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