooled logistic regression model were applied to examine the trends and patterns of inequalities over time.

KEY FINDINGS

The analysis of change over one and half decades (1992-2006) shows considerable variations in child immunization coverage across six geographical regions in India. Despite a decline in urban-rural and gender differences over time, children residing in rural areas and girls remained disadvantaged. Moreover, northeast, west and south regions, which had the lowest gender inequality in 1992 observed an increase in gender difference over time. Similarly, urban-rural inequality increased in the west region during 1992-2006.

CONCLUSION

This study suggests periodic evaluation of the health care system is vital to assess the between and within group difference beyond average improvement. It is essential to integrate strong immunization systems with broad health systems and coordinate with other primary health care delivery programs to augment immunization coverage.

Lessons learned from scaling up a community-based health program in the Upper East Region of northern Ghana

The original CHPS model deployed nurses to the community and engaged local leaders, reducing child mortality and fertility substantially. Key scaling-up lessons: (1) place nurses in home districts but not home villages, (2) adapt uniquely to each district, (3) mobilize local resources, (4) develop a shared project vision, and (5) conduct “exchanges” so that staff who are initiating operations can observe the model working in another setting, pilot the approach locally, and expand based on lessons learned.

Ghana's Community-Based Health Planning and Service (CHPS) initiative is envisioned to be a national program to relocate primary health care services from subdistrict health centers to convenient community locations. The initiative was launched in 4 phases. First, it was piloted in 3 villages to develop appropriate strategies. Second, the approach was tested in a factorial trial, which showed that community-based care could reduce childhood mortality by half in only 3 years. Then, a replication experiment was launched to clarify appropriate activities for implementing the fourth and final phase—national scale up. This paper discusses CHPS progress in the Upper East Region (UER) of Ghana, where the pace of scale up has been much more rapid than in the other 9 regions of the country despite exceedingly challenging economic, ecological, and social circumstances. The UER employed 5 strategies that facilitated scale up: (1) nurse recruitment from their home districts to improve worker morale and cultural grounding, balanced with some social distance from the village community to ensure client confidentiality, particularly regarding family planning use; (2) prioritization of CHPS planning and continuous review in management meetings to make necessary modifications to the initiative's approach; (3) community engagement and advocacy to local politicians to mobilize resources for financing start-up costs; (4) a shared and consistent vision about CHPS among health administration leaders to ensure appropriate resources and commitment to the initiative; and (5) knowledge exchange visits between new and advanced CHPS implementers to facilitate learning and scale up within and between districts.

Establishing a health demographic surveillance site in Bhaktapur district, Nepal: initial experiences and findings

Background

A health demographic surveillance system (HDSS) provides longitudinal data regarding health and demography in countries with coverage error and poor quality data on vital registration systems due to lack of public awareness, inadequate legal basis and limited use of data in health planning. The health system in Nepal, a low-income country, does not focus primarily on health registration, and does not conduct regular health data collection. This study aimed to initiate and establish the first HDSS in Nepal.

Results

We conducted a baseline survey in Jhaukhel and Duwakot, two villages in Bhaktapur district. The study surveyed 2,712 households comprising a total population of 13,669. The sex ratio in the study area was 101 males per 100 females and the average household size was 5. The crude birth and death rates were 9.7 and 3.9/1,000 population/year, respectively. About 11% of births occurred at home, and we found no mortality in infants and children less than 5 years of age. Various health problems were found commonly and some of them include respiratory problems (41.9%); headache, vertigo and dizziness (16.7%); bone and joint pain (14.4%); gastrointestinal problems (13.9%); heart disease, including hypertension (8.8%); accidents and injuries (2.9%); and diabetes mellitus (2.6%). The prevalence of non-communicable disease (NCD) was 4.3% (95% CI: 3.83; 4.86) among individuals older than 30 years. Age-adjusted odds ratios showed that risk factors, such as sex, ethnic group, occupation and education, associated with NCD.

