Treatment training manual

1.12 CD4 count cut-offs and the risks of opportunistic infections (OIs)

An opportunistic infection (OI) is the name given to an HIV-related illness.

These are often infections that without HIV, your body would be able to control.

The lower the CD4 count, the higher the risk of OIs. This is why HIV treatment (ART) is especially important with a low CD4 count.

You can still feel well and healthy with a low CD4 count. Even when the CD4 count is below 200, below 100 or even below 10. But the risk of serious health problems increases as the CD4 count drops. And even with a high CD4 count, some serious HIV related illnesses can occur.

HIV treatment guidelines recommend ART for everyone – but especially if the CD4 count is below 350 cells/mm3.

But since 2015, most guidelines routine recommend ART for HIV positive people at any CD4 count. Even if the CD4 count is above 500 cells/mm3.

Different illnesses become more likely at different CD4 counts. Many serious and life threatening illnesses become a risk when the CD4 count drops to under 200 cells/mm3.

Opportunistic infections that occur at different CD4 counts

At any CD4 count

  • The risk of TB is higher in HIV positive people. This can occur at any CD4 count.
  • Kaposi’s Sarcoma (KS) can occur at any CD4 count, though the risk increases as the CD4 count drops below 350-500.

CD4 count below 300

  • Diarrhoea from bacteria infections microsporidia and cryptosporidia.
  • Skin problems – candida (thrush), dry skin, etc.

CD4 count below 200

  • PCP (fungal pneumonia) and chest infections.
  • Toxoplasmosis – parasitic infection that can cause brain lesions.

CD4 count below 100

  • MAI /MAC (mycobacterium avium complex) – bacterial infections similar to TB.
  • Cryptococcus – fungal infection that can cause meningitis in the brain and PCP-like symptoms in the lungs.

CD4 count below 50

  • CMV (cytomegalovirus) – a viral infection that can cause permanent vision loss and blindness and can also affect other organs.

Information on these infections are included in the OI chapter of this resource.

  • The lower the CD4 count the higher the risk of OIs and other illnesses.
  • CD4 count increases after starting ART, often means your immune system can deal with these infections by itself.
  • After CD4 inncreases on ART, treatment to prevent OIs can often be stopped. Primary prophylaxis is the medical term for using a medicine to prevent a new infection. Secondary prophylaxis is when meds are used to prevent the return of an earlier infection.

Last updated: 1 January 2016.