Diseases & Conditions


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Human Immunodeficiency Virus (HIV) Infection


Human immunodeficiency virus (HIV) infection is a viral infection that progressively destroys certain white blood cells and causes acquired immunodeficiency syndrome (AIDS).

Only about 2% of the people infected with HIV in the United States are children or adolescents. Worldwide, HIV is a much more common problem in children.

There are two human immunodeficiency viruses—HIV-1 and HIV-2. Both progressively destroy certain types of white blood cells called lymphocytes, which are an important part of the body's immune defenses. When these lymphocytes are destroyed, the body becomes susceptible to attack by many other infectious organisms. Many of the symptoms and complications of HIV infection, including death, are the result of these other infections and not of the HIV infection itself. HIV infection may lead to various troublesome infections with organisms that do not ordinarily infect healthy people. These are termed opportunistic infections, and they may result from viruses, parasites, and—in children, unlike in adults—bacteria.

Acquired immunodeficiency syndrome (AIDS) is the most severe form of HIV infection. A child with HIV infection is considered to have AIDS when at least one complicating illness develops or when there is a significant decline in the body's ability to defend itself from infection.

Transmission of Infection

In young children, HIV infection is nearly always acquired from the mother. Less than 7% of children now living with AIDS acquired the infection from other sources, including blood transfusion (from blood products used to treat hemophilia) or sexual abuse. Because of improved safety measures in blood and blood products, very few current infections result from these mechanisms.

As many as 7,000 HIV-infected women give birth each year in the United States. Without preventive measures, 25 to 33% of them would transmit the infection to their baby. The risk is highest in mothers who acquire the infection during pregnancy, who have more virus in their bodies, or who are severely ill. Transmission often takes place during labor and delivery.

The virus also can be transmitted in breast milk—12 to 14% of babies not infected at birth acquire HIV infection if they breastfeed from an HIV-infected mother. Most often, transmission occurs in the first few weeks or months of life, although transmission may occur later. Transmission is more likely in mothers who acquire the infection while breastfeeding or who have infection of the breast (mastitis).

In adolescents, transmission is the same as in adults: through sexual intercourse—both heterosexual and homosexual—and through sharing of infected needles while injecting drugs.

The virus is not transmitted through food, water, household articles, or social contact in a home, workplace, or school. In very rare cases, HIV has been transmitted by contact with infected blood on the skin. In almost all such cases, the skin surface was broken by scrapes or open sores. Although saliva may contain the virus, transmission of infection by kissing or biting has never been confirmed.

Symptoms

Children born with HIV infection rarely have symptoms for the first few months. If the children remain untreated, only about 20% develop problems during the first or second year of life. For the remaining 80% of children, problems may not appear until age 3 or later even without treatment. With the use of effective anti-HIV drugs, children with HIV infection do not necessarily develop any signs or symptoms of HIV infection. The symptoms of HIV infection acquired during adolescence are similar to those in adults (see Human Immunodeficiency Virus HIV Infection: Symptoms ).

The first signs of HIV infection in children are usually slowed growth and a delay of maturation, recurring diarrhea, lung infections, or a fungal infection of the mouth (thrush). Sometimes children have repeated episodes of bacterial infections, such as a middle ear infection (otitis media), sinusitis, or pneumonia.

A variety of symptoms and complications can appear as the child's immune system deteriorates. About one third of HIV-infected children develop lung inflammation (lymphocytic interstitial pneumonitis), with cough and difficulty breathing.

Children born with HIV infection commonly have at least one episode of Pneumocystis pneumonia in the first 15 months of life if they are not receiving anti-HIV drugs. More than half of untreated children infected with HIV develop the pneumonia at some time. Pneumocystis pneumonia is a major cause of death among children and adults with AIDS.

In a significant number of HIV-infected children, progressive brain damage prevents or delays developmental milestones, such as walking and talking. These children also may have impaired intelligence and a head that is small in relation to their body size. Up to 20% of untreated infected children progressively lose social and language skills and muscle control. They may become partially paralyzed or unsteady on their feet, or their muscles may become somewhat rigid.

Anemia (a low red blood cell count) is common in HIV-infected children and causes them to become weak and tire easily. About 20% of untreated children develop heart problems, such as rapid or irregular heartbeat, or heart failure.

Less commonly, untreated children develop inflammation of the liver (hepatitis) or inflammation of the kidneys (nephritis). Cancers are uncommon in children with AIDS, but non-Hodgkin lymphoma and lymphoma of the brain may occur somewhat more often than in uninfected children. Kaposi's sarcoma, an AIDS-related cancer that affects the skin and internal organs, is extremely rare in children.

Diagnosis

The diagnosis of HIV infection among children begins with the identification of HIV infection in pregnant women through routine prenatal screening. Newborns of mothers with HIV infection or of mothers who are at risk for HIV infection because of lifestyle should be tested. The infants should be tested at frequent intervals—typically in the first 2 days of life, at about 1 month of age, and between 4 months and 6 months of age. Such frequent testing identifies most HIV-infected infants by 6 months of age.

In infants, the standard adult blood tests for HIV antibodies are not helpful, because an infant's blood almost always contains HIV antibodies if the mother is HIV-infected (even if the infant is not). To definitively diagnose HIV infection in children younger than 18 months of age, special blood tests (DNA polymerase chain reaction test) that identify the virus in the blood are used. The standard blood tests are used to diagnose HIV infection in children older than 18 months and in adolescents.

Once HIV infection has been diagnosed, doctors monitor the course of the infection by frequently measuring blood counts of CD4+ lymphocytes (which decrease with worsening infection) and taking counts of the number of virus particles in the blood (viral load, which increases with worsening infection).