Conclusion

Our baseline survey demonstrated that it is possible to collect accurate and reliable data in a village setting in Nepal, and this study successfully established an HDSS site. We determined that both maternal and child health are better in the surveillance site compared to the entire country. Risk factors associated with NCDs dominated morbidity and mortality patterns.

Health and Demographic Surveillance System in the Western and coastal areas of Kenya: an infrastructure for epidemiologic studies in Africa

Background

The Health and Demographic Surveillance System (HDSS) is a longitudinal data collection process that systematically and continuously monitors population dynamics for a specified population in a geographically defined area that lacks an effective system for registering demographic information and vital events.

Methods

HDSS programs have been run in 2 regions in Kenya: in Mbita district in Nyanza province and Kwale district in Coast Province. The 2 areas have different disease burdens and cultures. Vital events were obtained by using personal digital assistants and global positioning system devices. Additional health-related surveys have been conducted bimonthly using various PDA-assisted survey software.

Results

The Mbita HDSS covers 55 929 individuals, and the Kwale HDSS covers 42 585 individuals. In the Mbita HDSS, the life expectancy was 61.0 years for females and 57.5 years for males. Under-5 mortality was 91.5 per 1000 live births, and infant mortality was 47.0 per 1000 live births. The total fertility rate was 3.7 per woman. Data from the Kwale HDSS were not available because it has been running for less than 1 year at the time of this report.

Conclusions

Our HDSS programs are based on a computer-assisted survey system that provides a rapid and flexible data collection platform in areas that lack an effective basic resident registration system. Although the HDSS areas are not representative of the entire country, they provide a base for several epidemiologic and social study programs, and for practical community support programs that seek to improve the health of the people in these areas.

Improving public health training and research capacity in Africa: a replicable model for linking training to health and socio-demographic surveillance data

BACKGROUND

Research training for public health professionals is key to the future of public health and policy in Africa. A growing number of schools of public health are connected to health and socio-demographic surveillance system field sites in developing countries, in Africa and Asia in particular. Linking training programs with these sites provides important opportunities to improve training, build local research capacity, foreground local health priorities, and increase the relevance of research to local health policy.

OBJECTIVE

To increase research training capacity in public health programs by providing targeted training to students and increasing the accessibility of existing data.

DESIGN

This report is a case study of an approach to linking public health research and training at the University of the Witwatersrand. We discuss the development of a sample training database from the Agincourt Health and Socio-demographic Surveillance System in South Africa and outline a concordant transnational intensive short course on longitudinal data analysis offered by the University of the Witwatersrand and the University of Colorado-Boulder. This case study highlights ways common barriers to linking research and training can be overcome.

RESULTS AND CONCLUSIONS

This collaborative effort demonstrates that linking training to ongoing data collection can improve student research, accelerate student training, and connect students to an international network of scholars. Importantly, the approach can be adapted to other partnerships between schools of public health and longitudinal research sites.

A role for INDEPTH Asian sites in translating research to action for non-communicable disease prevention and control: a case study from Ballabgarh, India

BACKGROUND

The International Network of field sites with continuous Demographic Evaluation of Populations and Their Health (INDEPTH) has 34 Health and Demographic Surveillance System (HDSS) in 17 different low and middle-income countries. Of these, 23 sites are in Africa, 10 sites are in Asia, and one in Oceania. The INDEPTH HDSS sites in Asia identified chronic non-communicable diseases (NCDs) as a neglected area of attention. As a first step, they conducted NCD risk factor surveys within nine sites in five countries. These sites are now looking to broaden the agenda of research on NCDs using the baseline data to inform policy and practice.

METHODS

A conceptual framework for translating research into action for NCDs at INDEPTH sites was developed. This had five steps - assess the problem, understand the nature of the problem, evaluate different interventions in research mode, implement evidence-based interventions in programme mode, and finally, share knowledge and provide leadership to communities and countries. Ballabgarh HDSS site in India has successfully adopted these steps and is used as a case study to demonstrate how this progress was achieved and what factors were responsible for a successful outcome.

