HIV is the most deadly and contagious infection among all other infections. Though there are many causes for the infection,but it is closely connected with the sexual behaviour of individuals. HIV and AIDS are interchangeably used, however there is a slight difference between them. HIV  stands for Human Immuno Deficiency Virus and it is a causative agent for the illness whereas AIDS is the complete, manifestation of the disease while patient enters the advanced stage of illness. The first case of AIDS was recognized in India in the year 1982 . India makes the third largest HIV epidemic in the world, with 2.1 million people living with HIV. India's epidemic mainly affect vulnerable groups such as sex workers 

Classification of HIV

HIV is a member of the genus Lentivirus, which is a part of the family Retroviridae. 2 major types of HIV have been characterized based ontheir virulance. They are, HIV-1 and HIV-2. HIV-1 is the virus that was initially discovered and termed both lymphadenopathy associated virus (LAV) and human T-lymphotropic virus 3 (HTLV-III). HIV-1 is more virulent and infective than HIV-2  and the majority of HIV infections globally belongs to this group. HIV- 1 and HIV-2 are classified based  on the principal serological differences reside in the surface protein gp120. Depending upon the variability in the V3 (variable region) HIV-1 and HIV-2 are further divided into subtypes called clads.



As per the UNAIDS, in December 2019, 2 100 000 people were living with HIV. there was 1 case out of every 1000 uninfected— which means it is 0.1% among all people of all ages. The percentage of people living with HIV among adults of ages15–49 years was 0.2%.  88 000 people were newly infected with HIV and 69, 000 people died from an AIDS-related illness. Across the world, 1.7 million new cases have been added each year and the worry is that the rate is still rising.  India stands as the third-largest affected country in terms of HIV. India’s scenario is a bit strange becasue most of the affected are concentrated among key populations, including sex workers and gays. However, the efforts from the National AIDS Control program and many other hospital-level health care programs have successfully curbed the damage. India though was an epicentre once, the preventive protocols from the past 10 years have substantially managed the new cases across the country. HIV is one of the most challenging diseases in the world today. This is because of the nature of the illness that involves multi-system damage and the complete destruction of the immune mechanism of our body. Because of the involvement of each individual body systems, it is very hard to completely cure the infection. On the other hand, the HIV virus is a highly resistant organism against all the antibiotics. However, modern medicines are capable to keep a check against the viral load to some extent which helps in At least prolonging the course of illness. 


Structure of HIV

HIV is the most virulent and highly potent of all the virus. It is a highly resistant and virulent as it can survive in any adverse environment making it the most complicated infection to treat. As the name suggests, HIV( human immuno deficiency virus) works by attacking the  immune system and make it a highly vulnerable to further infections involving all body systems( multisystem infections). HIV measures approximately 1oo nm encompassing 72 external spikes projected out of its outer envelop. Furthermore, the 2 major glycoprotein envelopes surrounding the organism are,  gp120 and gp41.  There is also a lipid bilayer with a number of host-cell proteins. HIV appears cone-shaped,with a varied size. It has a dense nucleocapsid made up of core protein p24. This nucleocapsid produces 2 similar copies of single-stranded positive polarity RNA genome measuring 9.8 kb. The genome is known by names viral enzymes reverse transcriptase (RT), integrase-RNase H, and protease. Beneath the capsid, there is a ground substance called matrix.  Inside the matrix, the viral core is found and it is, made up of p24. The capsid in the middle is an isohedral body containing  small isohedral subunits that cover the entire capsid making it look like a bullet. HIV proteases are the enzymes that assist in breaking down the complex proteins into smaller ones. These smaller proteins combine with the genetic material of HIV to form a new HIV virus.


