Poliovirus detection in wastewater and stools following an immunization campaign in Havana, Cuba.

BACKGROUND: Recent outbreaks of poliomyelitis caused by vaccine-derived virus have raised concerns that vaccine-derived poliovirus may continue to circulate after eradication. In these outbreaks, the virus appears to have replicated for > or =2 years before detection. Early detection is critical for an effective response to these outbreaks. Although acute flaccid paralysis (AFP) surveillance will remain the standard for poliovirus detection, wastewater sampling could be a useful supplement. In this study, we evaluated the sensitivity of wastewater sampling by concurrently collecting stools from children aged < 3 years attending two neighbourhood clinics in Havana, Cuba, and wastewater from the same neighbourhoods.
METHODS: Sample collection was begun during the third week after the national immunization campaign, continued weekly through the seventh week, and was repeated during weeks 15 and 19. Virus detection and titration were performed using both cell culture and polymerase chain reaction techniques.
RESULTS: Wastewater sampling was found to be at least as sensitive as stool sampling under these conditions. Poliovirus was isolated from children through week 7, suggesting that viral shedding reached undetectable levels between weeks 8 and 14. The last virus-positive wastewater sample was collected during week 15.
CONCLUSIONS: Wastewater sampling under the conditions studied can be a sensitive supplement to AFP surveillance. Similar studies under different conditions are needed to determine the role of wastewater sampling in post-eradication surveillance.