RESULTS

Most of the HDSS sites are in the second step of the process of translating research to action (understand the problem). The conduct of NCD risk factor surveys has enabled an assessment of the burden of NCD risk together with determinants in order to understand the burden at the population level. The experience from Ballabgarh HDSS exemplifies that the following steps - pilot testing the interventions, implementing activities in programme mode, and finally, share knowledge and provide leadership - are also possible in rural settings in low-income countries. The critical success factors identified were involvement of a premier medical institution, pre-existing links to policy makers and programme managers, strong commitment of the HDSS team and adequate human resource capacity.

CONCLUSION

All INDEPTH HDSS sites now need to strengthen their links to health systems at different levels and enhance their capacity to engage different stakeholders in their respective country settings so as to translate the current knowledge into actions that can benefit the health of the population they serve and beyond.

Identifying humanitarian crises in population surveillance field sites: simple procedures and ethical imperatives

OBJECTIVES

Effective early warning systems of humanitarian crises may help to avert substantial increases in mortality and morbidity, and prevent major population movements. The Butajira Rural Health Programme (BRHP) in Ethiopia has maintained a programme of epidemiological surveillance since 1987. Inspection of the BRHP data revealed large peaks of mortality in 1998 and 1999, well in excess of the normally observed year-to-year variation. Further investigation and enquiry revealed that these peaks related to a measles epidemic, and a serious episode of drought and consequent food insecurity that went undetected by the BRHP. This paper applies international humanitarian crisis threshold definitions to the BRHP data in an attempt to identify suitable mortality thresholds that may be used for the prospective detection of humanitarian crises in population surveillance sites in developing countries.

STUDY DESIGN

Empirical investigation using secondary analysis of longitudinal population-based cohort data.

METHODS

The daily, weekly and monthly thresholds for crises in Butajira were applied to mortality data for the 5-year period incorporating the crisis periods of 1998-1999. Days, weeks and months in which mortality exceeded each threshold level were identified. Each threshold level was assessed in terms of prospectively identifying the true crisis periods in a timely manner whilst avoiding false alarms.

RESULTS

The daily threshold definition is too sensitive to accurately detect impending or real crises in the population surveillance setting of the BRHP. However, the weekly threshold level is useful in identifying important increases in mortality in a timely manner without the excessive sensitivity of the daily threshold. The weekly threshold level detects the crisis periods approximately 2 weeks before the monthly threshold level.

CONCLUSION

Mortality measures are highly specific indicators of the health status of populations, and simple procedures can be used to apply international crisis threshold definitions in population surveillance settings for the prospective detection of important changes in mortality rate. Standards for the timely use of surveillance data and ethical responsibilities of those responsible for the data should be made explicit to improve the public health functioning of current sentinel surveillance methodologies.

Demographic and health surveillance: longitudinal ethical considerations

Longitudinal data gathered from health surveillance, when combined with detailed demographic information, can provide invaluable insight into disease outcomes. Many such surveillance sites exist in the developing world, particularly in Asia and sub-Saharan Africa, and focus on diseases such as HIV/AIDS, cholera, malaria and tuberculosis. The indistinct positions of such surveillance systems, often inhabiting an area between research, treatment and population health monitoring, means that the necessity of and responsibility for ethical oversight is unclear. This regulatory vacuum is further compounded by a lack of attention to longitudinal surveillance systems in ethics literature. In this paper, we explore some key ethical questions that arise during demographic and health surveillance in relation to ethical principles of beneficence, respect for persons and justice: health-care provision, informed consent and study sustainability.

The effect of community nurses and health volunteers on child mortality: the Navrongo Community Health and Family Planning Project

BACKGROUND

Despite effective treatments and preventive measures for the major causes of child illness and death in less wealthy nations, child mortality remains high in resource-poor settings due in part to ineffective health service delivery models.

