Dcpp Surveillance

8/6/2019 Dcpp Surveillance

1/3

Public Health Surveillance

The Best Weapon to Avert Epidemics

Fogarty Internationa Center of the U.S. Nationa Institutes of Heath The Word Ban Word Heath Organization Popuation Reference Bureau | Bi & Meinda Gates Foundatio

www.dcp2.org

May 2008

Public health surveillance provides real-time, early warning

inormation to decisionmakers about health problems that

need to be addressed in a particular population. It is a critical

tool to prevent outbreaks o diseases and develop appropriate,

rapid responses when diseases begin to spread. Training and

equipping health workers in developing countries with the

skills and technology or surveillance are an absolute necessity

in todays world.

With millions o people traveling the globe every day, diseasescross boundaries within days and even hours. Recent experiences

have shown that epidemics are a threat to economies as well as

a public health menace. While the tools and expertise exist to

avert epidemics, political commitment and nancial support

are needed to ensure that all countries have systems in place to

detect, analyze, and respond to diseases as soon as they emerge.

What Is Pubic Heath Sureiance?

Public health surveillance is the ongoing, systematic collection,

analysis, and interpretation o data that is then disseminated

to those responsible or preventing diseases and other health

conditions. The data allow managers to respond quickly to a

populations health needs. This inormation is also essential

or ministries o health, ministries o nance, and donors to

monitor how well people are served. Surveillance enables

decisionmakers to lead and manage eectively.

Because the objective o surveillance is to guide health

interventions, the nature o public health concerns drives the

design and implementation o the system. For example, i the

objective is to prevent the spread o acute inectious diseases,

such as SARS (severe acute respiratory syndromesee box

on page 2), health program managers need to intervene

quickly. To do so, they need a system that provides early

warning inormation rom clinics and laboratories.

In contrast, chronic diseases and heath-related behaviors,

such as smoking, change more slowly, and managers need

only to monitor changes once a year or even less oten. A

surveillance system to measure the eects o a tuberculosis

control program might provide inormation only every one to

ve years, depending on the prevalence level, and could do so

through household surveys, described below.

Types of Sureiance Strategies

The ollowing are selected surveillance strategies, which

can each meet top managers needs or dierent types o

inormation:

Sentinel surveillance systemsconsist o a sample o health

acilities or laboratories in selected locations that report all

cases o a certain condition to indicate trends in the entire

population. Sample reporting is a good way to use limited

resources to monitor suspected health problems. Examples

include networks o health providers reporting cases o

infuenza or a laboratory-based system reporting cases o

certain bacterial inections among children.

Household surveyscan be used to monitor diseases i the

surveys are consistent and repeated periodically, say everythree to ve years. The surveys are population-based; that is,

they select a random sample o households representative o

the whole population. Examples include demographic and

health surveys in developing countries and the behavioral

risk actor surveillance system in the United States.

Laboratory-based surveillanceis used to detect and monitor

inectious diseases. For example, or ood-borne diseases such

as salmonella, the use o a central laboratory to identiy specic

strains o bacteria allows more rapid and complete identication

o disease outbreaks than a system that relies on reporting osyndromes rom clinics. In the United States, the Centers or

Disease Control and Prevention maintain PulseNet, an Internet-

based network o laboratories that uses standard methods or

identiying and reporting the genetic makeup o disease-causing

agents. PulseNet is also active in Canada and Europe and is

expanding in Asia and the Pacic and Latin America.

Integrated disease surveillance and response(IDSR) strategies

bring together data rom health acilities and laboratories


2/3

2 | Pubic Heath Sureiance: The Best Weapon to Aert Epidemics | Disease Control Priorities Project

in systems designed to monitor communicable diseases.

The emphasis is on integrating surveillance with response.

IDSR has several core activities: detecting, registering, and

conrming individual cases o disease; reporting, analysis,

use, and eedback o data; and preparing or and responding

to epidemics. In Arica, the World Health Organization is

helping a number o countries to build the inrastructure and

skills to develop and use these integrated systems.

Exampes of Uses of Sureiance

PREvENTING MAjOR OUTBREAkS OF DISEASE

The AIDS epidemic tragically spread to many countries in

Sub-Saharan Arica over many years beore it was detected and

control measures were started in the late 1980s. In recent years,

surveillance and response systems have been more eective at

identiying early and thereby preventing the spread o inectious

diseases. Examples include the SARS epidemic in China (see

box), the Ebola virus in Uganda, and avian fu in Thailand.

In 2000 in northern Uganda, a public health student discovered

a hospital jammed with patients with high evers, diarrhea, and

bleeding. He reported cases o viral hemorrhagic ever to the

Ministry o Health, which quickly arranged or samples to be

fown to South Arica (the nearest specialized laboratory) or

analysis. Once the laboratory tests conrmed that the illness

was Ebola, which usually kills more than hal o those inected,

the health minister quickly mobilized a surveillance and control

team to set up services in the aected region. Because the

disease spreads rapidly and many people were feeing the area,

the government mobilized the military to help identiy cases;

invited international health experts to assist with treatment and

control; and set up surveillance nationwide. Within one year, the

epidemic was controlled, with a atality rate lower than that o

previous Ebola outbreaks. Partially because o the lessons o this

epidemic, Uganda has become one o the leading countries in

implementing the IDSR program.

Thailand was host to one o the largest epidemics o avianinfuenza (bird fu) identied in eight Asian countries in early

2004. Later that year, the disease spread rom birds to humans,

killing 32 o the 44 people inected. Recognizing the global

threat posed by such a disease, the Thai Ministry o Health, in

partnership with eld epidemiologists and WHO, supported

laboratory studies that showed that the disease was being spread

rom human to human. The Thai example was critical in

raising public awareness o the possibility o a global catastrophe

caused by avian lu. It also showed that the disease can be

controlled with proven epidemiologic methodsincluding

rapid, on-site investigation by trained specialistsand good

communications.

