Chapter 14 Infection and Human Immunodeficiency Virus Infection and Chapter 13 Flashcards
An antigen is a substance that elicits an?
immune response. Most antigens are composed of protein. All of the body’s cells have antigens on their surface that are unique to that person and enable the body to recognize itself.
Immunity is classified as?
innate or acquired
Innate immunity is?
present at birth, and its primary role is first-line defense against pathogens. This type of immunity involves a nonspecific response, and neutrophils and monocytes are the primary white blood cells (WBCs) involved. Innate immunity is not antigen specific, so it can respond within minutes to an invading microorganism without prior exposure to that organism.
Acquired immunity is the?
development of immunity, either actively or passively
Active acquired immunity results from the?
invasion of the body by foreign substances such as microorganisms and subsequent development of antibodies and sensitized lymphocytes. With each reinvasion of the microorganisms, the body responds more rapidly and vigorously to fight off the invader. Active acquired immunity may result naturally from a disease or artificially through immunization. Because antibodies are synthesized, immunity takes time to develop but is long lasting.
Passive acquired immunity implies that the host?
- receives antibodies to an antigen rather than synthesizing them
- may take place naturally through transfer of immunoglobulins across placental membrane from mother to fetus
- Artificial passive acquired immunity occurs through injection with gamma globulin (serum antibodies). benefit of this immunity is its immediate effect
- passive immunity is short lived because person does not synthesize antibodies and does not retain memory cells for antigen
Active: Natural and Artificial Immunity
1) Natural: contact with antigen through actual infection (e.g., chickenpox, measles, mumps)
2) Artificial: Immunization with antigen (e.g., vaccines for chickenpox, measles, mumps)
Passive: Natural and Artificial Immunity
1) Natural: Transplacental and colostrum transfer from mother to child (e.g., maternal immunoglobulins passed to baby)
2) Artificial: Injection of serum with antibodies from one person (e.g., injection of hepatitis B immune globulin) to another person who does not have antibodies
Antibodies
Immune globulins produced by lymphocytes in response to antigens
Humoral immunity consists of antibody-mediated immunity. Since antibodies are produced by plasma cells (differentiated B cells) and found in plasma, the term humoral immunity is used. Production of antibodies is an essential component in a humoral immune response. Each of the five classes of immunoglobulins?
(IgG, IgA, IgM, IgG, IgE) have specific characteristics
Humoral Immunity
1) Cells involved
2) Products
3) Memory cells
4) Protection
5) Examples
1) Cells involved: B lymphocytes
2) Products: Antibodies
3) Memory cells: Present
4) Protection: Bacteria, Viruses (extracellular), Respiratory and GI pathogens
5) Examples: Anaphylactic shock, Atopic diseases, Transfusion reaction, Bacterial infections
Cell-Mediated Immunity
1) Cells involved
2) Products
3) Memory cells
4) Protection
5) Examples
1) Cells involved: T lymphocytes, macrophages
2) Products: Sensitized T cells, cytokines
3) Memory cells: Present
4) Protection: Fungus, Viruses (intracellular), Chronic infectious agents, Tumor cells
5) Examples: Tuberculosis, Fungal infections, Contact dermatitis, Graft rejection, Destruction of cancer cells
Tumor Necrosis Factor (TNF)
- Proinflammatory mediator
- Activates macrophages and granulocytes
- Promotes immune and inflammatory responses
- Kills tumor cells
- Responsible for weight loss associated with chronic inflammation and cancer
Cell-Mediated Immunity
Immune responses that are initiated through specific antigen recognition by T cells are termed cell-mediated immunity. Several cell types and factors are involved in cell-mediated immunity. The cell types involved include?
-Cell mediated immunity is of primary importance in?
T cells, macrophages, and NK cells.
Cell-mediated immunity is of primary importance in
(1) immunity against pathogens that survive inside of cells including viruses and some bacteria (e.g., mycobacteria) (2) fungal infections
(3) rejection of transplanted tissues
(4) contact hypersensitivity reactions
(5) tumor immunity
The primary clinical evidence of immunosenescence is the high incidence of?
malignancies in older adults. Older people are also more susceptible to infections (e.g., influenza, pneumonia) from pathogens that they were relatively immunocompetent against earlier in life. Bacterial pneumonia is the leading cause of death from infections in older adults. The antibody response to immunizations (e.g., flu vaccine) in older adults is considerably lower than in younger adults
A decline in immune function and immune response that occurs with aging
Immunosenescene
Researchers believe immunosenescence accounts for the increase in?
