Yudara Kularathne came up with the idea for an AI-driven app when a friend was worried about a bump on their penis.

Kularathne was then a consultant physician in Singapore in 2019, but he saw the potential for an app that could instantly identify a suspected sexually transmitted infection from a photo of male genitalia.

Calmara, which is specifically designed for people to check the penises of potential sexual partners, is one of two apps launched by Kularathne’s company to use AI to identify STIs.

Now experts are concerned about the privacy implications of the app.

“Friends don’t let friends use an AI STI test,” one tech site wrote last month.

Calmara allows users to share a photo of the partner’s penis with the app that analyses the photo using artificial intelligence that has been trained on thousands of photos of penises both without STIs, and those with genital warts, penile cancer, HSV infection, penile candidiasis and syphilitic chancres.

If the AI matches with a potential STI, it will flag to the user to hold off on sexual activity and suggest alternatives. It will not say what condition it may be.

If there is no match, it will give an “all clear”.

In both instances, the company says the image is immediately deleted. No personally identifiable information like name or address is collected.

Calmara is the new app from HeHealth, a company that developed the AI technology initially for identifying STIs on those who are concerned about something on their own penis. In that version of the app – launched in May 2023 – if the AI flags something, it will advise the user of potential next steps and allow them to download and submit a report to a medical practitioner, who can then conduct tests and treatment.

It is currently only running in the US, connecting users to practitioners in California, and has had about 35,000 users so far.

According to a paper on the development of the dataset that underpins the AI, it was trained on more than 200 images of penises with and without visible STIs, which has since expanded to over 20,000 images after the company did a call out for “dick pics for science”. The dataset took 18 months to build, and each image has been annotated by a physician on whether or not the penis has a visible STI and what STI it may be.

But experts said privacy was a “huge concern” for sexual health information, and while the technology might have a future, they were concerned about rushing the product to market.

“Recent events have shown us how easily private health information can be hacked and disseminated if the technology that collects that information isn’t supported by rigorous data security protocol,” the chief executive of Thorne Harbour Health, Simon Ruth, said.

Kularathne said the data was held in the US, with strict controls over who can access it.

Basil Donovan, a sexual health expert and emeritus professor at UNSW’s Kirby Institute, said the technology would have a future but that it shouldn’t replace proper testing.

“Even if you’re in a clinic with good lighting, and you’ve got a doctor with 30 years’ experience … looking at a lesion on someone’s penis, it has pretty weak diagnostic value on sight alone,” he said.

Ruth said AI could be used to help people make informed decisions about their sexual health and wellbeing “but there are really important considerations about privacy and the accuracy of the information that need to factored into the equation”.

“To fully realise the potential of AI and other emerging technologies, you’ll need meaningful collaborations and partnerships that bridge the gap between the tech industry and those of us working in sexual health,” he said.

“If the advances in technology engage people who have never taken steps to look after sexual health and wellbeing before, that’s a step in the right direction, but it’s not a substitute for regularly getting tested for STIs.”

Mei-Ling Lu, the chief executive of Calmara, said the app could be the “tip of the iceberg” in terms of potentially diagnosing STIs, given most are asymptomatic. It was hoped it would direct people towards treatment, she said.

“We say: ‘hey, you know what, this is it. But don’t worry. We [will] help you to understand it. And here are all the resources that you need to really help you manage the situation.’”