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HIV and TB (HIV (Testing and Counselling:
Pre & post-test counseling…
HIV and TB
HIV
Canada:
- Approximately 30% of persons living with HIV are not aware they are infected (PHAC, 2010)
- number of new cases of HIV infection are not decreasing
Most cases in men who have sex with men (MSM)
- Heterosexual transmission becoming more prevalent, now most common method of infection for women
- remains a disease of marginalized individuals
Transmission:
- Only by contact with infected body fluids:
blood, semen, vaginal secretions, breast milk
- Not transmitted through: tears, saliva, urine, emesis, sputum, feces, sweat
- Sexual intercourse with infected partner
- Exposure to HIV-infected blood/blood products (sharing injection equipment; blood transfusions; workplace needle-stick)
- Perinatal transmission during pregnancy at time of delivery or through breast feeding
Transmitting HIV during Pregnancy or Birth:
- About 1/4 to 1/3 of untreated HIV-infected pregnant women will pass the infection to their babies
- In general, pregnant women with HIV can use the same HIV regimens recommended for non-pregnant and should start as soon as possible
- With treatment, & delivery by cesarean section, the chances of the baby being infected can be reduced to a rate of 1 percent
- HIV can also spread to babies through breast milk of mothers infected with the virus
- HIV- infected pregnant women (treated with zidovudine (ZDV=AZT=Retrovir) the rate of perinatal transmission is decreased; combination ART – decreased risk of perinatal transmission <2%)
Prevention:
- Education & behavior change are most effective prevention tools
- Educational messages should be specific to patient’s needs, culturally sensitive, language appropriate & age specific
- Safe activities (those that eliminate risk)
- Risk-reducing activities (those that decrease risk, but do not eliminate it)
HIV: a ribonucleic acid (RNA) virus; retrovirus because it replicates in a "backward" manner going from RNA to deoxyribonucleic acid (DNA); can only replicate inside a living cell
Viral Load:
- Initial infection
- Viremia (large viral levels in blood) for 2 to 3 weeks (transmission is more likely when viral load is high)
- Followed by prolonged period (years) of low viral load
Pathophysiology:
- Cells with CD4 receptor sites are infected
- CD4+ T cells (T helper cells)
- Lymphocytes
- Monocytes/macrophages
- Astrocytes
- Oligodendrocytes
- HIV attacks these cells and uses them to make more copies of HIV
- Weakens immune system, makes it unable to protect body from illness and infection
- Immune dysfunction results mostly from destruction of CD4+ T cells (key cells for immune recognition and defense against pathogens)
- Normal T cell life span is 100 days, whereas infected cells live only 2 days
- Viral activity destroys 1 billion T cells daily
- Adults normally have 800-1200 CD4+ T cells per microliter (µL) of blood
- Immune problems start when CD4+ T cell counts drop below 500 cells/µL
Timeline:
- Acute Retroviral Syndrome: first few weeks after HIV infection; before antibody test results become positive; characterized by fever, malaise, lymphadenopathy & skin rash; symptoms may be mistaken for a cold or flu
- Early Chronic HIV Infection: 3 weeks to 3 months post infection; HIV antibody test becomes positive; CD4+ T cell count remains above 500 cells/µL; generally asymptomatic; flu-like symptoms often occur: fatigue, low-grade fever, night sweats, generalized lymphadenopathy; public health problem – individuals unaware they are infected
- Intermediate Chronic Infection: viral load increases; CD4+ T lymphocyte count DROPS to 200 to 500 cells/µL; most common infection is oropharyngeal candidiasis or thrush; severe fatigue & night sweats
- Late Chronic Infection or Acquired Immunodeficiency Syndrome (AIDS): immune system severely compromised
CD4+ T cell count plummets; viral load surges; AIDS is diagnosed when an individual with HIV develops at least one of these conditions (CD4+ T cell count drops below 200 cells/ul; development of one of a list of opportunistic infections; development of one of a list of opportunistic cancers; wasting syndrome occurs; dementia develops)
Disease Progression Varies:
- in untreated patients, the time between infection with HIV and the development of AIDS ranges from a few months to as long as 17 years (median: 10 years)
