One of the characteristic features of the HIV epidemic in sub-Saharan Africa has been the extent to which women have been disproportionately affected. This is especially the case for adolescent girls and young women between the ages of 15 and 24 years. In South Africa, this population is at the highest risk of being newly infected and is nearly three times more likely to be living with HIV than age-matched males. What’s more, pregnancy and breastfeeding place a considerable risk of HIV infection among exposed babies if women are left untreated (up to a 40% chance of transmission). It is for these reasons that adolescent girls and young women have been identified as a key population for HIV treatment and prevention strategies.

In 2015, South Africa implemented the World Health Organisation Prevention of Mother to Child Transmission Programme Option B+. This policy recommended a “universal test and treat” approach, with all HIV-infected pregnant and breastfeeding women initiated on life-long antiretroviral therapy regardless of clinical stage or CD4 count. Subsequent to the adoption of Option B+, the mother to child transmission rate has continued to drop, with the country achieving a less than 1% HIV transmission rate at birth. Although this is a remarkable achievement, the burden of paediatric HIV remains high on account of the sheer number of pregnant and breastfeeding women living with HIV. Each year in South Africa an estimated 250,000 babies are born to HIV-infected mothers, a statistic that is unlikely to change any time soon.

As a means of identifying opportunities to strengthen the Prevention of Mother to Child Transmission programme, the South African Medical Research Council recently undertook a multi-level evaluation of Option B+. Interviews were conducted among healthcare workers and service users, including young mothers and their male partners. The findings reveal both high-risk taking behaviour and a poor understanding of HIV among men. From choosing not to use a condom if a new partner is “too pretty, looking great”, to assuming that they are uninfected if their partner tests negative, and having unprotected sex with a known HIV-positive partner under the influence of alcohol, young men in South Africa can well be described as “The Darwin Generation”.

Naturally, Darwinners have the worst HIV outcomes of any age/sex disaggregated group in the country. Data from the National Health Laboratory Service suggests that less than a third of young men between the ages of 19 and 24 are currently on antiretroviral therapy and being monitored. Only one in four are virologically suppressed (doing well on treatment). Inevitably, this has an impact on mortality. Whereas the country as a whole has experienced a substantial increase in life-expectancy, largely attributable to access to antiretroviral therapy, the mortality rate for males aged between 15-24 years has remained static at 25 per 1,000 lives since 2011. Over the same period, the mortality rate for adolescent girls and young women has dropped from 23 to 17 per 1,000 lives.

Although seemingly hell-bent on removing themselves from the genetic pool, adolescent boys and young men also pose considerable risk to other groups. Brimming with testosterone and HIV, our burgeoning population of virulent Lotharios contribute to the high HIV incidence among adolescent girls and young women. Whereas the standard narrative maintains that most young women acquire HIV from older male partners, it would be naïve to think that HIV infected adolescent boys and young men are not having sex with their female peer-group.

Indeed, the success of the Prevention of Mother to Child Transmission programme over the past 15 years means that proportionately less and less infected adolescent males will have acquired HIV from their mothers. Currently, of the 130,000 HIV-infected virologically unsuppressed males aged 15-24 years in South Africa, approximately 30% were infected from having unprotected sex. What’s more, compared to their perinatally infected counterparts this “behaviorally-infected” group of lads are generally asymptomatic, less likely to know their status, less likely to be compliant with treatment, and more likely to infect other sexual partners. This, in turn, threatens efforts to eliminate mother to child transmission of HIV, as incident infection in pregnant and breastfeeding young women represents the highest risk of vertical transmission to a baby.

And so it would seem that the self-immolation of The Darwin Generation is unlikely to translate into significant gains for our species as a whole. On the contrary, unless adolescent boys and young men are brought into HIV treatment and prevention services the epidemic will never be brought under control. The same can also be said for other marginalised populations whose needs have similarly been drowned-out by the overwhelming demands placed on our maternal and child-centred health services.

Somewhat ironically, UNAIDS targets for 2020, which call for 90% of HIV infected people to be diagnosed, 90% of those diagnosed to be on antiretroviral therapy, and 90% of those receiving therapy to be virologically suppressed, will still be achieved in South Africa – at least among the general population in certain districts. This is highly commendable. However, it does not signal an end to AIDS. Within a health system in which young men are invisible, the achievement of the 90:90:90 targets is indicative of the uneven disease burden but good health outcomes among women.

But, deep in the shadows, young men unwittingly direct the HIV epidemic. Although they account for less than 5% of all those infected, they wield a disproportionate influence on the evolution of the disease. If we are to bring an end to AIDS in South Africa, we must find more effective ways of preventing and treating HIV in adolescent boys and young men. If we do not, the epidemic will continue to smoulder and choke the country for decades to come. MC

• Ahmad Haeri Mazanderani is a clinical virologist at the National Institute for Communicable Diseases.