Having someone spit in your mouth is an unpleasant thought and raises concerns about the potential health risks. Spit contains bacteria and viruses that could make you sick under certain circumstances. While the chance of catching a major illness is low, there are some important factors to consider.
What’s in spit?
Saliva contains bacteria, viruses, fungi, and trace amounts of blood. Up to 700 different species of microorganisms normally live in the human mouth. Though many are harmless, some have the potential to cause infections or diseases if they enter the body.
Here are some of the main microbes found in saliva that could potentially cause illness:
| Type | Examples | Illnesses |
|---|---|---|
| Bacteria | Streptococcus, staphylococcus, helicobacter pylori | Strep throat, pneumonia, stomach ulcers |
| Viruses | Epstein-Barr virus, herpes simplex virus, influenza | Mononucleosis, cold sores, flu |
| Fungi | Candida albicans | Thrush, respiratory infections |
In healthy people, these microbes are kept in balance by the immune system. But if they are introduced directly into the body, they can potentially multiply and cause infection.
Can you catch serious diseases like HIV or hepatitis from spit?
Two major illnesses people worry about catching through spit are HIV and hepatitis B or C.
HIV
HIV cannot be spread through saliva alone. The only ways HIV can be transmitted are:
– Having unprotected sex with someone who is HIV positive
– Sharing needles or syringes with someone who is HIV positive
– Direct blood contact (e.g. transfusion)
– Mother to child during pregnancy, birth or breastfeeding
The reason HIV is not spread through spit is that saliva contains only very low levels of the virus, far too low to infect someone.
However, contact with blood in saliva could potentially transmit HIV. This could occur if the saliva entered open sores or wounds. But again, the risk is very low.
Hepatitis B and C
Like HIV, hepatitis B and hepatitis C are spread through infected blood and bodily fluids. They are generally not considered to be contagious through saliva.
However, hepatitis B may be present in saliva in low concentrations. One study found HBV DNA in the saliva of 57% of chronic hepatitis B carriers. But it’s unknown whether the levels are high enough to cause transmission if ingested.
Overall, the risks of catching HIV, hepatitis B or hepatitis C from someone’s spit are extremely low except under unusual circumstances involving blood.
What other illnesses could you potentially catch from spit?
While serious diseases are unlikely to be transmitted through saliva, some more common and less dangerous illnesses can spread through spit contact.
Colds and flu
Viruses that cause colds like rhinovirus and influenza are very contagious through spit. If someone with a cold coughs or sneezes on their hand then touches an object, the virus can survive for hours. If you touch the object then touch your face, you can catch the illness.
In one study, rhinovirus survived on human skin for over two hours. And flu viruses have been shown to survive on objects for 24-48 hours.
So if someone with a cold spits on their hand then shakes your hand, it’s possible for the virus to transfer to you and cause illness. This is why good hygiene like hand washing is important to stop the spread of colds and flu.
Strep throat
Strep throat is an infection caused by group A streptococcus bacteria. It’s estimated that between 5-10% of sore throats in adults are caused by strep.
Strep throat spreads easily through saliva droplet transmission. If someone with strep throat coughs or sneezes near you, they can spread the bacteria through the air. You can also catch it from sharing food and drinks.
So if someone with strep throat spits on you or on an object you touch, it’s certainly possible to catch the illness, though the risk from a single exposure is fairly low.
Mononucleosis (mono)
Mononucleosis is an illness caused by the Epstein-Barr virus (EBV). It’s sometimes called the “kissing disease” because the virus spreads readily through saliva.
Studies show that the Epstein-Barr virus is present in the saliva of most people who have been infected, even when they aren’t showing symptoms.
So if someone with mono spits on you, there is a chance you could become infected with EBV. About half of children have caught the virus by age five, so many people are already immune. But teens and young adults are most at risk of developing mono from EBV infection.
Common cold viruses
In addition to rhinovirus and influenza, other viruses that can cause the common cold include respiratory syncytial virus (RSV), parainfluenza, adenovirus, and more.
All of these viruses can spread through contact with respiratory droplets from an infected person. Some cold viruses have even been detected in saliva up to a week after symptoms fade.
So if someone who has recently had a cold spits on you, they could pass one of these viruses. Your risk depends on factors like their viral load. But it’s certainly possible to come down with a cold after exposure to someone else’s saliva.
Gastroenteritis viruses
Viruses are also frequent culprits in cases of gastroenteritis (stomach flu). Two main types are norovirus and rotavirus.
Both norovirus and rotavirus can spread from person to person through fecal-oral transmission. This includes ingesting viral particles from contact with unwashed hands, contaminated food or objects, and possibly saliva.
In one study, rotavirus RNA was detected in 18% of adult saliva samples. Norovirus RNA has also been found in saliva, though the frequency is unknown.
So if someone with norovirus or rotavirus spits on their hand then touches an object you touch before eating, it’s possible to catch gastroenteritis. Proper handwashing is key to prevent this kind of transmission.
