CD4 Count Test

The CD4 Count Test is an indicator of the working of the immune system. By measuring the number of CD4 T lymphocytes or CD4 cells in the blood, it helps to predict and assess the progression of HIV. This count helps in planning antiretroviral therapy or ART. Monitoring the CD4 count through regular blood tests helps to determine the efficacy of the ART and whether the patient is at risk for other infections.

The CD4 lymphocytes are WBC that play a vital role in infection protection. HIV virus tag on to CD4 cells to propagate and spread the infection within the body. Thus an infected person will notice a reduced count of CD4 cells (less than 200 cells/mm3) when the normal range of CD4 cells is from 500 cells/mm3 to 1,200 cells/mm3.

Successful ART results in reduced CD4 count and lesser viral load in the blood. CD8 cells are another type of WBC that work against infections in the body including HIV.

Urine based HIV test

This was approved in 1996 by FDA as a screening test for HIV. This test uses urine samples to detect HIV antibodies using ELISA method. This test is not considered as accurate as blood test in detecting HIV infection. Urine based test could give false positive result in one or two persons out of hundred. Therefore a positive ELISA screening test must be followed by a confirmatory western blot test or IFA or RIPA and then results confirmed.

CD4 test: The CD4 count in individuals not affected by HIV is normally above 500 cells per cubic milliliter of blood. In HIV infected people, CD4 count is less than 200 cells per milliliter of blood. These patients are referred to as immunosuppressed. HIV people do not run the risk for complications until CD4 cells are fewer than 200 cells per milliliter of blood. A declining number of CD4 count indicates the advancement of the disease. A low CD4 cell count signals that the person is at risk for one of the many unusual infections that occur in individuals who are immunosuppressed. CD4 count is also indicative of the type of therapy the person should undergo to prevent 'opportunistic infections'.

Viral load: The viral load predicts whether or not the CD4 cells will decline in the coming months. Knowledge of the amount of viral load can be instrumental in predicting the development of the disease. Those persons with high viral loads are more likely to experience a decline in CD4 cells and progression of the disease than those with lower viral loads. The viral load is also a vital tool for monitoring the effectiveness of the new therapies and determining when the drug stops working. The greater the decline of viral load after beginning therapy, the longer it will remain suppressed. In general it can be said that a poor response to HIV therapy or treatment failure would include individuals who fail to experience a decline in viral load of approximately 100 fold in the first 8 weeks and have a viral load of greater than 500 copies per ml by week 12 or have levels greater than 50 -75 copies per ml by week 24.

Drug resistance testing: This test is being used in individuals who are experiencing poor response to HIV therapy or treatment failure. The US department of health and human services (DHHS) in their recent guidelines have suggested that 'resistance testing' can be considered in individuals who have never been on therapy particularly in the first months or even years of infection to determine if they might have acquired HIV that is resistant to drugs. DHHS even formally recommend such testing to be performed in individuals starting therapy for the first time.

Antiretroviral Therapy

Antiretroviral or ARV is used to treat HIV virus. A combination of ARV used to treat HIV - Antiretroviral therapy. Patients tend to take 3 or more combinations of ARV medication called the combination therapy. Currently the main treatment for HIV is through Antiretroviral therapy.

Antiretrovirals aim to inhibit the process which the virus resorts to kill T lymphocytes. More than 20 antiretroviral drugs have been approved to treat HIV. Some Antiretroviral drugs have been combined into one single pill known as a fixed dose combination. Different dosage of medicine is prescribed for different people depending on the severity of the infection in the blood.

ART medication cannot cure or treat HIV; however it helps in preventing the growth of the virus and reduces the risk of transmitting it to others. This prevents the virus from multiplying and slows down the virus and thereby HIV. Having less HIV in the body gives the immune system of the body a chance to recover and fight infections.

Significant advances have been made in this therapy since its introduction in 1987. ART involves ingesting a combination of HIV medicines on a daily basis as prescribed by the physician. If left untreated HIV can develop into AIDS. If only one drug is taken, HIV will become resistant to the drug very soon and the drug will stop working. Hence a combination of drugs is used. ART is often a lifelong treatment that is currently helping numerous HIV affected people lead a better quality of life. The effectiveness of the treatment largely depends on the adherence of medicine intake schedule.

When to start ART depends on the patients' need and condition. A blood test called the CD4 count is taken to measure the number of CD4 cells in a sample of blood. CD4 cells are infection-fighting cells in the immune system of the human body. HIV attacks and destroys these CD4 cells, thus making it difficult for the body to fight infection. A low or dropping CD4 count indicates that HIV is advancing and damaging the immune system. Under the guidance of a physician when the patient begins ART, the CD4 count begins to improve which indicates that the immune system in the body is recovering.

Physicians also may order a blood test to check and measure HIV by checking the viral load in the blood i.e. the amount of the virus in the bloodstream. ART aims at reducing the viral load in the blood to an extent that it can't be traced any longer while testing. HIV virus though present in the blood will be very low - not sufficient to cause any symptoms.

Combination ARV therapy is also available and is known as highly active ART or HAART. With the availability of HAART, HIV-1 infection is manageable as a chronic disease in patients. Antiretroviral drugs are used in combinations of three or more classes of drugs, called Combination Therapy. This therapy helps prevent drug resistance in patients. Six classes of drugs, Antiretroviral agents, exist currently:

• Chemokine receptor antagonists (CCR5 antagonists) such as maraviroc.
  
• Fusion inhibitors (FIs) such as enfuvirtide.
  
• Integrase inhibitors (INSTIs) such as dolutegravir and raltegravir.
  
• Nucleoside reverse transcriptase inhibitors (NRTIs) such as abacavir, emtricitabine and tenofovir.
  
• Non-nucleoside reverse transcriptase inhibitors (NNRTIs) such as efavirenz, etravirine, and nevirapine.
  
• Protease inhibitors (PIs) such as atazanavir, darunavir, andritonavir.

Each class targets a different step in the life cycle of the virus. Each of these drug classes includes more than 25 HIV medicines that are approved to treat HIV infection. ART regimen includes three or more Antiretroviral from at least two different classes.

Drugs have to be taken at the right time and in the right way for the drugs to work well. The regimen requires plenty of discipline. The drugs may cause side effects in a few. If patients stop taking the drug, they may develop resistance to the drug and thereby will stop responding to the treatment when continued at a later stage.

Few of the commonly reported side effects include loss of appetite, fatigue, depression, mood changes, weight gain, sleep disturbance and metabolic disturbance. ART is available for pregnant women so that they don't pass on the virus to the fetus in the womb. Post delivery, the mother is advised not to breast feed the baby as she may pass the HIV virus through this to the baby. Though ART is not a complete cure for HIV, it serves the purpose to:

• Reduced HIV viral load in the blood.
  
• Enhanced quality living for patients inflicted with HIV.
  
• Lesser damage to the immune system.
  
• Reduced transmission of HIV in the society.

Though ART is considered to be a great regimen in handling HIV, it has few limitations such as:

• Strict adherence to medication regimen; few tablets need to be taken at the same time of the day, everyday.
  
• Expensive medicines have to be continued life long.
  
• Side effects
  
• Virus cannot be eradicated completely from the body.
  
• Relapse is possible on discontinuation of drugs.