10 Human Health and Diseases - part 08 - AIDS

 

10 Human Health and Diseases - part 08 - AIDS

AIDS :
  • AIDS, the acquired immuno deficiency syndrome, is a usually fatal illness caused by a retrovirus (ss RNA) known as the human immuno deficiency virus (HIV) 
  • HIV weakens the body’s immune system, leaving the victim vulnerable to life –threating opportunistic infections, neurological disorders and unusual malignancies. 
  • AIDS can be called a modern pandemic (world wide), affecting both industrialized and developing countries.
  • AIDS was first noticed in USA in 1981.
  • In India, first confirmed case of AIDS was in April 1986 from Tamil Nadu.
Structure of HIV:


  • HIV is 100 to 140 nm in diameter. 
  • It is spherical. 
  • Virus particle shows centrally located two ss RNA molecules along with reverse transcriptase enzymes. 
  • It is covered by two layers of proteins. 
  • The outer layer is of matrix protein (p17) while in inner layer is capsid protein (p24).
  • Over the matrix protein layers there is an additional layer of lipids. 
  • Impregnated with glycoprotein GP120 and GP 41.
  • The virus replicates in actively dividing T4 lymphocytes and can remain in a latent state/stage in the lymphoid cells. 
  • The virus has unique ability to destroy human T4 lymphocytes .
  • HIV is found in greatest concentration in blood, semen and cerebrospinal fluid (CSF) and to lesser extent in tears, milk, urine, saliva, cervical and vaginal secretions.

The virus can be transmitted through :
  1. Unsafe sexual contact: Including oral, vaginal and anal sex.
  2. Blood : Via blood transfusions or needle sharing.
  3. From mother to child (Transplacental): A pregnant woman can transmit the virus to her foetus through their shared blood circulation, or a nursing mother can transmit it to her baby from her breast milk.
  • Other methods of spreading of the virus are rare and include - 
  1. Accidental needle injury
  2. Artificial insemination with infected donated semen and 
  3. Transplantation with infected organs.
  • AIDS virus has been found in urine, tears, saliva, breast milk and vaginal secretions but it seems not to be transmitted by these fluids unless it gets into injuries.
Always Remember :
HIV infection is not spread by:
  • Causal contact such as hugging, insect bite (mosquitoes), participation in sports, touching items previously touched by a person infected with the virus, hand shake, sharing clothes, swimming pools etc.
Clinical manifestations:
  • The clinical manifestations (symptoms) of AIDS have been classified into four broad categories.
  1. Initial infection with the virus and formation of antibodies, usually 2-8 weeks after initial infection.
  2. Asymptomatic carrier state in which no signs of disease, are seen. Incubation period ranges for 6 months to 10 years.
  3. AIDS related complex (ARC) with one or more of the following clinical signs: - recurrent fever for longer than one month, fatigue, unexplained diarrhea, night sweats, shortness of breath, loss of more than 10 per cent body weight, etc
  4. AIDS is the end stage of HIV infection : It is characterised by life threatening opportunistic infections (like pneumonia, tuberculosis, kaposi sarcoma, etc.).
Preventive measures:
  • AIDS has no cure, hence prevention is the best choice. 
  • The following steps help in preventing this dreadful diseasei.
  1. People, particularly those in high –risk group, should be educated about HIV transmission.
  2. Disposable needles and syringes should be used and disposed off properly and immidiately.
  3. Sexual habits should be changed immediately.
  4. High-risk groups should refrain from donating blood.
  5. Tooth brushes, razors, other articles that can become contaminated with blood should not be shared.
  6. Before receiving blood, ensure that it has been screened for not containing HIV infections.
  7. Routine screening must be done for –
  • Blood donors
  • Organ donors (kidney, liver, lung, cornea)
  • Donors of semen and growth hormone
  • Patients undergoing hemodialysis and 
  • females in high risk group who are pregnant or contemplating pregnancy.
Do u know?
  • Every year, December 1st is observed as World AIDS Day.
  • India started a National AIDS control Programme in 1987. 
  • “A red ribbon” is worn on World AIDS Day as a universal symbol of awareness and support for people living with HIV.
  • In India, 4 AIDS reference centers have been established-
  1. AIIMS – New Delhi.
  2. National Institute of Virology, Pune.
  3. Center of advanced research on Virology, Vellore.
  4. National institute of communicable diseases, New Delhi.
  • National AIDS Control Organization (NACO) was set up in year 1992 by the Ministry of Health and Family Welfare. 
  • The aim of this organization is - 
  1. to prevent further transmission of HIV
  2. to decrease morbidity and mortality associated with HIV infection and 
  3. to minimize the socio-economic impact resulting from HIV infection.
Laboratory diagnosis:
  • At first a test is used to detect the HIV antibodies, while a second confirmatory test is used to weed out any false positive results.
  • The first test is ELISA (Enzyme-Linked Immunosorbent Assay). 
  • The confirmatory test, usually a Western Blot, is a highly specific test. 
  • It is based on detecting specific antibody to viral core protein and envelope glycoprotein.
Treatment of AIDS :
  • Although AIDS has no cure, certain medicines called as Antiretroviral drugs can help in reducing the viral load and prolong the life of HIV patient. 
  • Examples of these drugs used in Antiretroviral therapy (ART) are - 
  1. TDF (tenofovir)
  2. EFV(Efavirenz)
  3. Lamivudine (3TC), etc.
  • The advancements made in biological sciences have helped us to deal effectively with many infectious diseases. 
  • The use of vaccines and immunization programmes have enabled us to eradicate completely the dreadful diseases like small pox. 
  • A large number of other infectious diseases like polio, diphtheria, pneumonia and tetanus have been controlled to a large extent by the use of vaccines. 
  • Biotechnology is on the verge of making available newer and safer vaccines. 
  • Discovery of antibiotics and various drugs has also enabled us to treat effectively infectious diseases like tuberculosis.

