Human immunodeficiency virus (HIV) is a retrovirus that infects and destroys specific lymphocytes (T-helper cells) and monocytes, ultimately disabling cell-mediated immunity cells containing the CD4+ antigen, particularly CD4+ T-helper cells. The virus enters the body through disrupted mucosal barriers and via contact with body fluids. Over time, morbidity and mortality occur due to opportunistic infections and malignancies that result from compromised immunity. Worldwide, approximately 37 million people are infected with HIV. According to the Centers for Disease Control and Prevention, about 39,500 cases of HIV infection occurred in 2015 in the US, and more than 1.2 million Americans are living with HIV.
Acquired immunodeficiency syndrome (AIDS) is defined as (1) a CD4+ count of < 200 cells/μL (the normal range is > 400 cells/μL) in an HIV-infected individual, or (2) the presence of an opportunistic infection resulting in an AIDS-defining illness. An opportunistic infection occurs when pathogens, such as bacteria, fungi, parasites, or atypical mycobacteria that would normally be controlled by a healthy immune system, flourish in patients with impaired immune systems.
Examples of opportunistic infections include: candidiasis of the esophagus or vagina; cryptosporidiosis with persistent diarrhea; cytomegalovirus (commonly as retinitis); herpes simplex infections of the esophagus, oropharynx, genitalia, or skin; Kaposi sarcoma; Mycobacterium avium complex infection; Pneumocystis jiroveci pneumonia (formerly known as Pneumocystis carinii); and toxoplasmosis of the brain.
HIV transmission occurs by sexual (including oral) intercourse, intravenous drug use with shared needles, vertical transmission through the placenta, breastfeeding, blood products, and open wound-fluid interchange. Perinatal infection can occur if the mother’s viral load is not suppressed and the baby is born vaginally. Transmissibility rises in direct proportion to the HIV viral load.
Acute HIV seroconversion is often asymptomatic, although patients may manifest nonspecific symptoms that can be difficult to differentiate from other viral infections. For example, the initial presentation may be a flu-like or mononucleosis-like syndrome (headache, fever, chills, cough, myalgia, adenopathy) with a rash that occurs within 4-14 days of infection and lasts less than 3 weeks. Patients may also have aseptic meningitis that appears to be of viral origin on spinal fluid examination. Patients then return to their baseline state of health for 2-10 or more years, while the virus replicates within T cells and the CD4+ cell count declines.
As the number of CD4+ T cells declines, patients become more susceptible to infection and neoplasm. Once the CD4+ cells are sufficiently depleted, patients experience multiple opportunistic infections and malignancies that may affect any organ system. These include:
Pulmonary: Pneumocystis jiroveci pneumonia, tuberculosis, pulmonary Kaposi sarcoma, or fungal pulmonary disease (e.g., coccidioidomycosis or histoplasmosis).
Neurologic: Bell’s palsy, dementia, meningitis (aseptic and cryptococcal), syphilis, histoplasmosis, coccidioidomycosis, cerebritis, spinal cord dysfunction (due to syphilis or viral infections such as cytomegalovirus), or peripheral neuropathy.
Gastrointestinal: Esophagitis due to candidiasis, herpes simplex virus, or aphthous ulcerations; diarrhea due to cytomegalovirus (colitis, proctitis) or parasites, including cryptosporidiosis and Giardia lamblia; liver disease due to hepatitis C coinfection, HIV-associated biliary tract disease, or cholangiopathy due to pneumocystis, cryptosporidiosis, cytomegalovirus, or Mycobacterium avium complex. Human papillomavirus-associated anal cancer in the MSM population would also be considered an AIDS-defining illness.
Dermatologic: Kaposi sarcoma (due to herpesvirus 8), herpetic lesions, molluscum contagiosum caused by the poxvirus.
Hematologic: B-cell lymphomas, thrombocytopenia.
Genitourinary: Human papillomavirus-associated cervical cancer.
High-risk sexual intercourse. This includes both anal and vaginal intercourse. Factors associated with increased risk of transmission include male-male sexual intercourse, lack of circumcision (female-to-male transmission), infection with a sexually transmitted infection (particularly those that cause genital ulcers), and sexual intercourse during menses (female-to-male transmission).
Injection drug use. Drug injection is a particularly important source of the HIV epidemics in Eastern Europe, Asia, and the Middle East, and accounts for approximately 6% of new HIV diagnoses in the US each year. For this reason, needle exchange programs have been implemented in several countries, resulting in decreased HIV transmission.
