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Introduction to HIV 

  1. I" recognition of AIDS came from US in 1981
  2. Initial reporting symptoms on presentation were P. jiroveci pneumonia and Kaposi's sarcoma
  3. HIV isolated in 1983
  4. In 1984, it was demonstrated that HIV is the causative agent of AIDS
  5. 1985, a sensitive ELISA developed for HIVI986: name "HIV" given
  6. 1986: the first HIV positive case was detected in India in a commercial sex worker in Tamil Nadu
  7. 1999: demonstrated that HIV in humans was a zoonoses (had originated from chimpanzees)
  8. 1st December: World AIDS Day


  1. We currently follow CDC classification system for HIV infected adolescents and adults
  2. This system is based on
    1. Clinical conditions associated with HIV infection
    2. CD4+ T lymphocytes count
  3. Confirmed HIV infection by ELISA and Western blot with CD4+ count <200 / mm3
    And / or
Category C condition:
  1. Candidiasis of bronchi, trachea, lungs, or esophagus
  2. Cervical cancer invasive
  3. Coccidioidomycosis disseminated or extra – pulmonary
  4. Cryptococcosis extra pulmonary
  5. Cryptosporidiosis, chronic intestinal (>1 month)
  6. Cytomegalovirus disease other than liver, spleen or node
  7. HIV encephalopathy
  8. Herpes simplex, chronic (>1 month), or bronchitis, pneumonia, or esophagitis
  9. Histoplasmosis, disseminated or extra pulmonary
  10. Isosporiasis chronic intestinal (>1 month)
  11. Kaposi sarcoma
  12. Lymphoma (Burkitt’s primary CNS)
  13. MAC disseminated or extra pulmonary
  14. M. tuberculosis any site
  15. Pneumocystis carinii pneumonia
  16. Pneumonia recurrent
  17. Progressive multifocal leukoencephalopathy
  18. Salmonella septicaemiae, recurrent
  19. Toxoplasmosis of brain
  20. Wasting syndrome due to HIV
  21. Using this system, any HIV infected individual with CD+ T cell count <200/μl has AIDS by definition, regardless of the presence of symptoms or opportunistic disease. 
Case definition of AIDS in adults in India (for persons above 12 years of age)
  1. Two positive tests for HIV infection by ERS test (ELISA/RAPID/SIMPLE)
  2. Anyone of the following criteria:-
  3. Significant weight loss (>10% of body weight) within last one month/cachexia (not known to be due to a condition other than HIV infection)
    Chronic diarrhea (intermittent or continuous) > I month duration or prolonged fever (intermittent or continuous) > I month duration
  4. Tuberculosis: Extensive pulmonary, disseminated, miliary, extra-pulmonary tuberculosis.
  5. Neurological impairment preventing independent daily activities, not known to be due to the conditions unrelated to HIV infection (e.g. trauma) .
  6. Candidiasis of the oesophagus (diagnosable by oral candidiasis with odynophagia)
  7. Clinically diagnosed life -threatening or recurrent episodes of pneumonia, with or without etiological confirmation
  8. Kaposi Sarcoma
  9. Other conditions:-
    1. Cryptococcal meningitis
    2. Neuro Toxoplasmasis
    3. CMV retinitis
    4. Pencillium marneffei
    5. Recurrent Herpes Zoster or multi-dermatomal herpes infection
    6. Disseminated molluscum
Table - Revised Classification System for HIV Infection and Expanded AIDS Surveillance Case Definition for Adolescents and Adults (CDC classification)
Clinical Categories
CD4+ T Cell Categories A Asymptomatic, Acute (Primary) HIV or PGL B Symptomatic, Not A or C Conditions C AIDS-Indicator Conditions
>500/L A1 B1 C1
200–499/L A2 B2 C2
<200/L A3 B3 C3
Category A: Consists of one or more of the conditions listed below in an adolescent or adult (>13 years) with documented HIV infection. Conditions listed in categories B and C must not have occurred.
Asymptomatic HIV infection
Persistent generalized lymphadenopathy
Acute (primary) HIV infection with accompanying illness or history of acute HIV infection
Category B: Consists of symptomatic conditions in an HIV-infected adolescent
or adult that are not included among conditions listed in clinical category C and that meet at least one of the following criteria: (1) The conditions are attributed to HIV infection or are indicative of a defect in cell-mediated immunity; or (2) the conditions are considered by physicians to have a clinical course or to require management that is complicated by HIV infection. Examples include, but are not limited to, the following:
Bacillary angiomatosis
Candidiasis, oropharyngeal (thrush)
Candidiasis, vulvovaginal; persistent, frequent, or poorly responsive to therapy
Cervical dysplasia (moderate or severe)/cervical carcinoma in situ
Constitutional symptoms, such as fever (38.5°C) or diarrhea lasting >1 month
Hairy leukoplakia, oral
Herpes zoster (shingles), involving at least two distinct episodes or more than one dermatome
Idiopathic thrombocytopenic purpura
Pelvic inflammatory disease, particularly if complicated by tuboovarian abscess
Peripheral neuropathy
Category C: Conditions listed in the AIDS surveillance case definition.
Candidiasis of bronchi, trachea, or lungs
Candidiasis, esophageal
Cervical cancer, invasivea
Coccidioidomycosis, disseminated or extrapulmonary
Cryptococcosis, extrapulmonary
Cryptosporidiosis, chronic intestinal (>1 month's duration)
Cytomegalovirus disease (other than liver, spleen, or nodes)
Cytomegalovirus retinitis (with loss of vision)
Encephalopathy, HIV-related
Herpes simplex: chronic ulcer(s) (>1 month's duration); or bronchitis, pneumonia, or esophagitis
Histoplasmosis, disseminated or extrapulmonary
Isosporiasis, chronic intestinal (>1 month's duration)
Kaposi's sarcoma
Lymphoma, Burkitt's (or equivalent term)
Lymphoma, primary, of brain
Mycobacterium avium complex or M. kansasii, disseminated or extrapulmonary
Mycobacterium tuberculosis, any site (pulmonarya or extrapulmonary)
Mycobacterium, other species or unidentified species, disseminated or extrapulmonary
Pneumocystis jiroveci pneumonia
Pneumonia, recurrenta
Progressive multifocal leukoencephalopathy
Salmonella septicemia, recurrent
Toxoplasmosis of brain
Wasting syndrome due to HIV





