3.7 The investigation in practice

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    3.7.1 What to do during the investigation?

    • Collect information on all suspected cases.
    • Verify the effectiveness of the surveillance and strengthen it, if necessary.
    • Collect laboratory samples to confirm the causative agent.
    • Make sure that patients are being managed effectively.
    • Decide whether outbreak response vaccination is needed.


    During the investigation, also collect information on the current response and available resources, and assess the response capacity in the field:

    • appropriate patient management ;
    • availability of drugs (name and quantity) ;
    • access to treatment: geographic coverage, cost per patient, sufficient number of staff ;
    • estimated vaccination coverage in recent years ;
    • cold chain capacity ;
    • previous outbreak response vaccinations and lessons learned.

    3.7.2 Composition of the investigation team

    The team should include an epidemiologist (or experienced person), a lab technician (or experienced person), and a logistic officer. Each person’s role should be clearly defined, to ensure that all activities are covered without any duplication.


    Recruit a driver who knows the region and, if possible, the local language.

    3.7.3 Preparing for the investigation

    Rigorous preparation makes the teams’ work in the field easier. This includes:

    • studying the responses to previous outbreaks (reports, surveillance data) and anticipated responses to future outbreaks (annual response strategy);
    • identifying the locations to be investigated, according to the alert from the surveillance system or information reported by the population;
    • obtaining pre-authorisation from the relevant central authorities;
    • organising the logistical resources;
    • preparing the supplies and the information and data collection forms;
    • preparing the supplies for collecting and transporting samples;
    • preparing “simple case” and “complicated case” treatment kits, to be distributed, if necessary, to the health posts and hospitals visited;
    • informing the local authorities;
    • drawing up the budget and make it available.

    3.7.4 Supplies and documents

    Logistics and communications

    • A terrain-appropriate vehicle in good working order
    • Maps of the region
    • Functional, appropriate means of communication

    A camera and a GPS may be useful.


    • Specimen collection and shipment supplies (e.g., syringes, needles, tubes, gloves, compresses, adhesive tape, filter paper, triple packaging bags)
    • Information cards for samples
    • Cold chain for samples, if necessary (vaccine carrier, ice packs and thermometer)

    Data collection

    • Population census
    • List of health care facilities, personnel (health system) and contacts
    • Inventory sheets for drugs, medical supplies and the cold chain
    • Reference documents (case definition, data collection sheets)
    • Paper, pens, calculator

    Medical supplies

    • Treatment protocols
    • Treatment kits
    • First aid kit