Q and A

Question

Please clarify how HIV is NOT transmitted.

I have just been browsing the How HIV is Not Transmitted page and have a few questions. Can you please clarify for me? Thanks.

1. You can get HIV from a toothbrush that has blood on it and also oral sex but not from food with blood on it.

2. Nurses can become infected from needle injuries but you cannot get it from a sewing needle or a cat scratch.

3. If semen comes into contact with your mucous membrane down below you can get it but not from blood getting on to your underwear.

4. Also is there a time when antigen is not detectable but antibodies have not yet been able to be detected in a blood test.

Answer

Thank you for your questions.

I will try and answer them in the order they are asked.

1. The factsheet does not say you can get HIV from a toothbrush with blood on it. You cannot get HIV this way. This is for various reasons, firstly a toothbrush usually has toothpaste on it which would kill the virus. Secondly, even the most unhygienic person would not give someone a toothbrush to use without washing the toothbrush first. If there was blood on the toothbrush then it would be washed away.

You cannot get HIV by eating food with blood on it. HIV in the blood does not survive long outside the body. The time the blood would spend in contact with the mucous membranes in the mouth is minimal, if at all, when consumed with food.

You can get HIV from oral sex but it is very low risk and not very likely (3-5% of new infections). Transmission through oral sex has only ever occurred in people who are giving oral sex to a man. There have been no known cases of someone getting HIV through giving a woman oral sex. There have been no known cases of people getting HIV from receiving oral sex. In the cases where infection has occurred as a result of oral sex there would have to have been a mixture of bad oral hygiene in the person giving oral sex e.g. bleeding gums, multiple open sores in the mouth etc. and a high viral load in the semen of the person receiving oral sex.

2. Most sewing needles will never make it into a vein but are more likely to make it into a finger. The amount of blood that gets on to the end of a needle with a finger prick is very tiny. Most fingers bleed after the needle prick and so would not bleed on the needle.

Needles used by nurses are usually hollow so that they can inject someone with medicine or a vaccine. Often they are inserted into the vein and can collect blood from the vein into the hollow part of the needle. Therefore if a nurse had a needle containing the blood of someone with HIV and immediately she then pricked his/her finger with the same needle there is a small chance of infection.

3. The mucous membrane ‘down below’ which I am assuming you mean ‘in the vagina’ is not the outside of the vagina but inside the vagina from the vaginal opening inwards. It would be impossible for blood to soak through the underwear and go inside the vagina.

4. Antigens are always detectable. They are usually proteins on the surface of the HIV cell membrane. Antibodies take a while for the body to produce (usually 2-4 weeks depending on the individual).

6 comments

  1. Lisa Thorley
  2. Madhukara

    I get tattoo 3 years back still don’t check the blood,I fear that I got HIV,is it possible?

  3. Lisa Thorley

    Hi Pam,

    Please see Q’as 1 and 9 here:

    https://i-base.info/qa/what-are-the-most-asked-questions

  4. Pam

    I had sex with a someone who is HIV positive, the condom broke, am I at risk?

  5. Roy Trevelion

    This service is for treatment information for HIV positive people. We don’t answer individual questions about transmission risks and testing.

    But most questions about transmission have already been answered on the Q&A factsheets:
    https://i-base.info/qa/factsheets/hiv-transmission-and-testing

  6. Raj

    I’m suffering from head pain and loosing weight. I’ve not had sex with anybody except my family in 6 Years. Am I at HIV risk?