AIDS-acquired immune deficiency syndrome

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AIDS-Acquired Immune Deficiency Syndrome

As the name implies, this disease consists of signs and symptoms revealing immune-suppression, acquired during the lifetime (not due to genetic predisposition - inborn disease) due to inoculation with HIV (Human Immunodeficiency Virus).

The low immunity renders the patients to the enhanced susceptibility to the other secondary infections.

Epidemiology: This infection is predominantly found in parts of Africa, though it has also been reported in certain regions of Europe as well as in USA.

During the past decades, there have been evidences revealing the rapid acceleration in its incidence in the South East Asian counties, including Thailand, India and Indonesia, due to negligence in awareness and misconceptions related to its transmission.

Transmission: The major routes of entry of HIV in the body of a healthy individual are:-

a)  Sexual contact (homosexual/ heterosexual) is the most common route. The virus is present in semen (both extracellular as well as mononuclear inflammatory cells) of males and in vaginal and cervical cells of females.

It enters the body through abrasions or lacerations or lesions in the mucosal membranes of genitals or the skin over the venereal.

b) Parenteral inoculation: It involves the intravenous drug abusers; or through blood transfusion or its components, seen predominantly in patients of hemophilia , sickle cell anaemia, thalassaemia; or in accidental victims or in females with extensive blood loss during parturition (child birth).

These days' hemophiliacs are at the reduced risk of contracting HIV as they are receiving clotting factors like VIII or IX; primarily through rDNA (recombinant DNA) technology where specific genes of human genome are incorporated in the genome of cell of another animal and stimulated to produce these clotting factors, instead of deriving them from plasma of donor's blood.

Use of infected blades, needles and syringes is also a predisposing factor for AIDS epidemiology as it enhances the exposure to HIV infected blood stains.

Accidental exposure of open lesions or broken skin to infected blood or semen.

c)      From Infected Mother to Infant: Recent studies have revealed that even HIV positive mothers can transmit the virus to her offsprings.

This mode of transmission occurs   primarily via:

1)  In utero (transplacental) during the embryonic stage

2)  during childbirth (intrapartum)

3)  after birth of the baby via the infected milk of breasts of mother (postpartum period)

There have been some misinterpretations related to the spread of HIV via touch, or using innate belongings of HIV positive individuals such as towels or handkerchiefs.

Etiology and Pathogenesis:

AIDS is primarily caused by HIV (2 strains-HIV1 and HIV 2) that primarily attack the immune system of the body along with the Central Nervous System.

HIV belongs to the family of Retrovirus, containing ssRNA (single stranded RNA) genome, enclosed by a protein capsid, along with some enzymes like reverse transcriptase, integrase and protease, etc.

The virus has specific glycoprotein's (Gp 120 and Gp 41) on its surface to recognize and attach to the host cell membrane. The virus attacks the T-lymphocyte (T-helper cells) and macrophages. It binds to CD4 and CCR5 (T-helper cells) / CXCR4(macrophages) receptors of host cells through its glycoprotein's.

Once it gains the entry into the host cell, its coat ruptures to release enzymes and the viral genome, RNA. The viral genome first transcripts to DNA" with the aid of reverse transcriptase enzyme. The latter (viral DNA") then binds with host DNA, incorporates the part of it in its genome and thus, produces new viral genomic RNA.This new viral genomic RNA then further translates to produce proteins or its enzymes and thereby, replicates using the host cellular machinery to produce its multiple copies.

This newly formed viral copies rupture and move out of the infected host cell to infest other healthy T-helper cells, thereby, reducing the count of T- and B-lymphocytes or attenuates the production of antibodies.

This phenomenon results in the profound immune-suppression and thus, creating conditions for the breeding of opportunistic infections like secondary neoplasms or secondary microbial infestations.

Manifestations: Initially, the patient represents with the symptoms of rapid weight loss, dermatitis, watery stools, prolonged fever, myalgia and enlarged lymph nodes or prominent swollen regions on the skin - referred to as ARC (AIDS Related Complex) due to its non-specificity.

Later, symptoms are developed in accordance with the secondary infections acquired later after the development of AIDS. The patient has increased susceptibility to death due to these opportunistic infections as the immunity is low.

Incubation period: It varies from few months to many years (usually 5 to 10 years) to show its manifestations.

Diagnostic test: ELISA (Enzyme linked Immuno Sorbent Assay) where the enzymes linked to HIV antibodies are exposed to substrate, resulting in change in color or fluorescence of the test plate.

It can be further confirmed by the Western Blot technique which involves the detection of the specific antibodies or interferon's produced in response to viral proteins.

The routine evaluation is done through PCR (Polymerase Chain Reaction) that aids in the detection of RNA, the genetic material of HIV. Though, this test can detect the presence of HIV particles in blood in its nascent form, even prior to the development of antibodies but it isn't being preferred due to its high cost or being time consuming and intensive labour involved in the procedure.

Treatment: There is no definite cure against AIDS. Though certain medications under the banner of HAART (Highly Active Anti-Retroviral therapy) are being exploited since the past two decades which interferes with the expression of enzymes like reverse transcriptase (i.e. it hinders the life-cycle of virus) without having any major adverse effects on the metabolism of the patient. These anti-retroviral medications, if taken soon after the detection of HIV in blood, enhances the life span of the patient.

Prophylaxis is the only option to curtail the transmission of HIV. It can only be regulated if prompt safety measures are espoused following the awareness related to AIDS.

In 1992, Ministry of Health and Family Welfare of the Indian government established a National AIDS Control Organization (NACO) to evaluate and aid the HIV patients along with the propagation of awareness of AIDS amongst the general population.

NACO along with certain NGOs aim to promote the:

1. safer sex via the use of physical contraceptives like condoms, vaginal and cervical caps, diaphragms, or avoiding sex with the HIV positive patients & /or multiple partners; as well as the control over the STDs,

2. use of disposable syringes and needles,

3. safe blood transfusions after proper screening of donor's blood against HIV antibodies,

4. routine evaluation of the blood of the pregnant females as well as that of the newborns against the occurrence of HIV antibodies,

5. Routine screening of the breast milk in the post partum females.   

NACO also provide anti-retroviral drugs at the subsidized rates or at free of cost to the HIV positive patients, soon after the detection of the virus in their blood or after the diagnosis of the disease as delay in the medications can attenuate their period of survival.    

Certain NGOs and social workers are working towards the motivation and upliftment of the HIV positive patients via the psychological counseling of the patients and their families.

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