The deep body fluids of an HIV infected person such as blood, semen (including pre-cum), rectal and vaginal secretions are contain of HIV.
You can got infected with HIV when your mucous membrane or an open wound come into contact with these body fluids. It may directly injected into your bloodstream (by a contaminated needle or syringe) for possible transmission. Mucous membranes can be found inside the rectum, the vagina or the opening of the penis, and the mouth. Therefore, HIV can be spread by the following routes:
In Hong Kong, more than 75% of cases are infected through sexual contact and about half of the new cases reported in recent years were infected through homosexual or bisexual contact.
- Anal sex is the riskiest sexual behaviour. Receptive anal sex ("bottoming") is riskier than insertive anal sex ("topping").
- Vaginal sex comes in second in terms of the riskiness of sexual behaviours.
- Oral sex (i.e. fellatio and rimming) carries much less risk than anal and vaginal sex. The risk is higher with receiving oral sex with cumming (ejaculating) in your mouth. Besides, other infections can be transmitted through oral sex. These include syphilis, gonorrhoea, herpes, warts, hepatitis A and B.
- Having multiple sex partners or having sexually transmitted infections (STIs) can increase the risk of HIV infection.
- Taking recreational drugs can easily affect your ability to make safe choices and lowers your inhibitions, such as having sex without a condom or having more rough sex.
Evidence has shown that people with HIV who achieve sustained viral suppression to an undetectable level by antiretroviral drugs have no chance of passing on the virus through sex. However, HIV transmission would still be possible if other STIs, ulcers or blood are present during the sexual contact.
An HIV-negative man, with an STI can have inflammation at the site of infection or ulcers, which increases the chance of getting HIV.
- Blood-borne transmission mainly occurs through sharing injection tools.
- Less commonly snorting equipment for drug taking can also transmit the virus.
- HIV transmission is also possible through transfusion of HIV-contaminated blood or blood products.
- Infected mothers can transmit the virus to their babies during pregnancy, delivery and breast-feeding periods.
Body fluids such as saliva, sweat or urine do not contain enough virus to infect other persons. You cannot get HIV through casual or day-to-day contact, including a kiss on the cheek, sharing meals, or sitting on toilet seats. Besides, there is no evidence to show that mosquitoes can transmit HIV.