METHODS

The Navrongo Community Health and Family Planning Project is a longitudinal community trial of alternative organizational strategies for health service delivery in a rural, impoverished area of Ghana. In one area, nurses are placed in communities with doorstep visitation and service responsibilities. A second area includes training of a local health volunteer and community involvement in health delivery. A third area combines both strategies. Under-five mortality rates were calculated and Poisson regression was used to adjust for potential confounding characteristics.

RESULTS

In areas with village-based community nurse services, under-five child mortality fell by 14% during five years of program implementation compared with before the intervention, with reductions in infant (5%), early child (18%), and late child (39%) mortality. The volunteer intervention was associated with a 14% increase in mortality, primarily driven by a 135% increase in early child mortality. Areas with both nurses and volunteers saw an 8% increase, with small increases in all age groups. Mortality in a comparison area with standard Ministry of Health services fell by 4% during the same time period.

CONCLUSIONS

These results suggest that convenient, accessible professional nursing care can reduce child mortality in impoverished African settings. However, they do not demonstrate a beneficial effect of community volunteers and suggest a possible negative impact on children's survival.

Should data from demographic surveillance systems be made more widely available to researchers?

BACKGROUND TO THE DEBATE

Demographic surveillance--the process of monitoring births, deaths, causes of deaths, and migration in a population over time--is one of the cornerstones of public health research, particularly in investigating and tackling health disparities. An international network of demographic surveillance systems (DSS) now operates, mostly in sub-Saharan Africa and Asia. Thirty-eight DSS sites are coordinated by the International Network for the Continuous Demographic Evaluation of Populations and Their Health (INDEPTH). In this debate, Daniel Chandramohan and colleagues argue that DSS data in the INDEPTH database should be made available to all researchers worldwide, not just to those within the INDEPTH Network. Basia Zaba and colleagues argue that the major obstacles to DSS sites sharing data are technical, managerial, and financial rather than proprietorial concerns about analysis and publication. This debate is further discussed in this month's Editorial.

Bridges to sustainable tropical health

Ensuring sustainable health in the tropics will require bridge building between communities that currently have a limited track record of interaction. It will also require new organizational innovation if much of the negative health consequences of large-scale economic development projects are to be equitably mitigated, if not prevented. We focus attention on three specific contexts: (i) forging linkages between the engineering and health communities to implement clean water and sanitation on a broad scale to prevent reworming, after the current deworming-only programs, of people by diverse intestinal parasites; (ii) building integrated human and animal disease surveillance infrastructure and technical capacity in tropical countries on the reporting and scientific evidence requirements of the sanitary and phytosanitary agreement under the World Trade Organization; and (iii) developing an independent and equitable organizational structure for health impact assessments as well as monitoring and mitigation of health consequences of economic development projects. Effective global disease surveillance and timely early warning of new outbreaks will require a far closer integration of veterinary and human medicine than heretofore. Many of the necessary surveillance components exist within separate animal- and human-oriented organizations. The challenge is to build the necessary bridges between them.

Spatial patterns of malaria in the Amazon: Implications for surveillance and targeted interventions

A measure of local spatial association, G(i)*(d), is applied to test for the presence of malaria clusters in a colonization area in the Brazilian Amazon. Clusters of high and low malaria rates at different moments in time are identified. They suggest unambiguous spatial patterns of transmission, most likely linked to the social and natural habitat. Results imply that a comprehensive identification of the determinants of malaria transmission requires a spatial framework of analysis, and that control strategies must be spatially targeted and guided by a surveillance system that constantly learns the specificities of local transmission and adapts interventions to them.

Mapping the environmental coverage of the INDEPTH demographic surveillance system network in rural Africa

OBJECTIVES

The INDEPTH DSS network was founded in 1998 to provide an international network of field sites for continuous demographic evaluation of populations and their health. Results from the network have been used to derive estimates of mortality, morbidity and health equity. Spatial extrapolation and logical summaries of these findings are dependent on the network covering a representative sample of the environments in a region and their interrelationships being known. Here, we investigate how comprehensive is the coverage of the network of rural DSS sites in Africa in terms of the range of ecological zones found across the continent.