Cytomegalovirus (CMV)
Cytomegalovirus is a very common herpesvirus. It often produces no symptoms, though it can cause mononucleosis-like illness.
Around 50% of adults have a cytomegalovirus infection by age 40. CMV spreads through body fluids including saliva, urine, genital fluids, and breast milk.
One study found CMV in saliva samples from over 50% of seropositive subjects. This shows the virus can be shed in spit frequently.
CMV is unlikely to cause illness in healthy adults exposed through saliva. But it may pose risks for pregnant women and those with weakened immune systems.
Oral herpes (cold sores)
The herpes simplex virus causes recurrent oral herpes outbreaks known as cold sores. HSV-1 is the main cause, though HSV-2 can also cause oral lesions.
Herpes viruses are highly contagious through direct contact. According to one estimate, 70% of the population has HSV-1. Many are infected in childhood from kissing relatives or sharing utensils.
Since herpes lives in saliva, spit contact could easily transmit the virus. Getting spit from someone with an active cold sore in your mouth puts you at high risk of developing an oral herpes infection.
What factors affect the risk of illness?
Not everyone who gets spit in their mouth will automatically get sick. There are several variables that come into play:
– The health of the spitter – Are they currently sick with a contagious illness? Do they have symptoms or carry harmful viruses/bacteria without symptoms? Their contagiousness matters.
– The amount of spit – Getting misted with a small droplet is less risky than getting a whole mouthful of someone else’s saliva. Higher fluid volume means more microbes to potentially transmit illness.
– Existing immunity – If you’ve been previously exposed to a virus like EBV or have antibodies from a past infection, re-exposure is less likely to make you sick.
– Type of contact – Direct spit in the mouth is riskier than indirect hand contact transferring microbes to your mouth.
– Where the spit lands – Spit landing directly on mucous membranes in your mouth, eyes, etc has a higher infection risk than landing on intact skin.
– Breaks in skin – Open cuts or wounds allow pathogens to infect the body more easily than healthy skin.
– Face touching – Rubbing your eyes or mouth after contact with spit spreads more germs internally.
So the short answer is yes, you could potentially get sick if someone spits in your mouth. But it depends on the exact situation and factors involved.
What are the odds of actually getting seriously ill?
While it’s plausible to get various common illnesses from spit contact, the odds of getting a truly serious disease like HIV are extremely small.
One study looked at the risks of HIV transmission through spitting, biting, and throwing bodily fluids.
Researchers reviewed over 100 cases where blood-filled saliva was thrown at victims, often into eyes, nose and mouth. The vast majority of victims didn’t get infected.
Based on their risk analysis, researchers estimated the probability of HIV infection through a single spit exposure as 1 in 1000.
The odds are higher if the spit enters injured tissue or a mucous membrane. But in general, a single spit exposure is unlikely to transmit most serious diseases like HIV, viral hepatitis or streptococcal infections.
However, repeated exposures to the same person’s saliva over time raises the overall risk significantly. The more frequent the contact with potentially infected spit, the more likely transmission becomes.
How to prevent getting sick from spit
To minimize the chances of getting sick from someone else’s spit, follow these precautions:
– Avoid close contact with people who are noticeably sick
– Wash hands thoroughly and often, especially before eating
– Avoid touching your face as much as possible
– Disinfect surfaces that may be contaminated with spit using bleach or alcohol-based cleaners
– Keep any cuts or wounds covered and clean
– Don’t share drinks, cigarettes, joints, lip products, or eating utensils
– Get tested and treated if you think you’ve been directly exposed to contagious spit
When to see a doctor
You should call your doctor if:
– You experience possible infection symptoms like fever, cough, sore throat, nausea, or diarrhea after someone spits on or in your mouth
– The spit entered your eyes, nose, mouth, or an open wound
– You know the spitter has a contagious illness like strep throat or hepatitis
– The exposure was a case of sexual violence or assault
Your doctor can assess your specific symptoms, exposure details, and medical history. They may recommend testing or treatment if warranted.
Be sure to tell them the timing and circumstances of your exposure. Prompt treatment with antibiotics or antivirals can be crucial with some illnesses.
Conclusion
Having someone spit in your mouth is thankfully an unlikely occurrence for most people. While the idea raises fears of contagious diseases, the actual risk of transmission is quite low in most cases.
Illnesses like colds, flu, strep, and gastroenteritis are more plausible than serious diseases like HIV. Still, a single exposure usually isn’t guaranteed to make you sick.
To limit infection risk, avoid direct contact with people who actively seem sick. Practice good hygiene and proper wound care. See your doctor about any concerning symptoms that develop after spit exposure.
If it happens repeatedly, your odds of getting some illness could increase over time. Overall though, try not to stress excessively about a one-time spit exposure, rinse your mouth, and take sensible precautions.