[The simple measure of handwashing to prevent the risk from biological agents: what has changed since the theories of Semmelweis].

In this manuscript, we consider the importance of hand hygiene as the chief measure of prevention and protection in the occupational context. In particular, we remember the physician who lived in the middle of the 19th century, Ignazio Semmelweis, genius but not understood creator of the theory for infection control, based on hand hygiene. Subsequent studies have clearly demonstrated the validity of Semmelweis' research, through scientific publications and the establishment of international guidelines, such as by the World Health Organization (WHO). It is important to remember the initial work and then, sharpen this tool, resulting in the adoption of simple, but effective behavioural practices, that should be spread by several means and tools of information, education and communication, addressed at all involved, for the reduction of exposure to the occupational biological risk.