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.”