Cancer and infections
Humoral protection
- Bacteria
- Viruses (extracellular)
- Respiratory pathogens
- Gastrointestinal pathogens
Cellular protection
- Fungus
- Viruses (intracellular)
- Chronic infectious agents
- Tumor cells
AIDS: Prevention of transmission in the healthcare setting
- Maintain standard precautions: hand washing/hygiene, protective barriers (gloves, mask, eye shield, gown)
- Do NOT recap needles and syringes
- Clean up spills of blood and body fluids immediately using germicidal solution
- Consider ALL body fluids to be contaminated
- Avoid contaminating the outside of specimen containers during collection
- Cleanse work surface ares with appropriate germicide (1:10 concentration of household bleach is effective)
Human immunodeficiency virus (HIV) is a?
retrovirus that causes immunosuppression. People with HIV are more susceptible to infections that are normally controlled through immune responses.
Transmission of HIV
HIV can be transmitted through contact with infected blood, semen, vaginal secretions, or breast milk. HIV transmission occurs through sexual intercourse with an infected partner; exposure to HIV-infected blood or blood products; and perinatal transmission during pregnancy, at delivery, or through breastfeeding. HIV is not spread casually
Sexual Transmission.
- most common mode of transmission is unprotected sexual contact with an HIV-infected partner
- Sexual activity involves contact with semen, vaginal secretions, and/or blood, all of which have lymphocytes that may contain HIV.
- genital lesions from other sexually transmitted infections (e.g., herpes, syphilis) significantly increase likelihood of transmission
Contact With Blood and Blood Products
- HIV can be transmitted from exposure to blood when sharing drug-using paraphernalia
- Needles, syringes, straws, and other equipment may be contaminated with HIV or other blood-borne organisms, and sharing this equipment can result in disease transmission
- Puncture wounds are the most common means of work-related HIV transmission. The risk of infection after a needle-stick exposure to HIV-infected blood is 0.3% to 0.4% (or 3 or 4 out of 1000)
Perinatal Transmission of HIV
Perinatal transmission from an HIV-infected mother to her infant can occur during pregnancy, delivery, or breastfeeding
- On average, 25% of infants born to women with untreated HIV infection are born with HIV. Fortunately, the risk of transmission can be reduced to less than 2% in settings in which pregnant women are routinely tested for HIV infection and, if found to be infected, treated with antiretroviral therapy (ART), a combination of medication used to control and suppress HIV replication.
Everyone who has AIDS has HIV infection. However, not everyone who has HIV has AIDS. The distinction rests with?
The number of CD4+ T cells the patient has and whether any opportunistic infections have occurred.
Pathophysiology of HIV
- HIV is an RNA virus.
- RNA viruses are called retroviruses because they replicate in a “backward” manner (going from RNA to DNA)
- HIV cannot replicate unless it is inside a living cell
- The CD4+ T cell (CD4 cell), a type of lymphocyte, is the target cell for HIV. HIV enters the CD4+ T cell by binding to protein receptors on the outside of the cell (Fig. 14-1). This process is known as fusion
- Once HIV attached and fused with CD4+ T cell, HIV RNA enters CD4+ T cell and triggers release of reverse transcriptase (enzyme transforms HIV RNA into single strand of DNA). This strand copies itself, becoming double-stranded viral DNA
- enzyme, integrase, allows newly formed double-stranded DNA to integrate itself into host’s genetic structure. This action has two consequences: (1) because all genetic material is replicated during cell division, all daughter cells are also infected and (2) viral DNA in the genome directs the cell to make new HIV
- Protease enzyme involved in replication process, cleaves newly formed strands of HIV genetic material into smaller pieces
- New HIV virions then formed and released. The CD4+ T cell is then destroyed after the HIV virions are released.
HIV destroys about 1 billion CD4+ T cells every day. For many years the body can produce new CD4+ T cells to replace the destroyed cells. However, over time the ability of HIV to destroy CD4+ T cells exceeds the body’s ability to replace the cells. The decline in the CD4+ T cell count impairs immune function. Generally, the immune system remains healthy with more than 500 CD4+ T cells/µL. Immune problems begin to occur when the count drops below?
