Unit 2, Personal Transmission and Risk Factors

Sufficient Dose

"Sufficient dose" refers to the concentration and amount of HIV necessary for infection to occur.

HIV Source and Body Fluids that can Transmit HIV

1. Anyone infected with the virus is potentially a source of HIV infection. Transmission occurs primarily through infected blood, semen, vaginal secretions or breast milk. Sweat, tears, saliva, urine and feces are not capable of transmitting HIV unless visibly contaminated with blood. 2. Medical operatories can be sources of infection due to the blood, saliva, and contaminated drill aerosols. 3. In settings such as hospital operating rooms, other fluids, like cerebrospinal fluid, synovial fluid, pleural fluid, pericardial fluid and amniotic fluid may be considered infectious if the source is HIV positive. These fluids are generally not found outside the hospital setting. 4. Therefore the most common body fluids considered potentially infectious for HIV are blood, semen, vaginal secretions and breast milk.

Biting and HIV

1. Biting poses very little risk of HIV transmission. 2. The possibility only exists if the person who is biting and the person who is bitten have an exchange of blood (such as through bleeding gums or open sores in the mouth.) 3. Bites may transmit other infections, and should be treated immediately by thoroughly washing the bitten skin with soap and warm water, and disinfecting with antibiotic skin ointment. 4. A good practice when working on HIV patients that may be at risk of biting a dental health worker (children, those with poor motor control, or the extreme mentally ill) is to use a bite block when working with in the mouth environment.

Probability of HIV Transmission from one HIV Exposure

1. Contaminated blood transfusion (prior to 1986) - 95% HIV infection rate 2. One intravenous syringe or needle exposure - 0.67% HIV infection rate 3. One percutaneous exposure (e.g. a needlestick) - 0.4% HIV infection rate 4. One episode of receptive anal sexual intercourse - 0.1%-3% HIV infection rate 5. One episode of receptive vaginal intercourse - 0.1%-0.2%HIV infection rate 6. One episode of insertive vaginal intercourse - 0.03-.09% HIV infection rate

How HIV is Transferred During Intercourse

1. HIV can enter the bloodstream through mucous membranes, breaks, sores and cuts in the mouth, anus, vagina or penis. 2. Anal, vaginal and oral intercourse (both receptive and penetrative) can transmit HIV from person to person.

HIV is not Transmitted by

1. HIV is not transmitted through the air. Sneezing, breathing and coughing do not transmit HIV. 2. Touching, hugging and shaking hands do not transmit HIV. 3. HIV transmission is not possible from food in a restaurant that is prepared or served by an HIV-infected employee. 4. HIV is not transmitted through casual contact in the workplace. 5. No cases of HIV transmission have been linked to sharing computers, food, telephones, paper, water fountains, swimming pools, bathrooms, desks, office furniture, toilet seats, showers, tools, equipment, coffee pots or eating facilities. 6. There have been no cases of HIV transmission by children playing, eating, sleeping, kissing and hugging. 7. However, personal items which may be contaminated with blood, including but not limited to razors, toothbrushes and sex toys, should not be shared.

Sexual Abstinence/Monogamous Relationships

1. Sexual abstinence (not engaging in anal, vaginal or oral intercourse or other sexual activities where blood, semen or vaginal fluid can enter the body) is a completely safe and 100% effective method for preventing the sexual transmission of HIV. 2. Non-penetrative sex, where the penis does not enter the vagina or anus, nor are penetrative sex toys shared, is a safer sex method that greatly decreases your risk of getting infected with HIV. 3. This practice will not transmit HIV, provided that there is no exchange of blood, semen, vaginal fluids or breast milk in the sexual contact. 4. Non-penetrative sexual intercourse may still be a risk factor for the transmission of other sexually transmitted diseases. 5. Monogamous long-term relationships (having sex with only one person who only has sex with you) is another choice to prevent/reduce the risk of HIV infection. 6. If neither partner is infected with HIV or other STDs, and neither has other sexual or injection equipment-sharing contacts, then neither partner is at risk of exposure to HIV or other STDs. 7. In order for monogamy to protect against HIV and STDs both partners must be free of disease and both partners must remain monogamous.

