Primary HIV infection frequently missed by GUM and HIV clinics

Primary HIV infection had been missed frequently in people newly diagnosed with HIV at a sample of UK sexual health clinics, investigators from the UK report in the International Journal of STD & AIDS.

A large number of HIV transmissions are thought to be acquired from people who have themselves only recently been infected with the virus. This early stage of infection is called primary HIV infection and is characterised by extremely high levels of HIV in blood and genital fluids. Identifying people during this stage of infection is therefore a public health priority. Possible interventions for people with primary infection could include counselling about their hyper infectiousness, or a short course of antiretroviral therapy to reduce their viral load and therefore the risk of infection to sexual partners.

It is difficult to identify people during primary infection. The symptoms are non-specific, can be mild and are often missed. Laboratory testing is therefore essential.

Earlier research has shown that primary HIV infection is often missed by GPs and other medical services that do not specialise in sexual health or HIV. The extent to which primary infection is missed at genitourinary medicine (GUM) and HIV clinics is currently unknown.

Investigators from Brighton, St Thomas’ Hospital, south London, and Imperial College, London therefore designed a study to see how often primary HIV infection was identified at specialist clinics.

A total of 311 blood samples from people diagnosed with HIV between January and August 2009 were tested in the laboratory of the Health Protection Agency (HPA) using an avidity assay to identify cases of primary infection. The investigators then checked the relevant case notes to see if primary infection was suspected and if appropriate safer sex counselling was provided.

Overall, 64 people with primary infection were identified. Most (80%) were gay or bisexual men, the mean age was 36 years and 20% were diagnosed with a sexually transmitted infection at the same time as HIV.

Concern about symptoms was reported as the reason for seeking an HIV test by 44% of patients, with a third expressing concern about a recent sexual contact.

Overall, only 48% of patients were correctly identified as having primary HIV infection.

The rate of detection differed between clinics and was highest in Brighton (73%).

Factors associated with identification of primary infection included being gay or bisexual (p = 0.024), identification of seroconversion symptoms (p = 0.0004), a documented HIV-negative test result within the previous six months (p = 0.024) and reported unprotected anal sex within the last three months (p = 0.017).

Suspicion of primary infection was related to the number of risk factors present in each individual.

Over three-quarters of individuals had at least one of these factors and 53% of these patients were identified in the clinic as having primary infection. Identification occurred in half the patients with one risk factor, in 50% of those with two risk factors and in 88% of individuals with three or more factors. The single patient with all four risk factors was successfully identified as having primary HIV infection.

In all, 77% of people with primary infection (recognised and unrecognised) received safer sex information. However, only a third of people identified with primary infection were informed of their increased infectiousness during this stage of HIV infection.

“Risk reduction strategies (such as safe-sex counselling, post-exposure prophylaxis provision for sexual partners) to reduce onward transmission could be improved and there was little documented evidence at any centre that individuals diagnosed with primary HIV infection were informed of the increased infectiousness state of primary HIV infection,” comment the authors.

They conclude, “to enhance awareness of primary HIV infection and thus improve management of individuals at this key stage of HIV infection, we propose more rapid availability of the HPA’s avidity assay and the development of a clinical algorithm incorporating a checklist of seroconversion symptoms, risk factors for primary HIV infection and previous HIV test results.”