500 CD4+ T cells/µL and Severe problems develop with fewer than 200 CD4+ T cells/µL
With HIV, a point is eventually reached where so many CD4+ T cells have been destroyed that not enough are left to regulate immune responses. This allows?
opportunistic diseases (infections and cancers that occur in immunosuppressed patients) to develop. Opportunistic diseases are the main cause of disease, disability, and death in patients with HIV infection
Clinical Manifestations and Complications for HIV
It is important to remember that (1) disease progression is highly individualized, (2) treatment can significantly alter this pattern, and (3) an individual’s prognosis is unpredictable
Acute HIV Infection
- Approximately 2 to 4 weeks after newly infected with HIV, individuals experience acute HIV infection, a period when people can have a mononucleosis-like syndrome of fever, swollen lymph nodes, sore throat, headache, malaise, nausea, muscle and joint pain, diarrhea, and/or a diffuse rash.
- Some people also develop neurologic complications, such as aseptic meningitis, peripheral neuropathy, facial palsy, or Guillain-Barré syndrome
- Duringthis time high viral load (amount of HIV circulating in blood) is noted, and CD4+ T cell counts fall temporarily but quickly return to baseline or near-baseline levels - Many people, including HCPs, mistake acute HIV symptoms for a bad case of the flu
- Individuals are most infectious DURING the acute infection stage because of the high amounts of circulating HIV
Chronic HIV Infection
Explain Asymptomatic Infection
- interval between initial HIV infection and diagnosis of AIDS is about 10 years in untreated infection.
- During first several years after initial infection, individuals typically asymptomatic w/no symptoms or relatively limited signs of infection.
- Because most symptoms during early infection are vague and nonspecific for HIV, people may not be aware that they are infected. During this time, infected people continue their usual activities, and may include high-risk sexual and drug-using behaviors.
- This is a public health problem because infected individuals can transmit HIV to others even though they have no symptoms
- Personal health is also affected because people who do not know that they are infected have little reason to seek treatment and are less likely to make behavior changes that could improve the quality and length of their lives.
Chronic HIV infection: Explain the symptomatic stage
- As CD4+ T cell count declines closer to 200 cells/µL and the viral load increases, HIV advances to a active stage. - Symptoms: persistent fever, frequent night sweats, chronic diarrhea, recurrent headaches, and severe fatigue may develop.
- common infections associated with this phase is oropharyngeal candidiasis (thrush)
- Other infections that can occur at this time include shingles (caused by the varicella-zoster virus); persistent vaginal candidal infections; outbreaks of oral or genital herpes; bacterial infections; and Kaposi sarcoma (KS), which is caused by human herpesvirus 8
- Oral hairy leukoplakia, an Epstein-Barr virus infection that causes painless, white, raised lesions on the lateral aspect of the tongue, is another indicator of disease progression
A diagnosis of acquired immunodeficiency syndrome (AIDS) is made when an HIV-infected patient meets criteria established by the CDC. These criteria occur when the immune system becomes severely compromised. Opportunistic diseases generally do not occur in the presence of a functioning immune system. Many infections, a variety of malignancies, wasting, and HIV-related cognitive changes can occur in patients with immune impairment. Organisms that do not cause severe disease in people with functioning immune systems can cause debilitating, disseminated, and life-threatening infections during this stage. Several opportunistic diseases may occur at the same time, compounding the difficulties of diagnosis and treatment. Advances in HIV treatment have?
decreased the occurrence of opportunistic diseases
Diagnostic Criteria for AIDS
AIDS is diagnosed when an individual with HIV develops at least one of the following conditions:
- CD4+ T cell count drops below 200 cells/µL.
