Human Immunodeficiency Virus and its management

Human Immunodeficiency Virus and its management

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  Human Immunodeficiency Virus RETROVIRUSES
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  INTRODUCTION • Family- Retroviridae •Subfamily- Orthoretrovirinae • Genus- Lentivirus • Species- HIV1 and HIV2 • HIV1- isolated in America, Europe, central Africa • HIV2-in west Africa, less virulent and spread is not as widely and rapidly as HIV 1 • In India, HIV 1 subtype C is the most popular CP baveja – Textbook Of Microbiology – 5th Edition
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  SUBTYPES OF HIVVIRUS CP baveja – Textbook Of Microbiology – 5th Edition
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  MORPHOLOGY • Spherical envelopedvirus, 90-120nm in diameter • Has 2 identical copies of ssRNA genome • Virus core- surrounded by nucleocapsid composed of protein • Envelope- made of lipoprotein • Major virus coded envelope glycoproteins- projects as spikes on surface and anchor transmembrane pedicles CP baveja – Textbook Of Microbiology – 5th Edition
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  Mode of transmission •1) Sexual contact (86%): most common mode, occurs among both homosexual and heterosexual individual. • 2) Parenteral transmission (89%)- via blood after receiving infected blood transfusions, blood products, sharing contaminated syringes and needles as intravenous drug abusers or accidental inoculation. • 3) Perinatal transmission / Vertical transmission(93%)– transmitted from infected mother to her child transplacentally or perinatally. CP baveja – Textbook Of Microbiology – 5th Edition
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  Replication CP baveja –Textbook Of Microbiology – 5th Edition
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  CLINICAL FEATURES CP baveja– Textbook Of Microbiology – 5th Edition
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  1. GROUP 1-Acute HIV infections- characterized by acute onset of fever, malaise, sore throat, myalgia, arthralgia, skin rash an lymphadenopathy. 2. GROUP 2- Asymptomatic infection – infected persons are usually well but show positve hiv antibody tests and are infectious. 3. GROUP 3- Persistent generalised lymphadenopathy- characterised by enlarged lymph nodes. 4. GROUP 4- Symptomatic HIV infection- CD4+ T lymphocyte count falls below 400 per mm cube, followed by symptoms like fever, diarrhoea, weight loss, night sweats and opportunistic infections. When CD4+ cells fall below 200 per mm cube, titer of virus increases markedly and there is irreversible breakdown of immune defence mechanisms Aids is the end stage of HIV infection CP baveja – Textbook Of Microbiology – 5th Edition
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  WHO CLASSIFICATION 1. Stage1: Asymptomatic or Persistent Generalized Lymphadenopathy Patients in this stage may be asymptomatic or have persistent generalized lymphadenopathy (swollen lymph nodes) for more than six months. 2. Stage 2: Mildly Symptomatic Characterized by mild symptoms like unexplained moderate weight loss, recurrent respiratory infections (sinusitis, bronchitis, etc.), or certain skin conditions (herpes zoster, angular cheilitis, etc.). 3. Stage 3: Moderately Symptomatic Includes conditions where a presumptive diagnosis can be made based on clinical signs or simple tests, such as severe weight loss, unexplained anemia, or neutropenia. 4. Stage 4: AIDS This stage is characterized by severe symptoms and the presence of opportunistic infections that indicate advanced HIV disease.
