Modeling the Cost-Effectiveness of the Integrated
Disease Surveillance and Response (IDSR) System:
Meningitis in Burkina Faso
Zana C. Somda1, Helen N. Perry1, Nancy R. Messonnier1, Mamadou H. Djingarey2, Salimata Ouedraogo
Ki3, Martin I. Meltzer1*
1Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America, 2WHO –IST West Africa, Ouagadougou, Burkina Faso, 3Ministe `re de la Sante ´,
Ouagadougou, Burkina Faso
Background: Effective surveillance for infectious diseases is an essential component of public health. There are few studies
estimating the cost-effectiveness of starting or improving disease surveillance. We present a cost-effectiveness analysis the
Integrated Disease Surveillance and Response (IDSR) strategy in Africa.
Methodology/Principal Findings: To assess the impact of the IDSR in Africa, we used pre- and post- IDSR meningococcal
meningitis surveillance data from Burkina Faso (1996–2002 and 2003–2007). IDSR implementation was correlated with a
median reduction of 2 weeks to peak of outbreaks (25thpercentile 1 week; 75thpercentile 4 weeks). IDSR was also correlated
with a reduction of 43 meningitis cases per 100,000 (25th–40: 75th-129). Assuming the correlations between reductions in
time to peak of outbreaks and cases are related, the cost-effectiveness of IDSR was $23 per case averted (25th-$30; 75th- cost
saving), and $98 per meningitis-related death averted (25th-$140: 75th– cost saving).
Conclusions/Significance: We cannot absolutely claim that the measured differences were due to IDSR. We believe,
however, that it is reasonable to claim that IDSR can improve the cost-effectiveness of public health surveillance.
Citation: Somda ZC, Perry HN, Messonnier NR, Djingarey MH, Ki SO, et al. (2010) Modeling the Cost-Effectiveness of the Integrated Disease Surveillance and
Response (IDSR) System: Meningitis in Burkina Faso. PLoS ONE 5(9): e13044. doi:10.1371/journal.pone.0013044
Editor: Abdisalan M. Noor, Kenya Medical Research Institute, Kenya
Received April 23, 2010; Accepted August 6, 2010; Published September 28, 2010
This is an open-access article distributed under the terms of the Creative Commons Public Domain declaration which stipulates that, once placed in the public
domain, this work may be freely reproduced, distributed, transmitted, modified, built upon, or otherwise used by anyone for any lawful purpose.
Funding: This research was supported by the U.S. Centers for Disease Control and Prevention (CDC) with funding from USAID Global Surveillance and Africa
Bureaus. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.
Competing Interests: The authors have declared that no competing interests exist.
* E-mail: email@example.com
More than 1.5 million children die each year in sub-Saharan
Africa, from diarrhea, malaria, measles, meningitis, respiratory
infections, yellow fever, and HIV/AIDS [1–6]. Well known and
effective interventions are available for controlling and preventing
the diseases that cause these deaths but they are often not applied to
their maximum potential [7–10]. The resulting deaths and the
associated economic costs to society could be reduced if timely
detection and control measures are implemented [11–13]. In
response to this problem, in 1998, countries in the World Health
Organization (WHO) African region adopted a regional strategy
named Integrated Disease Surveillance and Response (IDSR) [14–
16, Table S1]. IDSR is a strategy that seeks to strengthen the ability
of national and regional public health surveillance programs. The
goal of IDSR is to integrate a number of surveillance systems, both
existing and newly formed. This integration should encompass all
levels of public health (from the basic district-level through to the
national level), and should achieve efficiencies by avoiding
duplication of efforts. Areas of activity that IDSR focuses on to
improve efficiency include detection and identification of public
health problems, increased speed of reporting and notification
(especially for immediately notifiable diseases), analysis of data and
interpretation of trends, laboratory confirmation when required,
decision-making about responses, monitoring of progress and
regular evaluation of the surveillance system’s quality (14–16).
The net results of IDSR-implemented reforms in surveillance
systems should be that outbreaks are detected earlier, allowing
quicker public health response (e.g., vaccination campaigns).
Although considerable progress had been achieved with
implementation of the IDSR strategy (see http://www.cdc.gov/
idsr/implementation.htm#progress), the associated economic
benefits (e.g., cases and death prevented, costs of medical
treatments saved by the society, and the value of avoided year of
life lost) are poorly documented. Most studies on economic
evaluation of public health intervention programs in sub-Saharan
Africa have focused on individual disease-specific intervention
activities [17–23]. Relatively few studies have looked at the
economic benefits of surveillance and response activities [24,25].
In a previous study, we analyzed the costs of establishing and
subsequently operating activities for detection and response to the
priority diseases under the IDSR strategy . We add to the
literature by presenting a cost effectiveness analysis of IDSR, in
which we will assume that any average reductions in health
outcomes (e.g., incidence of cases and deaths, outbreak duration)
were due to implementation of IDSR.
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To model the cost-effectiveness of IDSR, we used data from
Burkina Faso because that country had fully established IDSR
leadership and structures at the national level by 2002, with
implementation at regional and district levels in 2003. Burkina
Faso had data, collected using the IDSR-supported surveillance
systems, on several meningitis outbreaks.