- One of the following opportunistic infections (OIs):
• Fungal: candidiasis of bronchi, trachea, lungs, or esophagus; Pneumocystis jiroveci pneumonia (PCP); disseminated or extrapulmonary coccidioidomycosis; disseminated or extrapulmonary histoplasmosis
• Viral: cytomegalovirus (CMV) disease other than liver, spleen, or nodes; CMV retinitis (with loss of vision); herpes simplex with chronic ulcer(s) or bronchitis, pneumonitis, or esophagitis; progressive multifocal leukoencephalopathy (PML); extrapulmonary cryptococcosis
• Protozoal: toxoplasmosis of the brain, chronic intestinal isosporiasis, chronic intestinal cryptosporidiosis
• Bacterial: Mycobacterium tuberculosis (any site); any disseminated or extrapulmonary mycobacteria, including Mycobacterium avium complex (MAC) or Mycobacterium kansasii; recurrent pneumonia; recurrent Salmonella septicemia - One of the following opportunistic cancers:
• Invasive cervical cancer
• Kaposi sarcoma (KS)
• Burkitt’s lymphoma
• Immunoblastic lymphoma
• Primary lymphoma of the brain - Wasting syndrome. Wasting is defined as a loss of 10% or more of ideal body mass
Diagnostic Studies: Diagnosis of HIV Infection
- Diagnosis of HIV infection is made by testing for HIV antibodies and/or antigens in the blood
- HIV screening tests detect HIV-specific antibodies or antigens, but typically it takes several weeks after initial infection before evidence of HIV can be detected on a screening test
- This delay is known as the window period
- HIV screening tests can be performed using blood or saliva
- Combination antibody and antigen tests (also known as fourth-generation tests) are able to detect HIV earlier than previous versions of HIV screening tests. The fourth-generation test decreases the window period to within 3 weeks following infection
The progression of HIV is monitored by?
CD4+ T cell counts and viral load
- CD4+T cell counts provide a marker of immune function and decrease as the disease progresses
- The lower the viral load the less active the disease
- reported as real numbers or as undetectable
Laboratory Studies in HIV Infection.
Two laboratory tests are used for monitoring HIV progression:
CD4+ T cell count and viral load
1) CD4+ T cell count provides marker of immune function. As disease progresses, number of CD4+ T cells decreases (normal range for CD4+ T cells is 800 to 1200 cells/µL)
2) Laboratory tests that measure viral levels provide assessment of disease progression. lower the viral load, the less active the disease.
- viral loads reported as real numbers (e.g., 1260 copies/µL)
- goal of treatment is suppress viral load to lowest level possible (below level of detection on a commercial assay) - often referred to as “undetectable.” refers to amount of circulating HIV in the blood is below the level of detection of the test
Laboratory studies for HIV infection
- Abnormal blood test results
- Decreased white blood cell (WBC) counts, below-normal numbers of lymphocytes (lymphopenia) and neutrophils (neutropenia), often seen
- Low platelet counts (thrombocytopenia) may be caused by HIV, antiplatelet antibodies, or drug therapy
- Anemia associated with chronic disease process and with adverse effects of ART
- Altered liver function, caused by HIV infection, drug therapy, or co-infection with a hepatitis virus, is common
- Early identification of co-infection with hepatitis B virus (HBV) or hepatitis C virus (HCV) extremely important because these infections have a serious course in patients with HIV, may ultimately limit options for ART, and can cause liver-related morbidity and mortality
Resistance tests can determine if a patient’s HIV is resistant to drugs used for ART. Genotype and phenotype assays are used to help HCPs know which medications can be used to control a patient’s infection. These tests are similar to culture and sensitivity testing used for antibiotic selection.
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Interprofessional care of the HIV-infected patient focuses on?
(1) monitoring HIV disease progression and immune function, (2) initiating and monitoring ART, (3) preventing the development of opportunistic diseases, (4) detecting and treating opportunistic diseases, (5) managing symptoms, (6) preventing or decreasing complications of treatment, and (7) preventing further transmission of HIV. To accomplish these goals, ongoing assessment, clinician-patient interactions, and patient teaching and support are required.
Rapid HIV-Antibody Testing
- Rapid testing is strongly recommended by the Centers for Disease Control and Prevention. Results are highly accurate, and it can be done in a variety of settings (mobile health units, HCPs’ offices, or even in the privacy of an individual’s home). Results are typically available within 20 minutes.
- In-home HIV test kits are available. Testing is done on saliva.
- Rapid tests are screening tests for antibodies, not for antigen.
- Negative rapid tests should be followed by a risk assessment to determine the need for repeat tests.
- Positive rapid tests can be disclosed to the patient but must be confirmed with a standard HIV assay. This step necessitates a blood draw and a return appointment to get results.