How HIV is Transferred During Drug Use

1. Sharing injection needles, syringes, etc. with an HIV-infected person can put HIV directly into the user's bloodstream and is the behavior which most efficiently transmits HIV, HBV and HCV. 2. Indirect sharing occurs when drug injectors share injection paraphernalia and/or divide a shared or jointly purchased drug while preparing and injecting it. 3. The paraphernalia that carries the potential for transmission are the syringe, needle, "cooker," cotton, and/or rinse water. sharing these items (sometimes called "works") may transmit HIV or other bacteria and viruses. 4. Example: Squirting the drug back (from a dirty syringe) into the drug cooker and/or someone else's syringe, or sharing a common filter and/or rinse water

How HIV is Transferred During Anal Sex?

1. Unprotected anal intercourse is considered to be the greatest sexual risk for transmitting HIV. 2. Anal intercourse frequently results in tears of mucous membranes, which makes it very easy for the virus to enter the bloodstream. The receptive partner ("bottom") is considered to be at more risk of getting HIV (if the virus is present.) 3. Risks may vary for the insertive ("top") partner.

The Following Activities can Cause HIV Transmission

1. Unprotected anal, vaginal, and oral intercourse 2. Sharing needles or other injection equipment 3. A mother passing the virus to her baby either before or during birth 4. An infected woman breastfeeding her infant 5. Accidental needle stick injuries, or infected body fluid 6. Coming into contact with the broken skin or mucous membranes of another person (as with healthcare workers) 7. A transfusion prior to 1986 of HIV-infected blood or blood products 8. In extremely rare cases, sharing razors or toothbrushes with infected individuals

Access to Blood

Access to another person's bloodstream involves behaviors or circumstances that place someone at risk for infectious fluid entering their bloodstream. The most common of the risk behaviors are: unprotected sexual intercourse (anal, vaginal, oral) with an infected person, and use of contaminated injection equipment for use in injecting drugs. HIV transmission may occur during practices such as tattooing, blood-sharing activities such as "blood brothers" rituals, or any other type of ritualistic ceremonies where blood is exchanged or unsterilized equipment contaminated with blood is shared. HIV transmission may also occur in non medical occupational settings.

HIV and Pregnancy

An HIV-infected woman may transmit the virus to her baby during pregnancy, during the birth process, and/or following pregnancy by breastfeeding. One of the predictors of how infectious the woman will be to her baby is her viral load (how much HIV is present in her bloodstream). Women with new or recent infections or people in later stages of AIDS tend to have higher viral loads and may be more infectious. In 1994, researchers discovered that a course of the antiretroviral drug AZT (zidovudine) significantly reduced the transmission of HIV from woman to baby. In 2002, medications such as AZT and others are used during pregnancy and delivery to prevent transmission of HIV

HIV Versus Hepatitis Viability

HIV is considered to be a fragile virus when exposed to air and room temperatures. Hepatitis B (HBV) and C (HCV) are both considered "stronger" viruses that can remain infectious for a longer period of time. When these viruses are outside the human body, much depends on environmental factors (heat, cold, exposure to oxygen, etc.).

HIV and Pregnancy Continued...

HIV is transmitted from an HIV-infected woman to her baby in about 25% of pregnancies if intervention with antiretroviral medications does not occur. The perinatal transmission rate has dropped dramatically in the U.S. due to the widespread use of AZT by HIV-infected pregnant women. When a woman's health care is monitored closely and she receives a combination of antiretroviral therapies during pregnancy the risk of HIV transmission to the newborn drops below 2 percent. In some pregnancies, caesarian section (C-section) may be recommended to reduce the risk of transmission from woman to baby. Advice about medications and C-section should be given on a case-by-case basis by a medical provider with experience in treating HIV+ pregnant women. Washington state law requires pregnant women to be counseled regarding risks around HIV and offered voluntary HIV testing.

Multiple Partners

Having "multiple partners" for drug injection and/or sexual intercourse increases the chances of being exposed to a person infected with HIV. Persons who have unprotected sex with multiple partners are considered to be at high risk for HIV infection. In some studies, the CDC defines multiple partners as six or more partners in a year. However, someone who has only one partner is still at risk if the person is HIV-positive and they have unprotected sex and/or share needles.

Gender and Equality Issues

Lack of power in a relationship can affect a person's ability to insist on sexual protection, such as the use of condoms. Women are often socially and economically dependent upon men in many countries. This can make them unable to ask their partner to use condoms or to leave a relationship that puts them at risk. In some cultures, females are not encouraged to learn about their bodies, sex, birth control, or other sexuality topics. Other cultures promote the value of the male having multiple sexual partners, while discouraging the same behavior in females.