- majority of individuals infected with HIV remain symptom-free for extended periods, but viral replication is active during all stages of infection and increases substantially as the immune system deteriorates
Testing and Counselling:
- Pre & post-test counseling
- Decreasing future risk of exposure
- Protecting partners
- Delay between infection & accurate test
- Possibility of false-negative tests during window period
- Positive test shows HIV infection & not AIDS
- in many provinces, if test done through doctor’s office or clinic, results reported to health officials
Antibody Testing:
- Sensitive screening test: enzyme immunoassay [EIA]
- Reactive screening test: Rapid test – diagnosis of HIV-1 infection within 30 min
- Reactive screening tests must be confirmed by a supplemental test (e.g., the Western blot [WB] or an immunofluorescence assay [IFA]
- HIV antibody is detectable in at least 95% of patients within 3 months after infection
- All infants born to HIV infected mothers will be positive on the HIV antibody test because maternal antibodies cross the placental barrier – these antibodies remain present in the infant up to 18 months
- Need to test for HIV antigen – can definitively diagnose HIV in infected infants by 4 wks of age
-
Collaborative Care Focus:
- Monitoring HIV disease progression and immune function
- Initiating and monitoring antiretroviral therapy (ART)
- Preventing and detecting opportunistic infections
- Managing symptoms
- Preventing and treating complications of therapies
Antiretroviral Therapy (ART):
- Antiretroviral drugs work at various points in HIV replication cycle
- HIV can become resistant to any of these drugs
- When multiple drugs (three or more) are used in combination, it is referred to as antiretroviral drug therapy (ART)
- Multidrug-therapy protocols have been shown to significantly reduce viral loads & reverse clinical progression of HIV
Drug Therapy:
- Goals: decrease HIV RNA levels to less than 50 copies/uL; maintain or raise CD4+ T cell counts to greater than 200 cells/uL [a range of 800 to 1200 cells/uL is preferred]; delay development of HIV-related symptoms; treatment decisions should be individualized
- Categories:
- Protease inhibitors (PIs) (e.g. Invirase); interfere with activity of enzyme protease, inhibit viral replication at later step
- Integrase inhibitors (e.g. Raltegravir); work by interfering with the enzyme integrase
- Fusion (entry) inhibitors (e.g. Fuzeon); Interfere with HIV CD4 receptor site binding and entry into cells
- Reverse Transcriptase Inhibitors (RTIs) nukes (nucleoside) or non-nukes (non-nuceloside); inhibit ability of HIV to make a DNA copy early in replication
- Adherence: taking drugs as ordered; difference with HIV (missing a dose can lead to viral mutations that allow HIV to become resistant to drug), adherence rates > 95% are required to prevent disease progression
Tuberculosis:
- Infectious disease caused by a bacterial infection (mycobacterium tuberculosis)
- Confused with cancer, bronchitis, pneumonia
- Usually attacks the lungs but can affect any part of the body (larynx, kidneys, meninges, bones, adrenal glands, lymph nodes)
- Only TB in the lungs or throat is infectious
- major adverse drug effect: hepatitis (requires liver function test monitoring)
Resurgence of TB:
- Dramatic decrease in 1940s & 1950s due to introduction of chemotherapeutic agents
- Now ~ 1600 new cases reported in Canada/year
- High rates of TB co-infection with HIV
- Multi-drug resistant (MDR) strains of TB
- Immigration
- Crowding in prisons/shelters
- Healthcare workers considered to be at high risk
Etiology:
- Spread via airborne droplets when infected person coughs, speaks, sneezes
- Not spread by hands or objects
- Brief exposure rarely causes infection
- Transmission requires close, frequent or prolonged exposure
TB Infection (Latent TB):
- Exposed to the TB bacteria but immune system strong enough to contain it
- Positive skin test
- No TB symptoms
- Not contagious
- At risk for developing the disease in future
- May be given medication to prevent disease from developing (Isoniazid 9 or 6 months OR Isoniazid and Rifapentine for 3 months OR Rifampin for 4 months)
TB Disease:
- TB bacteria is actively replicating
- TB skin test and sputum test may be positive
- Most show active TB on x-ray/CT/MRI of chest or other body parts (lymph nodes, spine, kidneys)
- Symptoms become worse over time
- Contagious if in the lungs/throat and not treated
- Needs treatment with several medications for months or longer to cure disease
Clinical Manifestations:
- Cough > 3 weeks
