Human Immunodeficiency Virus (HIV) Infection

Sexual practices such as fellatio and cunnilingus appear to be relatively low risk but not absolutely safe (see table HIV Transmission Risk for Several Sexual Activities HIV Transmission Risk for Several Sexual Activities ). Risk does not increase significantly if semen or vaginal secretions are swallowed. However, open sores in the mouth may increase risk.

The sexual practices with the highest risks are those that cause mucosal trauma, typically intercourse. Anal-receptive intercourse poses the highest risk. Mucous membrane inflammation facilitates HIV transmission; sexually transmitted infections, such as gonorrhea, chlamydial infection, trichomoniasis, and especially those that cause ulceration (eg, chancroid, herpes, syphilis), increase the risk several-fold. Other practices that cause mucosal trauma include fisting (inserting most or all of the hand into the rectum or vagina) and using sexual toys. When used during intercourse with an HIV-infected partner and/or with multiple concurrent sex partners, these practices increase the risk of HIV transmission.

In heterosexuals, the estimated risk per coital act is about 1/1000; however, risk is increased in the following:

Circumcision seems to reduce the risk of males acquiring HIV infection by about 50% by removing the penile mucosa (underside of foreskin), which is more susceptible to HIV infection than the keratinized, stratified squamous epithelium that covers the rest of the penis.

Recent evidence shows that HIV infected people in whom antiretroviral therapy has reduced their viral load below the current detectable level (virally suppressed) do not sexually transmit the virus to their partners. Undetectable virus equals an untransmittable virus.

Risk of HIV transmission after skin penetration with a medical instrument contaminated with infected blood is on average about 1/300 without postexposure antiretroviral prophylaxis. Immediate prophylaxis probably reduces risk to < 1/1500. Risk appears to be higher if the wound is deep or if blood is inoculated (eg, with a contaminated hollow-bore needle). Risk is also increased with hollow-bore needles and with punctures of arteries or veins compared with solid needles or other penetrating objects coated with blood because larger volumes of blood may be transferred. Thus, sharing needles that have entered the veins of other injection drug users is a very high risk activity.

Risk of transmission from infected health care practitioners who take appropriate precautions is unclear but appears minimal. In the 1980s, one dentist transmitted HIV to ≥ 6 of his patients by unknown means. However, extensive investigations of patients cared for by other HIV-infected physicians, including surgeons, have uncovered few other cases.

HIV can be transmitted from mother to offspring

Without treatment, risk of transmission at birth is about 25 to 35%.

HIV is excreted in breast milk, and breastfeeding by untreated HIV-infected mothers may transmit HIV to about 10 to 15% of infants who had previously escaped infection.

Transmission rates can be reduced dramatically by treating HIV-positive mothers with antiretroviral drugs while they are pregnant, in labor, and breastfeeding.

Cesarean delivery and treatment of the infant for several weeks after birth also reduce the risk.

Because many HIV-positive pregnant women are treated or take prophylactic drugs, the incidence of AIDS in children is decreasing in many countries (see Human Immunodeficiency Virus (HIV) Infection in Infants and Children Human Immunodeficiency Virus (HIV) Infection in Infants and Children Human immunodeficiency virus (HIV) infection is caused by the retrovirus HIV-1 (and less commonly by the related retrovirus HIV-2). Infection leads to progressive immunologic deterioration and... read more ).

Screening of blood donors with tests for both antibody to HIV and HIV RNA has minimized risk of transmission via transfusion. Current risk of transmitting HIV via blood transfusion is probably < 1/2,000,000 per unit transfused in the United States. However, in many developing countries, where blood and blood products are not screened for HIV, the risk of transfusion-transmitted HIV infection remains high.

Rarely, HIV has been transmitted via transplantation of organs from HIV-seropositive donors. Infection has developed in recipients of kidney, liver, heart, pancreas, bone, and skin—all of which contain blood—but screening for HIV greatly reduces risk of transmission. HIV transmission is even more unlikely from transplantation of cornea, ethanol-treated and lyophilized bone, fresh-frozen bone without marrow, lyophilized tendon or fascia, or lyophilized and irradiated dura mater.

