Thanks for your query. The question addresses some complex issues so we’ve asked our senior researcher Peter Saxton to provide a response below. We’re also assuming that your question relates to anal sex between males; if this isn’t the case please let us know since HIV transmission risk is heavily influenced by the type of sex occurring e.g. anal sex vs vaginal sex.

Your question has several parts to it so take them one at  a time.

First of all, from your posting it looks like you’re aware that oral sex is considered low risk for HIV. In fact, receptive oral sex is estimated to have a per-episode risk of HIV transmission of approximately 1 in 10,000, a risk that has been determined in NZ courts to not present a “significant risk” of HIV transmission. The reasons for this are important to clarify. Mainly, this is because the mouth does not contain high concentrations of cells that are vulnerable to HIV infection, nor does it contain many cells that harbour HIV virus. Also, saliva possesses protective qualities that help keep viruses and bacteria out of the body, in ways that anal mucus doesn’t. This is an important difference that explains why receptive oral sex is so much less risky than receptive anal sex as far as HIV is concerned – if someone ejaculates HIV infected semen into an anus, the risks for the HIV negative receptive man are far greater than if HIV infected semen is ejaculated into a mouth. The normally very low risk of oral sex is of course increased if the body’s immune system in the mouth is compromised, for example if you have bleeding gums, have recently had dental work, or if you have an ulcer. Even then, the risk from anal sex is still greater.

Second, unprotected anal sex is the most efficient way of sexually acquiring HIV. Again, the reason is due to the different biology of the anus. The anus has a very high concentration of cells that are both vulnerable to HIV infection, and which also harbour HIV virus. Sexually transmitted infections (STIs) such as syphilis, herpes, gonorrhoea and anal warts that are present in the anus can substantially heighten the risk of HIV acquisition and transmission, and many of these infections may go unnoticed and/or unchecked. In addition, a person with HIV is much more infectious in the early stages of infection, and when they have other STIs in addition to HIV (which may or may not be noticed/treated). Due to these issues and other biological and genetic factors, although the per contact risk of HIV transmission for unprotected receptive anal sex with an HIV positive man has recently been estimated at 1 in 70 episodes (and presents a “significant risk” of transmission in NZ law), in that study 12 of the 46 men who contracted HIV had experienced fewer than 10 episodes of unprotected receptive anal sex. It is still not well understood why some men become infected very quickly, and for others it takes many episodes. The probability of HIV transmission through unprotected anal sex can therefore be described as both high and variable. Receptive anal sex is also more risky than insertive anal sex, but both carry considerable transmission risks. Condoms effectively reduce this high biological risk by physically interrupting the way HIV is transmitted in the anus. By reducing the per contact risk to “below significant”, a condom also removes any legal risk (i.e. a man who knows he has HIV cannot be prosecuted for having anal sex if a condom is used).

Thirdly, you asked what effect an undetectable viral load might have on transmission risks. Four things are important to emphasise here: 

(a) the term “undetectable” merely describes the limits of the viral load tests currently available. HIV is still present, albeit at levels that are below what the current test can detect. The phrase “undetectable” is increasingly being replaced with “low viral load” in order to more accurately communicate that HIV is not absent.

(b) viral load tests are only conducted a few times a year, and in between tests HIV levels can increase (“blip”) for different reasons – sometimes because the HIV positive individual is fighting off another infection (e.g. a cold or an STI) , sometimes for reasons unknown. 

(c) standard viral load tests measure the quantity of HIV in blood, to help inform HIV treatment practices. However, it does not measure the quantity of HIV levels in semen, or in anal mucus, which are the main body fluids implicated in sexual practices. This is important because HIV levels in semen and in the anal mucus can differ from those measured in blood, meaning that a recent low blood viral load result may not mean that a person has low HIV viral load in semen or anal mucus. Unfortunately for gay and bisexual men, very little research has investigated HIV viral load in anal mucus, so it is difficult to say precisely in what ways it is different to HIV in semen or blood.

(d) while lower blood HIV viral loads can mean that a person is less infectious than someone with higher blood HIV viral loads, there is therefore mounting evidence that the last blood viral load test may not be a good indicator of current sexual infectiousness. Individuals with low blood viral load at their last test have transmitted HIV to sexual partners, even when that person has been adherent to HIV treatments, and in the absence of STIs.

For these reasons, it is still possible to contract HIV through unprotected anal sex with an HIV positive individual who has had a recent “undetectable” blood viral load test. For a one-off sexual encounter, the risk would be very difficult to quantify, because of the many variables at play – both known and unknown to both partners. Our practical recommendation is therefore to regard all unprotected anal sex as riskier than other sexual practices. It is also important to emphasise that condoms work very well to prevent HIV transmission through anal sex, and help protect both partner’s health in many other ways, while at the same time enabling partners to continue to enjoy having anal sex.

A short review of HIV treatment as prevention been published online which you might also find useful.

We hope this was helpful and answered your concerns, please let us know if you’d like to discuss this more.

Hi there, You can get yourself tested at any of NZAF's clinics in Aukcland, Wellington and Christchurch, and also from our network of counsellors at other locations in New Zealand. It's free and confidential. You can book online or call us. 

