by Dr Pandula Siribaddana

Created on: July 27, 2010   Last Updated: July 29, 2010

Overview:

Saliva is considered to be one of the most common mediums that diseases choose as their mode of spread and some of the most contagious diseases are given this status due to their ability to spread through saliva. The saliva that is present in the mouth would also be present as a thin layer on the surface of the throat as well as on the respiratory tract. These linings will be continuously kept moisturized by the salivary glands. At the same time, the mucosal lining of the nose would also continue with the lining in the back of the throat which makes it possible for infections to reach from one location to another.

Mode of spread:

The spread of an infection through saliva can take place using many mechanisms and following are several of such mechanisms:

Direct contact in instances such as kissing Spread of the tiny droplets containing saliva in instances such as coughing, sneezing as well as talking. Through foods and drinks. Spitting Contamination of surfaces which will be touched by others…etc.

Therefore, salivary spread is rather efficient and sometimes difficult to control unless the patients as well as the caregivers adhere to good cough etiquette and hygienic practices.

The diseases:

When considering the diseases that are transmitted through saliva, some of the most common diseases would be the ones which are termed ‘kissing diseases’. Although the classical kissing disease is considered to be the EB virus or infectious mononucleosis; infections such as cytomegalovirus can also spread through similar actions.

When considering the other diseases that can be spread through saliva, common cold and other viral upper respiratory tract infections would be high in the list.  At the same time, streptococcus infection can also spread through saliva and could give rise to many disease states including gum diseases.

Apart from the above mentioned diseases, researchers have detected viruses related to HIV and Hepatitis B in the saliva as well. Thus, in theory, these viruses do have the potential to spread from one person to another through saliva as well. But, saliva is not recognized as a major mode of transmission in any of these diseases. Let us see why.

Why?

In diseases such as HIV and Hepatitis B, their natural medium would be blood and therefore are considered to be blood borne diseases. But, when it appears in saliva, usually, the amount of virus load in each milliliter would be rather low when compared to blood. Due to this fact, the amount of virus that enters a person through saliva would be rather low and at times would not be able to mount an infection in that particular person.

But, although there are no reported transmissions of HIV through saliva, transmission of hepatitis B is documented in certain instances and therefore should be considered a risk factor in relation to hepatitis B.

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