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Humanitarian Charter and Minimum Standards in Humanitarian Response


Essential health services – control of communicable diseases standard 3: Outbreak detection and response

Outbreaks are prepared for, detected, investigated and controlled in a timely and effective manner.
 

Key actions (to be read in conjunction with the guidance notes)

Detection

Preparedness

Control

Key indicators (to be read in conjunction with the guidance notes)

(see guidance note 10).

Guidance notes

These steps do not need to be implemented in any strict order and control measures should be implemented as soon as possible.

  1. Early warning system for outbreak detection:
    The key elements of such a system will include:
    • a network of implementing partners
       
    • implementation at all health facilities and at community level if possible
       
    • a comprehensive risk assessment of all potential epidemic-prone diseases
       
    • identification, based on risk assessment, of a small number of priority conditions (10–12) for weekly surveillance and a select number of diseases for immediate “alert” reporting (see Appendix 2: Sample weekly surveillance reporting forms)
       
    • clear case definitions for each disease or condition on the standard surveillance form
       
    • alert thresholds defined for each priority disease or condition to initiate investigation
       
    • communications to ensure rapid notification of formal or informal alerts (rumours, media reports, etc.)to relevant health authorities
       
    • a system for recording and responding to immediate alerts
       
    • data reporting, entry into standard database and analysis on a weekly basis
       
    • feedback of weekly surveillance and immediate alert information to all partners
       
    • regular supervision to ensure data quality as well as timeliness and completeness of reporting
       
    • standard case investigation protocols and forms
       
    • standard procedures for information-sharing and initiation of outbreak response.
       
  2. Outbreak investigation and control plan: This must be prepared with full participation of all stakeholders. The following issues should be addressed:
    • the criteria under which an outbreak control team is to be convened
       
    • the composition of the outbreak control team
       
    • the specific roles and responsibilities of organisations and positions in the team
       
    • the arrangements for consulting and information-sharing at local and national levels

    • the resources and facilities available to investigate and respond to outbreaks
       
  3. Reserve stocks: On-site reserves should include material to use in response to likely outbreaks. A pre-packaged diarrhoeal disease or cholera kit may be needed in some circumstances. It may not be practical to keep some stocks on-site, such as meningococcal vaccine. For these items, procedures for prompt procurement, shipment and storage should be determined in advance so that they can be rapidly obtained.
     
  4. Reference laboratories: Laboratory testing is useful for confirming the diagnosis during a suspected outbreak for which mass immunisation may be indicated (e.g. meningococcal meningitis) or where culture and antibiotic sensitivity testing may influence case management decisions (e.g. shigellosis). A reference laboratory should also be identified either regionally or internationally that can assist with more sophisticated testing, e.g. serological diagnosis of measles, yellow fever, dengue fever and viral haemorrhagic fevers.
     
  5. Transport media and rapid tests: Sampling materials (e.g. rectal swabs) and transport media (e.g. Cary-Blair media for cholera, Shigella, E. coli and Salmonella) and cold chain material for transport should be available on-site or readily accessible. In addition, several rapid tests are available that can be useful in screening for communicable diseases in the field, including malaria and meningitis.
     
  6. Outbreak investigation: The ten key steps in outbreak investigation are:
    1. establish the existence of an outbreak
       
    2. confirm the diagnosis
       
    3. define a case
       
    4. count cases
       
    5. perform descriptive epidemiology (time, person, place)
       
    6. determine who is at risk
       
    7. develop hypotheses explaining exposure and disease
       
    8. evaluate hypotheses
       
    9. communicate findings
       
    10. implement control measures.
       
  7. Confirmation of the existence of an outbreak: It is not always straightforward to determine whether an outbreak is present, and clear definitions of outbreak thresholds do not exist for all diseases. Nevertheless, thresholds exist for the diseases listed below:
    • diseases for which a single case may indicate an outbreak: cholera, measles, yellow fever,viral haemorrhagic fevers
       
    • diseases for which an outbreak should be suspected when cases of, or deaths due to, the disease exceed the number expected for the location or are double the previous weekly averages
       
    • shigellosis – in non-endemic regions and in refugee camps, a single case of shigellosis should raise concern about a potential outbreak
       
    • malaria – definitions are situation-specific; an increase in the number of cases above what is expected for the time of year among a defined population in a defined area may indicate an outbreak. Without historic data, warning signals include a considerable increase in the proportion of fever cases that are confirmed as malaria in the past two weeks and an increasing trend of case fatality rates over past weeks
       
    • meningococcal meningitis – in the meningitis belt, for populations above 30,000, 15 cases/100,000 persons/week; however, with high outbreak risk (i.e. no outbreak for 3+ years and vaccination coverage <80 per cent), this threshold is reduced to 10 cases/100,000 persons/week. In populations of less than 30,000, five cases in one week or a doubling of cases over a three-week period confirms an outbreak. In a camp, two confirmed cases in one week indicate an outbreak
       
    • dengue – increase in fever cases in the past two weeks that show increased IgG levels (based on paired testing of consecutive sera-samples) of a febrile patient with 3–5 days illness and decreasing platelet count (<20,000).
       
  8. Outbreak response: Key components of outbreak response arecoordination, case management, surveillance and epidemiology, laboratory, specific preventive measures such as water and sanitation improvement depending on disease, risk communication, social mobilisation, media relations and information management, logistics and security.
     
  9. Control measures: Control measures must be specifically developed to halt transmission of the agent causing the outbreak. Often, existing knowledge about the agent can guide the design of appropriate control measures in specific situations. In general, response activities include controlling the source and/ or preventing exposure (e.g. through improved water source to prevent cholera), interrupting transmission and/or preventing infection (e.g. through mass vaccination to prevent measles or use of LLINs to prevent malaria) and modifying host defences (e.g. through prompt diagnosis and treatment or through chemoprophylaxis) (see Health systems standard 5Water supply standards 1 – standards 2Hygiene promotion standards 1–2 and Vector control standards 1–3).
     
  10. Case fatality rates: The acceptable CFRs for communicable diseases vary according to the general context, accessibility to health services and the quality and rapidity of case management. In general, aim to reduce CFRs to as low as possible. If CFRs exceed the minimum expected levels, an immediate evaluation of control measures should be undertaken and corrective steps followed to ensure CFRs are maintained at acceptable levels.