The nature of disease surveillance systems makes it impossible to
have a randomly controlled experiment to measure the impact of
IDSR on public health outcomes. We were unable to readily
collect comparable data from another country (e.g., one without
IDSR systems, or one that implemented IDSR systems after
Burkina Faso), and thus we were unable to conduct a comparison
between countries. We therefore relied on observational (before-
and-after) data from outbreaks of meningococcal meningitis to
assess the possible impact of IDSR-related activities in Burkina
Faso. We assumed that any correlations between the start of IDSR
activities, which includes both surveillance and response to disease
activity detected, and changes in the epidemiology of meningitis
outbreaks were due primarily to IDSR. With this assumption, we
calculated, on an outbreak basis, costs per case, per death and per
sequelae prevented. There could be other reasons for any
correlations that we measured (see discussion section).
As most health care and IDSR activities in Burkina Faso are
funded by the government, we took the perspective of the
government-funded public health care system (i.e., we only
recorded costs and savings incurred by the national government);
costs incurred by households were not included. All cost data were
recorded in local currency values and then converted into US
dollar values using the mean annual exchange rate. We used the
general consumer price index from Burkina Faso  and a
discount rate of 3% to adjust all costs into 2002 US dollars
We obtained from the WHO Multi-Diseases Surveillance
Center in Ouagadougou annual population data and district level
reports of weekly meningitis cases and deaths from Burkina Faso
for the years 1996–2007 (see Table S2). We then calculated the
weekly incidence and mortality, expressed as cases and deaths
per 100,000 inhabitants, by dividing the number of new cases
and deaths occurring per week by the mean annual population of
each reporting district. A 1988 study in The Gambia found that
27 out of 154 (17.5%) survivors of bacterial meningitis had
generalized neurological sequelae  We therefore assumed
20% of meningitis survivors would have neurological defects
We sorted the data into two groups: before (1996–2002) and
after (2003–2007) IDSR implementation at district level. During
this study period, all meningitis outbreaks in Burkina Faso only
occurred between January and June (23-week period). For each
group, we examined the weekly incidence rates in relation to the
WHO recommended alert threshold (5 cases per 100,000) and
epidemic threshold (10 cases per 100,000) . We defined the
start (end)of an outbreak when cases in a district exceeded
(returned below) the epidemic threshold. For each outbreak, we
calculated the time-to-peak of the outbreak as the number of weeks
elapsed from the first alert threshold to the week with the
maximum weekly incidence (i.e., the peak of the outbreak). We
also calculated the time to reach the median, 25thand 75th
percentiles of cumulative total incidence and mortality.
For each group of outbreaks before and after IDSR implemen-
tation (start 2003), we calculated the median, 25thand 75th
percentile for each of the following health outcomes: weekly and
cumulative total incidence, mortality and sequelae.
We first plotted the average weekly incidence rates over the time
period studied and the median weekly incidence and mortality
before and after IDSR implementation over the 23-week period of
meningitis outbreaks. We then compared the health outcomes (i.e.,
incidence, mortality, time to peak and time to reach a set
percentile of total cases per outbreak) using the Mann-Whitney test
using SAS statistical software version 9.1 (SAS Institute Inc., Cary,
NC, USA). In 1996 there was an ‘‘unusually’’ large epidemic of
meningitis in Burkina Faso. We therefore examined the influence
of 1996 data on the IDSR effectiveness measures by re-running
the analyses excluding 1996 data.
Response to outbreaks: Vaccine importation
As IDSR encompasses a deliberate response factor, it is
plausible that vaccine imports may increase post-IDSR imple-
mentation. In order to assess potential correlation between IDSR
implementation and meningococcal vaccine importation, we
obtained estimates of the doses of vaccine imported by the
Burkina Faso government from the WHO International Consul-
tative Group, UNICEF, and GlaxoSmithKline Biologicals.
Vaccine data were also collected from the WHO disease outbreak
website (http://www.who.int/csr/don/en/index.html) (Tables S3
and S4). We statistically tested if annual importation of doses was
impacted by IDSR implementation using the following general
Doses imported per year~
InterceptzYearzIDSR Implementation Perioddummyz error term
Where IDSR implementation period was recorded as a dummy
variable (Pre-IDSR =0; Post-IDSR=1). We ran six models, each
time varying the dependent variable (doses imported) as follows:
Total annual doses imported (including 1996 data); Total annual
doses imported (excluding 1996 data); Doses per 100,000
population in whole country (including 1996 data);
Doses per 100,000 population in whole country (excluding 1996
data); Doses per 100,000 population in districts where outbreaks
occurred (including 1996 data); and, doses per 100,000 population
in districts where outbreaks occurred (excluding 1996 data). To
check for autocorrelation, we calculated the Durbin-Watson
statistic for each regression.
We used the costs of IDSR-related activities reported in our
previous study [26; see also Table S5]. The costs include those due
to surveillance and response. In the case of meningitis, response is
mostly treatment of those ill and vaccination of populations near a
victim (e.g., those in the same village). The cost data for each
activity included personnel, transportation items, office consum-
able goods, public awareness campaigns, laboratory and response
materials and supplies, and capital items .
We also obtained direct medical care costs incurred by the
government to treat a patient with meningitis related-illness at
district health facility ($53) and regional hospital ($71) during the
2002 epidemic situation (unpublished data, Ministry of Health,
Burkina Faso; see Table S6)). These estimates include only the
immediate costs of meningitis case management (e.g., consultation
and hospitalization fees, drugs and other essential consumables,
and laboratory specimen testing). As the study perspective is the
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