HIV-Antibody/Antigen Testing (Fourth-Generation Testing)
A highly sensitive test detects antibodies and antigens associated with HIV. Blood samples that are negative for HIV infection are reported as negative. The new fourth-generation testing algorithm includes confirmatory testing with HIV viral load testing for any indeterminate results.
- If the patient has a negative fourth-generation test, but reports recent risky behaviors, encourage retesting in 4 to 6 weeks. Individuals at ongoing risk should be assessed or counseled for risk reduction interventions including preexposure prophylaxis (PrEP).
- If the results are positive and consistent with HIV infection, assist the patient in getting appropriate counseling, support, and follow-up HIV primary care.
Drug Therapy for HIV Infection.
The goals of drug therapy in HIV infection are to?
(1) decrease the viral load
(2) maintain or increase CD4+ T cell counts
(3) prevent HIV-related symptoms and opportunistic diseases
(4) delay disease progression
(5) prevent HIV transmission
- HIV cannot be cured, but ART can delay disease progression by decreasing viral replication
- When taken consistently and correctly, ART can reduce viral loads by 90% to 99%, which makes adherence to treatment regimens extremely important
Drugs used to treat HIV work at various points in the HIV replication cycle. The major advantage of using drugs from different classes is that combination therapy can inhibit viral replication in several different ways, making it more difficult for the virus to recover and decreasing the likelihood of drug resistance. A major problem with most drugs used in ART is that?
resistance develops rapidly when they are used alone (monotherapy) or taken in inadequate doses. For that reason, combinations of three or more drugs should be used.
Interaction of ART With Other Drugs
- Many ARTs have interactions with other commonly used drugs and herbal therapies (e.g., St. John’s wort).
- Significant interactions with ARTs also occur with over-the-counter drugs, including antacids, proton pump inhibitors, and certain supplements.
- Be sure to ask patients about prescribed and over-the-counter drugs as well as herbal products and supplements.
Drug Therapy for Opportunistic Diseases.
Management of HIV is complicated by the many opportunistic diseases that can develop as the immune system deteriorates. Prevention is the preferred approach to opportunistic diseases. A number of opportunistic diseases associated with HIV can be delayed or prevented with adequate ART, vaccines (including hepatitis B, influenza, and pneumococcal), and disease-specific prevention measures. Although it is usually not possible to eradicate opportunistic diseases once they occur, prophylactic medications can significantly?
decrease morbidity and mortality rates. Advances in the prevention, diagnosis, and treatment of opportunistic diseases have contributed significantly to increased life expectancy.
Preventing Transmission of HIV. Preexposure prophylaxis (PrEP) is a comprehensive HIV prevention strategy to reduce the risk of sexually acquired HIV infection in adults at high risk. PrEP should be used in conjunction with other proven prevention interventions such as condoms, risk reduction counseling, and regular HIV testing.
Tenofovir in combination with emtricitabine, also known as Truvada, is used to reduce the risk of HIV infection in uninfected individuals who are at significant risk of acquiring HIV. Tenofovir/emtricitabine is also currently used in combination with other antiretroviral agents for the treatment of HIV-infected people.
Nursing Assessment
Help individuals assess risk by asking some basic questions:
(1) Have you ever had a blood transfusion or used clotting factors? If so, was it before 1985?
(2) Have you ever shared drug-using equipment with another person?
(3) Have you ever had a sexual experience in which your penis, vagina, rectum, or mouth came into contact with another person’s penis, vagina, rectum, or mouth?
(4) Have you ever had a sexually transmitted infection?
(5) Have you ever had sexual contact with someone known to have HIV?
- These questions provide the minimum information needed to initiate a risk assessment. Follow up a positive response to any of these questions with an in-depth exploration of issues related to the identified risk.
Planning
Nursing interventions can help the patient to?
(1) adhere to drug regimens
(2) adopt a healthy lifestyle that includes avoiding exposure to other sexually transmitted infections and blood-borne diseases
(3) protect others from HIV
(4) maintain or develop healthy and supportive relationships
(5) maintain activities and productivity
(6) explore spiritual issues
(7) come to terms with issues related to disease, disability, and death
(8) cope with symptoms caused by HIV and its treatments
Healthy People
Prevention and Early Detection of HIV
- Increase safer sexual practices, including condom use.
