The change in CD4 T-lymphocyte levels associated with HIV infection is an indication of the immune system defense capability. As the CD4 cell count declines the body becomes susceptible to infections. Some of these infections are common and short-lived (acute) when contracted by a person with a healthy immune system (immunocompetent). Other infections are very rarely seen in the general population except in cases of immune deficiency whether related to HIV infection or not. These rare infections are referred to as opportunistic infections because it takes the opportunity to infect a person when the immune defenses are compromised.
Read more on :
Certain infections, diseases and clinical features are more likely to arise with different ranges of CD4 cell count. This does not mean that an HIV-positive person will definitely contract any of these infections. Nor does it mean that the infection will not occur in an HIV-positive person with a higher CD4 count. While these infection can occur in any person irrespective of the HIV status, it is more likely to occur once the CD4 count drops to the levels indicated below.
CD4 Count Less than 500 cells/mm3
Cervical intra-epithelial neoplasia is the precancerous stage of cervical cancer. Read more on stages of cervical cancer.
Idiopathic thrombocytopenic purpura (ITP) is type of clotting disorder characterized by excessive bleeding and bruising. This is a result of platelet destruction and is a well known complication of HIV infection.
Kaposi’s sarcoma is a rare type of cancer that is common with HIV infection and primarily affects the skin where it may appear as a red, purple or brown rash. It can affect any organ although it is more frequently seen on the skin, in the mouth and throat.
Lymphoid interstitial pneumonitis is a rare lung disease that arises as a result of white blood cells invading the alveolar (air sac) spaces and tissue.
Oropharyngeal candidiasis is the infection of the mouth and upper part of the throat (pharynx) with the fungus known as Candida albicans. The oral infection is commonly referred to as oral thrush and in HIV infection this extends to the pharynx.
Oral hairy leucoplakia are the formation of thick white patches in the oral cavity (mouth, tongue, gum, inner cheek) due to an infection with Epstein-Barr virus (EBV).
Pneumonia is an infection of the lung parenchyma and recurrent pneumococcal pneumonia is frequently seen with HIV infection. Read more pneumonia symptoms.
Pulmonary tuberculosis (TB of the lungs) is an infection of the lungs caused by Mycobacterium tuberculosis. Other mycobacteria that may also cause pulmonary TB include M.bovis and M.africanum but are uncommon.
Salmonellosis is an infection with the Salmonella bacteria typically causes inflammation of small and large intestine (enterocolitis) but in HIV infection, this bacteria may infect other organs and tissues outside of the gastrointestinal system.
Shingles (herpes zoster) is an infection caused by the Varicella zoster virus which causes a painful blistering rash. It infects the nerve and skin of a specific dermatome.
CD4 Count Less than 200 cells/mm3
Cryptosporidiosis is a severe infectious diarrhea caused by the parasite Cryptosporidium. With HIV infection it can be debilitating and persistent. It causes a watery and/or bloody stool as discussed under HIV diarrhea. Cryptosporidium may also affect other organs and systems.
Esophageal candidiasis is an infection of the esophagus (gullet) with the Candida albicans fungus. It arises from the spread of oropharyngeal candidiasis discussed above.
Extrapulmonary tuberculosis is an infection of organs other than the lungs with Mycobacterium tuberculosis.
Microsporidiosis is a a severe gastrointestinal and pulmonary (lung) disease caused by the Microsporidium parasites. It causes diarrhea (HIV diarrhea), pancreatitis, cholangitis and a host of pulmonary symptoms.
Mucocutaneous herpes simplex is an infection of the mucous membranes (mouth, genitalia, perianal and rectal) with HSV-1 or HSV-2. These viruses are known for causing herpes infections of the mouth and genitals but the infection can be more widespread in HIV infection.
Pneumocystis pneumonia is infection of the lung cause by the eukaryote, Pneumocystis jiroveci (previously known as Pneumocystis carini). It is rarely seen except in HIV infection and is an AIDS-defining disease.
CD4 Count Less than 100 cells/mm3
Cerebral toxoplasmosis is the formation of cysts in the brain due to infection with Toxoplasmosis gondii. With HIV infection, there may be reactivation of the cysts.
Cryptococcosis or cryptococcal meningitis is infection of the meninges (lining of the brain and spinal cord) with the fungi Cryptococcus neoformans or Cryptococcus gattii.
Cytomegalovirus (CMV) infection can affect any system in the body and therefore cause a host of signs of symptoms in HIV infection. Retinitis and gastrointestinal disease due to CMV is frequently seen in HIV/AIDS once the CD4 cell count drops below 100 cells/mm3, particularly below 50 cells/mm3.
HIV-associated dementia (HAD) occurs when there is significant damage and death of the neurons in the brain due to the presence of HIV proteins and inflammatory cells and chemicals.
Non-Hodgkin lymphoma is a type of cancer of the lymph node cells. Rad more on primary lymph node cancer.
Progressive multifocal leukoencephalopathy occurs with reactivation of the latent JC virus which results in damage to the nerve sheath (myelin). Symptoms include memory loss, problems with vision, coordination and speech and weakness of the arms and legs.