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  LABORATORY DIAGNOSIS • 1)Specific tests for HIV infections • A) Antigen detection: p24 is earliest virus marker to appear in blood, useful for diagnosis in window period • B) Virus isolation: isolated from CD4+ lymphocytes of peripheral blood, bone marrow, and serum, important test for diagnosis in window period when antibodies are absent in serum • C) Detection of viral nucleic acid: viral nucleic acid is diagnosed by PCR, test is highly sensitive and specific, used for diagnosis in window period • D) Antibody detection: demonstration of antibodies is simplest and most commonly used technique, may take several weeks to months for antibodies to appear after infection, IGM antibodies appear firs in 3-4 weeks after infection followed by IGG HIV infected persons remain negative for antibodies during window period ( here initial viral replication takes place for 2-3 weeks) CP baveja – Textbook Of Microbiology – 5th Edition
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  • 2 screeningtests • A) ELISA: most commonly used, highly sensitive and specific, here saliva is acceptable alternative to serum for antibody testing • B) Rapid tests: test takes less than 30 mins and do not require expensive equipment, includes dot-blot assay, particle agglutination and hiv spot and comb tests CP baveja – Textbook Of Microbiology – 5th Edition
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  • 3 supplementaltests • A) Western Blot test- hiv proteins are separated by polyacrylamide gel electrophoresis, separated proteins are blotted onto strips pf nitrocellulose paper. These strips are reacted with test sera, antibodies to hiv proteins if present in test serum, combine with fragments of hiv. Position of colour band on strip  fragment of antigen with which antibodies have reacted. - Positive result is confirmed after retesting the original - Test is cumbersome, expensive and not readily available CP baveja – Textbook Of Microbiology – 5th Edition
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  • B) Indirectimmunofluorescence test: hivinfected cells are fixed onto glass slides and then reacted with serum followed by fluorescein conjugated antihuman gamma globulin - Positve result apple green fluorescence Other non-specific tests • 1) TLC and DLC: there is leucopenia with lymphocyte count less than 400 per mm cube • 2) T-lymphocyte subset assay: normal cd4: cd8+ t cell ratio is 2:1 but here it is reveresed to 0.5:1, as cd4+ lymphocyte counts fall below 200 per mm cube CP baveja – Textbook Of Microbiology – 5th Edition
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  PREVENTION • 1) Sexualcontact  use of physical barriers can prevent transmission of virus • 2) Sharing needles  contaminated syringes or needles should not be shared • 3) Blood  all blood and blood products should be screened, and same applies for donation of cornea, semen, marrow, kidney and other organs • 4) Isolation of aids patient and initiation of treatment • 5) Control of infection  screening of individuals within risk groups helps to identify HIV infected persons CP baveja – Textbook Of Microbiology – 5th Edition
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  ANTIRETROVIRAL THERAPY • Highlyactive antiretroviral therapy is effective in inhibition of hiv replication in hiv-infected individuals • These drugs include both nucleoside and non nucleoside inhibitors of enzyme reverse transcriptase , viral protease inhibitor, fusion inhibitor, integrase inhibitor and entry inhibitor • These drugs can be used as monotherapy or in various combinations CP baveja – Textbook Of Microbiology – 5th Edition
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  POST EXPOSURE PROPHYLAXIS •Exposure to blood, body fluid, other potentially infected material or an instrument contaminated may lead to risk of acquiring HIV • Following exposure, postexposure prophylaxis may be required depending upon category of exposure and hiv status of exposure source • Zidovudine 300mg and lamivudine 150 mg bd are 2 basic drugs in this regimen • 3 drug PEP regimen: Lopinavir 400mg BD/ 800mg OD or Ritonavir 100 mg BD/200mg OD can be added as 3rd drug • To be effective  start these drugs within first 72 hrs and ideally within 2 hrs, followed through 4 weeks CP baveja – Textbook Of Microbiology – 5th Edition
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  NEEDLE STICK INJURIES •Needle stick injury poses as a major risk factor among dentists for HIV transmission. • It can occur during recapping of needles, while administering local anesthetics, disposing of needles, handling of trash. • Chances of transmission through NSI is 0.3%. • Ensure proper handling, recapping and segregation of needles.
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  UNIVERSAL PRECAUTIONS • Assumeall specimens / patients are potentially infectious for hiv and other blood borne pathogens • All blood specimens/ body fluids should be placed in leak proof impervious bags for transportation to labs • Use gloves while handling blood and body fluid specimens and other objects exposed to them, if there’s chance for splattering wear – facemask with googles • Wear lab coats or gowns while working in labs, and these should not be taken outside • Never pipette with mouth • Decontaminate lab surfaces with appropriate disinfectant after blood spillage and when procedures complete • Limit use of needles and syringes to situations for which there are no other alternatives • Biological safety hoods to be used • All potentially contaminated materials of labs to be decontaminated before disposal • Always wash hands after lab work and remove all protective clothing’s before leaving labs CP baveja – Textbook Of Microbiology – 5th Edition