Primary HIV Infection

oPatientPlus articles are written by UK doctors and are based on research evidence, UK and European Guidelines. They are designed for health professionals to use, so you may find the language more technical than the condition leaflets.

Synonym: acute retroviral syndrome; seroconversion illness

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In 2013, a total of 6,000 persons (4,500 men and 1,500 women) were newly diagnosed with HIV in the UK. The number of newly diagnosed heterosexual men and women has dropped over the years from 4,890 in 2004 to 2,490 in 2013) due to fewer diagnoses among people born in sub-Saharan Africa. 76% of infections in men who had sex with men (MSM) were acquired in the UK.[1] One study suggested that 16% of people newly diagnosed in England, Wales and Northern Ireland acquired their infection 4-6 months before diagnosis.[2] 19% of new diagnoses of HIV in 2012 were black Africans. Black Africans tend to present late in the infection, suggesting that more could be done to encourage early testing.[3] Research in 2011 suggested that 48% of people born abroad are likely to have acquired infection in the UK.[4] Approximately 70% of people with HIV infection experience symptoms during seroconversion.[5] The incubation period is one to three weeks.[6]

Of those who are seen in primary care with the illness, very few are correctly diagnosed.[7] If the diagnosis were made at such an early stage, benefits that may be assumed are:[8]

  • Early diagnosis should provide a better response to treatment.
  • Treatment can be initiated before the immune system is severely damaged and opportunistic infections take hold.
  • There will be less opportunity to spread the infection to others before the person's status is known.

Whilst the chance of early diagnosis may seem attractive, the reality is that early diagnosis is not often made and the disease is not usually diagnosed until the patient presents with opportunistic infections. Reasons for this include:

  • The patient may not present with the early illness to a doctor.
  • The signs and symptoms of HIV are so nonspecific that it may easily be missed and the doctor may not know that the patient has a lifestyle that puts them at risk.
  • It is easy to request FBC and glandular fever screening test without much concern but HIV testing needs preliminary counselling, including confronting the patient with the potential diagnosis.

New diagnoses have been declining since they peaked in 2005, mainly due to a fall in the number of diagnoses reported among heterosexuals from high HIV prevalence countries.[1] 

  • The illness resembles glandular fever. It is associated with fevers, sweats, malaise, lethargy, anorexia, nausea, myalgia, arthralgia, headaches, sore throat, diarrhoea, generalised lymphadenopathy, a macular erythematous truncal eruption and thrombocytopenia.
  • The most specific of these features is a maculopapular rash affecting predominantly the upper part of the body and mucosal ulcers affecting the mouth and genital areas.
  • A less common presentation is a predominantly gastrointestinal disease, including abdominal pain, nausea, vomiting, diarrhoea, hepatitis and even gastrointestinal haemorrhage.
  • Rarer presentations include encephalopathy, pneumonitis and rhabdomyolysis associated with acute kidney injury.
  • It starts two to six weeks after exposure and usually resolves in a week or two, although it can take considerably longer.
  • Those with more prolonged illness tend to have a poorer prognosis.[10]
  • Acute, severe immunosuppression may occur during primary infection and AIDS-defining illnesses may also develop and should arouse suspicion of seroconversion in patients with a recent negative result on HIV testing.

The relative frequency of symptoms has been reported as follows:[11] 

Main symptoms of primary HIV infection
Fever80%
Rash51%
Oral Ulcers37%
Arthralgia54%
Pharyngitis44%
Loss of appetite54%
Loss of more than 2.5 kg in weight32%
Malaise68%
Myalgia49%
Fever and rash46%

Tips on diagnosing primary HIV infection in primary care[8]

The challenge in primary care is to make the diagnosis at an early stage when symptoms are so nonspecific. GPs are used to spotting serious pathology when it presents with minor symptoms in the early stages and should use this approach when considering HIV.

When raising the possibility with patients, GPs should:

  • Explain in an open manner the clinical reasons why the diagnosis should be considered.
  • Talk to the patient in a non-judgemental way.
  • Reassure the patient about confidentiality.

It is clearly neither possible nor indeed appropriate for GPs to send every patient presenting with minor viral symptoms for an HIV test; however:

  • When considering glandular fever, think about HIV as well.
  • Consider the diagnosis in patients presenting with a blotchy rash on the trunk or oral or perianal ulcers.
  • Bear in mind commensural infections which can occur when the CD4 count drops rapidly - eg, oral candidiasis, shingles.
  • Headache, meningism and diarrhoea can be less common presentations.
  • If FBC shows low platelets, this may suggest the diagnosis, although sensitivity and specificity are low. Mild anaemia, atypical lymphocytes and abnormal LFTs may also be found.
  • Testing should comply with the guidelines of the British HIV Association (BHIVA). Currently these recommend simultaneous HIV antibody and p24 antigen tests.
  • If these tests are negative, they should be repeated if suspicion is high. Confirmatory antibody and antigen RNA tests are available; the local laboratory will advise.
  • Even in the early phases there is often a reduction in CD4 lymphocytes, a CD8 lymphocytosis and a ratio of CD4/CD8 which is low.

