Where does HIV hide? Avoid these high-risk actions to enjoy a happy sex life | AIDS Day Special

December 1st is World AIDS Day. "Fanpu" has specially launched a special article to explain in detail where HIV exists in the body and provide a comprehensive guide on how to prevent AIDS during sexual activities and how to deal with suspected HIV infection.

The theme of this year's World AIDS Day campaign is "Join hands to prevent and control AIDS and share health responsibilities", which particularly emphasizes the importance of global cooperation and universal participation in AIDS prevention and control. We must remember that our enemy is the HIV virus, not the people infected with the virus.

Written by Li Qingchao (Shandong Normal University)

Sexual activity is probably the most intimate form of contact between humans. Infectious diseases that can be transmitted through sexual activity are called sexually transmitted diseases (STDs). It is currently known that more than 30 different bacteria, viruses and parasites can be transmitted through sexual contact. It is estimated that more than one million people worldwide suffer from sexually transmitted infections (STIs) every day. These infections are often asymptomatic or have only mild symptoms. However, some pathogens may cause greater trouble to human health, such as bacterial sexually transmitted infections such as chlamydia, gonorrhea and syphilis; viral sexually transmitted infections such as genital herpes, HIV and genital warts, and parasitic infections such as Trichomonas and pubic lice - they can cause diseases and even death in severe cases. Among them, AIDS should be the most "eye-catching" disease among sexually transmitted diseases.

There are many ways to prevent sexually transmitted diseases, the core of which is to avoid sexual behaviors that may cause infection:

1) Abstinence, no sexual relations, "single dog, no friends, pure body, relying on hands" [crossed out].

2) Mutually loyal monogamous partners, both of whom only have sex with each other and neither of them has STDs. "Energy (pathogens) can neither appear out of thin air nor disappear out of thin air, especially not appear out of thin air."

3) Reduce the number of sexual partners to reduce the possibility of infection. "Life is like a box of chocolates. You never know what you're going to get. Maybe it's an STD."

4) Inject available vaccines, such as HPV, HBV vaccines, etc., conduct necessary pathogen testing in advance, and use condoms correctly. "Please, you have touched my bottom line."

"So, can kissing lead to pregnancy?"

"Student, please ride your baby bike and leave the scene immediately. Go home before dark."

Because next we are going to learn some knowledge about safe driving.

How AIDS is transmitted Human immunodeficiency viruses (HIV) can cause human immunodeficiency syndrome (AIDS), which is usually transliterated as "AIDS". AIDS is one of the top ten global threats to human health named by the World Health Organization (WHO). In 2019, approximately 38 million people were infected with HIV worldwide, with an estimated 1.7 million new infections and 690,000 deaths. December 1st of each year is "World AIDS Day". In 2020, while fighting the new coronavirus epidemic, the WHO also called on global leaders and citizens to unite and support "global solidarity" to maintain basic HIV prevention and treatment services. Next, this article focuses on the transmission of HIV and corresponding prevention measures.

HIV can infect anyone, regardless of their sexual orientation, race, gender or age. However, some groups are at higher risk of HIV infection. Men who have sex with men (MSM) are the most affected group (Figure 1). Taking the United States as an example, the MSM population only accounts for a small part of the total U.S. population (2%), but half of all HIV infections in 2008 were MSM, and nearly two-thirds of all new infections in 2009 occurred in this population. This is due to differences in their behavioral patterns and physiological characteristics.

Figure 1: New HIV transmission categories in the United States in 2010 | Source: NIH

To understand the risk of HIV transmission, we need to consider where HIV is present. HIV primarily infects CD4+ T cells in the blood, but also macrophages and dendritic cells in tissues. Therefore, HIV is undoubtedly present in:

1) In the blood, HIV can be transmitted through blood transfusion, drug injection and other blood-borne diseases. At the same time, HIV also exists in:

2) Semen and secretions such as the bulbourethral gland fluid discharged before ejaculation,

3) Vaginal discharge,

4) Rectal discharge,

5) In breast milk.