- Pleuritic pain
- Abnormal chest x-ray
- Fever and/or chills
- Night sweats
- Unexplained weight loss
- Hemoptysis (coughing blood) not common
- Dyspnea unusual
Medical Management:
- Standard therapy revised due to increased prevalence of MDR TB
- MDR TB occurs when resistance develops to two or more anti-TB drugs
- Managed aggressively with a combination of at least 4 drugs (to increase therapeutic effectiveness; to decrease development of resistant strains)
TB Medications:
- Five primary medications
Isoniazid (INH)
Rifampin (RMP)
Pyrazinamide (PZA)
Streptomycin
Ethambutol (EMB)
- Various drug & dosing combinations
- Combination drugs may enhance adherence
Rifamate: INH & RMP
Rifater: INH, RMP & pyrazinamide
- Patients on antiretroviral drugs for HIV cannot take RMP (interferes with ART)
Drug Therapy for Opportunistic Diseases: HIV management is complicated by opportunistic disease that can develop due to a poor immune system
Pneumocytis carinii pneumonia (PCP): caused by fungus; can be prevented by antibiotics; clinical manifestations: non-productive cough, hypoxemia, progressive shortness of breath, fever, night sweats, fatigue
Cryptococcal meningitis: brain infections caused by fungus (found mainly in dirt and bird droppings)
Cytomegalovirus retinitis (CMV): infection of retina, occurs primarily in AIDS patients; clinical manifestations: lesions on retina, blurred vision, loss of vision
Mycobacterium avium complex (MAC): gastrointestinal system affected; serious infection; clinical manifestations: watery diarrhea and weight loss
Kaposi's sarcoma (KS): cancer that develops in connective tissues such as cartilage, bone, fat; clinical manifestations: firm, flat, raised or nodular, hyper pigmented multi-centric lesion
Infection Precautions:
- Guidelines issued by the CDC & Health Canada
- Purpose: To prevent transmission of organisms between clients and healthcare providers
Routine Practices/Standard Practices:
- for care of ALL clients in hospitals and health care settings regardless of diagnosis or presumed infection status
Additional Precautions:
- for clients suspected of being infected with epidemiologically important pathogens that can be transmitted by:
- air: need private room with negative flow; wear N95 mask (ex. measles, TB, varicella)
- droplet: private or semi-private room; mask for activities within 1 metre of patient; ex. influenza, meningitis
- contact (with dry skin or contaminated surfaces)
Infection:
- Invasion of the body by a pathogen & resulting signs & symptoms that develop in response to the invasion
- Localized or systemic
- Most common causes: bacteria, viruses, fungi, protozoa
Bacteria:
- One-celled micro-organisms
- Many considered normal flora
- Cause disease when they enter body & grow inside cells (ex. TB) and/or secrete toxins that damage cells (ex. tetanus)
Viruses:
- Not cells like bacteria
- Consist of RNA or DNA & a protein envelope
Can only reproduce in the cells of a living organism e.g. HIV
Antibiotic-Resistant Organisms (AROs) or Multi-Drug Resistant Organisms (MDROs):
- Resistance: Occurs when pathological organisms change in ways that decrease the ability of a drug to treat disease
Methicillin-resistant Staphylococcus aureus (MRSA)
Vancomycin-resistant enterococci (VRE)
Penicillin-resistant Streptococcus pneumoniae
Healthcare-Associated Infections:
- Infections acquired in healthcare settings
- estimated 8000 Canadians die in hospitals each year due to HAIs
- At least 30% of HAIs can be prevented by following infection prevention strategies
Contact with Blood and Blood Products:
- Exposes health care workers to:
Acquired human immunodeficiency virus (HIV)
Hepatitis A virus (rare)
Hepatitis B virus (30%)
Hepatitis C virus (3%)
- Risk of HIV infection after a needle-stick exposure to HIV blood is 0.3% - 0.4%
Needle Stick Injuries:
- Report all blood exposures
- Routine post-exposure management includes serological markers of HIV, HBV & HCV infection
- Post-exposure prophylaxis with combination ART based on type & volume of exposure, & the status of the source patient has been shown to significantly reduce the risk of infection
Routine Practices or Standard Precautions:
- Hand hygiene: pre/post contact
- Gloves: touching body fluids, secretions & contaminated items, mucous membranes & nonintact skin
- Mask, eye protection/face shield: procedures likely to generate splashes or sprays of body fluids; within 1 m of coughing patient
- Gown: procedures likely to generate splashes or sprays of body fluids
