The body has a two –part Immune system which workers together to protect it from harmful micro organism such as bacteria, fungi, viruses and parasites, it is divided in to two:

Innate Immunity

This is the front-line defense which equips us from before birth to deal with the various microorganisms that we are likely to meet in our normal everyday lives

Innate Immunity Include:

Antibodies formed by a mother and passed on to the developing fetus and through infant breasting feeding

Tears containing the enzyme lysosome, to protect one eye from bacteria

Saliva in the mouth, also containing the anti-bacterial lysosome

Mucus and chemicals co-existing but with quite differing functions in the urethra Ureter (water tubes) and vagina

When the barriers of the innate immunity are penetrated ,while blood cells leukocyte.(phagocytes or devouring cells) and other while cells (principally serotoxin or natural cell-Killing cells)surround and a number of other naturally-produced substances such as interfere and a range of blood proteins (called the complement system combine to help in the destruction process.

Adaptive Immunity

Adaptive Immunity is the second line of defense and is called into service when the defenses of the innate immunity are breached well beyond the capability of its response, Its defense, instead of being a  general reaction is much more  specific as it adapts to the particular organism present hence adaptive immunity is often referred to as specific immune system to identify the invading micro-organism as being foreign to any of the body’s own protein  these foreign  or devouring cells) and other  while cells (principally  serotoxin or natural cell-killing cells) surround and attempt to destroy  the  invader. At the same time a number of other naturally-produced substances such as interferon and a range of blood proteins called the complement system) combine to help in the destruction process.

Adaptive Immunity

Adaptive Immunity is the second line of defense and is called into service when the defenses of the innate immunity are breached well beyond the capability of it response. It defence, instead of being a general reaction is much more specific  as it adapts to the particular organism present hence adaptive immunity is often referred to as specific immunity.

Body immunity is the ability  of the body o define  itself against foreign  bodies ( antigens) its commonly  associated  with the blood  cells  which  comprise  the soldier  cells  of the body.

Body immunity system it’s important because it equips   as our bodies with the ability to control act foreign invaders.

We have two types of immunity

  • Innate
  • Adaptive

Innate immunity- natural ability of the body to defend itself against micro –organism and it’s always transmitted from parent to children. Example of innate immunity

  1. Lysosome –protect eyes and mouth from being infected by bacteria.
  2. hairs-in nose help trap inhaled
  3. mucus has cilia  hairs found in trachea   and wind  pipe  when by they protect  the lungs  by ensuring  that foreign  matters  don’t affect.
  4. Skin – its layer protect the body surface, serviced by (sweat glands) sebaceous gland providing bacterial killing chemical s.
  5. acids – in stomach and intestine (HCl) which destroy harmful  microorganism  and also  permit   the present  of helpful bacteria.


This is artificially  induced  attenuation  ( inoculation) this is type  of immunity  called intro service when  the inmate  immunity is destroyed  beyond  response .

There are around 7 days between immune response as one part of the system takes over from the either.

The response can either be cellular or hormonal based on the type of invader.

Hormonal immunity response to bacteria while cellular responds to virus and parasite.

Effects of HIV/ aids on the body immunity

  1. Weaken the body immunity leading to opportunistic infection.
  2. Inhibit the production of CD4 cells.
  3. Destroy immune system.

T- Killer cells termed as cytolysis t- lymphocytes.

Upon entry in the body HIV moves n migrates to the lymph nodes in different parts of the body e.g. neck, groins and armpits.

The lymphatic system which include the lymph nodes act as a reservoir for the virus it then moves other parts of the body where it infect and destroy white blood cells (t- lymphocyte or CD4 cells)

The lymph nodes  normally trap bacteria  , fungi and virus to allow  easier  destruction by the WBC they are contracted   by    there   but as the virus  concentration  increases  there s both  breakdown  in the ability of the lymphocyte  to hold  back.

Infection and the destruction of the CD4 cells

The breakdown  of the lymph  nodes  barrier allow rapid  spread  of the virus  into  the blood  stream and other parts  of the body.

According to the  diamond  HIV / aids research centre  (US)  says  that infected die on average  every  two days   and that unto 100 billion new  viruses  are released  daily. When the virus   enter CD4 cell, it takes unto 30 hrs to cope with genetic material produce new enzyme and other viral component then they are assembled into new viruses.

Steps in viral replication

The HIV virus first defined in the US in 1983 is classified in the family of tentrovidae within genus retrovirus. Retrovirus has RNA genome which also poses   a unique transcriptase (reverse transcriptase)


Attachment (fusion)

HIV virus itself to human cell so as to inject its genetic materials   into the cell on the surface of the cell through molecules called receptors

Using receptors the HIV cells attaches itself and fuses into the cell membrane. a process  called fusion to do this  HIV  uses GP120  to attach  itself to human  cell and GP 41 to fuse into  the human  cell.

Step 11

Transcription process

After fusion with the cell, the virus transfers its instruction which reprogram the cell to produce copies of the cell. This instruction is known as RNA are similar to DNA contained by all cells of the body. An enzyme reversed transcriptase convert the single stranded HIV RNA to double stranded HIV DNA. A class of drugs known as transcriptase inhibitors


Once HIV has converted itself to HIV DNA moves towards the host   cell nucleus which is the command center of the cell It does so through the use of enzyme called intergraded inside the cell nucleus. HIV hides its DNA in the host cell DNA when does two things i.e.

