HIV infections is broadly categorized into three stages -- acute, chronic, and AIDS. Acute stage typically lasts for 3-6 months after infection. During this time the virus multiplies very rapidly while the immune system slowly develops its response. The viral load during this time is very high and the chances of transferring the virus to another person is therefore also high.
The chronic phase represents the majority of time between infection and death. During this time the amount of virus in the body is roughly constant, though continuously damaging the body. The CD4 T-lympocyte (a very important type of white blood cell that orchestrates the immune response) count slowly diminishes, making the body vulnerable to any and all infections. The person may or may not show any characteristic opportunistic infections like candida that suggest HIV infection. This phase can typically last between 2 to 10 years depending on the virus and the individual.
The third phase is called AIDS. Clinally it is characterized by when the CD4 T-lympocyte count falls below 200 per cubic millimeter of blood and the viral count starts to rise. However, many people present serious opportunistic infections prior to such low CD4 count, and depending on the severity of these opportunistic infections, such a person can also be considered to have AIDS. The chances of transmission from the patient to another person again rise in the AIDS stage.
I know people who have reached zero CD4 count and yet are living years later. This is possible only due to their having access to HAART and a communal support system. While nowhere near perfect, having many toxic side effects, and creating the risk of generating drug resistent strains due to improper prescription and adherence, HAART is a lifesaver. It is essential to make HAART available to all and to provide counselling and therapy. Generation of drug resistent strains is an irrelevent concern if the patient is taught to not transmit HIV through sex or through blood contact; HIV cannot be spread by casual contact.
The first period of HIV infection is called the acute stage, and it typically lasts for 3-6 months after infection. During this time the virus multiplies very rapidly while the immune system slowly develops its response. During this time the manifestations of the infection are typical of viral infections like influenza or mononucleosis and often accompanied by a rash. The symptoms include headache, loss of energy, fever, chills and possibly diarrhea. The typical duration of the symptoms is about a week, after which the person recovers. The problem with diagnosing HIV based on these symptoms is that they are very common (most people get one or two bouts of the flu every year) and there are no other obvious or characterestic symptoms for a long time after the person recovers from this initial "flu" which would cause the person to suspect HIV. The difference between HIV and other viral infections is that while the symptoms disappear, the virus is still present in the body and starts its slow destruction of the immune system.
The only way to determine the HIV status of a person is through a specific blood test. In almost all places in the world, the HIV test performed looks for anti-bodies to the HIV virus. Since the immune response to HIV is slow compared to other viral infections like influenza or measles, it takes a few months for the body to produce sufficient density of anti-bodies such that the test will miss detecting them. For this reason people are advised to wait for three months after suspected infection before taking the test in order to make it confirmatory. This initial period is called the window period. The test is 95% confirmatory after three months and over 99% confirmatory after six months. To make this point about the window period clear I restate it in a different way. If the HIV test (like ELISA or Western blot) is done ANYTIME and comes out positive, then it means the person is infected. Only if the test is negative could the patient be in the window period if exposure has been recent. In this window period it is possible that a patient is infected but the test fails to detect anti-bodies to HIV due to the slow immune response.
A good reason to take the test is if you have have had risky sex or you have come in contact with the blood of a person whose HIV status you do not know and if this blood could have entered your body through cuts, lesions, needle sticks, sores, etc..
The chronic phase can last anywhere from few months to fifteen years in persons who are not on anti-retroviral therapy. The duration of this phase depends on the severity of the infection, the type of infection (for example HIV-1 clade), the person's immune response, their general health and access to health care. As the infection progresses, the person takes longer and longer to recover from diseases like influenza and diarrhea. For example, a common cold instead of clearing within a week persists for weeks and may progress to pnuemonia. Diarrhea may persist for months and not respond to first level medicines. Recurrences of herpes simplex, veracella, HPV may become more common and severe. In addition, many patients exhibit diseases like unexplained weight loss of more than few percent, persistent headaches and sores.
The infection begins as soon as the HIV virus enters the blood system of a human being and starts replicating by infecting the CD4 cells. From that time onwards, once the viral reproduction cycle starts, the infection is established and we have no way of clearing it completely from the system. The infection is thereafter lifelong.
NO. Ten years is usually the average time that people in the USA lived for after HIV infection and in days before the discovery and availability of anti-retroviral drugs. There are many people who are now taking these medicines and have survived fifteen or more years and are still very healthy. So the life expectancy after infection depends on the robustness of the individuals immune system, how exposed they are in their daily life to opportunistic infections like tuberculosis, and whether they have access to the anti-retroviral drugs, and how soon after infection their HIV status is discovered and treatment started.
The usual life time is about 10 years. The exact life expectancy varies from person to person and without anti-retroviral treatment it can be anywhere from between 2-15 years. It depends on the physical and mental health of the person, on the severity of the infection, the sub-type of the virus, and the ability to get treatment for opportunistic infections like tuberculosis and acute diarrhea.
The exact time between the onset of AIDS and death depends on the individual and ranges from a few weeks to a couple of years. To a large extend this time depends on whether the person has access to treatment for opportunistic infections and can afford the anti-retroviral drugs to control the underlying HIV infection. There has been a very sharp drop in the price of these ARV drugs starting Feburary 2001, so hopefully more and more people can afford these drugs and live more productive lives for longer periods.
Rajan Gupta