In contrast to cold sores and Coxsackie virus blisters, canker sores have no infectious disease origin and cannot be spread through the saliva or kissing.
HIV and Hepatitis B Virus?
HIV and Hepatitis B Virus (HBV) are blood-borne and sexually transmitted infections that have been found in the saliva. Despite the presence of HIV in saliva, there have never been any reports of HIV transmission via this route.
In contrast, transmission of Hepatitis B virus through saliva has been well documented, as well as Hepatitis A and C.
Saliva has a natural cleansing role provided by its flushing activity. Other anti-microbial defences in the saliva include antibodies and other anti-microbial proteins like lysozyme and normal mouth flora (the ‘good’ bacteria that prevents growth of ‘bad’ bacteria).
The spread of infectious microbes through the saliva can occur when the natural resistance in the mouth is reduced. For example, gum infections can occur in people with Vitamin C deficiencies while thrush is caused by Candida II yeast infections, which is more likely to occur in people who have been taking antibiotics. People who are dehydrated have reduced salivary flow and four times more bacteria in their mouths.