  • Stays in the cell
  • Once activated uses the host cell DNA to make more copies of it.

Intergraded inhibitors are drugs used to inhibit the interrogation process.

Step I


The cell nucleus when activated commands the cell to reproduce HIV. The building block for the new HIV viruses reproduced in form of chain using an enzyme called process act as scissor, the long chain is cut into pieces and this process is called cleavage.


This cut pieces   packed together by the help of the protease enzyme   to form new virus protease inhibitors are drugs used to inhibit the process.


After packaging HIV moves to the outer part of the cell to escape process called budding.


HIV uses the part of the cell outer membrane to complete its final structure. The new HIV particles leave the cell in search of new cell to infect and start the process again.

Clinical stage in HIV

Modes and non modes of transmission of sexually transmitted disease and infection

HIV transmission is the spread of HIV virus from one person to another by different routes. HIV is spread   when an infected   individual   comes into contact with infected body fluids or cells. The virus is found in blood, breast milk, semen and virginal secretion. In high concentration and saliva in low conclusion

HIV can be  transmitted  through various  modes  sexual contact  – the commonest  mode, any unprotected  penetration  sex  whether  virginal  , anal or oral   can transmit  the virus  from  an infected  individual  to uninfected .

Sexual contact accounts for 70-80 percent transmission. Homosexual accounts for 10-15% HIV infection by sexually account for between 1-3%.

Oral sex   is associated with a lower risk but gonorrhea and genital cancer and syphilis do but the risk of transmission.

Deep kissing  weak ‘oral   saliva is exchanged  causes  some risk  of HIV  transmission  especially  when  one or both  partners  have bleeding  gums  , shivering  of tooth brush and toothpicks  have small risk.

Factors influencing the risk of HIV transmission

  • No of sexual partners. The higher the number off sexual partners one has the higher the chances of contracting HIV.
  • The level of virus in the body fluid. The higher level of risk in body fluid (blood, semen, virginal secretion) the higher the risk of transmission.
  • Sexual orientation. Being homosexual , homo sexual  or unprotected  sex influence  a great deal  of HIV transmission  , unprotected   guys  sex  causes great
  • the chances of a woman contracting  the virus  from an infected  man is statistically  higher  than the chances  of uninfected  man  can contract  the virus s from   an infected woman.
  • Younger women are at higher risk as opposed to other women this is because during sexual intercourse virginal tissue tears and get fractured because they are not fully developed.
  1. Sexually transmitted disease. Presence of STDS   increases chances of HIV infection because they cause ulcer and lesions that open up the skin.
  2. Mother to child transmission disease. World wide rate of HIV  infection  from mother to their children  ran from  13-40%  i.e. 4%  out of 10% children  born to HIV positive e mothers contract HIV.

Ways of mother to child transmission

  1. The child can be infected before birth by virus crossing from the mother blood to the child through placenta. About 35% of newly born infant which are HIV infected at birth.
  2. The child can contract HIV through exposure to mother blood and other expulsion during birth. This account for about 05% of newly born HIV infected at birth is most of mother to child transmission occur during birth.
  3. The child can contract HIV   positive mother  that get infected  with HIV  contract  virus  as a result  of breast feeding.

The following factors increase the chances of MTCT.

  • High level of HIV in mother blood and other body fluid and secretions.
  • Premature babies  more prone  to infection
  • Low birth weight
  • Prolonged membrane  rapture
  • Traditional birth delivery.
  1. Blood transfusion. Use o blood   products that have not been screened for HIV or have been poorly screened can lead to HIV transmission. It constitutes 3-5 % of all HIV infection.
  2. Intravenous drug use / contact with contaminated instruments. its the  administering  of drugs  of addiction  e.g. heroine  into blood stream  by injecting  into veins  most of the group  members  often shave  with some  needless of their r chances of infection , account  5-10% HIV infection. procedures  such as  ear piercing  , circumcision  when done  with poorly cleaned  and unspecialized  instrument  can lead to transmission for  previous  person  used on was HIV positive. Rape/ occupational exposure. Exposure to HIV can also be as a result of rape or occupational exposure to healthcare providers such as doctors and nurses. Occupational exposure is the accidental exposure of healthcare worker to body fluid form a positive infected person in their care. Can be due to needle pricks or cut with surgical instruments.

Rape  an sodomy victim could  also get infected with HIV if the  attacker  is HIV thus  its important  that the victim  seek  prompt medical  attention  as early  treatment with ARVS could reduce  chances of HIV infections.

The  HIV epidemic in sub Saharan  Africa has had a far more damaging  societal  impact  not only  because  of extremely  high  number  of people  infected  but also heterosexual  transmission.

Way HIV is not transmitted   

  • Mosquito bites
  • Sharing utensils
  • Living  with infected  person
  • Touching an infected person
  • Having your hair cut
  • Sharing drinks
  • Wearing second hand  clothes
  • Sitting next to an infected  person
  • Using the same  toilet with infected  person
  • Coughing and sneezing
  • Swimming

General trend of HIV

  • HIV is spreading  very rapidly  globally
  • No of orphans and vulnerable children are increasing more and more women and children are being infected.
  • More and more women  and children are being  infected
  • Between  4-5 girls and young women are infected with HIV for every one young man infected.
  • People who are living in poverty are more vulnerable to HIV infections.
  • Aids has no cure
  • HIV is preventive


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