Scientists are now following a new line of inquiry into the stings received by swimmers over the last few weeks at Rickmansworth Aquadrome – but they are still not certain what has been causing bathers to come out in painful rashes after leaving the water.

A suggestion that the white seeds and pollen from overhanging willow trees could be the cause has not been discounted either.

On Wednesday the following official statement was issued:

“In a continued endeavour to find the cause of bites affecting some swimmers in certain parts of Rickmansworth Aerodrome, biologists from the Medical Reasearch Council have been collecting snails from the weeds in the lake.

“These could be harbouring the larvae of a parasite which affects moorhens and water birds, and could also sting human swimmers.”

Dr W. Norman-Taylor, the medical officer of health, says there have been several cases where the rash could not, it is believed, have been caused by “water-boatmen”, but by microscopic parasites in the weeds which the biologists are now searching for.

This type of parasite is related to bilharzia in tropical waters, but the type found here and in the water birds of Europe is completely harmless to man and gets no farther than the skin, where the sting is similar to that of a stinging nettle, but more severe.

[From the Watford Observer of July 3, 1970]