Our series on global health trends began last November, with a look at the future prevalence of heart disease and diabetes, and viral conditions such as hepatitis, HIV and malaria; in February this year, we looked at what the following decades hold for chronic conditions such as asthma and psoriasis; and last week, we assessed the 21st century outlook for age-related conditions such as dementia and visual impairment.

In our fourth and final post in this series, we’ll be taking a look at the current and possible future trends of sexually transmitted infections such as chlamydia and gonorrhoea.

We’ll also be looking at whether erectile dysfunction will be more or less common in the years to come.

How common will STIs be in 2050?

Estimating the rates of STIs in the future is tricky; not least because cases have risen and fallen so erratically in previous decades.

The most recent figures from Public Health England report a 4% drop in overall STI diagnoses in England between 2015 and 2016. However, as we discussed in a recent post, some commentators have attributed this to fewer tests being carried out, and to cuts in public services.

The number of reported chlamydia diagnoses in England reached 211,372 in 2013. It dropped to 202,451 in 2015 and rose very slightly to 202,546 in 2016.

Since 2012, gonorrhoea has risen markedly, from 26,880 cases to 36,244 cases in 2016.

Between 2012 and 2016, the number of syphilis cases in the UK has nearly doubled, from 3,001 to 5,920.

The way STI figures were collated in England changed in 2012, which makes analyses of STI trends over a longer period problematic.

In the US, chlamydia rates have gradually increased since the current standard of surveillance began in 1984. There were 1.5 million cases reported in 2015, which is 478.8 persons per 100,000 of the population (to provide a comparison, the rate in England in 2016 was 366.5 per 100,000).

Gonorrhoea rates in the US peaked in the mid 1970s (464.1 diagnoses per 100,000 of the population), but dropped to an all-time low in 2009 (98.1 per 100,000). Since then, they’ve started to climb again (123.9 per 100,000 in 2015).

Since recent records began, syphilis (all stages) in the US was most prevalent in 1943 (447 cases per 100,000) but also fell dramatically in the decades that followed; to as low as 11.2 per 100,000 in 2000 and 2005. Once more, cases have risen again since, more than doubling to 23.4 per 100,000 in 2015.

On a worldwide basis, WHO estimates that there are 131 million chlamydia infections, 78 million gonorrhoea infections and 5.6 million syphilis infections each year.

These three STIs are treated with antibiotics; but how well the antibiotics that we currently have will continue to function in coming years is in serious doubt. As we’ve discussed previously, gonorrhoea has a capacity to quickly develop resistance to antibiotic drugs. Resistance in syphilis and chlamydia is not as common but, as noted by WHO, it does exist.

The extent to which this could affect those experiencing bacterial STIs - or any bacterial infection with resistant qualities - in the coming decades is therefore difficult to estimate.

Superbugs of all kinds resistant to antibiotics could cause as many as 10 million deaths per year by 2050, according to one report

Research into new antibiotic candidates is ongoing, and how successful this research is will undoubtedly play a crucial role in how easy STIs are to treat. Now and during the coming years, the conservation of the antibiotics we do have will continue to be vitally important. And again, promoting awareness and education of these conditions, and of safe sex practices, will be a significant determining factor in their future prevalence.

How common will erectile dysfunction be in 2050?

Predicting how common erectile dysfunction will be in 35 years is, as you would expect, a tricky exercise for a number of reasons; but chiefly because it’s difficult to determine with any real certainty how common it is now.

Erectile dysfunction can be acute or chronic, and many men who have the condition short-term may not need to seek treatment; so instances of the condition may go entirely unreported. In other cases, where the condition is chronic, many men may be unwilling to see a doctor about the condition, and not seek treatment at all.

The NHS estimates that ED affects half of all men over 40 in some way. A report from 2013 estimated that only one out of every four men with newly diagnosed ED is under 40.

Taking this into account, one would presume that erectile dysfunction is likely to increase in overall prevalence, due to the estimated rise in the ageing population: the ONS estimated in 2015 that there were 32.8 million people (men and women) in the UK over the age of 40. They estimate that this number will rise to 39.4 million by 2035.

We should also keep in mind that the prevalence of other contributing factors in ED, such as obesity and diabetes, are on the rise.

Besides those already available, other oral and topical treatments for ED are in development. Uprima and Topiglan are examples of medicines currently under investigation.

But another possibility being explored, as reported by WebMD, is gene therapy. The idea is that this form of treatment helps the development of certain proteins in the body: proteins that aren’t working as they should in men affected by impotence. This form of treatment, although in its very early stages, has reportedly shown promise in clinical trials.

We’ve written before that there are several factors which can contribute towards ED, both physical and psychological. Treatment aside, the more we learn about these factors, the easier it will be for men who might be susceptible to erection problems to manage and prevent ED.