Perinatal transmission. Children are at risk in utero, during delivery (especially during vaginal delivery), and during breastfeeding. Prior to the initiation of antiretroviral therapy during pregnancy, transmission rates were as high as 25% and cesarean sections were recommended. However, through suppression of the HIV viral load with antiretroviral therapy during pregnancy, transmission rates have markedly declined and elective cesarean deliveries are no longer recommended. Avoidance of breastfeeding in HIV-positive mothers is recommended.
Occupational exposure. Risk of transmission after an accidental needle stick exposure is less than 1%. Hollow-bore needles have a greater risk of transmitting HIV, compared with solid-bore needles, which are used for suturing, piercing, etc.
Blood transfusion. Since 1985, the screening of blood products has significantly decreased the HIV transmission rate. The risk of transmission due to blood transfusion is now about 1 in 2 million units of blood.
Early diagnosis is important, because early antiretroviral treatment enhances immunologic responses to HIV and delays progression to AIDS.
Several tests are available to identify HIV infection:
Rapid HIV-1/2 antibody detection kits are simple and rapid assays that can provide results within 30 minutes and are useful when a preliminary screening test result is required and in non-clinical settings. Several home testing kits are now available, including OraQuick HIV Test that uses a sample of saliva, and Home Access HIV-1 Test System that requires a finger stick to obtain a serum sample that is then sent to a lab for rapid antibody testing. Supplemental laboratory-based testing using the algorithm below should confirm all positive results of rapid tests.
Step 1. Combination HIV-1/HIV-2 antibody/p24 antigen screening enzyme immunoassay (EIA) ["4th generation immunoassay"] is the initial laboratory diagnostic test recommended for detection of HIV and is positive in > 99% of cases within 6 weeks of infection.
Step 2. HIV-1/HIV-2 antibody differentiation immunoassay is performed on all specimens positive by the initial combination screening assay above, in order to differentiate HIV-1 from HIV-2 infection.
Step 3. HIV RNA detection by nucleic acid amplification (NAT) is the most sensitive test for identifying primary HIV infection and is used to resolve indeterminate results on the HIV-1/HIV-2 antibody differentiation assay above. It is also used to follow disease progression by detecting the "viral load". During acute infection, the viral load can be greater than 500,000 copies/mL, but it then falls significantly.
Western blot or immunofluorescence assays (IFA) as well as isolated p24 antigen testing are historic assays that are no longer part of the recommended diagnostic algorithm.
CD4+ count is used to monitor the progression of HIV infection: the lower the value, the greater the risk for opportunistic infections. For example, Pneumocystis jiroveci pneumonia is more likely to occur with a CD4+ count of < 200 cells/μL, while cytomegalovirus infections occur with CD4+ counts < 75 cells/μL. Abnormal complete blood count (CBC) is common and may reveal leukopenia, lymphocytosis, thrombocytopenia, and/or anemia.
After diagnosis, the CD4+ count and viral load are followed every 3-6 months to evaluate the progression of infection and the need for prophylaxis of opportunistic infections.
It is important to screen for other sexually transmitted infections, including gonorrhea, chlamydia, syphilis, herpes simplex virus, and hepatitis A, B, and C. Tuberculosis and toxoplasmosis screening are also done at the initial visit.
HIV genotyping and phenotyping should be done to assess drug resistance. Up to 25% of persons receiving antiretroviral therapy can still transmit resistant HIV.
Routine follow-up is important, with CBC, creatinine, renal function tests, and liver function tests to evaluate for medication side effects.
Other diagnostic tests are indicated, as necessary, for diagnosis of opportunistic infections (e.g., chest x-ray, viral titers).
Antiretroviral therapy has significantly improved the prognosis for HIV, reducing progression to AIDS, opportunistic infections, hospitalizations, and death. Most patients will achieve full viral suppression within several months of beginning therapy. Antiretroviral therapy is indicated for all HIV-infected persons, regardless of CD4+ count. Evidence suggests that early initiation of antiretroviral therapy regardless of CD4+ count delays the onset of AIDS, and reduces risk of transmission. Physicians and patients may consider enrollment in a clinical trial to take advantage of experimental therapies. Due to the complexity of treatment and the ever-changing landscape of antiretrovirals, HIV-infected individuals should be treated by clinicians with specific expertise in HIV care.
