Frequently Asked Questions

Community Based Surveillance

When and Where is CBS useful?

CBS can be useful in contexts where the existing surveillance system is not able to capture health risks/events from the community level that can lead to outbreaks. This is often due to lack of access to health care facilities, which is where traditional surveillance systems are often based. These gaps can also occur during conflicts, emergency situations, such as natural disasters, large outbreaks, due to lack of resources or other challenges and are particularly relevant in very remote communities.
CBS can help fill the surveillance gap by getting information from the community level to the level necessary to trigger an early response. Implementing CBS should be done in collaboration with the national health authorities, and as an addition to complement existing surveillance systems. CBS provides information about people and animals with signs and symptoms of health risks or other events which can indicate diseases or lead to disease outbreaks. It does not report on confirmed cases and can thus not replace a regular surveillance system for diseases. CBS can be used both in emergency response, and in everyday routine preparedness. Have a look at some of the implementation stories here, (click the heading "implementation') this may help you better understand how implementation can look under different circumstances.

When CBS is used as a component of a community health programme it helps link the communities to the closest existing health clinic which can then support in investigation of a report. In some cases, if the National Societies has mobile/fixed clinics (e.g. Somaliland) these components can be supported by the Red Cross Red Crescent National Society.

How does CBS work?

The decision to implement CBS as a component of a community health program, and which health risks/events to include, is decided together with the Ministry of Health. The community volunteers, who are most often existing National Society volunteers, should be identified by the community. CBS can be done in different ways using different tools, but the core purpose is for community members to share information about health risks or events directly from their community to trigger investigation and responses when needed. They report to their assigned supervisor in their National Societies on health risks/events, while providing a first level community response to the health risks. For CBS to be implemented, it is necessary to have a mechanism in place to ensure there is a response and investigation to the reports coming from the community.

How do I know if CBS is the right approach for the context I am working in?

Before starting any planning for CBS it is important to complete an assessment. An assessment will tackle the questions if CBS is needed and justified, how it would fit into the surveillance landscape, and if it is feasible. As well, an assessment will see if there is a clear response mechanism in place. It is crucial to ensure action can be taken when needed from the alerts, such as investigation of suspected cases, laboratory confirmation or vaccination campaigns.

It is important to know if there is a gap in the existing surveillance system and what the key public health challenges are. This allows you to answer the question if CBS could be an appropriate strategy to fill in the gaps and if CBS would help to adapt the response. Have a look through the IFRC CBS Assessment Template to get an overview of the CBS assessment process.

How do volunteers report from the community?

CBS reporting can be done in different ways including the use of paper forms, SMS and or mobile apps. Mobile technology has been used widely in recent years to ensure data is shared in real-time. A digital platform called Nyss has been developed by and for the Red Cross Red Crescent Movement. Nyss works to directly aggregate SMS reports fromvolunteers, as well as automatically analyzes and visualizes data and triggersalerts to supervisors who shares appropriate data with health authorities tofacilitate a response.

The Red Cross Red Crescent CBS technical working group has developed a global list of community case definitions for health risks/events in collaboration with partners like WHO, CDC, and Ministries of Health. These are based on signs, symptoms and events which can indicate that there is a possible transmittable disease in the community.

What is the difference between CBS, contact tracing and surveys?

CBS is systematic detection and reporting of an observed health risk/event in the community to ensure a rapid response. It is often used to be able to do immediate reporting for early warning. Contact tracing is identification and follow up of contacts when a confirmed case is identified. Surveys are structured informatio ngathering from a sample of people, often done once, or on a regular basis toobtain specific information

What is the difference between CBS and Event based surveillance? what is the rational for applying CBS over Event based surveillance? 

EBS, or ‘event-based surveillance’ reports on broad, general events only (such as unusual health events and clusters of animal or human deaths). CBS is ‘community-based surveillance’ which is slightly more specific using lay community case definitions which correspond to specific epidemic disease threats. Both EBS and CBS have advantages and limitations.

EBS events are broader and can pick up undefined diseases, it is simpler and requires less training of community reporters. However, the EBS method may be too broad and result in many unnecessary general reports which are not severe threats and can also miss some health risks as they are not as specific as community case definitions. 

CBS is more specific to clearly identified known risks in an area. It is “the systematic detection and reporting of events of public health significance within a community,by community members”. Community members must be trained to recognize health risks-based community case definitions. This is more efficient as it minimizes unnecessary reports, which waste precious resources for unnecessary investigations. It should be noted that CBS alone can overlook signs of a new or unknown threat. It is ideal for CBS to include an EBS component in the system, such as ageneral alert for ‘a cluster of unusual illnesses or deaths.’ 

How is animal health included?

Many diseases pass from animals to people, plus the burden of animal diseases has important impact on the livelihoods and wellbeing of families. Volunteers can be trained to report early signs of potential animal epidemic threats to trigger early action and disease control.   