Structure of HIV Virion-image by NIAID


How HIV works

The main mechanism of HIV is, attacking the immune system, consequently, there is gradual debilitation of all the body systems resulting in multisystemic infections. The immune system, skin, lymph nodes, intestine are the major target systems for the HIV infection. It is difficult to identify the illness at its early stages as the incubation period is very long . During this phase person is asymptomatic and this is why the disease itself is  more challenging for the health practitioners. However, early diagnosis plays a vital role in managing HIV. HIV has a  unique genetic material made up of RNA. The virus has an ability to easily consolidate with the normal cells of the body, This makes the immune system very difficult to identify the virus.


Transmission of HIV

HIV is a sexually transmitted infection, but infection can also be spread from an HIV infected blood transfusion. The transfusion with contaminated blood is a highly efficient means of transmission. Transmission by heterosexual (vaginal) intercourse is of 0.1% to 1%. But this is not the case always. If either one or both the partners suffered from vaginal diseases and ulcers then the rate of transmission is way too high. Pregnant mothers suffering from HIV can easily transmit the infection to newborn, however, the recent medical advancements helped to block the transmission from mother to child ( fetoplacental transmission).


Difference between HIV and AIDS

HIV is the state of infection in which an individual may not have enough viral load to express the symptoms  whereas AIDS is an advanced stage in which there is a high viral load (percentage per ML of blood). AIDS is probably a case of high risk and the sufferer must be inching close towards death.


Symptoms of AIDS 

AIDS is a multi-system disorder, affecting various systems in the body. Patient might demonstrate the partial or complete failure of organs and body systems. A person suffering from AIDS might experience being always tired, swelling of lymph glands and nodes, chronic fever lasting for more than 10 days, excessive night sweats, sudden and unexplained loss of weight, anaemia, loss of hunger, variations in the sugar levels. In advance stages multi organ failure is evident.


Prevention and control of HIV

Because there is no known cure or vaccine for HIV infection, prevention and control strategies are extremely important. The main approaches towards AIDS prevention is

1. Promotion of safer sexual behaviours: Since the onset of the pandemic, information, education, and communication campaigns have been vital in reducing behaviours that resulted in risk of infection. These campaigns are of two types: broad mass communication for the public, and targeted, intensive behavioural change communication strategies aimed at vulnerable groups. Person-to-person education programs are important for certain vulnerable groups as they can increase the knowledge about AIDS and high-risk behaviours.

2. Promotion of condom use: The promotion of safer sexual behaviours, including the use of condoms is an integral part of prevention and control strategies. Condom use is encouraged through programs that involve market research, product importation,  advertising, media promotion, distribution, and management.

3. Measures to the prevention and treatment of STDs: Conventional STDs are facilitated by the transmission of HIV. Because of its adverse effect on the immune system, HIV infection can alter the incidence, natural history, and response to treatment of other STDs. In addition, these diseases rank among the top 10 of the most important health problems in the semi-urban and rural populations. The early diagnosis and treatment of sexually transmitted diseases combined with behavioural intervention is recommended.

4. Prevention of unsafe drug administration: It is carried out by conducting some outreach programs to educate the need to eliminate needle sharing, instructions regarding sterilization of needles and the use of packed ( sterile packed) injection needles.

5. Provision of a safe blood supply: Transfusion-induced HIV infection can be prevented by safe blood screening initiatives. The donor blood must be thoroughly examined for HIV and related viruses. Yet, as many as 3% to 5% of HIV-infected individuals in sub-Saharan Africa and parts of Asia become infected by contaminated blood. 

6. Targeted interventions: For individuals at high risk of HIV infection, epidemiologically a sound set of preventive activities (interventions) are put together as a package to manage the infection. These interventions not only are easy to implement but they are cost-efficient and their impact is measurable.



Practice questions

  1. Distinguish between HIV and AIDS
  2. Brief the classification of HIV.
  3. Which of the body system is responsible for the causation of HIV?
  4. What is an STD?
  5. What is the difference between HIV and AIDS?
  6. Which family of viruses does HIV belong to?
  7. What are  gp120 and gp41?


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Concept of health and disease


Structure and Functions of Human Sperm





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