Common classes of antiretroviral agents include:
Nucleoside reverse transcriptase inhibitors (NRTIs): (e.g., zidovudine, tenofovir, tenofovir alafenamide, didanosine, lamivudine, emtricitabine, stavudine, abacavir)
Non-nucleoside reverse transcriptase inhibitors (NNRTIs): (e.g., efavirenz, nevirapine, delavirdine, r ilpivirine)
Protease inhibitors (PI): (e.g., indinavir, lopinavir, atazanavir, fosamprenavir, darunavir)
Pharmacokinetic (PK) enhancer ("booster"): (e.g., ritonavir, cobicistat)
Integrase strand transfer inhibitor (INSTI or "integrase inhibitor"): (e.g., dolutegravir, elvitegravir, raltegravir)
Fusion inhibitors (FI): (e.g., enfuvirtide)
CCR5 antagonist: (e.g., maraviroc)
A regimen combining three antiretroviral medications—known as antiretroviral therapy (ART)—is used to avoid or delay drug resistance. Strict adherence is essential to avoid resistance. In an HIV-infected individual who has not previously been treated with ART, a typical initial regimen would include two NRTIs along with a third antiretroviral agent such as an NNRTI, a boosted PI, or an INSTI.
All HIV-infected individuals should undergo HIV genotyping (i.e., antiretroviral resistance testing) following confirmation of diagnosis in order to inform selection of ART regimen. Once antiviral therapy begins, the CD4+ count and viral load should be assessed every 3-6 months, along with medication resistance studies if there is evidence of viral progression.
Pre-exposure prophylaxis (PrEP): indicated for people who are at high risk of contracting HIV but who are not yet infected. PrEP treatment consists of taking a daily pill (tenofovir and emtricitabine). When taken daily, PrEP has shown to be about 92% effective at preventing HIV infection in high risk individuals.
Post-exposure prophylaxis (PEP): involves the use of anti-retroviral medication within 72 hours or less of an exposure to HIV to prevent seroconversion.
Regular exercise can reduce some side effects of antiretroviral treatment. Aerobic exercise can help reduce total body and visceral fat and normalize lipid profiles in HIV-infected patients. Combinations of aerobic exercise and progressive resistive exercise (done for at least 20 minutes ≥ 3 times per week) may also lead to significant reductions in depressive symptoms and improvements in cardiopulmonary fitness, muscle strength, and quality of life.
Psychological approaches can provide benefits for persons with HIV. Although further research is needed to confirm initial findings, available evidence suggests that excessive psychosocial stress can reduce resistance to opportunistic infections in HIV-positive persons. In women with HIV, higher indications of psychosocial stress increased the odds of developing progressive, persistent HPV-related squamous intraepithelial neoplasia 7-fold, compared with women experiencing the least life stress. Greater stress also accounted for 46% of the variance in recurrence of genital herpes lesions. Various psychological approaches are significantly associated with decreased viral load, higher CD4+ cell counts, and greater adherence to antiretroviral therapy. HIV-positive men assigned to cognitive-behavioral stress management or active coping interventions were shown to have greater numbers of CD4+ cells.
Nutritional issues in HIV infection relate to macronutrient and energy needs, lipid disorders, and micronutrient adequacy.
Macronutrient and Energy Needs
HIV infection can trigger a chronic-inflammation, wasting syndrome with increases in protein turnover and energy requirements. HIV wasting syndrome is defined as a 10% unintentional weight loss over baseline accompanied by chronic diarrhea, fever, or weakness.
A grossly undernourished state in HIV-positive patients at the start of ART (as indicated by a low body mass index, [BMI]) is a strong and independent predictor of mortality. In asymptomatic HIV-infected adults, energy requirements are estimated to increase by 10%, and during symptomatic HIV and AIDS, energy needs increase by approximately 20%-30%. Increased energy needs are offset to some degree by the reduction in physical movement due to illness. Some degree of wasting is common, despite ART; accordingly, patients should not be encouraged to lose significant amounts of weight unless they are obese. Studies have consistently shown that HIV-infected patients with a BMI > 25 have higher CD4+ cell counts, decreased risk of viral progression, and decreased mortality compared with their thinner (BMI < 25) counterparts. This relationship may be explained by the elevated leptin production in heavier persons, which supports CD4+ cell proliferation. Loss of excess weight may be helpful, however, for overweight patients on ART whose risk factors for heart disease and diabetes have been elevated by these drugs.
Protein intake is associated with lean body mass, loss of which is strongly associated with disease progression and death in HIV-positive persons. A review of available evidence noted that protein requirements of 1-1.4 g per kg of body mass are indicated for maintenance of lean mass, and 1.5-2 g per kg for anabolism. Nevertheless, a Cochrane review concluded that nutritional (i.e., protein-calorie) supplementation did not significantly alter clinical, anthropometric or immunological outcomes in HIV patients when compared with placebo.