HIV transmission is possible via artificial insemination using sperm from HIV-positive donors. Some cases of infection occurred in the early 1980s, before safeguards were introduced.

In the United States, sperm washing is considered an effective method of reducing the risk of partner insemination from a known HIV-positive sperm donor.

Two main consequences of HIV infection are

CD4+ lymphocytes are involved in cell-mediated and, to a lesser extent, humoral immunity. CD4+ depletion may result from the following:

Infected CD4+ lymphocytes have a half-life of about 2 days, which is much shorter than that of uninfected CD4+ cells. Rates of CD4+ lymphocyte destruction correlate with plasma HIV level. Typically, during the initial or primary infection, HIV levels are highest (> 10⁶ copies/mL), and the CD4 count drops rapidly.

The normal CD4 count is about 750/mcL, and immunity is minimally affected if the count is > 350/mcL. If the count drops below about 200/mcL, loss of cell-mediated immunity allows a variety of opportunistic pathogens to reactivate from latent states and cause clinical disease.

The humoral immune system is also affected. Hyperplasia of B cells in lymph nodes causes lymphadenopathy, and secretion of antibodies to previously encountered antigens increases, often leading to hyperglobulinemia. Total antibody levels (especially IgG and IgA) and titers against previously encountered antigens may be unusually high. However, antibody response to new antigens (eg, in vaccines) decreases as the CD4 count decreases.

Abnormal elevation of immune activation may be caused in part by absorption of components of bowel bacteria. Immune activation contributes to CD4+ depletion and immunosuppression by mechanisms that remain unclear.

HIV also infects nonlymphoid monocytic cells (eg, dendritic cells in the skin, macrophages, brain microglia) and cells of the brain, genital tract, heart, and kidneys, causing disease in the corresponding organ systems.

HIV strains in several compartments, such as the nervous system (brain and cerebrospinal fluid) and genital tract (semen, cervico-vaginal fluid), can be genetically distinct from those in plasma, suggesting that they have been selected by or have adapted to these anatomic compartments (2-4 Pathophysiology references Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more ). Thus, HIV levels and resistance patterns in these compartments may vary independently from those in plasma.

During the first few weeks of primary infection, there are humoral and cellular immune responses:

Plasma HIV virion levels, expressed as number of HIV RNA copies/mL, stabilize after about 6 months at a level (set point) that varies widely among patients but averages 30,000 to 100,000/mL (4.2 to 5 log₁₀/mL). The higher this set point, the more quickly the CD4 count decreases to a level that seriously impairs immunity (< 200/mcL) and results in the opportunistic infections and cancers that define AIDS (5-6 Pathophysiology references Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more ).

Risk and severity of opportunistic infections, AIDS, and AIDS-related cancers Cancers Common in HIV-Infected Patients AIDS-defining cancers in HIV-infected patients are Kaposi sarcoma Lymphoma, Burkitt (or equivalent term) Lymphoma, immunoblastic (or equivalent term) Lymphoma, primary, of central nervous system read more are determined by 2 factors:

Risk of specific opportunistic infections increases below threshold CD4 counts of about 200/mcL for some infections and 50/mcL for others, as in the following:

For every 3-fold (0.5 log₁₀) increase in plasma HIV RNA in untreated patients, risk of progression to AIDS or death over the next 2 to 3 years increases about 50% (6 Pathophysiology references Human immunodeficiency virus (HIV) infection results from 1 of 2 similar retroviruses (HIV-1 and HIV-2) that destroy CD4+ lymphocytes and impair cell-mediated immunity, increasing risk of certain... read more ).

Without treatment, risk of progression to AIDS is about 1 to 2%/year in the first 2 to 3 years of infection and about 5 to 6%/year thereafter. Eventually, AIDS almost invariably develops in untreated patients.

Initially, primary HIV infection may be asymptomatic or cause transient nonspecific symptoms (acute retroviral syndrome).