It is important to consider the capacity for response. National Society should not report on more than what they could respond to in collaboration with National Authorities, such as Ministry of Health, and must connect with local veterinary service providers if they choose to include animal health in their CBS system. In many locations both animal health (including abortions and unusual deaths) is easily reported alongside human health risks in the same CBS system.

How is personal informationprotected when doing CBS?

The Red Cross Red Crescent CBS approach is designed in such a way that personal or identifiable information is not sent out from the community. The volunteers will know who they aresending the report about to ensure the response can reach the right person if necessary. However, the information sent by SMS or on paper only contains the health risk/event they have seen, the sex and age group of the person. This is all the information needed to be able to determine if and which response is needed. All volunteers have RC/RC supervisors who are the link between the community and the authorities, who are responsible for the response. It is essential to have trust within the community and agreement among community members about how CBS should be conducted in their community, because a CBS alert may require a response/ follow-up from local health authorities.

For the CBS platform Nyss, the volunteers are registered with their personal information, but they are informed about what this means and must give consent. Personal identifying information is only visible for the supervisors and the National Society staff involved in CBS.

How many volunteers are needed for a CBS system?

The number of volunteers required depends on the context – factors such as the scope of the CBS program, workload to be distributed, the terrain and geographic accessibility to households, density of population, and security. It can also be very difficult to define community and determine the true population of a village. For example, some villages may have unclear geographical boundaries or moving populations.

As general guidance, 2-7 volunteers per village depending on the size of the community. Remember to engage community members in the CBS system, not only Red Cross Red Cresent volunteers – provide orientation to certain key community members, such as teachers, community leaders, traditional healers, religious leaders etc, to serve as ‘Community Informants’ – they can notify the volunteer, when they see or hear of a potentially serious illness or death.

The right selection of volunteers is crucial.  This should bedone with the community leaders and based on trust, likelihood of retention, activeness of the person, etc. Also ensure that gender and age balance is considered according to context.

How many supervisors/team leaders are needed in a CBS system? Who should I choose to be thesupervisors?

The number of supervisors/team leaders required depends on the context and the scope of their role and task-load, the geographic accessibility to the volunteers, and their capacity, You must have enough supervisors / team leaders to easily reach the volunteers within their catchment area to support them with weekly, 2-weekly or monthly supervision according to their need.

What systems and tools do I need for implementation of CBS?

A CBS project should be timely. The key advantage of CBS is that community illnesses are alerted quickly to authorities, or to a response agency. To achieve that, your CBS tools should feed alerts into a system as fast as possible. All CBS tools have advantages and limitations. 

Some things should be considered when deciding what method of communication to use. This can include the number of community members and volunteers have access to phones, there charge costs, battery failures, security threats, reach of the network signal, and who is in place to receive the SMSs and manage the incoming alerts data. The Red Cross Red Crescent CBS Technical Working Group can support you when deciding what tool would be the best fit. Paper can also be used for CBS, but it may lead to delays in alerting the authorities.

CBS should be a low-resource system, but realistically any program requires investment to achieve results. Aim for a CBS program which may have start-up costs (such as training and resources) but has minimal ongoing routine costs. 

How long should a CBS project continue for? When should I stop the CBS program?

Use the IFRC CBS Assessment Template to review your CBS program. A clear need, and the capacity to continue the CBS system is key to deciding on how long it should continue. 

Some CBS projects are needed only for a short time for an emergency response to control a defined outbreak, other CBS projects are useful in epidemic preparedness as ongoing early detection. 

CBS can be flexible to the situation. Because of this flexibility, you have the option to:

  • Continue CBS as an ongoing epidemic preparedness program integrated into other community activities
  • Handover CBS to another agency for ongoing management, such as a RC National Society Branch, development partner, or local Government
  • Close the CBS program and exit once the urgent outbreak has been controlled.

How do I select health risks?  

The health risks chosen should have a significant potential for a high impact on morbidity, disability and/or mortality. It should also have a potential for sudden epidemics or ongoing transmission with seasonal epidemics. It is important the information provided by CBS will enable significant, rapid, and cost-effective public health action. The health risks should be chosen in coordination with the local health authorities and ministry of health as they understand the local context, and it enables sustainability of the projects. Have a look at the global list of community health risks for CBS withing the RCRC membership here.

What is a community case definition?

A community case definition is a set of criteria that must be met for an individual to be regarded as a case of a particular disease for surveillance purposes. Every health risk in CBS must have an associated community case definition.  An example of a community case definition is diarrhoea x3 or more times in one day with or without vomiting and the disease of concern is cholera.

A set of Community Case Definitions which should be adapted for use in each country, in consultation with Ministry of Health, WHO and/or other stakeholders.

What is an alert threshold and how do I set one?  

The alert thresholds are the number of reports which combine to trigger an alert. The threshold for reports is set at a specific number, which when exceeded will trigger an alert. For some health risks, the alert threshold will be one single report, which must trigger prompt follow-up and cross-checking by supervisors.

