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Updated on June 4, 2009



Human immunodeficiency virus(HIV) is the cause of acquired immune deficiency syndrome(AIDS).HIV destroys CD4 lymphocytes resulting in impairment of cell mediated immunity with consequent susceptibility to opportunistic infection.

Important Properties of HIV Virus:   HIV is one of the two important human T-cell lymphotropic retroviruses.HIV is prefentially infects and kills helper (CD4) T lymphocytes, resulting in the loss of cell mediated immunity and a high probability that the host will develop opportunistic infections. Others cells (e.g. macrophages and monocytes) that have CD4 proteins on their surfaces can be infected also. HIV belongs to the lentivirus subgroup of retroviruses, which cause “slow” infections with long incubation period.

HIV Transmission: HIV is transmitted mainly by blood, blood contaminated body fluids, semen and vaginal fluids. High risk behaviors or situation that define high risk groups include having multiple sex partners of the same or opposite sex, having a sexual partner who is high risk or infected, intravenous drug abuse, hemophiliac treatment, blood transfusion and infants born to an infected mother. Casual, nonsexual contact, including social kissing and sharing towels or food among family members in a household with an AIDS patient, has not transmitted the infection. Exposure to infected fluid leads to a risk of acquiring infection is dependent on the integrity of the exposed site, type and volume of body fluid, and viral load.


1. Sexual transmission: infections especially genital ulcers, menstruation, non-circumcised, increase  number of sexual partners, rectal or vaginal trauma.

2. Injection drug use transmission: sharing needles, frequency of use, prostitutes, intravenous use.

3. Occupational transmission (nurses, doctors, lab workers): deep injury, visible blood on device.

4. Vertical transmission: (paripartum and breast feeding): older gestational age, lower birth weight, prolonged rupture of membranes, fetal trauma, no paripartum  prophylaxis, vaginal delivery, longer duration of breast feeding, mastitis.

Primary Infection / Seroconversion:

Primary infection is symptomatic in 70% to 80% of cases and usually occurs 2-4 weeks after exposure (incubation period).

The major clinical features are: 

Fever, erythematous maculopapular rash mainly over trunk, fatigue, pharyngitis with cervical lymphadenititis, headache, arthralgia and myalgia, mucosal ulceration ( mouth, genital), neurological presentation (rare) manifesting as aseptic meningitis, encephalitis, myelitis, polyneuritis, opportunistic infections such as oropharyngeal candidiasis, pnumocystis.

Symptomatic recovery occurs in 1-2 weeks but may take up to 10 weeks.

Asymtomatic Infection:

Asymptomatic infections follows for a variable period during which the infected individualremains well with no evidence of disease except for possible presence of persistent generalized lymphadenopathy. The virus continues to replicate and the person is infectious. The median time is 10 years from infection to development of AIDS. Older age is associated with more rapid progession.

Mildly symptomatic disease:  

These patients present with chronic weight loss, fever  , diarrhea, oral or vaginal candidiasis, oral hairy leukoplakia, recuurent herpes zoster, severe pelvic inflammatory disease, cervical dysplasia and ITP.

Acquires immunodeficiency syndrome AIDS:

Acquired immunodeficiency syndrome is defined by the development of specified opportunistic infections and tumors. As HIV infection progresses the viral load rises, CD4 count falls and clinical features as a result of immunosuppression.


·       HIV antibody: confirmation of HIV is by ELISA antibody testing.

·       PCR for HIV RNA.

·       Viral load (HIV RNA): by PCR or bDNA or NASBA method.

·       Absolute CD4 count.



Nucleoside reverse transcriptase inhibitors:

·       Zidovudine (AZT).

·       Didanosine.

·       Lamivudine

Non-nucleoside reverse transcriptase inhibitors:

·       Efavirenz

·       Nevirapine

Protease inhibitors:

·       Saquinavir.

·       Indinavir.

This diagram represents the structure of human immunodeficiency virus (HIV). HIV is part of a family or group of viruses called lentiviruses.


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