Acute retroviral syndrome usually begins within 1 to 4 weeks of infection and usually lasts 3 to 14 days. Symptoms and signs are often mistaken for infectious mononucleosis or benign, nonspecific viral syndromes and may include fever, malaise, fatigue, several types of dermatitis, sore throat, arthralgias, generalized lymphadenopathy, and septic meningitis.

After the first symptoms disappear, most patients, even without treatment, have no symptoms or only a few mild, intermittent, nonspecific symptoms for a highly variable time period (2 to 15 years).

Symptoms during this relatively asymptomatic period may result from HIV directly or from opportunistic infections. The following are most common:

Asymptomatic, mild-to-moderate cytopenias (eg, leukopenia, anemia, thrombocytopenia) are also common. Some patients experience progressive wasting (which may be related to anorexia and increased catabolism due to infections) and low-grade fevers or diarrhea.

When the CD4 count drops to < 200/mcL, nonspecific symptoms may worsen and a succession of AIDS-defining illnesses develop (see sidebar AIDS-Defining Illnesses AIDS-Defining Illnesses ).

In patients with HIV infection, certain syndromes are common and may require different considerations (see table Common Manifestations of HIV Infection by Organ System Common Manifestations of HIV Infection by Organ System ). Some patients present with cancers (eg, Kaposi sarcoma, B-cell lymphomas) that occur more frequently, are unusually severe, or have unique features in patients with HIV infection (see Cancers Common in HIV-Infected Patients Cancers Common in HIV-Infected Patients AIDS-defining cancers in HIV-infected patients are Kaposi sarcoma Lymphoma, Burkitt (or equivalent term) Lymphoma, immunoblastic (or equivalent term) Lymphoma, primary, of central nervous system read more ). In other patients, neurologic dysfunction may occur.

Evaluation may detect infections that do not typically occur in the general population, such as

Infections that also occur in the general population but suggest AIDS if they are unusually severe or frequently recur include

Detection of antibodies to HIV is sensitive and specific except during the first few weeks after infection (termed the "window period" of acute HIV infection). However, the HIV p24 antigen (a core protein of the virus) is already present in the blood during most of this time and can be detected by assays. Currently, a 4th-generation antigen/antibody combination immunoassay is recommended; it detects antibodies to both HIV-1 and HIV-2 as well as the p24 HIV antigen. The laboratory version is probably preferred over the point-of-care one for diagnosing early infection, but both can be done quickly (within 30 minutes). If the test result is positive, an assay to differentiate HIV-1 and HIV-2 and an HIV RNA assay are done.

Earlier-generation enzyme-linked immunosorbent assay (ELISA) antibody assays are highly sensitive, but because they do not test for antigen, they are not positive as early as the 4th-generation combination test. Also, results are rarely false-positive. Positive ELISA results are therefore confirmed with a more specific test such as Western blot. However, these tests have drawbacks:

Newer point-of-care tests using blood or saliva (eg, particle agglutination, immunoconcentration, immunochromatography) can be done quickly (in 15 minutes) and simply, allowing testing in a variety of settings and immediate reporting to patients. Positive results of these rapid tests should be confirmed by standard blood tests (eg, ELISA with or without Western blot) in developed countries and repetition with one or more other rapid tests in developing countries. Negative tests need not be confirmed.

If HIV infection is suspected despite negative antibody test results (eg, during the first few weeks after infection), the plasma HIV RNA level may be measured. The nucleic acid amplification assays used are highly sensitive and specific. HIV RNA assays require advanced technology, such as reverse transcription–polymerase chain reaction (RT-PCR), which is sensitive to extremely low HIV RNA levels. Measuring p24 HIV antigen by ELISA is less sensitive and less specific than directly detecting HIV RNA in blood.

When HIV is diagnosed, the following should be determined:

Both are useful for determining prognosis and monitoring treatment.

The CD4 count is calculated as the product of the following:

Using the numbers above, the CD4 count (4000 x 0.3 x 0.2) is 240 cells/mcL, or about 1/3 of the normal CD4 count in adults, which is about 750 ± 250/mcL.