HIV Infection is Lifelong

Once a person becomes infected with HIV, their blood, semen, vaginal secretions and/or breast milk will always be potentially infectious. There is evidence of transmission of multi-drug resistant forms of HIV. People who have been infected with HIV and have used a number of the available antiretroviral medicines may transmit forms of HIV that are resistant to some of these available drug therapies. This reduces the treatments available for the newly-HIV-infected person

HIV is not easy "to catch" It must be acquired

Source-An HIV source Dose-Sufficient dose of virus Access-Access to infected blood into the body through mucus membranes or cuts

STD's Increase Risk of Transmission Continued...

The presence of infection with other STDs increases the risk of HIV transmission because: 1. STDs like syphilis and symptomatic herpes can cause breaks in the skin, which provide direct entry for HIV 2. Inflammation from STDs, such as chlamydia, makes it easier for HIV to enter and infect the body 3. HIV is often detected in the pus or other discharge from genital ulcers from HIV-infected men and women 4. Sores can bleed easily and come into contact with vaginal, cervical, oral, urethral and rectal tissues during sex

STD's Increase Risk of Transmission

The presence of other sexually transmitted diseases (STDs) increases the risk for HIV transmission, because the infected person may have a much larger number of white blood cells (infected with HIV) present at the sore or infected area(s). The infected person's immune system may be less able to suppress or combat HIV infection. Sores or lesions from STDs break down the protective surface of the skin or mucous membrane, which makes the infected person more vulnerable to other infections.

How HIV is Transferred During Vaginal intercourse

The women is more at risk (Using a Condon can Save a Life) 1. Unprotected vaginal intercourse with the exchange of semen, pre-ejaculate fluid (pre-cum), menstrual blood or vaginal fluids is also a risk for HIV transmission. 2. Studies have shown that women are more likely to become infected with HIV through vaginal sex than men. 3. The larger amount of mucous membrane surface area of the vagina is a probable reason for women's greater rate of HIV infection from their male partners.

Unusual Cases of HIV Transmission

To date, there have been less than a dozen known cases of HIV transmission that have occurred in household settings in the U.S. and other countries. Reports of these cases have been thoroughly investigated by the CDC. The researchers determined that the transmissions were caused by sharing a razor contaminated with infected blood, the exposure of infected blood to cuts and broken skin, and possibly deep kissing involving a couple who both had bleeding gums and poor dental hygiene. It is important to remember that these cases were extremely unusual. Sensible precautions with bleeding wounds and cuts and not sharing personal hygiene items would have prevented these cases of infection. There are also isolated cases of transmission from health care workers to patients. To date, there were three instances where transmission of HIV could only be tracked to the HIV-infected doctor, dentist or nurse treating the patient. At least one of these cases occurred prior to the implementation of strict equipment disinfection.

Transmissionby Transfusions

Transmission by contaminated blood or blood products occurred in the United States before March, 1985 Testing for HIV at blood banks and organ transplant centers began in 1985 and has almost completely eliminated these risks for transmission in developed countries. In 1999, about 1% of national AIDS cases were caused by transfusions or use of contaminated blood products. The majority of those cases were in people who received blood or blood products before 1985. HIV. Your risk of getting HIV from a blood transfusion is lower than your risk of getting killed by lightning. Only about 1 in 2 million donations might carry HIV and transmit HIV if given to a patient. Hepatitis B and C. The risk of having a donation that carries hepatitis B is about 1 in 205,000. The risk for hepatitis C is 1 in 2 million. If you receive blood during a transfusion that contains hepatitis, you'll likely develop the virus.

Use of Non-injecting Drugs

Use of other substances, including alcohol and non-injected "street drugs," can also put a person at risk for getting HIV. These substances can impair judgment which can increase the likelihood that a person will take risks (having unprotected sex, sharing needles) or may place the person in unsafe situations. Additionally, some substances have physiological and biological effects on the body, including masking of pain and the creation of sores on the mouth and genitals, which can create additional "openings" for HIV and other sexually transmitted diseases

How do we practice safe sex?

When buying lube, it's important to find the right kind — one that works for you and one that works for your condom. Never use oil-based lube with a latex condom — it can break down latex. Use only water or silicone-based lube with latex. Read the package insert if you have any questions about what you can use.