Global pandemic
95% of new cases and -90% of all cases in developing countries
  1. Globally, India has the third .highest estimated number of HIV infected people in any single
  2. country, next only to South Africa and Nigeria.
  3. Approx no. of cases in India: 3.82 - 4.58 million (2002)
  4. 90% cases in 15-49 y age group
  5. MC mode of spread is heterosexual (FAQ)
    1. Group I: high prevalence- generalized epidemic
      1. >5% in high-risk group; 1% in" ANC; spread from urban to rural areas
      2. Maharashtra, TN, AP, Karnataka, Manipur, Nagaland
    2. Group II: moderate prevalence - concentrated epidemic  
      1. >5% in high risk group; < 1% in ANC
      2. Goa, Gujarat, Kerala, west Bengal
    3. Group III: low prevalence  
      1. <5% in high risk group; <1 % in ANC
      2. Other states (incl. Bihar, MP, UP, Rajasthan) 
Etiologic agent
  1. HIV belongs to family of human retroviruses and subfamily of lentiviruses
  2. There are 4 recognized human retroviruses; which can be grouped into 2 broad groups-
  3. Transforming Retroviruses - HTLV - I, HTLV -II
  4. Cytopathic retroviruses –     HIV - 1 and HI V-2
  5. Both HIV -I and HIV - 2 are zoonotic diseases
  6. The most common cause of HIV disease throughout world is HIV - 1 (LQ 2012) but HIV 2 is common in west Africa-Park-20th edition, page 301) (LQ 2012)
  7. Pan troglodytes species of chimpanzees is the natural reservoir of HIV - 1 and the most likely source of original human infection
  8. HIV-2 is more closely related phylogenetically to the simian immunodeficiency virus (SIV) than to HIV-1  
Morphology of HIV
From the antigenic point of view, we can group HIY Structure into
  1. Envelop - Main component for binding to CD4+ T cells Principal antigens are - gp41, gp 120
  2. Nucleocapsid - consists of
    1. Outer icosahedral shell - Principal antigen is p 18 (shell antigen)
    2. Inner cone shaped core - Core antigens - p24 (principal antigen) Other - P15, P35  
  3. RNA - Constitutes the genome Polymerase antigens - p31, p51, p66
  1. Most common form world wide is subtype C viruses (of M group)
  2. In U.S, Canada, certain countries in S. America, W. Europe, Australia most predominant form is subtype B
  3. In Sub-Saharan Africa - most common form is subtype C
  4. In Asia - most common forms are CRF01_AE, subtype C and B.
  5. In India - most common form is subtype C
  6. Many countries have co-circulating viral subtypes that are giving rise to new CRFs

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