METHODS

We used satellite imagery to define an environmental signature for each INDEPTH DSS site, and then calculate Euclidean distances from these signatures to the environmental signatures of every image pixel across Africa. These distances were then mapped and a gridded population surface used to mask uninhabited areas to illustrate the extent of the environmental coverage of the INDEPTH network. Environmental similarities between DSS sites were also calculated, hierarchically clustered and visualized as a dendrogram to examine between site relationships. Finally, an ecozonation of Africa was used to analyse the per-ecozone environmental similarity of the INDEPTH DSS network.

RESULTS AND CONCLUSIONS

The current INDEPTH DSS network in Africa spans all the major environmental zones, but within these zones the environmental coverage of the network varies. These variations were mapped by ecozone. These maps provide valuable information in determining the confidence with which relationships derived from rural INDEPTH DSS sites can be extended to other areas. The results also indicate suites of sites that form environmentally cohesive groups and from which data can be logically summarized. Finally, the results highlight areas where the location of new INDEPTH DSS sites would increase significantly the environmental coverage of the network.

New initiatives against Africa's worms

Since 1999, the funding available for the control of diseases of poverty (neglected diseases) has increased mainly due to leverage resulting from donations by the Bill and Melinda Gates Foundation and loans from the World Bank. Many countries have embarked on control programmes on a national scale due to drug donations by pharmaceutical companies through vertical programmes. The Schistosomiasis Control Initiative has expanded its operations to cover six countries in sub-Saharan Africa, but overlap of treatments between different vertical programmes is now a reality, and so care is needed to ensure that too many different drugs are not given together. Dialogue between programme managers has increased, and integration of some programmes may offer chances of synergy.

Malaria risk on the Amazon frontier

Frontier malaria is a biological, ecological, and sociodemographic phenomenon operating over time at three spatial scales (micro/individual, community, and state and national). We explicate these linkages by integrating data from remote sensing surveys, ground-level surveys and ethnographic appraisal, focusing on the Machadinho settlement project in Rondônia, Brazil. Spatially explicit analyses reveal that the early stages of frontier settlement are dominated by environmental risks, consequential to ecosystem transformations that promote larval habitats of Anopheles darlingi. With the advance of forest clearance and the establishment of agriculture, ranching, and urban development, malaria transmission is substantially reduced, and risks of new infection are largely driven by human behavioral factors. Malaria mitigation strategies for frontier settlements require a combination of preventive and curative methods and close collaboration between the health and agricultural sectors. Of fundamental importance is matching the agricultural potential of specific plots to the economic and technical capacities of new migrants. Equally important is providing an effective agricultural extension service.

Validity and completeness of death reporting and registration in a rural district of Vietnam

AIMS

Assessment was made of the validity of mortality estimates based on data collected during 1999-2000 by quarterly follow-up visits and compared with other methods (re-census, communal death registration, and neighbourhood survey).

METHODS

This study was carried out within a longitudinal epidemiological laboratory in Bavi, District, Vietnam (called FilaBavi), covering a sample of 11,089 households with 51,024 inhabitants. Deaths within FilaBavi during 1999-2000 were collected by four methods and compared: quarterly household follow-ups, the re-census carried out in 2001, the Commune Population Registration System (CPRS), and a neighbourhood survey.

RESULTS

Within these four methods, a total of 471 deaths were detected in the FilaBavi sample. Quarterly household follow-ups detected 470 deaths (99.8%). The re-census missed 19 deaths, of which eight were infants, and two-thirds of the missed deaths fell in 1999. The CPRS missed 89 cases (19%), the majority being infant and elderly deaths. The neighbourhood survey over-reported deaths.

CONCLUSIONS

Quarterly follow-ups were the best method for death registration. The re-census approach was less complete, with problems of recall bias. The completeness and quality of death registration by CPRS was low, especially for infant and elderly mortality.