If any of the above body fluids containing HIV virus come into contact with the mucous membrane or skin wound of the human body, it is possible to transmit the virus, thus leading to AIDS infection. The above body fluids are very likely to be exchanged during sexual intercourse, especially vaginal intercourse and anal intercourse, which also creates the possibility of HIV transmission. HIV can also be transmitted from mother to child during pregnancy and childbirth. General daily contact such as kissing, hugging, shaking hands or sharing personal items, food or water will not cause people to be infected.

Will the human body be infected if it comes into contact with body fluids containing the HIV virus?

In fact, two factors affect the risk of transmission: one is the amount of virus in the body fluids, and the other is the surface that is touched.

The outside of the human body is covered by skin, which is composed of three layers: epidermis, dermis and subcutaneous tissue. The epidermis can be divided into many layers, the most important of which are the spinous layer and stratum corneum. The stratum corneum is highly keratinized and is generally considered to be dead flat cells. It has a waterproof effect and is the first barrier between humans and the outside world. Generally, viruses or bacteria find it difficult to pass through the stratum corneum and infect the human body.

The inner lumen or channels of the human body are covered by mucosa, mainly including the mucosa of the digestive tract and the mucosa of the urogenital tract. These mucosa are relatively thin, and the surface is covered with columnar or squamous epithelial cells, which are relatively moist, soft, elastic, large in surface area, and updated relatively quickly. Therefore, the mucosa is where most infections occur. For example, colds are caused by infections of the nasal mucosa, while oral-fecal diseases are transmitted in the mucosa of the digestive tract, and sexually transmitted diseases can naturally be transmitted in the mucosa of the reproductive tract.

In fact, the mucosa itself also has a certain ability to resist infection - the mucosa can often secrete mucus, creating an antibacterial environment with a low pH value or containing antimicrobial peptides. At the same time, the mucosa also contains a large number of immune cells, called the mucosal immune system, which can secrete molecules such as cytokines and antibodies. Although the protective effect is not as good as that of the skin, there are intercellular connections between cells on the surface of the mucosa, which can separate the external environment from the internal environment (Figure 2).

Figure 2. Differences in skin and mucosal structures | Source: Yale University

There is no impenetrable wall. The skin may be scratched by various sharp objects, and the mucous membrane may also have minor wounds due to tearing or friction. Even if these wounds do not bleed, they destroy the natural barrier function of the epidermis or epithelium, thus allowing pathogens to enter the body. In terms of virus susceptibility, the susceptibility of damaged mucous membranes is greater than that of mucous membranes, and the susceptibility of these two is much greater than that of skin: damaged mucous membranes>mucous membranes≫skin.

During different penetrative sexual intercourses, semen or pre-ejaculatory secretions carrying HIV virus may infect the vaginal mucosa or rectal mucosa, while vaginal secretions or rectal fluids containing the virus may also infect the epithelium of the glans penis or foreskin (Figure 3).

Figure 3. Main sites of HIV transmission | Source: Peter Anton et al., 2011

In heterosexual intercourse, males infect females more efficiently than females infect males;

In male homosexuals (MSM), the chance of the top (top) infecting the bottom (bottom) is much higher than the chance of the bottom infecting the top (Figure 4). The risk of the bottom contracting HIV is also much higher than that of women. This is because the rectal structure does not anticipate the entry of foreign objects, and the secretions are less, making it difficult to fully lubricate, and the intestinal mucosa is more likely to tear, making it very easy to get infected.

Figure 4: Behavior patterns and HIV transmission risk | Source: BUMC

Unprotected sexual activity as shown in the figure above with a high-risk person whose infection status is unknown should be considered high-risk sexual activity.

HIV risk factors and prevention measures 1 Pre-testing √ Currently, AIDS test strips can detect HIV infection 2 to 6 weeks after high-risk behavior. They are very convenient to buy (available in pharmacies) and use. The operation time is about 15-20 minutes. You can do the test yourself according to the instructions.

Please note that a negative test result does not mean that the virus is absent, because there is a window period of 2 to 6 weeks after high-risk sexual behavior, during which one may be able to infect.