Hi, thank you for your question. Many reputable HIV research organisations have concluded studies that show no evidence whatsoever of HIV transmission via mosquitos or any other insect, so it is not possible that your father has acquired HIV from a mosquito that bit you. The risk of transmitting HIV through sharing eating utensils or drinking from the same glass is also extremely unlikely. There is a lot of research showing that saliva acts as a natural barrier to the HIV virus, so transmission of HIV via saliva is very low. Blisters are a known symptom of HIV but there is no reason to conclude that your father’s blisters represent a presence of HIV infection. HIV is transmitted through unprotected anal sex, direct blood to blood contact, breastfeeding, childbirth and sharing needles. Without giving your father an HIV test we could not confirm if he has acquired HIV, but we can confidently say that if you have not partaken in the above activities with your father, then he has not acquired HIV from you. Naturally this is a stressful experience for you so we would like to extend our support through our free and confidential counselling services, should you like to discuss this further with one of our support centre staff. We have centres in Auckland, Wellington and Christchurch and can provide services in many other locations around the country also. 

Hi. You can get a free and anonymous HIV rapid test (results in 20 minutes) at one of the three NZAF clinics located in Auckland, Wellington and Christchurch. We also contract counselors who can provide testing in other regions outside of these main centers. To book an HIV test through us, click the Get Tested icon at the top right of the NZAF website homepage; simply complete the form and someone will be in touch with you. Alternatively you can search the White Pages for your nearest sexual health clinic, who will also provide a free, anonymous test. It is important to bear in mind that there is a window period of up to 3 months after exposure to HIV before antibodies to HIV appear in the bloodstream (an HIV test tests for antibodies to HIV rather than HIV itself). Getting tested immediately after exposure may give a false negative result, so it is very important to have an HIV test at the 3 month period.

It would be against NZ human rights law to quarantine a person based on HIV status, so no you would not be quarantined if you tested positive for HIV. You will also be able to continue work as employers in NZ are not allowed to discriminate on HIV status. If you are in New Zealand on a visa and if you tested positive for HIV during the term of your visa, you can stay in New Zealand until the current visa runs out - you will not be kicked out. If you then re-applied for an extension of a visa you would have to undergo a medical exam and you would need to disclose if you were HIV positive. We are not in a position to comment directly on immigration policy and rules, but in our experience, you would be denied an extension to your visa if you became positive for HIV.

Access to free or subsidised HIV treatment is only available to New Zealand citizens or Australian citizens living in New Zealand (we have a reciprocal health care agreement with Australia). If you are in NZ on a visa you would not be able to access free or subsidised HIV medication - you would either have to return to your country of origin for treatment, or seek advice from a NZ HIV specialist about paying full price for HIV medication here.

As mentioned above, we are not in a position to advise directly on visa or immigration policy, so if you are not currently a NZ citizen, we would suggest you seek further advice on this topic from the Department of Internal Affairs and Immigration New Zealand. We hope this information helps.

Hi, thanks for your question. Unfortunately we are not authorised to comment on, or across all individual organisations' policies around health screening. Having said that, in New Zealand, employers are not allowed to request mandatory HIV screening unless there is a clear risk of transmission in the role the candidate would be applying for. For example, a surgeon would present a potential risk to his/her patients if he/she was HIV positive - conversely, a office clerk would not. We would suggest that you contact the NZ Royal Navy about their policy and follow up with the Department of Labour if you require more information on employment law in regards to mandatory health screening.

Hi. All HIV and hepatitis tests available in NZ are blood tests. If your niece is terrified of needles, we might have a solution for her. At the NZAF we do rapid tests for both HIV and hepatitis C and there are no needles involved, just a very quick and painless finger prick that draws a single drop of blood. The drop of blood is placed into a sterile testing device and you have your results 20 minutes later.These tests are highly accurate and are approved by the Food and Drug Administration and Medsafe NZ, and are only available through the NZAF and our affiliated partners.

The testing process is simple and we have a video that will show you can show your niece. It shows what it is like to get a test at one of our centers. You can also make an appointment online, or by calling us. Appointments are available at NZAF's centers or our outreach clinics. Full STI screening is also available at our Burnett Centre every Monday night 5-7pm. We hope this information helps.

Hi there, thanks for getting in touch. If the semen of a HIV positive man came into contact with your vagina then there is a risk of you contracting HIV as the virus is transmitted via bodily fluids. We would strongly recommend you book a free and confidential rapid HIV test, and you can do online. One thing to keep in mind is that it can take up to three months for HIV to become detectable in the bloodstream. We would recommend that you test immediately then return again 90 days after the time of sexual intercourse, for a conclusive result. We also offer free and confidential counselling to anyone affected by HIV in anyway.

Hi there, thanks for your question. From the situation you've described you've no risk of contracting HIV and wearing a condom means your risk of contracting other STIs from this situation was also greatly reduced. If you are concerned still about your sexual health then it is best to go for a full check up. NZAF offers sexual health check ups at our centres in Auckland, Wellington and Christchurch.You can book online to access our free and confidential service. Otherwise, if you're not near one of our main centres you can access one of our trained counsellors for the rapid test.

Hi there, Your risk of HIV or STI transmission is increased if your had a cut in the end of your penis during unprotected sex, particularly if it was raw or bleeding, as this could allow infected vaginal fluid to get into your bloodstream. It's impossible to say whether your symptoms are related without having a test, so we would encourage you to have a full STI screening and HIV test through your GP or nearest sexual health clinic. It's important to note that with HIV has a window period of up to three months and is detected in a test after this period.