The management of primary HIV infection remains controversial. UK guidelines recommend the following indications:[14] 

  • Neurological involvement. 
  • Any AIDS-defining illness. 
  • Confirmed CD4 cell count <350 cells/mL.

Although some data suggest possible immunological, virological, or clinical benefit of early treatment, other studies show no difference in these outcomes over time, after early treatment is discontinued. Evidence is emerging that treatment of acute HIV infection may have short-term benefit on viral set point when compared to delayed therapy as well as reducing the risk of transmission to others.[9] Furthermore, studies suggest that use of relatively short-acting potent agents such as recombinant immunotoxins might prove sufficient for HIV eradication, obviating the need for long-term therapy.[15] 

Currently, the CD4+ count remains one of the best indications that antiretroviral therapy is indicated; the trigger for treatment is generally to be taken to be a count of 350 cells per μL or lower.[16] The World Health Organization recommends a higher threshold ≤500 cells per μL but this has yet to be adopted in the UK.[17] 

The primary disease is caused by viraemia and so it is unsurprising that those with a prolonged illness, being those who cope poorly with the viraemia, will have a poor prognosis. One study found that patients with more severe and numerous symptoms during primary HIV-1 infection had faster disease progression.[18]

Further reading & references

  • Atfelt M, Walker BD; Acute HIV-1 Infection, HIV Medicine
  • Daskalakis D; HIV diagnostic testing: evolving technology and testing strategies. Top Antivir Med. 2011 Feb-Mar;19(1):18-22.
  1. HIV in the United Kingdom: 2014 Report; Public Health England
  2. Review of HIV epidemiology in London, 2013; Public Health England
  3. HIV and AIDS in the UK; AVERT
  4. HIV and Black African Communities in the UK; National Aids Trust, 2014
  5. Primary HIV Infection: knowledge amongst gay men; National AIDS Trust, 2011
  6. Truong H et al; What is the role of acute HIV infection in HIV prevention?, Center for AIDS Prevention Studies at the University of California San Franciso, 2006
  7. Sudarshi D, Pao D, Murphy G, et al; Missed opportunities for diagnosing primary HIV infection. Sex Transm Infect. 2008 Feb;84(1):14-6. Epub 2007 Oct 30.
  8. HIV in Primary Care; Medical Foundation for AIDS & Sexual Health (2011)
  9. O'Brien M, Markowitz M; Should we treat acute HIV infection? Curr HIV/AIDS Rep. 2012 Jun;9(2):101-10. doi: 10.1007/s11904-012-0113-0.
  10. Fox J, Weber J, Fidler S; Primary HIV. Sex Transm Infect. 2006 Aug;82(4):267-8.
  11. Hoffmann C et al; Acute HIV-1 Infection, hivbook.com, 2011.
  12. Dubrow R, Sikkema KJ, Mayer KH, et al; Diagnosis of acute HIV infection in Connecticut. Conn Med. 2009 Jun-Jul;73(6):325-31.
  13. UK national guidelines for HIV testing; British HIV Association (September 2008)
  14. Guidelines for the treatment of HIV-1 positive adults with antiretroviral therapy 2012 (updated November 2013); British HIV Association
  15. Dey B, Berger EA; Toward an HIV cure based on targeted killing of infected cells: different approaches against acute versus chronic infection. Curr Opin HIV AIDS. 2015 Feb 23.
  16. May MT, Gompels M, Delpech V, et al; Impact on life expectancy of HIV-1 positive individuals of CD4+ cell count and viral load response to antiretroviral therapy. AIDS. 2014 May 15;28(8):1193-202. doi: 10.1097/QAD.0000000000000243.
  17. Consolidated guidelines on the use of antiretroviral drugs for treating and preventing HIV infection, Chapter 7 – Antiretroviral therapy (supplement 3); World Health Organization, 2013
  18. Daar ES, Pilcher CD, Hecht FM; Clinical presentation and diagnosis of primary HIV-1 infection. Curr Opin HIV AIDS. 2008 Jan;3(1):10-15.

Disclaimer: This article is for information only and should not be used for the diagnosis or treatment of medical conditions. EMIS has used all reasonable care in compiling the information but make no warranty as to its accuracy. Consult a doctor or other health care professional for diagnosis and treatment of medical conditions. For details see our conditions.

Original Author:
Dr Laurence Knott
Current Version:
Peer Reviewer:
Dr John Cox
Document ID:
1118 (v25)
Last Checked:
04/04/2015
Next Review:
02/04/2020