Human immunodeficiency virus/ Acquired immunodeficiency syndrome
The full form of HIV is Human immunodeficiency virus and full form of AIDS is Acquired immunodeficiency syndrome.
Human immunodeficiency virus attacks the immune system cell (CD4 helper cell or T cell) and destroys. If HIV infection is not treated, it can lead to Acquired immunodeficiency syndrome (AIDS).
In Humans HIV infection came from a type of chimpanzee in Central Africa.
Currently there is no effective cure of HIV means once individual get HIV infection, it for have lifetime. People with HIV infection only given proper, effective and supportive medical care and follow HIV prevention meaures, diagnosis, HIV and opportunistic infections can be controlled.
The causative agent of HIV is human immunodeficiency virus; (Retrovirus or RNA Virus)
Retrovirus – Type of virus that uses RNA as its genetic material. When a retrovirus infects a host cell, it makes a DNA copy of its genome that is inserted into the DNA of the host cell.
Epidemiology Triad
Agent – HIV infection is caused by human-immunodeficiency virus (HIV ). This Virus has ability to destroy human T4 helper cells (CD4 cells).
Reverse transcriptase (RT) enzyme found in HIV. HIV uses reverse transcriptase (RT) to convert its RNA into viral DNA, a process called reverse transcription
Note– HIV can cross blood brain barrier and destroy brain cells. During the pregnancy, HIV can pass through the placenta barrier and infect the fetus. During labor and delivery, baby can be exposed to the HIV infection in contact with the mother’s blood and other body fluids.
The causative agent of HIV infection is found in blood, CSF, semen in great concentrations, but in tears, breast milk, saliva vaginal secretions and cervical secretions shed in less concentration. The HIV present in lymph nodes, bone marrow, brain tissue and skin (casue HIV rash).
HIV mutates fast and multiply faster, it constantly makes copies of itself and developed new strains that multiply faster.
Host Factors – Most commonly HIV infection in between the age group 20-49 years, sexually active people. Virus remain in human body life long after being HIV infected .
Environmental Factors – 1. High risk in male homosexuals people
2. Male bisexual have multiple partners
3. Intravenous drug abusers
4. Blood transfusion recipient
5. Having unprotected anal or vaginal sex
6. Infected with Sexually transmitted infection (STI) such as syphilis, herpes; herpes simplex virus (HSV), chlamydia, gonorrhoea and bacterial vaginosis (vaginal inflammation)
7. Sharing contaminated needles, syringes and other injecting equipment
8. Administrating or receiving unsafe injections
9. Via Blood transfusions, organ/tissue transplantation, and medical procedures or equipment, involve unsterile cutting or piercing.
9. Accidental needle stick injuries
10. Infected mother to fetus/ baby
Mode of Transmission
1. Sexual transmission
2. Via Blood transfusion – if blood is contaminated with HIV/ AIDs infection
3. Maternal foetal transmission (Mother tochild ) – HIV can cross through placenta barrier and infect the foetus.
Mother to child exposure or transmission can occur during pregnancy, during birth, or breastfeeding to baby.
4. Sharing contaminated needle – Syringe, needle or any skin piercing instrument with HIV/AIDs
5.ViaBody fluids from infected people, such as blood, breast milk, semen and vaginal secretions
6. Intravenous drug abusers
7. Accidental needlestick injury; among in health worker
Incubation Period
The incubation period of HIV is from a few months to 10 years or even longer period.
Primary symptoms of HIV infection may show up 2 -4 weeks after initial exposure of infection. Individual may experience flu-like symptoms on 1 to 4 weeks after first infected with virus, known as acute or primary HIV infection stage .
HIV Pathophysiology
1. People get exposure to HIV Virus
2. HIV attacks T cells (lymphocytes)
3. Infection cause asymptomatic, in this stage no symptoms occur in 1- 6 weeks after acquiring the infection. Person may feel flu like illness.
4. During the acute phase HIV infection; induced lysis of cell and killing of infected cells by cytotoxic T cells (CD8 cell) accounts for CD4+ T cell depletion.
Cytotoxic T cell (CD8+T-cell) often called cytotoxic T lymphocytes has CD8 receptor on its cell surface. CD8 cell is very important for immune defence found on natural killer cells, dendritic cells.
5. HIV lead to severe damage to the immune system and constantly and eventually destroys CD4+ helper T cells by using the DNA to replicate itself
CD4 serves as a co-receptor for the T- helper cell receptor. CD4 surface proteins found on the surface of immune cells such as T helper cells, macrophages, dendritic cells and monocytes.
6. Cause Lymphadenopathy (PGL), lymph nodes are swollen and enlargement of one or more lymph nodes
7. Now Symptoms of HIV infection Appears
8. HIV destroyed the CD4 cells by using their replication and creates new copies of the virus. This lead CD4 cells to swell and burst.
9. When the Virus has lyses or destroyed a certain number of CD4 cells are destroy and CD4 count drops below 200, individual will have progressed to AIDS.
(A normal CD4 cell count ranges from 500–1,200 cells/mm3)
10. Loss of CD4+ cells results, the development of opportunistic infection
11. In this stage HIV infection manifest with symptoms and opportunistic infections may be occurs. This collection of signs and symptoms referred to AIDS-related complex (ARC) and is consider as a prodrome (early symptom indicating the onset of a disease or illness) or precursor to AIDS.
12. AIDS (Acquired immunodeficiency syndrome) stage is characterized by chronic, severe immunodeficiency with multiple symptoms.
This stage of infection is characterized by CD4 T-cell count below 200 cells/mm3.
