HIV stands for “Human Immunodeficiency Virus”. It is the virus that can lead to “Acquired Immune Deficiency Syndrome”, or AIDS.

HIV damages a person’s body by destroying specific blood cells, called CD4+ T cells, which are crucial to helping the body fight diseases.

AIDS stands for Acquired Immunodeficiency Syndrome.

Acquired – means that the disease is not hereditary but develops after birth from contact with a disease-causing agent (in this case, HIV).

Immunodeficiency – means that the disease is characterised by a weakening of the immune system.

Syndrome – refers to a group of symptoms that indicate or characterise a disease. In the case of AIDS, this can include the development of certain infections and/or cancers, as well as a decrease in the number of certain specific blood cells, called CD4+ T cells, which are crucial to helping the body fight disease.

AIDS is the last stage of HIV infection when a person’s immune system is severely damaged and has difficulty fighting diseases.

1.　Sexual contact
The virus can be transmitted through body fluids like blood, semen and vaginal secretion. One might have gotten infected when having unprotected intercourse including vaginal sex, oral sex and anal sex with someone who has HIV.

Preventive Measure: Practise Safer Sex

i) Maintain stable and monogamous relationship
Be in a long-term mutually monogamous relationship and limit your number of sex partners.

ii) Understand your sex partner
Understand the sex history of your partner and be alert when you are going to have sex with others. If you have doubt, you surely have the right to refuse any sexual contact.

iii) Use condom correctly and consistently
Proper and consistent use of condom can effectively reduce the chance of getting HIV infection.

Proper use of condom
1. Always check expiration date before use;
2. Open the package carefully to avoid damaging the condom;
3. Use the thumb and forefinger to gently press any air out of the receptacle tip before putting on the condom;
4. Unroll the condom to cover the entire shaft of the penis;
5. Hold on the base of the condom after ejaculation and withdraw the swollen penis together with the condom from your partner’s sex organ; and
6. Wrap the used condom in paper and throw it away in a waste container.
Remarks: Use each condom once only; and never put on more than one condom at a time as rubbing will break the condoms.

2.　Blood contact
Transmission through blood can be a result of transfusion of blood or blood products with HIV and the sharing of contaminated needles.

Preventive Measures:

i) Avoid substance abuse and sharing of needles
Do not inject drugs and always avoid sharing needles with others. If you inject drugs, you should get counselling and treatment to stop or reduce your drug use. If you cannot stop injecting drugs, use a new syringe every time. If you must share needles, please do not forget to use bleach and distilled water to clean the syringe so as to reduce the chance of getting HIV infection.

ii) Always handle cuts carefully
Never handle others’ cuts or blood with bare hands. It is necessary to use protector like latex gloves to avoid direct contact with the wounds or blood of other people to prevent contracting blood borne diseases such as tetanus, hepatitis B and HIV.

3.　Mother-to-child transmission
A mother infected with HIV has a 15% to 40% chance of passing the virus to her child during pregnancy, labouring or breast-feeding.

Preventive Measure: Universal antenatal HIV testing

The universal antenatal HIV testing programme has been implemented in Hong Kong since September 2001. HIV screening is now available free-of-charge to all expectant mothers attending the Maternal and Child Health Clinics of the Department of Health and antenatal clinics of the Hospital Authority.

If the infected mother and the new born baby receive early and appropriate treatment such as antiretroviral therapies during pregnancy, labouring and after birth periods, the chance of infecting the baby can be reduced to 1-2%.

HIV cannot reproduce outside the human body. Therefore, casual contacts like shaking hands, kissing, sharing toilets and drinking fountains, eating together, going to school together or working together cannot transmit HIV.

Saliva
Up to now, HIV infection caused by saliva, tears, sweat, urine or feces has not been reported. While these body fluids of the infected can have the virus, the amount is not enough to cause infection. To cause infection, it will require at least two litres of these fluids with the virus entering the body at one time.

Mosquito bites
Mosquito bites cannot pass on HIV as the virus cannot live inside the body of a mosquito. Mosquitoes will digest the blood they sucked and will not spit it out. Even if the mouth part of a mosquito has some infected blood, the quantity is too small to cause infection.

Blood donation
Donating blood to the Hong Kong Red Cross will not get infected with the virus since all needles used are new and will only be used once.

HIV tests can tell if you have become infected with the virus. There are a few types of test. Rapid test is one of the convenient and common methods. It can be conducted away from specialized laboratory facilities and give results in less than 30 minutes. However, a reactive result is only preliminary and it should be followed up by confirmation tests

Biotin, also named vitamin H, vitamin B7 or coenzyme R, is commonly used in dietary supplement products that improve hair, skin and nail conditions. Taking high dose (10 mg or more per day) of biotin may affect many laboratory test results, including false negative result of HIV antibody and antigen tests. If you are taking dietary supplements containing biotin, please stop taking it 48 hours before the test. In addition, biotin amount in ordinary food products do not affect the test results.

For details, please refer to the Important Safety Alerts of the Medical Device Division of the Department of Health:
https://www.mdd.gov.hk/en/safety-alerts-communications/safety-alerts-special-warnings/archive/important-safety-alerts/index-id-1646.html

There are a few stages that one may go through before the development of AIDS.

Infection
The earliest stage is right after you are infected and about 50% of the infected will have flu-like symptoms like headache, fever, fatigue, during this time. However, symptoms do not always develop and some people can be symptom-free.

Window period
The next stage is when the body responds to the virus. Even if one does not feel any difference, his/her body is trying to fight the virus by producing HIV antibody against it within 2 weeks to three months. This is called “window period”, when the infected go from being HIV negative to HIV positive.

If someone has done the HIV Antibody Test during the window period, the result will not be accurate as the amount of HIV antibody is not sufficient enough to be detected. For most infected persons, the amount of antibody will usually be sufficient for the Test after a period of 3 months.

Asymptomatic incubation period
Without treatment, about half of infected will be developed into AIDS in about ten years.

AIDS
AIDS is the last stage of HIV infection when a person’s immune system is severely damaged, making the infected vulnerable to attack by virus and bacteria.

If you want to know more about coping with HIV and the latest treatment of HIV/AIDS, please visit Information for the Affected.

According to estimates by WHO and UNAIDS, 39 million people were living with HIV as at the end of 2022. That same year, some 1.3 million people became newly infected, and 630 thousand died of AIDS.

Although infection with HIV is serious, people with HIV and AIDS are living longer, healthier lives today with the help of new and effective treatments.