How is HlV passed on

HlV can be passed from one person to another through sexual contact, and in a number of other ways. You can have HlV and pass it on regardless of your sexuality and how many sex partners you have.

HlV can be passed on through heterosexual or homosexual sex. Most people with HlV will look and feel healthy, so you cannot tell who has the virus and you can pass on HlV without knowing you have it. HlV can be passed on even if someone is taking anti-HlV drugs. HlV is passed on when the blood, semen, pre-ejaculate, vaginal fluids or breast milk of an infected person enters the body of an uninfected person by:

  • Having unprotected vaginal, oral or anal sex
  • Sharing sex toys
  • Using a needle or syringe (works) which has already been used by someone who is infected with HlV.
  • The risk of catching HlV from unprotected oral sex is low but it can happen. You are at a higher risk if:
  • Your throat or mouth is inflamed or you have cuts, sores, abrasions or any unhealed piercing (e.g. lip and tongue piercing) in your mouth
  • Your partner ejaculates in your mouth
  • You have just brushed or flossed your teeth
  • You are giving oral sex to a woman who is having her period.

Having another sexually transmitted infection increases the risk of getting HlV or passing HlV on if you already have it. Although HlV can be detected in urine and saliva, the level of virus in these fluids is too low to be infectious. You cannot get HlV from hugging, kissing, sneezes, coughs, sharing baths or towels, from swimming pools, toilet seats or from sharing cups, plates or cutlery. You cannot get HlV from any animals or insects, including mosquitoes.

Introduction of HlV & AIDS

AIDS stands for Acquired Immune Deficiency Syndrome. It is caused by a virus called Human Immunodeficiency Virus (HlV). Once someone is infected with HlV, the virus will remain in the body for the rest of their life. When someone becomes HlV positive, the virus destroys the white blood cells called CD4-T lymphocytes and weakens the immune system, which will eventually disable the patient’s ability to fight against infections and cancers. In other words, HlV infections may progress to AIDS at the end, and that inability to fight against the serious illnesses caused by HlV invasion will eventually cause mortality in HlV/AIDS patients.

1 If not treated properly, around 50% of HlV infections progress to AIDS in 10 years.
There is no cure for HlV and no vaccine to prevent people from the infection. However, drug treatments can help most people with HlV to live much longer and feel well.

Becoming HlV positive does not equal to having AIDS.

Development stages of HlV


Many people infected with HlV have no signs and symptoms at all. Within a few weeks after infection, about half of the people experience flu-like symptoms including fever, a rash, swollen glands, a sore throat, mouth or throat ulcers and aching muscles or joints. This also calls sero-conversion illness and usually last for about 1-4 weeks.

Window period

Within 2 weeks to 3 months after infected with HlV, the body will try to fight the virus by producing HlV antibody against it. This is called “window period”. However, the amount of HlV antibody is insufficient to be detected, if doing the HlV Antibody Test during this period, the result may not be accurate. Some infected people may be misled by the “false negative” result and not knowing they already infected with HlV. For most cases, the amount of antibody will usually be sufficient for the test after a period of 3 months.

Asymptomatic incubation period

At this stage, HlV-positive people will look and feel healthy and may show no signs or symptoms. For most cases, the asymptomatic incubation period lasts around 10 years, though the duration is dependent on health and psychological conditions of the infected person, as well as whether treatments have been done. If treatment is delayed or ineffective, about half of the infections will be developed into AIDS in 10 years.


AIDS is the final stage of HlV infection when the immune system is severely damaged and cannot fight against virus and bacteria that lead to different serious diseases and even death.


Many people infected with HlV have no signs and symptoms at all. Within a few weeks after infection, about half of the people experience flu-like symptoms including fever, a rash, swollen glands, a sore throat, mouth or throat ulcers and aching muscles or joints. This also calls sero-conversion illness and usually last for about 1-4 weeks.

HlV tests

HlV tests are used to detect the presence of the HlV in the human body. By detecting HlV antibody, antigens or RNA, people can be diagnosed whether they are infected with the virus or not. Blood test is the most common HlV test to detect HlV infection.

How soon can I have a test after sex?

After being infected with HlV, it takes a period of time for antibodies/ antigen/ virus to reach a detectable level. This period is known as the “window period”. The length of window period varies among individuals and various laboratory tests. Some may take up to three months. With the advancement in testing technology, not only has the window period of antigen and antibody tests been shortened, HlV can now be detected through RNA test. As RNA test is done by checking the genetic substance of HlV, its window period is shorter than antigen and antibody tests. Thus, HlV can be detected through blood test at an earlier stage of infection.

  • HlV p24 antigen test: P24 antigen is one of the proteins that make up of the HlV. After HlV infection and before the production of antibodies, the level of p24 antigen will elevate in the body. This can be detected in the blood sooner than HlV antibodies.
  • HlV antibody test: When HlV enters the body, the body reacts in response to fight the infection and the immune system starts to produce antibodies. Although these antibodies cannot fight off the infection, their presence can help diagnose whether a person has HlV inside the body.
  • HlV antigen & antibody combo test: Using the “fourth-generation” technology, the combo test can detect both HlV p24 antigen and HlV type 1 & type 2 antibodies. It is generally recommended to have the HlV combo test 21 days after sex.
  • HlV RNA test: RNA test looks for genetic substance of the HlV with blood sample to detect the very early infection when HlV antibodies are undetectable. It is generally recommended to have the HlV RNA test 7 days after sex.

What does the test results mean?

The virus/ antigen or antibody level varies from one to another. If doing a test within the window period, there is a chance of having a “false negative” result given the level of virus/ antigen or antibody is still undetectable. Therefore, if you have engaged in unprotected sex or other high-risk activity, there is still the risk of HlV infection and you may still infect others with HlV. It is recommended to re-test 3 months after the suspected infection day to confirm the result.


Once HlV is diagnosed, you will be given a number of tests to monitor the stage of the infection and to determine if or when treatment should be started.

At the moment, there is no cure for HlV or AIDS, but there are drugs, known as Anti-Retroviral Therapy (ART) or combination therapy, that reduce the level of HlV in the blood and prevent or delay the development of AIDS. Most people with HlV are benefitted from these treatments, such as live longer and have better health than those had not taken them. There are also treatments available that can help prevent or treat many of the illnesses that people with HlV are more likely to get.

The treatments for HlV can be difficult to take and they can have unpleasant side effects. Our doctor can give you full information about options, side effects and long-term effects of the treatments.