Fomite Transmission and STI Risk

Fomite transmission refers to the transmission of infectious diseases, including sexually transmitted infections (STIs), by objects. More specifically, it refers to the transmission of infectious diseases by germs left on objects.

One common example of this is how the cold virus can be spread by people sneezing and touching door handles. Another is how food can become contaminated on uncleaned cutting boards.

Overview

Fomite transmission occurs when viruses or bacteria that remain on surfaces cause infections. This is as opposed to diseases 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. These include:

• The bacterium or virus involved
• How much of the bacterium or virus someone needs to be exposed to in order to become infectious
• Temperature and humidity of the room
• Whether the surface is porous or nonporous

Other factors may also be involved.

How Contamination Occurs

There are many ways that fomites can end up on surfaces where they will pose a risk to others. Sneezing and coughing can disperse pathogens directly onto surfaces. Flushing a toilet may aerosolize them and lead to their presence on other surfaces. Even hand driers in public bathrooms can spread bacteria around a room. However, the most important way that surfaces get infected is from hands.

The following can cause fomite transmission to surfaces and then to others:

• When people don't wash their hands after sneezing or coughing
• When people don't wash their hands after going to the bathroom
• When people don't wash their hands after touching potentially contaminated surfaces

Prevention

The most important thing you can do to reduce fomite transmission is to wash your hands. If you have done anything that might have put you in contact with bodily secretions, wash your hands. If you have changed a diaper, or wiped your nose, wash your hands. If you sneeze, wash your hands. Washing your hands after touching dirty or potentially contaminated objects, like cutting boards, is also a good idea.

Surface cleaners also play a role in reducing the spread of infections. However, not all disinfectants work equally well at killing off all viruses and bacteria. Some pathogens are more susceptible to specific detergents than others. Still, 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% effective.

If you share a household with someone with an infectious disease and you are concerned about fomite transmission, start at the store. 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.

It’s also important to not cross-contaminate, meaning unintentionally transferring pathogens from one surface to another. So, use the right cleaner and change your rags often, or use paper towels and dispose of them after cleaning each surface.

STIs That Can Be Transmitted by Fomites

HPV (human papillomavirus) has been found on numerous surfaces. It can be transmitted from hands to genitals. It's also likely HPV can be transmitted from surfaces, such as sex toys.

Hepatitis C, as well as the other hepatitis viruses, may also be transmitted by fomites. Fortunately, hepatitis A and hepatitis B are both preventable by vaccines. There are also new, more effective treatments for hepatitis C.

Other Diseases That Can Be Transmitted

Many diseases can also be transmitted by fomites. In fact, fomite transmission is most often discussed in the context of respiratory diseases and gastrointestinal diseases. Some of the infections that can be transmitted by fomites include:

• Respiratory syncytial virus (RSV, which causes infections of the lungs and respiratory tract)
• Rhinovirus (usually the cause of the common cold)
• Influenza (the flu)
• Coronavirus (including SARS-CoV-2, which causes COVID-19)
• Rotavirus (most common cause of severe, watery diarrhea in children)
• Adenovirus (can cause a range of illnesses, with symptoms such as pneumonia, diarrhea, and bronchitis)
• Norovirus (highly contagious virus causing vomiting and diarrhea)
• Clostridioides difficile (C. diff, a bacterium causing severe diarrhea and inflammation of the colon)
• Hand, foot, and mouth disease (virus that causes fever, mouth sores, and skin rashes in or on the hands, feet, or mouth)