3.7 The investigation in practice

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