Prevention

The most effective means of preventing infection in newborns is for HIV-infected women to avoid pregnancy. If an infected woman does become pregnant, anti-HIV drugs are fairly effective at minimizing transmission. Women who do not meet criteria for combination therapy with three anti-HIV drugs are given zidovudine (ZDV, also called AZT) by mouth during the 2nd and 3rd trimesters (last 6 months) of pregnancy; ZDV is also given intravenously during labor and delivery. ZDV is then given daily to the newborn for 6 weeks. This treatment reduces the rate of transmission from about 33% to about 8%. The rate is less than 2% in women receiving combination therapy. Also, cesarean delivery reduces the baby's risk of acquiring HIV infection.

In countries where good infant formulas and clean water are readily available, HIV-infected mothers should bottle-feed their babies and should be strongly discouraged from donating to milk banks. In countries where the risks of malnutrition or infectious diarrhea from unclean water are high, the benefits of breastfeeding outweigh the risk of HIV transmission.

Because a child's HIV status may not be known, all schools and day care centers should adopt special procedures for handling accidents, such as nosebleeds, and for cleaning and disinfecting surfaces contaminated with blood. During cleanup, personnel are advised to avoid having their skin come in contact with blood. Latex gloves should be routinely available, and hands should be washed after the gloves are removed. Contaminated surfaces should be cleaned and disinfected with a freshly prepared bleach solution containing 1 part of household bleach to 10 to 100 parts of water.

Prevention for adolescents is the same as for adults (see Human Immunodeficiency Virus HIV Infection: Prevention ). All adolescents should have access to HIV testing and should be taught how HIV is transmitted and how it can be avoided, including abstaining from sex or using safe-sex practices.

Prognosis

With current drug therapy, most children born today with HIV infection live well beyond age 5 and about 50% live beyond age 10. More and more children are surviving well into adolescence and early adulthood. The prognosis is worse for those in whom the virus is detected early (within the first week of life) or who develop symptoms in the first year of life.

Treatment

Drug Treatment: Children are treated with most of the same anti-HIV drugs as adults (see Human Immunodeficiency Virus HIV Infection: Treatment and Sexually Transmitted Diseases: Treatment ), typically a highly active antiretroviral therapy (HAART) combination of two or more reverse-transcriptase inhibitors and a protease inhibitor. However, not all of the drugs used for adults are available to small children, in part because some are not available in liquid form. It may be difficult for parents and children to follow complicated drug regimens, which can limit the effectiveness of therapy. In general, children develop the same types of side effects as adults but usually at a much lower rate; however, the side effects of drugs may also limit the treatment. A doctor monitors the effectiveness of treatment by regularly measuring the amount of virus present in the blood and the child's CD4+ cell count (see Human Immunodeficiency Virus HIV Infection: CD4 Count ). Increased numbers of virus in the blood may be a sign that the virus is developing resistance to the drugs or that the child is not taking the drugs. In either case, the doctor may need to change the drugs.

Prevention of Opportunistic Infections: To prevent Pneumocystis pneumonia, trimethoprim-sulfamethoxazole Some Trade Names BACTRIM SEPTRA is given to all children with proven HIV infection and a significantly impaired immune system, and to all infants who were born to HIV-infected women beginning at 4 to 6 weeks of age (continued until testing shows the infants are not infected). Children 5 years old and older who cannot tolerate trimethoprim-sulfamethoxazole Some Trade Names BACTRIM SEPTRA can be given pentamidine Some Trade Names NEBUPENT PENTAM 300 . Dapsone is an alternative drug for children younger than 5 years who cannot tolerate trimethoprim-sulfamethoxazole Some Trade Names BACTRIM SEPTRA .

Children with a significantly impaired immune system also are given azithromycin Some Trade Names ZITHROMAX or clarithromycin Some Trade Names BIAXIN to prevent Mycobacterium avium complex infection. Rifabutin Some Trade Names MYCOBUTIN is an alternative drug. Children with recurring bacterial infections may be given intravenous immune globulin once a month.

Vaccination: Nearly all HIV-infected children should receive the routine childhood vaccinations, including diphtheria, tetanus, and pertussis (DTaP); inactivated polio vaccine; Haemophilus influenzae ; Streptococcus pneumoniae ; and hepatitis B. Vaccines containing live viruses such as the oral polio virus, varicella, and measles-mumps-rubella can cause a severe or fatal illness in children with HIV whose immune system is very impaired. However, the measles-mumps-rubella vaccine and varicella vaccine are recommended for children with HIV infection whose immune system is not severely impaired. Yearly influenza immunization is also recommended for all HIV-infected children over 6 months of age. However, the effectiveness of any vaccination will be less in children with HIV infection.

Social Issues: For children who need foster care, child care, or schooling, a doctor can help assess the child's risk of exposure to infectious diseases. In general, transmission of infections, such as chickenpox, to the HIV-infected child (or to any child with an impaired immune system) is more of a danger than is transmission of HIV from that child to others. A young child with HIV infection who has open skin sores or who engages in potentially dangerous behavior, such as biting, should not attend child care.

HIV-infected children should participate in as many routine childhood activities as their physical condition allows. Interaction with other children enhances social development and self-esteem. Because of the stigma associated with the illness and the fact that transmission of the infection to other children is extremely unlikely, there is no need for anyone other than the parents, the doctor, and perhaps the school nurse to be aware of the child's HIV status.

As a child's condition worsens, treatment is best given in the least restrictive environment possible. If home health care and social services are available, the child can spend more time at home rather than in a hospital.

Last full review/revision May 2007 by Mary T. Caserta, MD

Source: The Merck Manual Home Edition