Communicable diseases remain the most common causes of death, illness and disability in African countries. Lopez et al. (2006) reported that one-third of the deaths in low-and-middle income countries in 2001 were from communicable and parasitic diseases and maternal and nutritional conditions [1,2]. In addition, the economic cost in terms of prevention, treatment, and loss of productivity is enormous [3-5]. Although a number of studies on economic evaluation of interventions against communicable diseases have been reported in the literature [6,7], most of these studies in sub-Saharan Africa have focused on individual disease-specific intervention programs, such as prevention or treatment of malaria, measles, meningitis, tuberculosis and HIV/AIDS [5,8-15]. Relatively few studies have looked at the economics of integrating resources for disease surveillance and public health response activities [16].

Surveillance is an important component of disease prevention and control programs. It is useful in early detection of unusual events for effective and timely action, monitoring and evaluation of interventions and guiding selection of appropriate corrective measures [17]. In 1998, the Regional Committee of the World Health Organization Africa region (WHO-AFRO) adopted a strategy called Integrated Disease Surveillance and Response (IDSR) [18]. Under the IDSR strategy, countries address improvements in infrastructure capacities and support activities and select a number of priority diseases and health risk conditions from a list of the 19 communicable diseases that affect African communities (Figure 1) [19-21]. By December 2007, considerable progress had been achieved, with 43 of the 46 countries having assessed their national surveillance system and developed plans of action; 41 countries had already adapted the technical guidelines to meet their own public health priorities and situations and then launched IDSR activities at their district levels; and 33 countries had trained staff on IDSR in at least 60% of their districts (Table 1).

In order to better understand the investment and implementation costs of this IDSR strategy, the IDSR multi-partner task force that guides the implementation of this regional strategy recommended that the partners undertake cost analyses and cost-effectiveness studies. Therefore, the purpose of this study was to analyze the incremental costs of establishing and subsequently operating activities for detection and response to the priority diseases under the IDSR.

Table 3 summarizes the mean annual costs by resource categories at the region, district, and primary health care center level in the three countries. Detailed costs are shown in Additional file 1, Appendix 3. As expected, because of larger populations and types of IDSR activities, regional-level costs were greater in all categories than at the level of district and primary health care center. However, the cost of running IDSR at each site varied substantially by resource-type. Since disease surveillance requires trained staff, mean annual personnel costs were among the largest components of the region (10% to 47%) and district (16% to 44%) total IDSR costs in all three countries. Based on the results from Eritrea and Mali, we estimated that the laboratory and treatment costs ranged from 4% to 35% of the total IDSR cost in Burkina Faso. The proportion of the total IDSR cost due to treatment varied considerably (2% to 13%) by health structure in Eritrea and Mali. In general, the annualized capital costs constituted 2% to 13% of the total annual cost of IDSR in Eritrea, 6% to 12% in Mali, and 8% to 15% in Burkina Faso.

The mean annual costs by health structure levels from the three countries surveyed are presented in Table 4. Eritrea had the highest total IDSR-related costs, and Burkina Faso had the lowest costs. The mean cost of IDSR, expressed as percentage of all HRS cost, also varied by health structure level (Table 4). In all three countries, the mean annual IDSR costs were 20% to 43% of the all HRS costs. In Burkina Faso and Eritrea, the highest costs ($39,419 and $91,362) of IDSR program per region occurred in 2003, and the highest costs ($13,297 and $15,781) per district in 2004 (Fig. 2). These were possibly associated with start-up costs of IDSR implementation at regional and district levels. By the end 2003, for example, Eritrea had completed training on IDSR in all the provinces; Burkina Faso had trained 18 national core trainers, 135 province supervisors, 110 laboratory technicians, and 1233 district and primary health care personnel; and Mali had trained only 406 health personnel from 28 districts of the four regions including Bamako.

Costs disaggregated into IDSR activities are shown in Table 5. Detailed costs by year per IDSR activity are presented in Additional file 1, Appendix 4. As expected, the surveillance activities (e.g., detection, report, and analysis) that are carried out on a routine basis absorbed more resources than the support activities (e.g., evaluation and monitoring). Outbreak investigation and treatment of confirmed cases also constituted a substantial component (23% to 67%) of the total IDSR cost. When evaluating costs allocation at district level, detection of cases cost 21% to 40% of total IDSR costs, while outbreak investigation and verification accounted for only 2% to 18% of total IDSR cost. However, primary health care centers spent 8% to 67% of the total IDSR resources on detection and treatment of disease cases.