Note – CD8+ T cells lyses HIV infected cells and secrete cytokines. CD8+ T cells are able to defeat and inhibit HIV replication and block the virus to entry into CD4+ T cells. Development of CD8+ T cells is important for control and inhibit of HIV replication.
Clinical Manifestation
Signs and symptoms of HIV infection are vary, depending on the stage of infection.
Once HIV infected, virus remains in the body of infected person, so that person act as a carrier.
In first few weeks (within 2 – 4 weeks ) after initial infection person may experience have no symptoms or flu-like illness called acute HIV infection, including; fever, headache, sore throat , rash appear and most of individual remain without symptoms for many years.
HIV antibodies also appear 2 to 12 weeks after the infection and the period before antibodies are produced is known as window period
As the HIV infection progressively weakens the immune system, they can develop other signs and symptoms, such as –
1. Lymphadenopathy – swollen lymph node
2. Weight loss – loss of body weight more than 10% of body weight
3. Malaise, fatigue, night sweats, Fever
4. Unexplained diarrhoea lasting longer than 1 month
5. Oral thrush
6. Muscle aches
7. Mouth ulcers
8. Persistent cough for more than 1 month
9. Herpes zoster/ shingles
10. Hepatitis
11. Skin infection
After being damage of immune system after a longer period due to AIDS. Without treatment, they could also develop severe illnesses AND opportunistic infection such as –
1. Tuberculosis (TB)
2. Cryptococcal meningitis – Type of meningitis caused by a fungus
3. Severe bacterial infections
4. Enlarged liver or spleen- Hepatomegaly and Splenomegaly
5. Cytomegalovirus candidiasis
6. Lymphomas and Kaposi’s sarcoma (cancer forms in the lining of blood vessels and lymph vessels).
7. Hairy leukoplakia – white patches on your tongue triggered by Epstein-Barr virus (EBV)
Stages of HIV
Stage 1: Acute HIV Infection
Stage 2: Chronic HIV Infection
Stage 3: Acquired Immunodeficiency Syndrome (AIDS)
Stage 1: Acute HIV Infection
Some Individual have flu-like symptoms. Only nucleic acid tests (NATs) or antigen/antibody tests can diagnose HIV acute infection.
Stage 2: Chronic HIV Infection
This stage is also known as asymptomatic HIV infection or clinical latency.
Individual may transmitted HIV infection in this phase. At the end of this phase, the amount of HIV viral load in the blood raised and the CD4 cell count declined.
When the HIV viral load levels increase in the body, in person have appeared more symptoms and then person moves into Stage 3.
People with HIV infected, who take HIV medicine as prescribed may never move into Stage 3.
Stage 3: Acquired Immunodeficiency Syndrome (AIDS)
AIDS, severe phase of HIV infection. Individual with AIDS is very infectious can have a high viral load.
Person with AIDS disease, worse damaged immune systems and get an increasing number of severe symptoms/ illnesses and developed opportunistic infections.
Individual get AIDS diagnosis when their CD4 cell count depleted below 200 cells/mm3, or if develop certain opportunistic infections.
Without treatment of AIDS, person life expectancy after a stage 3 HIV diagnosis is about 3 years.
Laboratory Diagnosis
1. ELISA test (enzyme-linked immunosorbent assay)
2. Western blot test – If an ELISA test result is positive then next Western blot test administered, usually to confirm the diagnosis.
3. CD4 lymphocyte marker – Normal CD4 cell count ranges from 500 – 1,200 cells/mm3 in adults and teens. A low CD4 cell count indicates that person immune system had affected by HIV and/or the disease is progressing.
4. P24 antigen and anti-HIV antibodies
5. Rapid HIV test
Get complete detailed information about HIV diagnostic tests, how to collect the sample and know the HIV Positive and Negative test results.
Treatment of HIV
There is no vaccine or cure for treatment of HIV infection or AIDS but these cases treated with antiretroviral therapy (ART) are the drugs that treat HIV infection.
Note – It is important to note that person with HIV infection who are taking ART (Antiretroviral treatment) are virally suppressed do not transmit the HIV infection.
Taking Antiretroviral treatment, people can live long and healthy lives with HIV and improve the health of people with HIV and also to prevent HIV transmission.
Antiretroviral therapy drug are-
Zidovudine, Didanosine, Tenofovir, Ritonavir, Nevirapine (reduces HIV viral loads and increases CD4 counts).
Prevention and Control of AIDS
1. Diagnosis and treatment
in case of surveillance, presence of generalized Kaposi’s sarcoma or cryptococcal meningitis is sufficient for the diagnosis of AIDS.
2. Post exposure prophylactic treatment
If any individual get accidental exposure to virus, antiretroviral therapy should be started within hours.
According to US Centers for Disease Control and Prevention; Treatment for health care workers who are accidently exposed to HIV recommended antiretroviral medicatio are Zidovudine, Lamivudine.
3. Surveillance and resurvey
Prophylactic treatment includes – Benzathine Penicillin G and need to do regular follow up.
4. Screening
CDC recommends between the ages of 13 and 64 get tested for HIV at least once.
All pregnant women recommended screening for HIV test. If a pregnant woman is treated early for HIV in her pregnancy, the risk of transmitting HIV infection to her baby is extremely low.
5. Reduce the risk of HIV infection by limiting exposure to risk factors
1. Protective sexual intercourse
2. Testing and counseling for HIV and STIs and Tuberculosis (TB) care
3. Elimination of mother-to-child transmission of HIV
4. Follow Universal precautions measures