2 Use condoms correctly√ Male latex condoms and male/female polyurethane condoms provide a reliable barrier to block the transmission of HIV, HBV (hepatitis B virus) and other sexually transmitted diseases.

Notice:

Use latex or polyurethane condoms

Check the expiration date and check for damage

Avoid using silicone-based or oil-based lubricants

Wear a condom throughout sexual intercourse and be careful to avoid slipping or breaking

Prevent semen from leaking out after ejaculation and dispose of it properly after taking it out

The failure of condom protection is often caused by condom breakage and condom slippage. The use of oil-based lubricants can also cause condom breakage.

In addition, the "natural membrane condom" is a condom made from sheep cecum, which has limited ability to protect against sexually transmitted diseases.

3 Oral sex? Oral-genital contact is not an effective way for HIV to be transmitted. The probability of occurrence is extremely low, but it cannot be ruled out. The problem is that oral sex can spread other viruses such as HPV (human papillomavirus).

You can use "Dental Dams" to provide protection during oral sex. Dental Dams are similar to latex handkerchiefs and can be used as a substitute for dental dams by cutting the condom lengthwise.

4 Enema or foreign body invasion of the rectum × Studies have shown that rectal irrigation or foreign body invasion in MSM increases the risk of transmission, which may be caused by destroying the mucus protective layer of the rectum or causing rectal trauma. Please refer to the second solution.

5 Spermicide or disinfectant and lubricant Nonoxynol-9 (N-9) as a spermicide cannot block HIV infection. Lubricants can reduce the possibility of genital or rectal trauma, but they do not have antiviral ability. For solutions, refer to the second article. For solutions, refer to the second article.

6 Post-exposure prophylaxis √ Post-exposure prophylaxis (PEP) refers to taking medication to prevent HIV after high-risk sexual behavior. PEP should only be used in emergency situations. PEP should be considered in the following situations:

High-risk sexual behaviors without condoms or with condom breakage

Sharing syringes

Sexual assault

PEP must be started within 72 hours of possible exposure to HIV, and is most effective the earlier it is started, and should be taken daily for 28 consecutive days.

The PEP drug regimen recommended by WHO, the US CDC, etc. generally consists of three ingredients: tenofovir + (emtricitabine or lamivudine) + (dolutegravir or raltegravir). The commercial drugs available in my country are mainly "Sutfovir" produced by Gilead, "Taidou" produced by Baker, "Acent" produced by Merck and "Tivica" produced by GSK. You can choose one of the combinations of Sufatai + Tivica, Taidou + Tivica, Sufatai + Acent, Taidou + Acent for PEP prevention. Because the above drugs have certain side effects, especially for patients with liver and kidney dysfunction and hepatitis B infection, they must be used according to doctor's advice.

PEP has an effective rate of over 80% (clinical data from 1997). PEP failure is often caused by untimely medication, incomplete treatment, or repeated viral exposure. It is not suitable for regular use by people who are frequently exposed to HIV, and PEP cannot be used as a routine measure to prevent HIV.

If you are pricked by a needle with unknown blood, the risk of transmission is similar to that of sharing syringes. You should receive PEP treatment promptly and report to the relevant departments.

7 Pre-exposure prophylaxis√ Pre-exposure prophylaxis (PrEP) is a drug taken by high-risk people who are expected to be at risk of contracting HIV to prevent HIV infection through sexual intercourse or injection drug use. When taken as prescribed, PrEP is very effective in preventing HIV. PrEP can also be used by medical staff to prevent the risk of HIV exposure during medical procedures. The most commonly used drug for PrEP now is Truvada. PrEP drugs can provide good protection, and the risk of failure is often caused by missed doses.

Please note that both PEP and PrEP are unconventional prevention methods used in emergency situations. The prescription drugs used may not be easy to obtain in some cases and both have certain side effects. PEP and PrEP cannot replace conventional prevention measures.

8. Ejaculation outside the body × Semen is the main body fluid transmitted by HIV. Condoms should be worn throughout sexual intercourse because secretions such as urethral gland fluid before ejaculation may also carry the virus. In addition, vaginal or rectal secretions can also transmit HIV.

