An interesting story recently from Japan, a man almost died from
allergic reaction shock after being repeatedly bitten by his hamster
it was reported having a reaction to its saliva that almost put him in
a coma if not for medical intervention. Though extremely rare, his
reaction built up until the proverbial "straw that broke the camel's
back" occurred (I think also referred to in the historic record for
strychnine). Maybe some cats chasing rats behind walls have had a
similar reaction?

A recent cat intervention story occurred here in NYC. On Rikers Island
(completed by filling using household solid trash mostly coal ash and
other materials in 1903) there is a causeway connecting the city
prison facility with the borough of Queens, though once by ferry
connected to the borough of the Bronx, and cases originating there are
still held in the Bronx, and cats have increased in great numbers over
there, with some of the land in garden and other remotely inaccessible
places there. A volunteer group of vets have completed an inventory
and a spay/neuter program to help control their population.

George Myers