The mean cost in Eritrea for an integrated surveillance system per capita was $0.16, which was 4 and 8 times larger than the $0.04 and $0.02 per capita recorded in Burkina Faso and Mali, respectively (Table 6). When we estimated costs using PPP, the mean cost per capita of IDSR for Eritrea was $0.87 and $0.06 for Mali (14 times larger). Eritrea's higher costs were possibly tied to post-war rebuilding of the national infrastructure, including the health system (see Additional file 1, appendix 5 for detailed IDSR budget in Eritrea). In Burkina Faso, we did not collect laboratory and treatment data. Instead, we extrapolated the costs from average annual cost of laboratory supplies and treatment for Eritrea and Mali. Without the laboratory and treatment costs, the mean annual per capita cost of IDSR in Burkina Faso and Mali was $0.02 compared to $0.13 in Eritrea. Using annual population estimates (Table 2) and the average per capita costs (Table 6), we estimated that the total annual national integrated surveillance program cost $476,208 in Burkina Faso, $690,957 in Eritrea and $270,360 in Mali. These accounted for 24% to 40% of the total HRS costs in all three countries. The per capita costs spent on all IDSR activities represented 3.2% (in the case of Eritrea) or less (in the case of Burkina Faso and Mali) of the total per capita government health budget.

IDSR attempts to integrate multiple, competing vertical systems in order to use surveillance and response-related resources more efficiently and reduce duplication of effort, especially at district and primary health care center levels [20,21]. In this study, we measured the incremental costs of setting-up and implementing an integrated surveillance and response strategy in Burkina Faso, Eritrea and Mali. In each country, the cost of IDSR was dependent on the health structure level. The district and primary health care center levels had much lower costs, as they usually had only lower cadre health workers and disease surveillance officers to provide services. A full understanding of the between-country differences in per capita costs of IDSR will require further study. As shown when we used PPP to convert local costs into US dollars, difference exchange rates may alter the degree of differences between countries.

The study's main limitation is the potential inaccuracy when we apportioned total cumulative surveillance activities cost (e.g., personnel time and building, equipment and vehicle use-time) to IDSR-specific activities. Log books of time and expenses did not provide the level of details needed to accurately divide out costs between IDSR and other surveillance and public health activities. As explained, we used the proportion of personnel time given to IDSR to proportion other costs. Furthermore, our retrospective survey may not have fully captured all costs due to the limitations of data records (e.g., no personnel time keeping records and the usual recall bias) in these countries. It is also possible that our data collection methods missed some surveillance-related expenditures. This is because, in Africa, donors often support specific public health projects (such as surveillance for a specific disease) that run parallel to the national public health system. Such projects often have a distinct identity (i.e., names and logos), and may even have staff paid directly by donor funds. Public health staff may not consider such projects part of the general public health system when enumerating costs associated with surveillance and IDSR. Another limitation of this study is the reliance on expenditure data, which may be weakened by over- and under-estimation and incomplete recording and do not reflect the whole economic cost. Further, indirect costs and productivity losses were not incorporated. Moreover, our estimate of IDSR cost based on 4-year data may be higher than when a longer term perspective is taken due to non-recurring start up costs. Absolute difference in cost per capita will depend upon the exchange rates used.

This study focused only the cost of resources accrued to IDSR activities and not the impact on the indicators used by the countries to monitor and evaluate their progress with their IDSR activities. In Eritrea, for example, the completeness of reporting case-based data from the health care center to the next high level increased from 50% in 2000 to 93% by the end of 2003. In Burkina Faso, the timeliness of surveillance reporting, especially data on epidemic-prone diseases, increased from 71% in 2000 to 99% by the end of 2004. Although Mali had also achieved the 80% target for these progress indicators, the transmission of complete data on time (83%) in 2005 was lower than that in Burkina Faso and Eritrea.

There are few studies on the costs of disease surveillance, and those are often not directly comparable to our study [16,24]. For example, John et al. (1998) measured the cost of emerging childhood vaccine-preventable diseases in India [16]. They found surveillance cost $0.01 per capita (1998 US $), which is approximately equal to the costs we measured in Burkina Faso and Mali (Table 6). However, the program in India only included childhood vaccine-preventable diseases, while the IDSR system includes not only childhood and adult vaccine-preventable diseases but also epidemic-prone diseases and endemic epidemics such as HIV/AIDS, malaria, TB, childhood diarrhea and acute respiratory infections. We can, therefore, consider IDSR a low cost public health system although the benefits, such as cases prevented, due to the IDSR program have yet to be quantified.

The authors declare that they have no competing interests.

ZCS, MIM, HNP conceived, carried out the study, analyzed the data, and drafted the manuscript. UA, MS, KT, and SOK each participated in the organization and coordination of the field data collection. NRM, TO, WA and IS participated in the design and coordination of the study. All authors read and approved the final manuscript.