What are HIV and STIs?

Some of the most frequently asked questions on HIV and STIs

What is HIV?

HIV stands for Human Immunodeficiency Virus.

HIV is a lot like other viruses, including those that cause the "flu" or the common cold. But there is an important difference – over time, your immune system can clear most viruses out of your body. That isn't the case with HIV – the human immune system can't seem to get rid of it. That means that once you have HIV, you have it for life.

We know that HIV can hide for long periods of time in the cells of your body and that it attacks a key part of your immune system – your T-cells or CD4 cells. Your body has to have these cells to fight infections and disease, but HIV invades them, uses them to make more copies of itself, and then destroys them.

Over time, HIV can destroy so many of your CD4 cells that your body can't fight infections and diseases anymore. When that happens, HIV infection can lead to AIDS, the final stage of HIV infection.

However, not everyone who has HIV progresses to AIDS. With proper treatment, called “antiretroviral therapy” (ART), you can keep the level of HIV virus in your body low. ART is the use of HIV medicines to fight HIV infection. It involves taking a combination of HIV medicines every day. These HIV medicines can control the virus so that you can live a longer, healthier life and reduce the risk of transmitting HIV to others. Before the introduction of ART in the mid-1990s, people with HIV could progress to AIDS in just a few years. Today, a person who is diagnosed with HIV and treated before the disease is far advanced can have a nearly normal life expectancy.

What are the symptoms?

Some people notice no symptoms when they're first infected with HIV. But within six weeks of infection most people suffer a short illness (lasting around two weeks) as their body reacts to the virus. This involves two or more of the following: body rash, sore throat or fever. Once this passes an infected person usually feels fine for a number of years. However, unless they start treatment before the virus causes too much damage, as years go by they will usually start to suffer life-threatening illnesses such as cancer, TB and pneumonia. This is because HIV is destroying cells (CD4 or T-cells) that our immune system needs.

How do you catch HIV?

The most common was that HIV is acquired is through infectious body fluid (such as blood or semen) getting inside another person. This allows the virus to enter their blood stream. This can happen during vaginal and anal sex and sometimes oral sex too though this is much less common - or when an object that has a body fluid on it goes from inside one person and into another.

How contagious is HIV?

Unlike many viruses, HIV is not easily passed on. When HIV was first discovered there was much fear and consequently stigma around HIV and many myths emerged about ways it could be contracted which further added to the stigma around the disease. It is not transmitted in the following ways:

• casual social contact (eg, handshake, kissing, hugging)
• through coughing or sneezing (HIV does not travel in the air)
• through tears, sweat, saliva (and spitting), urine or faeces
• sharing objects someone with HIV has touched or used to eat or drink from
• from toilet seats, swimming pools, showers, hot tubs, towels, etc
• insect bites (including mosquitoes) or from animals
• mouth-to-mouth resuscitation (giving 'the kiss of life')

What are STIs?

STI stands for sexually transmitted infection. They are caused by specific bacteria, viruses and parasites. Some people refer to STIs as STDs or sexually transmitted diseases. There are many types of STI. For more information on types of STIs click here.

Are they treatable?

Most can be cured with medication. However, some of them can only be treated to reduce symptoms but will stay in your system once you have been infected. 

How do I contract an STI?

STIs are infections that can be passed on from an infected partner during sex (vaginal, anal and oral). In some cases, you may be at risk even if you don't have full sex. Kissing and touching each other's genitals may pass on some STIs.

Should I get tested?

Whatever your result might be, there are now many good reasons to test and few reasons to avoid testing. It's never a good idea to be unsure of your HIV status or if you have an STI. Testing puts you in control and will give you peace of mind. If you have HIV the earlier that it is discovered the better. Over time, if left untreated, HIV greatly affects your health. Your immune system becomes so damaged that it can no longer fight off infections and cancers. Perhaps your HIV status is not what you think it is. A test at least once a year is a good idea for people who have more than one sexual partner. Testing at the start of a relationship as part of a full sexual health check-up also makes sense. A test is also recommended after unprotected sex that could have put you at risk of HIV and STIs.

Where should I get tested?

There are many options for testing available to people including a network of STI clinics across the country, primary care centres, sexual health NGOs and home testing. To learn more about getting tested click here.

How do I find out more?

For further information on HIV and STIs check some of the following sites:

• www.yoursexualhealth.ie- is a HSE website looking at all areas of sexual health


• www.man2man.ieis a Irish sexual health website for gay and bisexual men which aims to provide you with clear and accurate information and advice about sex and sexual health


• The GUIDE Clinic, Dublin, is the largest, free STI, HIV and Infectious Disease service in Ireland. 

The Terence Higgins Trust is an UK based HIV charity with extensive HIV information