How did wild polio virus get into French sewers?
In May this year an outbreak of 60 cases of gastroenteritis led officials in the French city of Strasbourg to investigate water pipes which they found to be contaminated by sewage. The officials were surprised to also find polio virus there. Initially they thought it was the weak strain produced by Sabin vaccine, which is not infrequently found in sewage. However analysis at the World Health Organisation’s enterovirus laboratory showed that it was a Mahoney-type strain of polio virus. This strain of wild polio virus, which once killed thousands of people every year before vaccination began in the 50s, had been thought to be extinct in France though it is used in some research laboratories. The journal, New Scientist (18 November 2000), reports that laboratories in the area are being investigated to see if they have used the strain in the last 10 years. New Scientist says that, Some of Strasbourg’s citizens must have swallowed the virus. The four-month incubation period for poliomyeliti