9 Circumcision√ There is strong epidemiological evidence that uncircumcised men are at a much greater risk of contracting HIV than circumcised men. In contrast, the latter are two to eight times less likely to be infected with HIV. In addition, circumcision protects against other sexually transmitted diseases such as syphilis and gonorrhea. The inner surface of the foreskin contains Langerhans cells (a type of dendritic cell that can be infected with the HIV virus) with HIV receptors, and these cells are likely to be the main site of viral entry into the uncircumcised man's penis.

10 HIV carriers? Our enemy is the AIDS virus, not the people infected with the virus.

With increasing access to effective HIV prevention, diagnosis, treatment and care measures, HIV infection has become a manageable chronic health condition and people living with HIV have the potential to live long and healthy lives.

HIV infection should be treated immediately. Regardless of the stage of infection, effective antiretroviral therapy can improve the health of HIV-infected people and greatly reduce the chance of HIV transmission to sexual partners.

After treatment, HIV-infected people cannot detect the virus and are not contagious (Undetectable = Untransmittable, U=U). If HIV-infected people take antiretroviral drugs as prescribed every day and achieve and maintain an undetectable viral load, these HIV carriers will not be at risk of transmitting the virus to their sexual partners.

HIV-positive women can give birth to healthy babies. If a woman with HIV does not take HIV medicines, her baby has a one in four chance of being infected with HIV. In fact, antiretroviral drugs can be taken when trying to conceive or during pregnancy. With effective treatment, the chance of a baby being infected with HIV is only 0.4% or less. After delivery, the baby should receive antiretroviral treatment for at least 4-6 weeks.

HIV positive people should not breastfeed their children. HIV can be transmitted through breast milk. HIV positive mothers are advised not to breastfeed their babies but to use formula instead.

11 “Four Frees and One Care” Policy√ The “Four Frees and One Care” policy is a powerful policy measure for AIDS prevention and treatment stipulated in the Regulations on AIDS Prevention and Treatment issued by my country in 2016. Its specific contents are:

(1) Provide free antiretroviral drugs to AIDS patients in rural areas and economically disadvantaged urban residents who are not covered by basic medical insurance or other medical security systems;

(2) Implement free voluntary consultation and testing;

(3) Provide free schooling for orphans of AIDS patients;

(4) Provide free HIV consultation, screening and antiretroviral drug treatment to pregnant women with HIV to reduce mother-to-child transmission.

(5) “One care” means that AIDS patients with difficulties in life are included in the scope of government assistance, necessary living relief is provided in accordance with relevant national regulations, and AIDS patients with production capacity are actively supported to participate in production activities. High-risk groups and HIV carriers or AIDS patients should actively seek policy assistance.

12 Education and self-help√ AIDS prevention and control requires the joint efforts of the whole society, and education is an important part of it. my country has planned corresponding AIDS prevention and control education content for people of all ages. For example, the "Guidelines for Health Education in Ordinary Colleges and Universities" stipulates that college students should understand "the spread, prevalence and control of AIDS, high-risk behaviors and prevention measures that are prone to AIDS, AIDS consultation, testing and services, and non-discrimination against AIDS patients and patients." If you are unfortunately infected with HIV, you should cherish yourself, actively help yourself and seek help, actively participate in treatment, prevent the disease from worsening, and avoid infecting others. You should not be negative and pessimistic, and you should not spread infectious diseases in revenge. my country has clear provisions on the crime of maliciously spreading infectious diseases and spreading sexually transmitted diseases in the "Regulations on AIDS Prevention and Control", "Law on the Prevention and Control of Infectious Diseases" and "Criminal Law".

Conclusion 2020 is a special year for the global pandemic of the new coronavirus, and HIV will continue to be a major threat to human health for quite some time. This year, the theme of my country's World AIDS Day campaign is "Joining hands to prevent and control AIDS, and share health responsibilities" (Global solidarity, shared responsibility), which particularly emphasizes the importance of global cooperation and universal participation in AIDS prevention and control. For individuals, everyone's sexual interests are different, but everyone should do a good job in AIDS prevention and control.