A nerve gas used in the Second World War is the active ingredient of flea collars used by cat owners in the UK. Diazinon ( aka dimpylate) can lead to blurred vision, vomiting, loss of co-ordination and even death. The collars are now banned in France on the basis that children might ingest the drug while cuddling their pets. Manufacturers in the UK are sceptical of the dramatic findings.
A cat flea under a microscope.