Download MBBS (Bachelor of Medicine, Bachelor of Surgery) General Medicine 2022 PPT 9 Hiv Aids Part I Lecture Notes
Infectious diseases
4/5th Semester Classes on Infectious Diseases, 8-9AM, Tuesdays (LT-1)
Topics
1
Approach to Infectious Diseases and their prevention
2
Antibiotic stewardship practices
3
Community-Acquired Infections
4
Health Care?Associated Infections
5
Gram-Positive Bacteria (part-1)
6
Gram-Positive Bacteria (part-2)
7
Gram-Negative Bacteria (part-1)
8
Gram-Negative Bacteria (part-2)
9
Spirochetal Diseases
10
Diseases Caused by Atypical/Miscel aneous Bacterial Infections
11
Revision-cum-exam on bacteria (Must to know type)
12
Infections Due to DNA Viruses
1
13
Infections Due to RNA Viruses (part 1)
14
Infections Due to RNA Viruses (part 2)
15
HIV/AIDS ? part 1
16
HIV/AIDS ? part 2
17
Fungal Infections
18
Parasitic Infections (part 1)
19
Parasitic Infections (part 2)
20
Revision-cum-exam on Virus, Fungal, and Parasite (Must to know type)
HIV/AIDS
? HIV is a retrovirus which attacks the T-cel s in the immune
system
? Acquired Immuno deficiency syndrome or AIDS, is a
collection of symptoms due to underlying infections
and malignancies resulting from specific damage to
immune system caused by human immunodeficiency
virus (HIV).
A Global view of HIV Infection
? Approximately > 40 million people are currently living with HIV
infection, and 25 million have already died
AIDS
? The first indication of this new syndrome came in 1981 in
homosexual drug addict males;
? They had two things in common- Pneumocystis pneumonia and
Kaposi's sarcoma
? In 1983, HIV was isolated from a patient with
lymphadenopathy, and by 1984 it was demonstrated clearly to
be the causative agent of AIDS
? In 1986, The International Committee on virus Nomenclature
decided on the generic name of the causative virus as the Human
Immunodeficiency Virus
Structure of HIV
? It has a diameter of 100-120 nm
with a spherical morphology
? Cone-shaped core surrounded
by lipid matrix containing key
surface antigens and
glycoproteins
? Viral core contains 2 copies of
genomic RNA, reverse
transcriptase, integrase and
protease
Based on molecular and antigenic differences, two types of HIV have been recognized
HIV 1
HIV 2
? HIV-1 is more common in
? HIV-2 is found in West Africa,
india
Mozambique, and Angola.
? Easily transmited.
? Less easily transmitted.
? Pathogenic in nature
? Less pathogenic.
? Duration of infection is
? Duration of infection is shorter
quite long.
.
? classified in to at least
? Relatively rare and has not
ten subtypes based on
been reported from India.
sequence analysis of
their gag and env genes
(Group M (For major) is
largest.
Antigenic variations in HIV
? HIV is a highly mutable virus and exhibits frequent antigenic variations
as wel as dif erences in other features such as nucleotide sequences,
cell tropism, growth characteristics and cytopathology
? Not only are there dif erences between isolates of HIV from different
races or persons but also between sequential isolates from the same
person, and even between those obtained from different sites of the
same person at the same time.
? This great variability is believed to be due to error prone nature of
reverse transcription
Mode of transmission
1. Sexual contact- In 75 % cases , transmission
is by sexual contact.
? People who already have a sexual y
transmit ed disease, such as syphilis, genital
herpes, chlamydial infection, gonorrhea, or
bacterial vaginitis, are more likely to acquire HIV
infection during sex with an infected partner
Mode of transmission
2. Parenteral- In 15 % cases, it is by blood transfusion or blood
product transfusion.
3. Sharing of unsterilized needles or syringes in drug addicts
contaminated with blood from an infected person can spread
virus.
4. HIV can be spread in health-care set ings through accidental
needle sticks or contact with contaminated fluids.
5. HIV can also spread through organ transplantation.
6. Mother to child
From mother to child
? 30% of children born to
infected mothers have
the acquired infection
unless virus is treated by
antiviral drugs before
pregnancy.
? In nursing mothers
transmission can occur
through breast milk.
Pathogenesis
CD 4+ cel s are present in- T helper cels, B -lymphocytes ,
macrophages, monocytes , and dendritic cels
Steps of viral entry in to the host cell
o Strains of HIV that utilize
CCR5 as a co-receptor are
referred to as macroph e
ag
tropic viruses (M ?tropic
viruses)
o Strains of HIV that utilize
CXCR4 are referred to as -
T
tropic viruses.
o Many virus strains are dual
tropic in that they utilize
both CCR5 and CXCR4.