- Decrease equipment sharing among IV drug users.
- Increase clinician skills to assess for risk factors for HIV infection, recommend HIV testing, and provide counseling for behavior change.
- Make voluntary HIV testing a routine part of health care.
- Increase access to new HIV testing technologies, especially rapid testing.
- Increase access to HIV testing facilities in traditional health care settings, as well as in alternative sites such as drug and alcohol treatment facilities and community-based organizations.
- Increase risk assessment and individualized behavior change messages to people with HIV to prevent new infections.
- Decrease perinatal HIV infection by offering voluntary HIV testing as a part of routine prenatal care.
- Provide counseling and appropriate HIV therapy to those who are infected.
A wide variety of activities can reduce the risk of HIV infection. Individuals choose the methods that best fit their needs and circumstances. Prevention techniques can be divided into?
safe sexual activities (those that eliminate risk) and risk-reducing sexual activities (those that decrease, but do not eliminate, risk).
- goal is to develop safer, healthier, and less risky behaviors. The more consistently and correctly prevention methods are used, the more effective they are in preventing HIV infection. It is also a good idea to use a combination of prevention methods (e.g., using condoms and decreasing the number of sex partners) to increase the prevention effect.
Safe sexual activities eliminate the risk of exposure to HIV in semen and vaginal secretions. Abstaining from all sexual activity is an effective way to accomplish this goal, but there are safe options for those who cannot or do not wish to abstain. Limiting sexual behavior to activities in which the?
mouth, penis, vagina, or rectum does not come into contact with a partner’s mouth, penis, vagina, or rectum eliminates contact with blood, semen, or vaginal secretions.
- Safe activities include masturbation, mutual masturbation (“hand job”), and other activities that meet the “no contact” requirements. Insertive sex between partners who are not infected with HIV and not at risk of becoming infected with HIV is also considered safe.
Risk-reducing sexual activities decrease the risk of contact with HIV through the use of barriers. Barriers should be used when engaging in insertive sexual activity (oral, vaginal, or anal) with a partner who has HIV or whose HIV status is not known. The most commonly used barrier is the?
male condom. Male condoms can be used for protection during anal, vaginal, and oral intercourse. Female condoms provide an alternative to male condoms. Squares of latex (known as dental dams) can be used as a barrier during oral sexual activity.
Decreasing risks related to drug use.
Drug use, including alcohol and tobacco, can cause immunosuppression, poor nutrition, and a host of psychosocial problems. However, drug use does not cause HIV infection. The major risk for HIV related to using drugs involves sharing equipment or having unsafe sexual experiences while under the influence of drugs. Basic risk reduction rules are?
(1) do not use drugs
(2) if you use drugs, do not share equipment
(3) do not have sexual intercourse when under the influence of any drug (including alcohol) that impairs decision making
Decreasing risks related to drug use.
Safest method is to abstain from drugs, but this may not be a viable option for users who are not prepared to quit or have no access to drug treatment services. The risk of HIV for these individuals can be eliminated if they do not share equipment.
1) Injecting equipment (“works”) includes?
2) Equipment used to snort (straws) or smoke (pipes) drugs can also be contaminated with?
1) Injecting equipment (“works”) includes needles, syringes, cookers (spoons or bottle caps used to mix the drug), cotton, and rinse water
2) Equipment used to snort (straws) or smoke (pipes) drugs can also be contaminated with blood and should not be shared
Decreasing risks related to drug use.
Access to sterile equipment is an important risk elimination tactic.
-Cleaning equipment before use can also reduce risk by?
decreasing the chance of blood contact
Decreasing HIV risks of perinatal transmission
- best way to prevent HIV infection in infants is to prevent HIV infection in women
- Women already infected with HIV should be asked about their reproductive desires
- maintaining pregnancy and using ART to decrease the risk of transmission.
- If HIV-infected pregnant women are treated during pregnancy, the rate of perinatal transmission can be decreased from 25% to less than 2%
- ART has decreased risk for infants born to HIV-infected women
- current standard of care is for all women who are pregnant or contemplating pregnancy to be counseled about HIV, routinely offered access to voluntary HIV-antibody testing, and, if infected, offered optimal ART