Comments

Post a Comment

Popular posts from this blog

2. Systematics of Living Organisms part 03 - Units of Classification

  2. Systematics of Living Organisms part 03 - Units of Classification Units of Classification : Species : Species is the  principal natural taxonomic unit , ranking below a genus and denoted by  latin binomial  (considered as the basic) unit of classification.  It is a  group of organisms  that can interbreed under natural condition to produce fertile offspring.  It was thought to be an  indivisible, stable and static unit.   However in the modern taxonomy, subdivision of species such as  sub-species, varities and populations  are seen and given more importance. Genus :  Genus is a taxonomic rank or category  larger than species  used in the biological classification of living and fossil organisms.  Genus is a  group of species   bearing close resemblance to one another in their morphological characters but they do not interbreed.  e.g.  Tiger, Leopard, Lion  all three belong to same  genus  Panthera.  They have common characters yet are different from each other because their genus i
Read more

2. Systematics of Living Organisms - part 04 - Nomenclature

  2. Systematics of Living Organisms - part 04 - Nomenclature Nomenclature : The art of naming the objects is in fact, a science called  nomenclature.  All living organisms are known by a particular name. 1.Vernacular / Local names / Common names:  Widely distributed organisms have a large number of common names.  Pansy (Viola  tricolor  L.)  grown in most European and American gardens has about 50 common English names.  In a multilingual country like India, almost all useful plants have local names which differ from language to language and even from dialect to dialect.  As in Ayurveda,  mango (Mangifera  indica  L.)  is known by over 50 different names, all in the Sanskrit language. Hence the common names obviously have limited usage and for universal applications, a unique name for a particular individual is very much essential. 2. Scientific Names :  To overcome the difficulties raised by common names, scientist have given scientific names to all the known organisms.  These are sys
Read more

2. Systematics of Living Organisms - part 05 -Salient features of Five Kingdoms

Image
  2. Systematics of Living Organisms - part 05 -Salient features of Five Kingdoms  Salient features of Five Kingdoms : 1. Kingdom Monera : It contains unicellular organisms with prokaryotic cellular organization.  Monera includes  unicellular prokaryotic organisms. These are omnipresent.  They are found in all types of environment which are not generally inhabited by other living beings.  Few are  photoautotrophs or chemoautotrophs ; but  majority are heterotrophic  in nature.  These organisms do  not have well defined nucleus . DNA exists as a simple double stranded circular single chromosome called as  nucleoid. Smaller circular molecules of DNA as extrachromosomal genetic elements called  plasmids  are often present.  Cell wall is made up of  peptidoglycan  (also called  murein ) which is a polymer of sugars and amino acids. Membrane bound organelles e.g.  mitochondria, chloroplast, endoplasmic reticulum are absent.  Ribosomes are smaller in size  (70S)  than in eukaryotic cells.  T
Read more