Decreases in opportunistic illnesses

The effectiveness of antiretroviral therapy has been clearly demonstrated by the decline in opportunistic infections in countries where highly active antiretroviral therapy (HAART) is widely available.1 As antiretroviral therapy has enabled immune recovery, fewer people develop opportunistic infections and many have been able to stop prophylactic drugs. For further discussion of ceasing prophylaxis, see Immune recovery and opportunistic infection prophylaxis.

Whilst the incidence of most opportunistic illnesses fell after the introduction of HAART, the decrease in infections that occur at very low CD4 counts – such as Pneumocystis pneumonia (PCP), cytomegalovirus (CMV), Mycobacterium avium intracellulare (MAI) and progressive multifocal leukoencephalopathy (PML) – was particularly pronounced.

In the US HOPS cohort, the incidence of PCP, MAI and CMV fell from 21.9 cases per 100 person-years in 1994 to 3.7 in 1997.2 The rate further declined to 0.32 in 2004.3 A Swiss HIV Cohort study comparing the incidence of new opportunistic infections in the six months before a person started HAART and in the three months after found that rates of PCP, CMV, Kaposi’s sarcoma, oesophageal candidiasis and toxoplasmosis all declined significantly. In total, the incidence of opportunistic infections fell from 15.1 to 3.57 per 100 person-years.4

Assessment of declines in opportunistic illnesses has been complicated by an increase in opportunistic infection symptoms associated with immune restoration syndrome in some people starting HAART. Such flare-ups happen as the recovering immune system attacks pre-existing pathogens, and do not signal new or worsening infections. For further information, see Immune reconstitution inflammatory syndrome.

Opportunistic infections continue to occur among people who are not on antiretroviral therapy. This includes a significant number of people who are never tested or diagnosed as HIV-positive during the early stages, and only discover they are infected after they develop an AIDS-related illness. In England and Wales between 1997 and 2002, 13% were diagnosed with HIV when they already had severe immune impairment.5

For discussion of particular opportunistic infections and HAART, see the specific disease entries in A to Z of illnesses.


  1. Mocroft A et al. Decline in the AIDS and death rates in the EuroSIDA study: an observational study. Lancet 362(9377): 22-29, 2003
  2. Palella FR et al. Declining morbidity and mortality among patients with advanced human immunodeficiency virus infection. New England Journal of Medicine 338(13): 853-860, 1998
  3. Palella FJ et al. Mortality in the highly active antiretroviral therapy era: changing causes of death and disease in the HIV outpatient study. J Acquir Immune Defic Syndr 43: 27-34, 2006
  4. Ledergerber B et al. Clinical progression and virological failure on highly active antiretroviral therapy in HIV-1 patients: a prospective cohort study. Lancet 353: 862-869, 1999
  5. Chadborn TR et al. Late diagnosis of HIV infected adults in England and Wales: 1997-2002. Second International AIDS Society Conference on HIV Pathogenesis and Treatment, Paris, abstract 11128, 2003
Community Consensus Statement on Access to HIV Treatment and its Use for Prevention

Together, we can make it happen

We can end HIV soon if people have equal access to HIV drugs as treatment and as PrEP, and have free choice over whether to take them.

Launched today, the Community Consensus Statement is a basic set of principles aimed at making sure that happens.

The Community Consensus Statement is a joint initiative of AVAC, EATG, MSMGF, GNP+, HIV i-Base, the International HIV/AIDS Alliance, ITPC and NAM/aidsmap

This content was checked for accuracy at the time it was written. It may have been superseded by more recent developments. NAM recommends checking whether this is the most current information when making decisions that may affect your health.

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