As with other diseases, can an HIV-infected person can act as a carrier -- where the virus is present in the body but inactive? If so, does this affect whether the person can enjoy sex? Is there a way for an HIV-infected person to become a parent for a child without transmitting HIV?

Nick

A person who is a carrier of a disease has no symptoms, yet can pass the disease on to others. Although infectious diseases usually come to mind when people think of carriers, the term also can apply to genetic disorders where one or both parents each are carriers of a disease-linked genetic abnormality. In such cases, the parents are completely well, but their children could develop the disease.

There are many infectious diseases where a person can act as a carrier. One of the most famous examples of such a carrier was Typhoid Mary. She was notorious for infecting dozens of people with typhoid fever, despite the fact that she was not ill herself. Other common causes of the carrier state are hepatitis B virus and hepatitis C virus. Both of these viruses can cause acute and chronic hepatitis (liver inflammation), end-stage liver disease and liver cancer. However, many people unknowingly carry these viruses and can infect others.

When a person becomes infected with HIV, the virus that causes AIDS, it takes an average of 7-10 years before he or she develops certain kinds of infections or cancers that define the advanced stage of HIV infection we call AIDS. Many people have the impression that all HIV-infected patients will develop AIDS and die of their illness, but that is not always the case. It is true that before the availability of some of the newer anti-HIV drug regimens, the infection progressed to AIDS in more than 90 percent of patients. Without treatment, patients who develop AIDS almost certainly die from an infection or a malignancy.

However, there are some people called long-term non-progressors who do not progress to AIDS, despite many years of being infected with HIV. Many of them have a genetic abnormality that makes it more difficult for HIV to enter the virus's chief target, white blood cells called T cells. Because of this, the virus does not replicate efficiently and cannot easily infect new cells. As a result, the viral load, or the amount of virus in the person's blood, is very low. It is not known how long these people will continue to display no signs or symptoms of the illness, but they can be considered to be carriers of HIV. They are infected and can probably pass it on to others, but they do not become ill.

Anyone infected with HIV can transmit the virus to others through sexual intercourse. Many people with HIV do have sex. With condom use, the risk of transmission is low, especially if the infected person has a very low viral load. But the risk of transmission is never zero, even if the patient is receiving anti-HIV treatment.

Without treatment, about 25 percent of HIV-infected pregnant women will pass the virus to their babies. With treatment, the risk is far lower, around 5 percent. A prospective father with HIV can infect the baby indirectly, by infecting the mother through unprotected sex. If the man has an undetectable viral load from treatment, his risk of infecting his partner is low, but not zero. Whether the risks to partner and child are acceptable is up to each prospective parent.

Another option is IVF (in vitro fertilization), a fertility procedure that involves removing an egg surgically from the woman, fertilizing it with sperm from the man, and implanting the resulting embryo in the woman's uterus. In the case of an HIV-infected father, the sperm can be "washed" to remove viruses; this procedure is not foolproof, but it is relatively safe and carries little risk of infecting the mother.