Morphology of Virus : Virus contains two strands of genetic material (RNA) .The Virus replicate in active dividing T4 Lymphocytic cell, like other virus remain latent in lymphoid cell It has the unique ability to destroy human T-4Lymphocytes .The virus can pass through Blood Brain Barrier.
Sources of Infectious: The Virus has been found in greater concentration in blood, Semen, Cerebrospinal fluid. It is found in lower concentration in Milk, Urine, and Cervical and Vaginal secretion. HIV has also been isolated in brain tissue, lymph node and bone marrow cell. To date only blood and semen have conclusively shown to transmit the virus.
Frequently people only begin to feel sick when they progress toward AIDS (Acquired Immunodeficiency Syndrome). Sometimes people living with HIV go through periods of being sick and then feel fine. As early as 2-4 weeks after exposure to HIV (but up to 3 months later), people can experience an acute illness, often described as “the worst flu ever.” This is called acute retroviral syndrome (ARS), or primary HIV infection, and it’s the body’s natural response to HIV infection. During primary HIV infection, there are higher levels of virus circulating in the blood, which means that people can more easily transmit the virus to others.
Symptoms can include:
- Night sweats
- Muscle aches
- Sore throat
- Swollen lymph nodes
- Ulcers in the mouth
Factors that Affects the transmission:
a. Age: Disease is transmitted in sexual active age which ranges from 20-49 years
- 51% cases were reported in homosexual and bisexual men. In Africa, sex ratio is equal
- Certain practices increases the risk of infection more than other e.g. multiple sex partner, anal intercourse, and male homosexuality.
- Higher rate of infection is found in prostitute.
b. High Risk Groups :
- Male Homosexual and Bisexual Male.
- Heterosexual partner (including prostitute)
- Intravenous drug abuser.
- Transfusion Recipient of blood and blood products.
- Hemophiliac and Sexually transmitted Disease ( STD ).
The immune system disorder associated with HIV Infection /AIDS are considered to occur, primarily the gradually depletion in a specialized group of white blood cells (Lymphocytes) called T-helper or T-4 cell. The full name of the helper cell is CD4 –T lymphocytes and is commonly known as CD4+T-Lymphocytes.They play a important role in regulating the immune response. HIV infect T-helper cell apart from several other cell in the immune system such B-Cell macrophages and nerve cells. The virus reproduce in infected helper cells are destroyed, the patient with AIDS has overall low platelet cell. The ratio of T-helper cells as compared to T-suppressor cell are more in the normal body, In HIV Infection ratio of T-suppressor increases. This is an Indicator of reduced cellular immunity. One of the profound feature in AIDS is Lymphopenia and total lymphocyte count is below 500cc.Antibody to HIV are too low.
Mode of Transmission:
1. Sexually Transmitted
- AIDS is first the foremost a sexually transmitted disease (STD). Any vaginal, oral, anal sex can spread the disease.
- Percent ratios of cases are more in homosexual or bisexual men.
- HIV infected person exposes to uninfected person risk of infection. The size of risk is affected by the number of factors
· Presence of Sexually Transmitted Disease.
· Age and sex of infected partner.
· Virulence strain of HIV.
· Ratio of transmission HIV Infection from male to female is twice.
· Generally women are more prone to infection as compared to men; the concentrations of HIV are more in semen than cervical and vaginal secretion.
· Adolescent girl and woman above 45 years of age are more prone to HIV infection.
· Infected people with HIV are more prone to developed infection before the formation of HIV antibodies.
2. Blood Contact:
a) AIDS is transmitted by contamination of blood transfusion, white blood cells, and platelets and factors VIII & XI derived from human plasma. Risk of contracting HIV infection from transfused blood is 95%. The blood depends upon the dose of virus infected and risk of getting infected through injected contaminated needle/syringe.
3. Maternal –Fetal (Vertical –Transmission)
HIV Infection is transmitted from Mother to her fetus through
b) During delivery
c) Breast feeding, the rate of infection vary from 15-30% without breast feeding .Risk of infection in per partum period accounts for one third to two third.
d) Risk of infection is higher if the mother is newly infected or has already developed AIDS.
e) Transmission of HIV from to child can be prevented entirely by
· Elective Caesarian section before the onset of labor and rupture of membrane.
· Refraining breast feeding.
· Using antiretroviral prophylaxis.
· There is no evidence of HIV transmission by mosquito any other infected person including within the household or food and water.
Clinical Stages of AIDS
There are four stages
1.Initial Infection : Initial infection with virus results in development of antibodies it takes approximate 2-12 weeks to appear in the blood, the patient feel mild throat infection.
2. Asymptomatic Carrier Stage: In this stage the infected person has antibodies but no overt sign.
3. AIDS related Complex: Patient develops illness which damages the immune system but without opportunistic infection.
4. AIDS: Is the end stage of HIV infection with number of opportunistic infections normally occurs at this stage.
Antibodies to HIV are far easier to detect than virus itself. The blood of the individual HIV antibodies is called HIV seropostive if he is infected with AIDS. Two different test is used .First is sensitive test to detect HIV antibodies and second is confirmatory test is used to weed out false positive test.
· Sensitive Test used is ELISA.
Confirmatory test used Western Blot which is highly specific to detect antibodies to viral infection.
· Viral Isolation is expensive test.
Certain markers are available to provide prognostic information and guide the therapy decision. Widely used marker is absolute CD4 lymphocyte count 950 CD4 Cell/ul of blood and the number falls during the course of HIV infection. If the CD4 numbers of cells are below 200 cells/ul the individual is suffering from acute infection. If the count of CD4 marker is above 500 cells/ul then antiretroviral therapy is instituted. This is necessary to evaluating the efficacy of antiviral therapy and P.Carini prophylactic therapy respectively. Diagnostic test may also be useful to gauge the magnitude and course of the epidemic.
Control of AIDS:
1) Preventive measures
a) Education: Until vaccine or cure to AIDS is found the only means of present approach available is health education to enable to make life saving choices e.g.
· Avoid indiscriminate sex.
· Avoid shared razor & tooth brush
· Intra-drug user should be informed that sharing of needle and syringes involves special risk.
· Women suffering from AIDS are at the higher risk of infection should avoid to become pregnancy, since infection can be transmitted to newborn.
· Educational material and guideline for prevention should be made available.
· All mass channels should be involved in educate the people on AIDS its nature of transmission and preventions and this include International Travel.
b) Prevention of Blood Borne HIV transmission :
· High risk group should be urged to refrain from donating blood, body organ, sperm, other tissues.
· All blood should be screened for HIV 1 and HIV 2 before transmission.
· Transmission of infective haemophiliacs can be reduced by introducing heat treatment, of factor VIII and IX.
· Strict sterilization practices should be ensured in Hospital and Clinics.
· Pre-sterilized disposal syringes and needles should be used as far as possible.
· One should avoid injection unless they are absolutely necessary.
c) Antiretroviral Treatment:
At present there is no vaccine or cure for treatment of HIV infection/AIDS. Drugs that suppress the HIV infection itself rather than its complication have been important development. Antiviral chemotherapy which is not a cure has proved to be useful in protecting the life of severely ill patients. Current concept is to initiate treatment for asymptomatic HIV disease with CD4 count or very high viral load (< 100,000 mu) should be considered for early treatment.
d) Preventing Parental transmission of HIV :
· Administration of Zidovirdixine drug to woman during pregnancy, labour and to newborn, the rate of HIV, transmission has been reduced to two-third.
· Breast feeding is thought to increase the rate of transmission by 10-20%, should be avoided.