Diet and Lipid Disorders
Diet therapy is recommended for both primary prevention and control of dyslipidemia in HIV patients on ART. Protease inhibitors exacerbate the effects of HIV infection on lipid metabolism and insulin resistance, leading to lipodystrophy. Medication-related decreases in the catabolism of both apoB and nuclear sterol regulatory element binding proteins in the liver and adipocytes bring about increases in fatty acid and cholesterol biosynthesis, insulin resistance, and lipodystrophy. As a result, 10%-50% of patients on protease inhibitors have hypercholesterolemia, and 40%-80% of these individuals have hypertriglyceridemia. However, non-nucleoside reverse transcriptase inhibitors, in spite of raising total and LDL cholesterol and triglycerides, also increase HDL by approximately 40%, depending on the specific type.
ART has resulted in a significant reduction in HIV-associated cardiomyopathy, due to a reduction in opportunistic infections. On the other hand, exposure to protease inhibitors nearly triples the risk for acute myocardial infarction (AMI) when compared with individuals not taking these drugs. However, a systematic review indicated a significantly greater risk for MI with only certain kinds of nucleoside reverse transcriptase inhibitors (abacavir) and protease inhibitors (lopinavir, indinavir).
A review of cardiovascular risk in HIV patients concluding that a combination of dyslipidemia, insulin resistance, inflammation, impaired fibrinolysis (and in some persons, diabetes as well) occurs in HIV infection. Nutritional interventions that improve the parameters listed above would therefore seem a prudent measure. Plant-based diets, especially those that include plant sterols, viscous fibers, soy protein, and nuts, have been found to help manage dyslipidemia and prevent or reduce insulin resistance. The high fiber content of these diets can also aid fibrinolysis and reduce inflammation.
Plant-based diets have not, however, been widely tested in HIV patients. A meta-analysis of studies of adult HIV patients using conventional diet therapies (AHA Step I and Step II diets) and treatment with fish oil found significant reductions in triglyceride levels with each treatment compared with control conditions, but no significant reduction in cholesterol levels.
Probiotic supplements. HIV enteropathy causes pronounced CD4+ T-cell loss, increased intestinal permeability, and microbial translocation, which are implicated in disease progression. Controlled trials have demonstrated the ability of probiotics and synbiotics (combinations of pre- and probiotics) to significantly increase CD4+ count. ,
Preliminary evidence suggests that higher intakes of fruits, vegetables, and juices increase T-cell proliferation or reduce CD38+/CD8+ count, a marker of disease progression. Fruits and vegetables also provide many nutrients that are deficient in persons with HIV and help reduce the oxidative stress that may occur as a side effect of ART.
Low blood concentrations of many micronutrients are common in HIV-positive individuals and are associated with disease progression and increased mortality. A meta-analysis found that, in individuals not on antiretroviral therapy, micronutrient supplementation was associated with an almost 40% reduction in disease progression when compared with controls. Clinical trials using multivitamin supplements (combinations of B-vitamins and vitamin C, vitamin A, selenium and zinc, or vitamins A, D, zinc, N-acetyl cysteine and other minerals) have demonstrated that these raise CD4 count and reduce morbidity and mortality. In African children, vitamin A supplementation reduced mortality by half.
Selenium appears to be particularly important for HIV patients, given that the selenium-dependent enzyme TrxR1 is a negative regulator of an HIV-encoded (Tat) protein required for viral replication. The ability of selenium to improve the health status of HIV patients who are deficient or low in this mineral has been confirmed. However, questions remain regarding whether the effects seen in clinical trials of selenium supplementation (e.g., reduced frequency of opportunistic infections and increase in CD4 count, with a lack of increase in viral load over during the trial period ) are the result of optimizing selenium status within the normal range, or the result of a pharmacologic effect.
Vitamin D deficiency is associated with both HIV/AIDS progression and mortality
and increases the risk of mother-to-child transmission by 46% and the risk of death in newborns by 61%. Evidence regarding the ability of vitamin D supplementation to affect immune parameters in HIV patients is limited, and further studies are needed.
A systematic review found that zinc supplementation reduced the incidence of opportunistic infection in HIV patients in general and immunological failure in adults ( defined as a drop in CD4 counts to < 200 cells ⁄ mm 3). However, viral load, mortality, mother-to-child transmission of HIV and fetal outcomes were not significantly changed.
See Coronary Heart Disease chapter.
Nutrition consultation to assess nutritional requirements.
HIV infection is not currently curable, but is rather a chronic disease manageable with ART. Progressive immunosuppression and life-threatening, opportunistic infections can be greatly diminished through a combination of medications and a healthful diet. Emotional support from family, friends, and community, and also psychotherapeutic treatments, may provide additional immune benefits for persons with HIV. Family members can encourage healthy lifestyle changes through diet, regular exercise, and abstinence from tobacco and alcohol.