Human Immunodeficiency Virus (HIV) is a virus that attacks the human immune system and leads to Acquired Immune Deficiency Syndrome (AIDS) if untreated. HIV leads to a short period of acute illness that is not unlike the common cold or the flu. It then remains latent for years to moths gradually damaging the immune system.
Immune system cells known as CD4 cells are the primary target of HIV. Destruction of these cells leads to opportunistic infections – atypical infections that generally affect immunocompromised hosts. AIDS is a common cause of death worldwide, buts its medical treatment in developed countries has led to a significant reduction in mortality and complications. Despite this, many underserved countries still suffer grave consequences from this serious viral illness.
HIV is caused by the human immunodeficiency virus. HIV can be transmitted through blood and bodily fluids. The most common routes of transmission are through unprotected sexual intercourse and exposure to infected blood via shared needles during IV drug use and accidental needle sticks in medical settings. In the past, HIV was transmitted by human blood products such as blood and plasma. New universal screening techniques have virtually eliminated its spread in this manner.
This virus enters the blood stream and infects CD4 cells – a form of white blood cell – eventually leading to cellular death. These cells are important for proper function of the immune system. Primary viral infection generally produces flu-like symptoms – however, unlike the flu, HIV goes on to suppress the immune system, resulting in opportunistic infections. In fact, HIV infection is a leading cause of immunosuppression worldwide and in the United States.
The virus tends to lie dormant for months or years, slowly and progressively killing immune cells. Patients eventually develop opportunistic infections as their CD4 counts decrease below 200. Once this occurs the condition is known as AIDS.
HIV is relatively uncommon in the United States, the U.S. Centers for Disease Control estimate that 1.2 million individuals in the United States are living with HIV. Since HIV is a chronic condition that does not present with severe symptoms until several years have passed it is estimated that 160,000 individuals are living with HIV without currently knowing it.
Worldwide 37 million individuals are estimated to be infected with HIV with 1 million dying of complications every year. The prevalence of HIV seems to be stabilizing overall. Since 2001, there has been about a 38% decrease in the incidence of HIV infection.
Acute HIV infection generally occurs several days to a week after exposure to the virus. These symptoms are generally flu-like but may last for multiple weeks. The most common symptoms are:
- Enlarged and painful lymph nodes – lymphadenopathy
- Sore throat
- Body aches
- Weight loss
- Night sweats
- Anorexia – loss of appetite
These symptoms subside and the virus then slowly damages the CD4 cells of the immune system. Months or years later, the CD4 cells become significantly depleted and patients develop an opportunistic infection. Opportunistic illnesses generally happen when the CD4 count is below 200 and are commonly referred to as “AIDS defining illnesses.” These conditions indicate that the immune system is damaged enough for the patient to be considered to have AIDS. The most common AIDS defining illnesses include Pneumocystic jiroveci pneumonia, esophageal candidiasis, Kaposi sarcoma, wasting syndrome, and disseminated Mycobacterium avium infection.
The diagnosis of HIV usually begins with identifying risk factors for HIV exposure. A history of multiple sexual partners or IV drug use will prompt testing for HIV. HIV testing is also done routinely as a part of STD screening which is recommended yearly for any sexually active individuals.
It is very common for HIV to present as AIDS due to its long chronic phase. Any one of the AIDS defining illnesses will generally prompt a physical to perform HIV testing. Your doctor will typically check you for HIV viral load, HIV PCR and antibodies, as well as CD4 counts. They will also typically test for HIV resistance patterns to guide treatment.
Other commonly ordered blood tests include a CMP (comprehensive metabolic panel), CBC (complete blood cell count), and thyroid function (TSH, free T4). They will also usually check your cholesterol levels and screen for diabetes. Urine tests typically include a urinalysis and gonorrhea/chlamydia PCR.
Additional blood tests for sexually transmitted infections include hepatitis B and C serology, and RPR for syphilis. Your doctor will also usually order a TB test and or obtain a chest x-ray to evaluate for any lung disease.
Any HIV infection is treated with antiretroviral therapy (ART). This typically includes nucleoside reverse transcriptase inhibitors, nonnucleoside reverse transcriptase inhibitors, and protease inhibitors.
The most common Nucleoside reverse transcriptase inhibitors are:
- Ziagen (abacavir)
- Videx (didanosine)
- Emtriva (emtricitabine)
- Epivir (lamivudine)
- Zerit (stavudine)
Non-nucleoside reverse transcriptase inhibitors are usually given in combination with nucleoside reverse transcriptase inhibitors. The most common of these are:
- Rescriptor (delavirdine)
- Sustiva (efavirenz)
- Intelence (etravirine)
protease inhibitors are also used in combination with the above two medications, the most common are:
- Crixivan (indinavir)
- Kaletra (lopinavir/ritonavir)
- Viracept (nelfinavir)
- Norvir (ritonavir)
- Invirase (saquinavir)
Integrase inhibitors such as Isentress (raltegravir) may also be recommended depending on the genotype of the virus in a given patient.
Treatment for HIV typically includes a combination of all the above medications. They have varying side effects that differ greatly depending upon the patient. Treatment for HIV is life-long as the virus is latent within the cells of the immune system and cannot be eliminated. The exact combination of medications used may change over time as the virus can develop resistance to specific medications.
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