"You know, 20% of germs you'll transmit are passed through handshakes," the man some in the United States fondly call Dr Germ joked in a kitchen in Dunedin's Regent Theatre yesterday.
"Just think, it gets worse when you consider the number of people who might blow their nose or cough into their hand before they do so - but I suppose we can't go through life thinking like that."
Prof Gerba had just finished delivering a 45-minute presentation on the the link between basic hygiene, cleanliness and disease to about 70 Dunedin workers and employers.
They learned the average office desk could have 400 times the amount of bacteria of a toilet seat, and that many workplaces were potentially more harmful after they were cleaned without disinfectant.
The Arizona University researcher's work found at least half of studied workplaces in the United States were contaminated with influenza viruses and that norovirus was on 20% of surfaces.
Those and many other horror statistics translated to illness and absenteeism.
Studies in schools suggested simple and effective cleaning and hand washing could cut absenteeism by half.
New Zealand businesses and officials needed to remember the "health" component of occupational safety and health.
"After all, there is only so much that can now be done by eliminating workplace hazards.
I get the impression that the Labour Department and businesses have been very good at that," Prof Gerba said.
"The next battle, I suppose, is for people to turn their attention to ensuring the basic health of a workplace so that occupational safety continues to improve."
Prof Gerba was brought to New Zealand by Dunedin company Crest Commercial Cleaning.
Managing director Grant McLauchlan said hygiene-related absenteeism could account for 3% of a business's wage bill.
Chairman of directors Martin Perkinson said the company planned to work with the Labour Department and Health Ministry to see how workplace cleanliness and protocols could improve staff wellbeing and economic performance.