Kissing, in most cases, is an exciting and wonderful experience, sometimes even unexpected. However, we must not forget that passionate kisses, besides conveying feelings and sensations to our partner, can also be an easy and efficient way to spread sexually transmitted infections.
Among the various known forms of disease transmission, we find oral transmission, which includes the spread of bacteria through saliva, food, or drinks. When we kiss someone, the act of swallowing allows contaminated saliva to reach the throat and enter our body, which can lead to infections such as infectious mononucleosis, commonly known as the ‘kissing disease,’ caused by the Epstein-Barr virus (EBV) and cytomegalovirus (CMV). Additionally, some bacteria, like Streptococcus, can adhere to the inner surfaces of the cheeks, mouth, tongue, or teeth, causing gum and throat infections such as tonsillitis.
The mucous surfaces of the respiratory tract share anatomical similarities and spaces, such as the nose, mouth, and throat. This means that microbes present in saliva can spread to the respiratory tract and cause colds and other upper respiratory tract infections.
Saliva plays an important role in protecting against infections, as it has natural washing and sweeping properties due to its continuous flow. Dehydrated individuals have a higher number of bacteria in the mouth, as decreased saliva flow reduces this cleaning effect. Saliva also contains antibodies, antimicrobial proteins, and a normal oral flora composed of “good” bacteria that help prevent the growth of “bad” bacteria. However, when the natural resistance of the mouth is compromised, the spread of diseases through saliva can occur. For example, vitamin C deficiency can increase the prevalence of gum diseases, and prolonged use of antibiotics can favor the occurrence of oral candidiasis.
Some diseases that can be transmitted through saliva include:
Infectious mononucleosis: It is an infection mainly caused by the Epstein-Barr virus, although in rare cases, it can also be caused by cytomegalovirus. It spreads through saliva, which is why it is commonly known as the ‘kissing disease.’ Symptoms usually include fever, sore throat, and swollen lymph nodes, especially in the neck. Treatment focuses on relieving symptoms through rest, adequate hydration, pain and fever medication, and gargling warm saltwater to alleviate throat irritation. Most people recover within a period of two to four weeks, and severe complications are rare. However, a feeling of tiredness may persist for several months after overcoming the disease.
Herpes: There are two types of herpes simplex virus (HSV). Oral herpes, also known as fever blisters or cold sores, is caused by herpes simplex virus type 1 (HSV-1) and is transmitted through active lesions on the lips or around the mouth. Herpes is contagious in all its stages, especially when the lesions are ulcerated and have fluid drainage. It can be acquired through kissing but can also spread through sharing utensils and glasses. The infection can manifest as a single isolated outbreak or as recurrent infections. Symptoms include a burning or itching sensation, followed by the appearance of small blisters that break and form open sores. Eventually, a crust forms, and after a few days, the lesion heals without scarring. Although there is currently no cure for herpes, effective treatments can be used to control outbreaks.
Regarding HIV and hepatitis B, they are sexually and blood-transmitted diseases. While HIV has been shown to be present in saliva, the concentration of the virus is so low that it is not sufficient to cause an infection. In fact, no cases of HIV transmission through saliva have been reported to date. On the other hand, transmission of hepatitis B has been documented in cases where there are bleeding wounds in the mouth or periodontal disease that
causes bleeding gums. Hepatitis A is transmitted through fecal exposure, such as consuming contaminated water or oral-anal contact, while hepatitis C requires exposure to infected blood.
Although saliva-transmitted diseases are not mostly considered sexually transmitted infections (STIs), it is important to highlight that mouth-to-mouth kissing generally only transmits herpes, unlike oral sex (bucogenital contact), which can spread numerous STIs such as gonorrhea, syphilis, genital warts, chlamydia, and hepatitis A, B, and C.