Fomite transmission occurs when viruses or bacteria that remain on surfaces cause infections -- rather than being transmitted from person to person, in the air, in infected water, or in another manner. Some diseases are more likely to be transmitted by fomites than others.
Just because living pathogens can be found on surfaces does not necessarily mean that fomite transmission to humans can take place. The risk of fomite transmission varies depending on a number of factors, not all of which are well understood.
While surface cleaners play a role in reducing the spread of infections, as does hand-washing, not all disinfectants work equally well at killing off all viruses and bacteria. Some pathogens are more susceptible to specific detergents than others. However, regular cleaning of surfaces that come into contact with potentially infectious body fluids is a good way to reduce the risk of fomite transmission -- even if it is not 100 percent effective.
If you share a household with someone with an infectious disease and you are concerned about fomite transmission, read the label on the disinfectant you are using as a surface cleaner. Most of them will spell out which pathogens they are effective against. That way you can pick the disinfectant best suited to your needs.