Plasma HIV RNA level (viral load) reflects HIV replication rates. The higher the set point (the relatively stable virus levels that occur after primary infection), the more quickly the CD4 count decreases and the greater the risk of opportunistic infection, even in patients without symptoms.

Baseline HIV genotype can be determined using a sample of blood; availability of this testing varies by location. HIV genotyping is used to identify mutations known to cause resistance to certain antiretroviral drugs and to help select a drug regimen likely to be effective for a specific patient with HIV infection.

HIV infection can be staged based on the CD4 count. In patients ≥ 6 years old, stages are as follows:

The CD4 count after 1 to 2 years of treatment provides an indication of ultimate immune recovery; CD4 counts may not return to the normal range despite prolonged suppression of HIV.

Diagnosis of the various opportunistic infections, cancers, and other syndromes that occur in HIV-infected patients is discussed elsewhere in The Manual. Many have aspects unique to HIV infection.

Hematologic disorders (eg, cytopenias, lymphomas, cancers) are common and may be usefully evaluated with bone marrow aspiration and biopsy. This procedure can also help diagnose disseminated infections with MAC, M. tuberculosis, Cryptococcus, Histoplasma, human parvovirus B19, P. jirovecii, and Leishmania. Most patients have normocellular or hypercellular marrow despite peripheral cytopenia, reflecting peripheral destruction. Iron stores are usually normal or increased, reflecting anemia of chronic disease (an iron-reutilization defect). Mild to moderate plasmacytosis, lymphoid aggregates, increased numbers of histiocytes, and dysplastic changes in hematopoietic cells are common.

HIV-associated neurologic syndromes can be differentiated via lumbar puncture with cerebrospinal fluid analysis and contrast-enhanced CT or MRI (see table Common Manifestations of HIV Infection by Organ System Common Manifestations of HIV Infection by Organ System ).

Screening antibody tests or newer combination antigen/antibody tests should be offered routinely to adults and adolescents, particularly pregnant women, regardless of their perceived risk. For people at highest risk, especially sexually active people who have multiple partners and who do not practice safe sex, testing should be repeated every 6 to 12 months. Such testing is confidential and available, often free of charge, in many public and private facilities throughout the world.

The World Health Organization suggests that in low and middle-income countries HIV testing be done using a combination of 2 different rapid antibody tests (see Consolidated guidelines on HIV testing services, July 2015). Rapid tests have the advantage of offering preliminary test results at the initial encounter in less than 25 minutes. They are especially useful for people who are unlikely to return for their test results. People receiving HIV testing should also be provided information on prevention, care, and treatment services (including links to online resources when appropriate).

ART aims to

A poor CD4 count response is more likely if the CD4 count at initiation of treatment is low (especially if < 50/mcL) and/or the HIV RNA level is high. However, marked improvement is likely even in patients with advanced immunosuppression. An increased CD4 count correlates with markedly decreased risk of opportunistic infections, other complications, and death. With immune restoration, patients, even those with complications that have no specific treatment (eg, HIV-induced cognitive dysfunction) or that were previously considered untreatable (eg, progressive multifocal leukoencephalopathy), may improve. Outcomes are also improved for patients with cancers (eg, lymphoma, Kaposi sarcoma) and most opportunistic infections.

ART can usually achieve its goals if patients take their drugs > 95% of the time. However, maintaining this degree of adherence is difficult. Partial suppression (failure to lower plasma HIV RNA levels to undetectable levels) may select for single or multiple accumulated mutations in HIV that make viruses partially or completely resistant to a single drug or entire classes of drugs. Unless subsequent treatment uses drugs of other classes to which HIV remains sensitive, treatment is more likely to fail.

Patients with most acute opportunistic infections benefit from early ART (initiated during the management of the opportunistic infection). However, for some opportunistic infections, such as tuberculous meningitis or cryptococcal meningitis, the evidence suggests that ART should be delayed until the first phase of antimicrobial therapy for these infections is finished because of the increased frequency of adverse events and death.

