The Queen has shaken hands with a HIV patient in public for the first time, while touring an Aids clinic during her state visit to Uganda.
The Queen meets Steven and Grace Wakodo who are both HIV positive
Dozens of children and adults living with the virus were met by the monarch at treatment facilities established by the UK-based Aids charity Mildmay.
The Queen and Duke of Edinburgh saw an outpatients clinic and a newly expanded children's hospital in Kampala.
The Queen described Mildmay's work in Uganda as "impressive".
The handshake came when the Queen met Steven Wakodo, who is HIV positive and has been treated at the facility on a monthly basis since 2002.
The Queen was introduced to Mr Wakodo and stretched out her arm to shake his hand as he gave a short bow of his head.
A Mildmay staff member explained the medical history of the 40-year-old, who was joined by his 35-year-old wife, Grace, and 13-year-old daughter, Winternahwama - both of whom also have the virus - and his five-month-old daughter, Austraunt.
The handshake is likely to evoke memories of Diana, Princess of Wales, who famously punctured early myths about HIV by holding hands with a man with Aids on his sickbed in the late 1980s.
Music and dance
As the royal party toured the outpatient clinic's complex of buildings, they smiled as they were given a traditional welcome of high pitched yelps from staff and visitors.
The Queen and Duke watch an orphan performing at the HIV centre
Ruth Sims, a vice-president of Mildmay and founder of the Ugandan centre and hospital, said she wanted to show a different side to HIV patients.
She organised a number of colourful displays of African music and dance to contrast with negative impressions of those with HIV.
"I wanted to show these are normal children. What does it matter what they have got - you can treat them and they can get better," she said.
"I told the Queen that we tried to give her something that was different and that she would enjoy. She said to me, 'This is certainly different and I do enjoy it'."
Before leaving, the Queen unveiled a plaque for the hospital's new Elizabeth Wing, named in her honour.
The Queen continued her tour with a visit to the Ugandan parliament.
In a speech to MPs and President Yoweri Museveni, she highlighted the east African country's fight against HIV and Aids.
Infection rates have fallen from 30% to 10% since the early 1990s - thanks to education initiatives and a greater use of condoms - but appear to be rising again.
The Queen said: "The scourge of HIV infection and Aids has touched the lives of so many of Uganda's people.
The Queen addressed MPs and the country's president
"It is difficult sometimes, when the sorrow associated with this disease is so profound, to avoid a sense of despair.
"And yet there are growing numbers of people and organisations whose work gives cause for real hope."
The Queen is in Uganda ahead of Friday's Commonwealth heads of government meeting.
The conference, which is held every two years, is expected to be dominated by the state of emergency in Pakistan.
The Queen and the Duke of Edinburgh will be joined later by the Prince of Wales and the Duchess of Cornwall, who are also making an official visit to the country.
It will be the first time Prince Charles has been to a gathering of Commonwealth leaders held abroad.