Surveillance is as important as immunization to the success of the Region’s polio eradication initiative. In order to eradicate polio, it is necessary to search out not only the polio cases, but also conditions that may resemble polio clinically. Acute flaccid paralysis (AFP) is a clinical condition with sudden paralysis in one or more limbs. Several different diseases can cause AFP including Guillain-Barré syndrome, transverse myelitis and traumatic neuritis. Since nearly all cases of paralytic polio have AFP, searching for AFP is the best way of finding polio cases.

Forty-four laboratories have been brought together to form a Regional laboratory network to help with the investigation of AFP cases. Thousands of public health workers and laboratory technicians across the Region have received the necessary training and laboratory equipment to investigate suspected polio cases.

As part of the investigation, health care workers collect stool samples from children and send them to one of the designated laboratories for analysis. The presence of wild poliovirus in the stools of an AFP case is the most reliable way to confirm polio. Two stool samples must be taken within two weeks of onset of paralysis. Logistics are critical to the process: samples must be kept refrigerated until they reach a designated laboratory and laboratory technicians must test the samples thoroughly.

Computer databases have been set up in nationally designated polio surveillance centres and laboratories for up-to-date and accurate case reporting. Since the last polio case in 1997, over 50 000 AFP cases have been reported and investigated. A steady rate of reporting of AFP cases reflects an efficient surveillance network.

Weekly bulletins, which are published on this website, cover key quality indicators of AFP surveillance based on regular reports received by all countries. Data are forwarded to WHO Headquarter in Geneva and global AFP surveillance reports can be reviewed on a quarterly basis in the Weekly Epidemiological Record.