The success of ART is assessed by measuring plasma HIV RNA levels every 8 to 12 weeks for the first 4 to 6 months or until HIV levels are undetectable and every 3 to 6 months thereafter. Increasing HIV levels are the earliest evidence of treatment failure and may precede a decreasing CD4 count by months. Maintaining patients on failing drug regimens selects for HIV mutants that are more drug-resistant. However, compared with wild-type HIV, these mutants appear less able to reduce the CD4 count, and failing drug regimens are often continued when no fully suppressive regimen can be found.

If treatment fails, drug susceptibility (resistance) assays can determine the susceptibility of the dominant HIV strain to all available drugs. Genotypic and phenotypic assays are available and can help clinicians select a new regimen that should contain at least 2 and preferably 3 drugs to which the HIV strain is more susceptible. The dominant HIV strain in the blood of patients who are taken off antiretroviral therapy may revert over months to years to the wild-type (ie, susceptible) strain because the resistant mutants replicate more slowly and are replaced by the wild type. Thus, if patients have not been treated recently, the full extent of resistance may not be apparent through resistance testing, but when treatment resumes, strains with resistance mutations often reemerge from latency and again replace the wild-type HIV strain.

Many patients living with HIV infection are taking complex regimens involving multiple pills to control the HIV RNA level (viral load), but often, no conventional HIV RNA resistance tests were done when viral treatment failed. With the availability of new co-formulated HIV drugs, many patients could benefit from simplification of their ART regimen, guided by HIV DNA archive genotype testing (GenoSure Archive). The HIV DNA genotype archive provides HIV-1 antiretroviral drug resistance data when conventional HIV RNA resistance testing cannot be done because patients have a low plasma HIV RNA level (< 500 copies/mL). The HIV DNA archive genotype test analyzes integrated and unintegrated archived HIV-1 proviral DNA embedded in host cells. The test amplifies cell-associated HIV-1 DNA from infected cells in whole blood samples, then uses next-generation sequencing technology to analyze the HIV-1 polymerase region. The positive predictive value of the HIV DNA archive resistance test results may enable clinicians to identify HIV-resistance mutations that were previously unidentified and to select a potentially simpler regimen with co-formulated drugs (≥ 2 drugs in a single pill).

Patients beginning ART sometimes deteriorate clinically, even though HIV levels in their blood are suppressed and their CD4 count increases, because of an immune reaction to subclinical opportunistic infections or to residual microbial antigens after successful treatment of opportunistic infections. IRIS usually occurs in the first months of treatment but is occasionally delayed. IRIS can complicate virtually any opportunistic infection and even tumors (eg, Kaposi sarcoma) but is usually self-limited or responds to brief regimens of corticosteroids.

IRIS has two forms:

Paradoxical IRIS typically occurs during the first few months of treatment and usually resolves on its own. If it does not, corticosteroids, given for a short time, are often effective. Paradoxical IRIS is more likely to cause symptoms and symptoms are more likely to be severe when ART is started soon after treatment of an opportunistic infection is started. Thus, for some opportunistic infections, ART is delayed until treatment of the opportunistic infection has reduced or eliminated the infection.

In patients with unmasked IRIS, the newly identified opportunistic infection is treated with antimicrobial drugs. Occasionally, when the symptoms are severe, corticosteroids are also used. Usually, when unmasked IRIS occurs, ART is continued. An exception is cryptococcal meningitis. Then ART is temporarily interrupted until the infection is controlled.

Determining whether clinical deterioration is caused by treatment failure, IRIS, or both requires assessment of the persistence of active infections with cultures and can be difficult.