MEETING OTHER CRITICAl HEAlTH

INFORMATION NEEDS

Because health managers need inormation or a wide variety

o purposes, dierent types o surveillance systems have been

developed, including:

SURvEIllANCE AND THE GlOBAl

RESPONSE TO SARS

In November 2002, public health ocials detected an epidemic

o severe pneumonia o unknown cause in Guangdong

province, China, and put in place control measures based on

the way the disease spread rom person to person. In February

and March 2003, the disease spread to Hong Kong, Vietnam,

Singapore, Canada, and elsewhere. Health experts named it

severe acute respiratory syndrome (SARS); identied a specic

virus as the cause by March 2003; and mapped the ull genome

by April. The pandemic ended in July 2003, as transmission

was interrupted ater more than 8,000 patients in 26 countrieswere aected and 774 deaths were conrmed.

The World Health Organization spearheaded the eort to

control the pandemic, working with national and subnational

health workers, the Chinese Center or Disease Control, and

a team o eld epidemiologists. (Field epidemiologists are

disease detectives who work on-site to nd and interview

patients with diseases, collect specimens, and apply statistical

methods to assess the causes o illness and recommend

control measures.) In Canada, which had the most cases

o SARS outside o China, ield epidemiologists beganinvestigations, developed prevention and control guidelines,

inormed the media and the public, and planned and

implemented studies o the disease.

The success o this global eort to control the irst new

epidemic o the 21st century depended on open collaboration

among scientists and politicians o many countries, and

rapid communication o surveillance data among countries.

Once the spread o SARS was recognized, a worldwide

surveillance network was established based on an agreed-

upon case deinition that was speciic enough to ensure

accurate reporting.


3/3

Monitoringtheadverseeffectsofenvironmental

hazards such as toxic chemicals and biologic agents in

the air, water, soil, or ood.

Collectingdataoninjuries,whichareamongthe

leading causes o death and disabilities worldwide,

most o which are preventable.

Detectingandmanagingoutbreaksof bioterrorism,

in which the causes are man-made but the outbreaks

are similar to other epidemics: Early detection and

warning are critical to saving lives.

Monitoringandrespondingtodisastersandcomplex

emergencies, including mapping o possible hazards

and training o rescue teams.

Monitoringrefugeepopulationstoidentifyand

eliminate preventable causes o illness and death in

these communities.

Who Shoud Pay for Sureiance?

The spread o diseases is expensive and can be economically

devastating in aected countries, as HIV/AIDS in Arica has

demonstrated. Although the private sector beneits rom

disease surveillance and response, surveillance systems are an

essential element o public health and thereore all within the

responsibility o countries and international organizations.

Public health surveillance can be considered a global public good

when it is used to eradicate diseases that cross national borders.

The greatest need or and use o public health surveillance

is within countries; thereore, governments should and do

bear most o the inancial and human resource costs o

building and maintaining surveillance systems. Nevertheless,

many developing countries will require assistance rom

international donor and technical agencies or some time to

build the skills and inrastructure necessary to protect the

local population, as well as those o other countries, rom

outbreaks o disease.

Improements Needed in Deeoping

Countries

A challenge or developing countries is to ensure the quality

and eectiveness o surveillance and public health responses.

Accomplishing this will require developing and maintaining a

cadre o competent and motivated surveillance and response

workers. Core competencies that need to be developed include

eld epidemiology (the on-site investigation and analysis o

diseases); and the ability to conduct scientic investigations,

analyze and interpret the ndings, and recommend logical and

practical actions based on the ndings.

Developing country governments, their unding partners, and

multilateral organizations need to invest in the inrastructure

and training to make surveillance systems work well. Using new

inormation technologies and compatible reporting systems

will help bring about the needed improvements. Increasingly,

new technologies such as sotware available over the Internet

and geographic inormation systems are transorming public

health surveillance in developing countries. The U.S. Centers

or Disease Control and Prevention, along with WHO, have

collaborated with more than 30 countries since 1975 to

strengthen health systems and train health workers in the latest

methods o disease detection and response.

ConcusionsTo be useul, public health surveillance must be approached as a

scientic enterprise, applying rigorous methods to address critical

public health concerns. The problems acing the developing and

developed worlds are increasingly similar and overlapping.

The rise o global epidemics, in particular, calls or integrated,

worldwide networks that bring together health practitioners,

researchers, governments, and international organizations to

address surveillance needs that cross national boundaries.

Although it is reassuring that disease outbreaks such as SARS,

Ebola, and avian fu have thus ar been averted through rapid

surveillance and response, there is no reason or complacency.

Health experts are certain there will be urther outbreaks,

possibly o SARS or avian lu. Thus, the question is not

whether but when new disease outbreaks will occur, and

whether the world community will be ready or them.

For More Information

Peter Nsubuga, Mark E. White, Stephen B. Thacker, Mark A.

Anderson, Stephen B. Blount, Claire V. Broome, Tom M. Chiller,Victoria Espitia, Rubina Imtiaz, Dan Sosin, Donna F. Stroup,

Robert V. Tauxe, Maya Vijayaraghavan, and Murray Trostle. 2006.

Public Health Surveillance: A Tool or Targeting and Monitoring

Interventions. InDisease Control Priorities in Developing Countries,

2nd ed., ed. D. T. Jamison, J. G. Breman, A. R. Measham, G. Alleyne,

M. Claeson, D. B. Evans, P. Jha, A. Mills, and P. Musgrove, 997-1015.

New York: Oxord University Press.

www.dcp2.org

Documents

Dcpp Surveillance