A disease of the immune system caused by HIV(human immuno deficiency virus).AIDS is the late stage of HIV infection.
STRUCTURE of AIDS :
The shape of the virus is spherical.The virus is composed of a capsid core which contains the genetic materials and it it has a protein envelope.This protein envelope has many glycoprotein (gp 120,gp 41).The envelope of the HIV also contais other proteins including some HLA (human leucocyte antigen).The genetic material of this virus contains two helices of RNA molecule in folded form.The enzyme REVERSE TRANSCRIPTASE aids the virus in the conversion of RNA to DNA in host cell.The enzyme INTEGRASE helps the viral genome to be incorporated in the host cel.
Prevalence of HIV is approx. 37 million worldwide. Approx. age for peak incidence of HIV is 20-40 years. However, the advanced stage of the disease known as AIDS is seen more predominantly in people in their 4th decade.
ROUTES OF TRANSMISSION :
About 80% of infections worldwide are transmitted through sexual transmission. The risk of transmission depends on various factors including - sexual partner's viral load, the type of sexual exposure, coinfection with other conditions like HPV, and genital inflammation or damage.
Needle stick injuries
Infectious blood on mucous membrane
When the virus spreads from mother to child during When the virus spreads from mother to child during pregnancy, childbirth or during breast feeding, it is called as vertical transmission. The Risk of transmission can be lowered significantly if HIV infection is treated consistently and viral load is maintained below the limit of detection.
COMMON CLINICAL SIGNS AND SYMPTOMS :
ACUTE HIV INFECTION:
In early HIV infection, the patients are generally asymptomatic. The viral incubation period is about 2-4 weeks, after which they may present with flu-like symptoms of acute infection for a period of 2-4 weeks. The infectiousness occurs in two peaks. The first peak occurs within the first few months after infection. The second peak occurs during the AIDS stage. In Acute HIV infection, also called as Acute Retroviral Syndrome (ARS), the patients present with the following non-specific flu like symptoms -
In chronic HIV infection, the patients are asymptomatic and it lasts for a period of 2-10 years. The HIV Viral load increases in the blood and the immune cell count (T-cell, CD4+ cell) decreases.
The presence of HIV in the body can be detected by testing for HIV virus (viral antigen) and HIV antibody (chemicals produced in the blood to fight HIV) in the blood of the suspected patient. Also, the CD4+ T-cell count in the blood is tested to diagnose HIV. The various diagnostic tests for HIV and AIDS consist of the following:
SCREENING TESTS (detects HIV antigen and anti-HIV antibodies in the blood)
Combination antigen/antibody tests -
detects both HIV antigen (p24) and anti-HIV antibodies
4th Generation HIV test
Antibody only tests (HIV serology)
ELISA (enzyme-linked immunosorbent assay)
CONFIRMATORY TESTS (detects anti-HIV antibodies in the blood)
HIV-1/HIV-2 antibody differentiation immunoassay
First choice of confirmatory test
can detect both HIV-1 and HIV-2 in ∼ 20 minutes and distinguish between the two types
tests may be negative up to 2 months after infection
results are usually available after several days
DETECTION OF VIRAL RNA (NUCLEIC ACID TEST/ VIRAL LOAD TEST)
This test can detect HIV infection earlier than antibody/antigen-based tests (within 10-33 days of exposure).
TREATMENT AND PROGNOSIS :
All persons infected with HIV (regardless of CD4 cell count) should begin combined antiretroviral therapy (cART). Treatment of the co-morbidities/coinfections should also be initiated.
Antiretroviral HIV therapy includes the following groups of drugs:
Untreated HIV infection has a mortality rate of > 90%
The prognosis depends upon various factors
Adequate retroviral treatment
Viral load at the beginning of the clinical stage of HIV infection
CD4 count over the course of the disease
Presence/ absence of opportunistic infections
Individual genetic properties
HIV species and subtype.
Screening of blood before Transfusion
Screening of blood for pregnancy women.
Avoid sharing needles
Use Sterilization protocol whenever it is needed.
Avoid sharing of razor blades or toothbrushes.
Follow safe sexual practices
Tell your sexual partners that you have HIV.
Take preexposure prophylaxis(intake of antiretroviral drugs) when your partner is HIV positive.
In cases of injury with HIV-contaminated instruments or needles , unprotected sex or contact of open wounds with HIV contaminated fluids, a HIV post-exposure prophylaxis should be initiated as soon as possible (ideally with 3 hours after exposure).
Recovery Period :
The time it takes to transfer from HIV to AIDS is 5-10 years.Recovery is deteriorated since immune system is slowly shut down in HIV.
Medicines used in the Treatment :
The Recommended regimens include the following:
3 NRTI (e.g., zidovudine, lamivudine, abacavir) OR