HIV and STIs: The Basics

Sexually transmitted infections (STIs), also known as sexually transmitted diseases (STDs) or venereal diseases (VDs), are infections that are spread by sex — including vaginal, anal and oral sex — with an infected partner. STIs often are asymptomatic, meaning that people who have an STI may have no visible signs of infection in the early stages and may not know they are infected.

The most common STIs are syphilis, chlamydia, gonorrhea, genital warts, genital herpes, and Human Immunodeficiency Virus (HIV). Left untreated, HIV can progress to Autoimmune Deficiency Syndrome (AIDS).

HIV/AIDS was first seen in Michigan in 1981. Like most other STIs, HIV is on the list of mandatory reportable conditions in Michigan. Health care providers and local health departments report HIV and other STIs using a web-based tool known as the Michigan Disease Surveillance System (MDSS).

STIs are a danger to everyone who has sex, even once. They are transmitted during vaginal, oral, and anal sex. They also can be passed from a mother to her unborn child or from an infected person who shares a needle or syringe for drug use, tattooing, piercing, or other activity with another person. If left untreated, STIs can result in serious negative health outcomes, including:

  • sterility in men;
  • infertility in women;
  • increased risk for certain types of cancer;
  • pelvic inflammatory disease in women;
  • brain damage;
  • heart disease;
  • birth defects;
  • low birth weight;
  • premature birth;
  • blindness; and/or
  • death.

Having any STI can break down the body's natural defense system and increase a person's risk of getting HIV. In addition, any sore or break in skin or a mucous membrane can provide a way for HIV to enter the body.

How Are HIV and Other STIs Spread?

STIs, including HIV, are spread through contact with infected body fluids, such as blood (including menstrual blood and any blood in saliva, urine, and feces), semen (“cum”) and other male sexual fluids (“pre-cum”), vaginal secretions, and breast milk. STIs also can be transferred through contact with infected skin or breaks in mucous membranes, such as sores or lesions in the mouth or genital area.

Activities that expose you to infected body fluids or skin include:

  • vaginal, anal or oral sex without proper use of a condom or other barrier method; and
  • sharing needles or syringes for drug use, tattooing, piercing, etc.

Anal or rough sex are especially risky, because they often can cause tearing or bleeding.

In addition, health care providers and medical lab workers can be at risk if they come into contact with other body fluids, such as cerebrospinal fluid around the brain and spinal cord, synovial fluid around the joints, and/or amniotic fluid around a developing fetus. Most other people do not come into contact with these fluids.

Most Activities Don't Spread HIV and Other STIs

You cannot become infected with HIV or another STI from everyday, non-sexual activities, such as:

  • giving blood;
  • sitting next to, or touching, an infected person;
  • sharing eating utensils with an infected person;
  • sitting on a toilet seat; or
  • swimming in a pool.

How HIV Works

HIV attacks the body's immune system, specifically a certain type of white blood cells called CD4 cells (also known as T cells).1 Over time, the virus destroys so many CD4 cells that the body is left without enough defenses to fight off infections and disease. That's why PLWH have regular doctor visits to monitor their viral load and CD4 cell count.

CD4 counts are measured as the number of CD4 cells in a millimeter of blood. Normally, the body has a CD4 cell count between 500 and 1,500. But, as HIV progresses, a person's CD4 count falls. If the CD4 count drops below 200, the person receives a diagnosis of AIDS. The goal of medical care for PLWH is to achieve viral suppression, a status in which the measurable virus level in their blood is 200 or lower. PLWH who are virally suppressed can maintain a higher CD4 cell count and, as a result, will have better immune health and be less likely to transmit the virus to their partners.

Doctors prescribe antiretroviral (ARV) medications to lower a person's viral load. ARVs target HIV and suppress its ability to replicate and invade blood cells. They are effective, but they are also relatively expensive. PLWHs can get help paying for medications and medical care visits through the Ryan White HIV/AIDS Program (RWHAP) and the Michigan Drug Assistance Program (MIDAP).

How Can You Avoid STIs and HIV?

There are safe alternatives to vaginal, anal or oral sex. For example:

  • Avoiding sex. Abstinence from sex is the only sure way to avoid infection.
  • Kissing. This can be a safe way to be physically close/intimate, as long as both partners are free of sores in the mouth.
  • Massage. Caressing and stroking can express affection and give pleasure.
  • Masturbation. Masturbation alone or with your partner (on unbroken skin) can provide sexual pleasure safely.
  • Fantasy. The brain is one of the most powerful sex organs. Use your imagination.
  • If you have sex, have sex with one partner who:
    • is only having sex with you, and
    • does not have an STI, including HIV.

If you are not in a monogamous relationship, be sure to:

  • Use barrier methods like condoms. Used consistently and correctly, condoms are your best protection from infection. But, remember: Even condoms are not 100 percent effective at protecting you.
  • Limit the number of partners you have. The more partners you have, the greater your risk of exposure. Remember: You can’t tell if someone has HIV or another STI just by looking at them.
  • Have regular physical exams and ask your health care provider to be tested for HIV and STIs.
  • Talk with your health care provider to find out if you would be a good candidate for PrEP.

If you think you’ve been exposed, get tested right away! Early care and treatment is most effective.

Getting Tested

Local health departments across Michigan distribute condoms and perform HIV and STI testing. Local health staff also follow up with people who are newly diagnosed with HIV and/or syphilis to help them understand the importance of immediate treatment and to offer them partner services, including referrals for case management and/or medical care, risk reduction counseling, and partner notification.

Once a person has tested positive, notifying his or her sexual and/or needle sharing partners of their possible exposure enables them to take advantage of testing and possible treatment, reducing their risk of becoming infected (and possibly transmitting the infection to others).

PrEP, PEP and nPEP: Helping Prevent Infection Medically

Although prevention of new infections is best achieved by safe sex practices, new medications are also available that can help prevent infection with HIV.

Pre-exposure prophylaxis (PrEP) is a once-a-day pill that can be taken by people who have tested negative for HIV and wish to maintain their negative status. When taken daily, PrEP is nearly 90 percent effective at preventing HIV infection.

Medication also can be taken following a possible exposure to HIV to help prevent transmission of the virus. In such cases, the medications are referred to as post-exposure prophylaxis (PEP) or non-occupational post-exposure prophylaxis (n-PEP). PrEP, PEP and nPEP can be prescribed by a doctor or a nurse practitioner.

The Status of HIV in Michigan

The number of new cases (incidence) of HIV in Michigan has remained stable since 2000, but the number of persons living with HIV (prevalence) has increased. That rise in prevalence can be traced to new medications and standards of care that have made HIV a manageable, chronic condition and led to a sharp decline in the death rate among persons living with HIV (PLWH).

MDHHS Division of HIV and STI Programs – Surveillance and Epidemiology Section tracks the frequencies and proportions of PLWH in Michigan that are in selected stages of HIV care (Infected with HIV, Diagnosed with HIV, In Care for HIV, and Virally Suppressed).

The team issues an annual Michigan HIV Care Continuum (also known as the HIV Treatment Cascade) report. That and other data and analyses about HIV in Michigan can be found on our Data & Statistics page.


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1 Definitions of HIV-related terms can be found in the Understanding HIV/AIDS Glossary, a resource of the U.S. Department of Health and Human Services HIVinfo project.