Events that transpire from primary HIV infection
Summary of early events in HIV infection
? Lymphoid tissues are the major anatomic sites for the establishment and propagation of
HIV infection
? Immune activation and inflammation contribute substantially to:
(1) the replication of HIV,
(2) the induction of immune dysfunction, and
(3) the increased incidence of chronic conditions associated with persistent immune
activation and inflammation
? Accelerated aging syndrome
? Bone fragility
? Cancers
? Cardiovascular disease
? Diabetes
? Kidney disease
? Liver disease
? Neurocognitive dysfunction
Increased occurrence and/or exacerbation of certain autoimmune diseases like:
? Psoriasis,
? Idiopathic thrombocytopenic purpura,
? Graves' disease,
? Antiphospholipid syndrome, and
? Primary biliary cirrhosis
Immune reconstitution inflammatory syndrome (IRIS) is an autoimmune-like phenomenon
characterized by a paradoxical deterioration of clinical condition, which is usually
compartmentalized to a particular organ system, in individuals in whom cART has recently been
initiated.
? It is associated with a decrease in viral load and at least partial recovery of immune
competence, which is usually associated with increases in CD4+ T cell counts.
? Commonly seen with underlying Mycobacterium tuberculosis and cryptococcosis
Immune deficiency in HIV Infection
Typical course of an untreated HIV-infected individual
(The combination of viral pathogenic and immunopathogenic events decides the disease)
? Long-term nonprogressors are by definition long-term
survivors; however, the reverse is not always true
? Long-term nonprogressors were first described in the
1990s, defined if
? They had been infected with HIV for a long period (10
years),
? Their CD4+ T cell counts were in the normal range, and
? They remained stable over years without receiving Cart
Laboratory Diagnosis of HIV infection
1) Non Specific Tests- The fol owing tests help to establish the
immunodeficiency in HIV infection.
? Total Leukocyte and lymphocyte count- to demonstrate leucopenia
and lymphopenia. The lymphocytic count is usual y below
2000/mm3
? T cell subset Assays- Absolute CD4+ cell count is reduced with T4 :
T8 ratio is reversed
? Platelet count-shows Thrombocytopenia.
? IgA and Ig G levels are raised
? Diminished cell mediated Immunity as indicated by skin tests
? Lymph node biopsy shows profound abnormalities
Laboratory Diagnosis of HIV infection
2.Specific Tests for HIV infection- Diagnosis depends on the
demonstration of antibodies to HIV and/or the direct detection of HIV or one of its
components
Detection of antigen - p24 Capture ELISA assay, is positive in about
30% of the infected persons.
? In the first few weeks after infection and in the terminal
phase, the test is uniformly positive
Detection of antibodies - It takes 2-8 weeks to months for the
antibodies to appear in circulation
Recently, the interval between infection and detection (window period) has decreased from
22 days for antibody testing to 16 days with p24 antigen testing and subsequently to 12 days
with NAT
Laboratory Diagnosis of HIV infection
ELISA (most frequently used method for
screening for HIV antibody)
1)First generation - whole viral lysates
2)Second generation - recombinant antigen
3)Third generation - synthetic peptide
4)Fourth generation - antigen + antibody
(Simultaneous detection of HIV antigen and
antibody) - HIV duo
Laboratory Diagnosis of HIV infection
Supplemental Tests
? Western Blot Test (gold standard)
? Indirect Immunoflorescence test
? Radio ImmunoPrecipitaion Assay
Rapid Tests
a) Dot Blot assay
b) Particle Agglutination tests
c) HIV spot and comb test
d) Flurimetric microparticle techn
Laboratory Diagnosis of HIV infection
Demonstration of viral Nucleic
acid
? Three different PCR techniques
namely
? RT- PCR,
? Nucleic acid sequence based
amplification (NASBA) and
? branched-DNA (b-DNA) assay
have been employed to
Extremely high sensitivity
develop commercial kits
Clinical Manifestations
The center for disease control (CDC) has classified the
clinical course of HIV infection under various groups.
1. Acute HIV infection
2. Asymptomatic or Latent infection
3. Persistent generalized lymphadenopathy (PGL)
4. AIDS related complex
5. Full blown AIDS (Last stage)
Thank you
This post was last modified on 05 April 2022