As the roach staggers around for hours or even days, it infects other roaches in the nest, with toxicant transfer through feces, which then go on to infect others. This secondary transmission occurs through direct contact with, or ingestion of, traces of baits dispersed in the environment by contaminated cockroaches.

Cockroaches may spread a range of diseases. It is believed that the cockroach may be a reservoir for a range of bacteria including salmonella, staphylococcus and streptococcus. The cockroach can also harbour viruses such as the polio virus.

Try homemade cockroach baits. Mix one part powdered (not granular) boric acid (sometimes sold as a roach-killing powder, but often available in pharmacies), one part white flour, one part powdered white sugar. The sugar and flour attracts the roaches, and the boric acid kills them.