An estimated 29,000 undiagnosed HIV cases in France

HIV diagnoses reached highest-ever level in gay and bisexual men in 2012 due to testing rise
This article is more than 10 years old. Click here for more recent articles on this topic

An estimated 29,000 individuals in France were living with undiagnosed HIV infection in 2010, investigators report in the online edition of AIDS. Sixty per cent of people with undiagnosed HIV had a CD4 count below 500 cells/mm3 and were therefore eligible for immediate antiretroviral therapy. The investigators believe their findings are of relevance to HIV screening strategies, and that universal HIV testing for men would be appropriate and cost effective, especially in high-prevalence cities, such as Paris.

People living with undiagnosed HIV are unable to benefit from HIV treatment and care. Research has shown that the majority of new HIV transmissions originate in undiagnosed individuals, and late diagnosis increases the risk of serious HIV-related illness and death.

HIV testing strategies in France have traditionally relied on voluntary counselling and testing. Annual HIV tests are recommended for high-risk groups such as gay men, people who inject drugs and heterosexual people from high-prevalence settings who report multiple sexual partners. In addition, all individuals aged between 15 and 70 are recommended to have at least one HIV test during their lifetime.



Cost-effectiveness analyses compare the financial cost of providing health interventions with their health benefit in order to assess whether interventions provide value for money. As well as the cost of providing medical care now, analyses may take into account savings on future health spending (because a person’s health has improved) and the economic contribution a healthy person could make to society.

mathematical models

A range of complex mathematical techniques which aim to simulate a sequence of likely future events, in order to estimate the impact of a health intervention or the spread of an infection.


The transition period from infection with HIV to the detectable presence of HIV antibodies in the blood. When seroconversion occurs (usually within a few weeks of infection), the result of an HIV antibody test changes from HIV negative to HIV positive. Seroconversion may be accompanied with flu-like symptoms.


To better inform HIV screening strategies, investigators used mathematical modelling techniques to estimate new infections, time to diagnosis and the number of people with undiagnosed HIV at the end of 2010. 

Approximately 83,000 people newly acquired HIV in France between 2000 and 2010. Of these, an estimated 29,000 remained undiagnosed at the end of 2010. The majority (70%) of those undiagnosed individuals were men. As regards HIV risk group, gay and other men who have sex with men (MSM) comprised 32% of undiagnosed individuals, French-born heterosexuals 35%, non-French-born heterosexuals 32% and people who inject drugs 2%.

Undiagnosed prevalence was 10 per 10,000 among men compared to 4 per 10,000 among women. The prevalence in men was at the 0.10% threshold at which universal HIV testing becomes cost effective.

Analysis by exposure groups showed that the rate of undiagnosed infections was highest among MSM at 295 per 10,000, followed by people who inject drugs (62 per 10,000), non-French-born heterosexuals (36 per 10,000) and was lowest among French-born heterosexuals (3 per 10,000).

The authors estimated that 29% of undiagnosed individuals had acquired HIV within the last year and that 16% acquired HIV five or more years ago. There was a higher prevalence of old infections among men than women (18 vs 12%). Heterosexual men were the group most likely to have been living with an undiagnosed infection for five or more years (20%).

French national guidelines now recommend the initiation of HIV therapy at a CD4 count of 500 cells/mm3 and 60% of undiagnosed individuals had a CD4 count below this threshold. The investigators were especially concerned that approximately a fifth of people with undiagnosed HIV had a CD4 count below 200 cells/mm3.  They note that “a recent study showed that, in France, patients presenting to care with CD4+ below 200 cells/mm3 were 13 times more likely to die from HIV within the next 6 months after enrolment than patients presenting with CD4+ above 200 cells/mm3.”

Heterosexual men were the group most likely to have a low CD4 count.

“New screening strategies to reach out to undiagnosed individuals are needed in order to reduce HIV transmissions and ensure timely access to HIV care for these individuals,” the authors conclude. “Universal screening of men could be cost-effective in the areas most affected by the epidemic, such as the metropolitan area of Paris, and thus should be further evaluated.”

More gay men than ever diagnosed with HIV

Data released this week show that more French gay men than ever were diagnosed with HIV in 2012. Whereas the annual number of diagnoses increased by around 3% each year from 2003 to 2011, it jumped by 14% in the year 2011 to 2012, with 2600 men diagnosed.

Diagnoses have not increased among heterosexual people – 3500 were diagnosed in 2012, just over half being female, and half born in an African country.

While there are clear signs of ongoing transmission among gay men, public health officials attribute the jump in diagnoses to improved testing behaviour. In 2012, 52% were diagnosed with a CD4 cell count over 500 cells/mm3 or with symptoms of seroconversion (up from 47% in 2011). Similarly, using a recent infection testing algorithm (RITA), it is thought that 47% of gay men were diagnosed within a few months of their infection (up from 42% in 2011).

Far fewer heterosexuals, especially those born overseas and those over the age of 50, were diagnosed promptly.

Analysing the evolution of the situation since the release of a new national strategy in 2010, public health officials argue that campaigns and recommendations encouraging regular testing, as well as the availability of rapid testing in community settings, have had a measurable impact among men who have sex with men. However the same measures have not been implemented sufficiently to reach heterosexual people with undiagnosed HIV.


Superie V et al. The undiagnosed HIV epidemic in France and implications for HIV screening strategies. AIDS 28, advance online publication ahead of print. DOI: 10/1097/QAD.0000000000000270, 2014.

Cazein F et al. Découvertes de séropositivité VIH et sida – France, 2003-2012. Bulletin Epidémiologique Hebdomadaire, April 1 2014.