For health risks that are endemic and/or may be predicted, the alert threshold is based on the historical trend – it is a calculated number which signifies a greater than usual number of cases during a certain period of time and distance.  

In emergencies, where prior data in the area may not be available to indicate the trend, this needs to be calculated using moving averages over a short period of time.

Decide on the alert threshold together with Ministry of Health.

What is a CBS Protocol and what is included in it?

A CBS protocol is a structured guidance for comprehensive planning and design of CBS, based on findings of the assessment. Its purpose is to support the design of a comprehensive CBS system and rapid preparation of a draft prior to inputs by stakeholders. It also can act as a living document to be revised based on feedback during implementation and therefore supports future expansion or scale-up. You can see the CBS Protocol guideline here.

How can I ensure that the CBS project is sustainable?

Firstly, not all CBS projects need to be sustainable. For example, a short-term emergency implementation of CBS for a particular outbreak may no longer be needed after the outbreak has ended.

If CBS is being used as a preparedness measure, then the sustainability of the project becomes important. To ensure a CBS project is sustainable community engagement and ownership is very important. It is crucial to include community leaders and local health workers in the training, planning and system. If presented with simple,low-cost solutions these community leaders can maintain CBS structures even after departure. Also, you must ensure a retention plan is in place when recruiting staff and volunteers. Ensuring there is capacity for continued training of supervisors and volunteers is also crucial

CBS must be coordinated with health authorities and relevant stakeholders. It is also ideal to start small and scale up once shown to be functional and effective. As well, health risk control actions by the community, and response by authorities is clear and agreed on from the beginning.

What if the word ‘surveillance’ is not appropriate in my context?

In some contexts, the use of the word ‘surveillance’ may cause concern by the community or the government. In these settings, the language can be changed to something more appropriate. One option is to change the wording to better explain the methodology, for example community-based disease information could be an alternative to the traditional community-based surveillance.


What do I need to start implementing CBS using Nyss?

After the initial assessment period, there will be a joint discussion with the National Society and Ministry of Health to decide how and where CBS will be implemented. If it is decided to use Nyss, trainings to facilitate the use of Nyss will be required. For the volunteers to be able to send reports to the Nyss platform, the National Society needs tohave configured SMSEagle (a physical device that turns SMS into electronic reports). This device will be configured with the help of the software developers who are based at the Norwegian Red Cross who support Nyss. It requires continuous connection to the internet and a reliable power source. The NS has the ownership of the platform. Ministry of Health and other external partners can have access to the dashboard which contains the epidemiological data.

The platform can also be used by Ministry of Health or other partners for their CBS programmes. Contact IFRC or Norwegian Red Cross CBS focal point to get more information. They will also support the advocacy of the National Society with Ministry of Health to use the Nyss platform if decided relevant.

You can find moreinformation about the CBS platform Nyss here.

Do the volunteers need internet access to send reports when using Nyss?

The volunteers do not need internet access for the reports to be sent. This is done through a short-coded SMS, describing the health risks, gender and age. Therefore, the only necessity for volunteers is a relatively stable mobile signal.

How do I configure the SMS Eagle?

The Nyss team at Norwegian Red Cross will assist you in configuring the SMS Eagle. When this is done remotely, the team needs the following to ensure it goes smoothly:  

  • The SMS Eagle and your computer are connected to internet using the same connection, preferably using a cable. This way we can access the local network to find the SMS Eagle device and connect to it. If you are unsure how to connect the two devices to the same network, ask an IT person in your office for help.
  • Remote access to your computer through Team Viewer. We kindly ask you to download and install TeamViewer prior to meeting the Nyss team for configuration
  • A SIM card to test sending SMS messages when the configuration is done

 What type of SIM card do I need to use Nyss?

The only requirements are the SIM card can send and receive SMS messages. Ideally the volunteers would be able to send messages to the SIM card free of charge, but this is NOT a requirement for Nyss to work. To enable this, we recommend you make anagreement with the telecom provider. There are different ways to do this, and one is not better than the other. A common option is to use a short code service.

Where is the Nyss database located and why?

The Nyss server is in Ireland at the Microsoft Azure data center for Northern Europe. This server uses state-of-the-art security features to provide secure storage. Through this security we can adhere to the European General Data Protection Regulation and provide a high standard of data protection for our users. Our aim is to have Nyss globally available, and by using Microsoft as our server provider we ensure high availability, while still having resources to focus on usability and the improvement of Nyss as a tool. Having an in-country server where the CBS project is being implemented would lead to additional costs and potential security issues. Although we use Microsoft as our service provider, we are the legal owners of the data and Microsoft is not allowed access. Additionally, we have developed a data protection agreement that every Head Manager needs to accept. This agreement passes the legal rights of the data from Norwegian Red Cross to each implementing country. In short, as an implementor of CBS with Nyss, you are the legal owner of your own data.