When it is decided that outbreak control is necessary, certain information should be gathered and a plan of required actions adopted. The decision to adopt measures to combat an outbreak should be based on epidemiologic analysis (which at that point may, but need not, include laboratory results). Although it is difficult to list all the criteria that need to be met in order to start taking action against an outbreak, this decision may be made if one or more of the following conditions are present:

• A case of AFP in which the wild virus has been isolated;
• Cases of AFP that seem to be epidemiologically connected with no obvious external cause (for example, poisoning from organophosphorus compounds);
• Cases of AFP with the clinical characteristics of polio;
• Detection of wild poliovirus or vaccine-derived virus in neighboring areas or countries; and
• Low vaccination coverage.

The following factors, among others, need to be taken into account when managing an outbreak:

• Population data: Obtain the most recent data on population size and distribution.
• What's been done: List any measures already taken.
• Case review: List cases reported in the area in the last six months. Construct an epidemic curve.
• Coverage rates: Obtain existing coverage data, including official estimates.
• Spot map: On a map, use pins or a pen to mark the location of cases and areas targeted for vaccination.
• Resources: Determine what resources are available at all levels (transportation, vaccine, cold chain materials, etc.). Field personnel to assist in outbreak control should include teams from other programs, district staff, medical and nursing students, interpreters, and drivers. Arrange for transportation and payment of travel advances.
• Coordination: Inform appropriate health and community authorities when and where the team will be arriving and ask that specific health system staff and community representatives be present.
• Supplies: Organize necessary supplies to take to the outbreak area:
• Adequate supply of OPV vaccine for estimated target population;
• Cold chain materials: ice packs, portable refrigerators/cold boxes, vaccine shipping containers, vaccine control cards, thermometers. Determine whether refrigerators for the ice packs are locally available or need to be brought (e.g., a kerosene refrigerator);
• Adequate supply of forms: line-listings for probable cases and laboratory information, AFP case investigation forms, summary of outbreak control measures, and mop-up work tally sheets.
• Outbreak monitoring: Information on cases, immunization activities, and villages visited needs to be updated continuously and monitored during an outbreak.

This information on control measures should be kept on a form that can be quickly summarized. Outbreak containment will have been successful if no additional cases are reported one month after the second round of immunizations. At that time, special reviews and checks should be made to ensure that no new cases have occurred.

Source: Poliomyelitis Eradication Field Guide, Third Edition