Interruption of ART is usually safe if all drugs are stopped simultaneously, but levels of slowly metabolized drugs (eg, nevirapine) may remain high and thus increase the risk of resistance. Interruption may be necessary if intervening illnesses require treatment or if drug toxicity is intolerable or needs to be evaluated. After interruption to determine which drug is responsible for toxicity, clinicians can safely restart most drugs as monotherapy for up to a few days. NOTE: The most important exception is abacavir; patients who had fever or rash during previous exposure to abacavir may develop severe, potentially fatal hypersensitivity reactions with reexposure. Risk of an adverse reaction to abacavir is 100-fold higher in patients with HLA-B*57:01, which can be detected by genetic testing.

Although antiretroviral therapy has dramatically increased life expectancy for patients with AIDS, many patients still deteriorate and die. Death may result from the following:

Death is rarely sudden; thus, patients usually have time to make plans. Nonetheless, patients should record their plans for health care early, with clear instructions for end-of-life care. Other legal documents, including powers of attorney Durable power of attorney for health care Advance directives are legal documents that extend a person's control over health care decisions in the event that the person becomes incapacitated. They are called advance directives because... read more and wills, should be in place. These documents are particularly important for those patients whose partners, loved ones, or caregivers are not legally recognized, which may result in those partners or other loved ones being unable to visit or be involved in decision-making or carry out funeral and burial wishes, being excluded from inheriting assets, possibly including the family home, or other dire consequences.

As patients near the end of life The Dying Patient Dying patients can have needs that differ from those of other patients. So that their needs can be met, dying patients must first be identified. Before death, patients tend to follow 1 of 3... read more , clinicians may need to prescribe drugs to relieve pain, anorexia, agitation, and other distressing symptoms. The profound weight loss in many people during the last stages of AIDS makes good skin care difficult. The comprehensive support provided by hospice programs helps many patients because hospice providers are unusually skilled at symptom management, and they support caregivers and patient autonomy.

Vaginal microbicides (including antiretroviral drugs) inserted before sexual contact have thus far proved ineffective, and some appear to increase risk for women, perhaps by damaging natural barriers to HIV.

Effective measures include the following:

Potential consequences of exposure to HIV have prompted the development of policies and procedures, particularly preventive treatment, to decrease risk of infection to health care workers.

Preventive treatment is indicated after

Body fluids such as saliva, urine, tears, nasal secretions, vomitus, or sweat are not considered potentially infectious unless they are visibly bloody.

After initial exposure to blood, the exposed area is immediately cleaned with soap and water for skin exposures and with antiseptic for puncture wounds. If mucous membranes are exposed, the area is flushed with large amounts of water.

The following are documented:

Type of exposure is defined by

Risk of infection is about 0.3% (1:300) after a typical percutaneous exposure and about 0.09% (1:1100) after mucous membrane exposure. These risks vary, reflecting the amount of HIV transferred to the person with the injury; the amount of HIV transferred is affected by multiple factors, including viral load of the source and type of needle (eg, hollow or solid). However, these factors are no longer taken into account in PEP recommendations.

The source is qualified by whether it is known or unknown. If the source is unknown (eg, a needle on the street or in a sharps disposal container), risk should be assessed based on the circumstances of the exposure (eg, whether the exposure occurred in an area where injection drug use is prevalent, whether a needle discarded in a drug-treatment facility was used). If the source is known but HIV status is not, the source is assessed for HIV risk factors, and prophylaxis is considered (see table Postexposure Prophylaxis Recommendations Postexposure Prophylaxis (PEP) Recommendations ).

The goal is to start PEP as soon after exposure as possible if prophylaxis is warranted. CDC recommends providing PEP within 24 to 36 hours after exposure; a longer interval after exposure requires the advice of an expert.

Use of PEP is determined by risk of infection; guidelines recommend antiretroviral therapy with ≥ 3 antiretroviral drugs given for 28 days. The drugs should be carefully selected to minimize adverse effects and provide a convenient dosing schedule and thus encourage PEP completion. Preferred regimens include a combination of 2 NRTIs and an integrase inhibitor, either raltegravir or dolutegravir. In patients with childbearing potential, raltegravir is preferred because dolutegravir is possibly teratogenic during the first trimester of pregnancy—this is under epidemiologic investigation. Alternative regimens include 2 NRTIs plus a protease inhibitor. For detailed recommendations, see the CDC's Updated Guidelines for Antiretroviral Postexposure Prophylaxis After Sexual, Injection Drug Use, or Other Nonoccupational Exposure to HIV—United States, 2016 and Interim Statement Regarding Potential Fetal Harm from Exposure to Dolutegravir – Implications for HIV Post-exposure Prophylaxis (PEP).

