Clinical indicator diseases

Recommendations from the European AIDS Clinical Society (EACS) in 2008¹ outline the concept of clinical indicator diseases: in other words, diseases which could indicate the presence of HIV infection.

The authors suggest that a policy of universal HIV testing (as proposed by the CDC in the United States) would not be acceptable to most European governments, and that an alternative approach to tackling late diagnosis is to encourage non-HIV clinicians to offer HIV testing to people with illnesses associated with HIV infection. Testing should be considered when an illness may have been caused by HIV infection and immunosuppression, or when there is evidence that there is a higher HIV prevalence among patients of that condition than among the general population.

Nonetheless the authors acknowledge that, while there are good data on the prevalence of different diseases among people with HIV, there is less evidence available on the prevalence of HIV in people with those diseases. Therefore, the recommendations often rely on expert opinion rather than published data.

Clinical indicator diseases also figure in the British testing guidelines, although the list of diseases is not exactly the same. Moreover, the World Health Organization/UNAIDS guidelines recommend that in all types of epidemics, HIV testing and counselling should be recommended to any person who presents to health facilities "with signs, symptoms or medical conditions that could indicate HIV infection".²

The EACS recommendations start with a list of illnesses that are well-recognised as being directly related to HIV infection and immune deficiency – in other words, the list of conditions which, in a person with HIV, would prompt an AIDS diagnosis. This includes Kaposi’s sarcoma, various lymphomas, recurrent pneumonia, tuberculosis (TB) and invasive cervical cancer, among others.

Universal HIV testing is recommended for people with these conditions. However this is not always current practice – for example, HIV testing in people with TB is far from universal.

The authors then provide a list of other conditions which whilst being common in the general population, are seen more frequently in people who subsequently turn out to be HIV positive:

• Mucosal candidiasis (the prevalence of oral candidiasis among people with HIV can be as high as 50%).
• Herpes zoster, i.e. shingles (African studies show a very high HIV prevalence among people with the condition, and multiple lesions are suggestive of immunosuppression).
• Fungal skin infections (florid or difficult-to-treat infections are associated with immune deficiency).
• Oral manifestations of HIV disease, including hairy leukoplakia, acute necrotising gingivitis and palatal Kaposi’s sarcoma (sometimes experienced by people with HIV disease progression).
• Sexually transmitted infections including hepatitis B and C (for behavioural reasons, there is a high HIV prevalence among people with STIs).
• Pregnancy (acknowledged not to be a disease, but testing is recommended because of the availability of effective preventive measures).
• Respiratory infections (testing recommended for people with prolonged illnesses, atypical courses, recurrent infection, poor response to treatment, or very unusual infections).
• Neurological diseases (unusual forms of meningitis; space-occupying lesions).
• Gastrointestinal problems (highly common among people with HIV; if problems are persistent or caused by unusual organisms, HIV testing should be offered).
• Constitutional symptoms, e.g. prolonged fever, weight loss or non-specific diarrhoea (if other causes are not apparent, testing should be offered as these problems are associated with advanced HIV disease).
• Mononucleosis-like acute illness, i.e. what seems to be glandular fever (seroconversion illness may be mistaken for glandular fever).
• Laboratory indicators, including low blood count (common in people with HIV).
• Tumours (as well as the AIDS-defining cancers, anal cancer and Hodgkin’s lymphoma are common in people with HIV; HIV prevalence may be high in people with rare tumours).