If the source’s virus is known or suspected to be resistant to ≥ 1 drug, an expert in antiretroviral therapy and HIV transmission should be consulted. However, clinicians should not delay PEP pending expert consultation or drug susceptibility testing. Also, clinicians should provide immediate evaluation and face-to-face counseling and not delay follow-up care.

(See also the United States Public Health Service and the HIV Medicine Association of the Infectious Diseases Society of America’s Guidelines for Prevention and Treatment of Opportunistic Infections in HIV-Infected Adults and Adolescents.)

Effective chemoprophylaxis is available for many opportunistic infections and reduces rates of disease due to P. jirovecii, Candida, Cryptococcus, and MAC. If therapy restores CD4 counts to above threshold values for > 3 months, chemoprophylaxis can be stopped.

Primary prophylaxis depends on the CD4 count:

If latent tuberculosis Tuberculosis (TB) Tuberculosis is a chronic, progressive mycobacterial infection, often with an asymptomatic latent period following initial infection. Tuberculosis most commonly affects the lungs. Symptoms include... read more is suspected (based on tuberculin skin tests, interferon-gamma release assays, high-risk exposure, personal history of active tuberculosis, or residence in a region with high tuberculosis prevalence), regardless of CD4 count, patients should be given isoniazid 5 mg/kg (up to 300 mg) orally once/day plus pyridoxine (vitamin B6) 10 to 25 mg orally once/day for 9 months to prevent reactivation.

For primary prophylaxis against some fungal infections (eg, esophageal candidiasis, cryptococcal meningitis or pneumonia), oral fluconazole 100 to 200 mg once/day or 400 mg weekly is successful but is infrequently used because the cost per infection prevented is high and diagnosis and treatment of these infections are usually successful.

Secondary prophylaxis (after control of the initial infection) is indicated if patients have had the following:

Detailed guidelines for prophylaxis of fungal (including Pneumocystis), viral, mycobacterial, and toxoplasmic infections are available at ClinicalInfo.

The CDC 2020 recommendations for vaccination of HIV-infected patients include the following:

Generally, inactivated vaccines should be used. These vaccines are effective less often in patients who are HIV-positive than in those who are HIV-negative.

The herpes zoster vaccine Herpes Zoster Vaccine Chickenpox (varicella) and shingles ( herpes zoster) are caused by the varicella-zoster virus; chickenpox is the acute invasive phase of the virus, and shingles represents reactivation of the... read more (for boosting immunity to prevent reactivation as zoster) could be useful in HIV-infected adults. The original live-attenuated zoster vaccine is contraindicated in patients with a weakened immune system and if the CD4 count is < 200/mcL. However, the newer recombinant zoster vaccine is not contraindicated in patients with HIV. The US Department of Health and Human Services recommends that adults with HIV age ≥ 50 years receive the recombinant zoster vaccine, but the Advisory Committee on Immunization Practices (ACIP) has yet to formally recommend vaccination to prevent herpes zoster in people with HIV (see CDC 2020 Adult Conditions Immunization Schedule).

Because live-virus vaccines are potentially dangerous for patients with severe immunosuppression, expert opinion should be sought when dealing with patients at risk of primary varicella; recommendations vary (see vaccination information in HIV in Infants and Children Vaccination Human immunodeficiency virus (HIV) infection is caused by the retrovirus HIV-1 (and less commonly by the related retrovirus HIV-2). Infection leads to progressive immunologic deterioration and... read more and see table Considerations for Use of Live Vaccines in Children With HIV Infection Considerations for Use of Live Vaccines in Children With HIV Infection ).