Their interviewer is Rath Chan Molika. The 22-year-old recently quit her job as an entertainment worker and is now an outreach worker and lay counsellor with Smartgirl, a sexual health and empowerment programme for entertainment workers that provides community-based HIV testing.

Molika says the women feared getting tested at public health clinics because they're scared of going alone, as well as of the needle and blood.

But with Smartgirl, a pioneering programme launched in April 2013 and one of the first of its kind in the region, things are changing. The traditional test - drawing blood with a needle and syringe for lab analysis - is replaced with a rapid finger prick test that can be done by trained counsellors at any location at any time.

"Bringing the facility close to the people is always the best. People don't have to use sophisticated laboratory equipment," says Dr Ly Penh Sun, director of the National Centre for HIV/Aids, Dermatology and STD Control.

In 2014, Cambodian authorities reported that about 20,000 people from key populations - this includes men who have sex with men, transgender people, sex workers and people who inject drugs - were tested, double the number in 2012.

WATCH Molika tell her story and see how she helps others

If a person has a positive result with the first rapid test, they are accompanied by outreach workers to health facilities for confirmatory tests with a medical professional. If the result is confirmed, the person is provided with free HIV treatment.

This Cambodian peer-to-peer testing model was presented at a two-day meeting of Aids managers in Manila this month, and used as a positive case study of how to scale up HIV testing in the region through community-based testing.

Since the programme began nearly 700 lay counsellors have gone through a five-day training course in how to provide HIV counselling and testing.

"The people who are conducting the tests are familiar with the people they are testing. They can interact more. They can support each other," says Choub Sok Chamreun, deputy director of Khana, which leads the programme implementation along with Family Health International 360 and Population Services Khmer.

Across the western Pacific region - of which Hong Kong is a part - knowledge about HIV testing and counselling among key populations is low. Key populations are at higher risk of HIV, but only one-third of them knew their HIV status in 2013.

At the meeting, organised by the WHO's regional office for the western Pacific and the Joint UN Programme on HIV/Aids (UNAids), 10 national HIV/Aids and sexually transmitted infection programmes, civil society and development partners in the western Pacific region joined forces to push for expanded HIV testing coverage.

The goal set by the UN and its partners is to end the Aids epidemic by 2030. In the next five years, the aim is to ensure that 90 per cent of people living with HIV know their status, 90 per cent of people who know their status have access to treatment, and 90 per cent of people on treatment have suppressed viral loads.

But community-based testing is just one part of a diversified approach to expanding HIV testing, according to UNAids. Hospitals, clinics and other health facilities need to offer more voluntary HIV testing and counselling during routine check-ups, including antenatal visits. Voluntary testing of intimate partners of people living with HIV should also be included.

The WHO will soon launch new guidelines on HIV testing services and has started a global social media campaign called #Test4HIV.

As in many other countries in the region, Cambodia's Aids epidemic is concentrated in key populations at higher risk of HIV. Despite efforts to scale up HIV testing, latest available data from Cambodian health authorities found significant numbers of key populations have not had an HIV test - 32 per cent of entertainment workers, 14 per cent of men who have sex with men and 85 per cent of people who inject drugs.

The Cambodian government and its civil society partners along with international organisations decided in 2013 to promote HIV testing among key populations using the rapid finger prick test, a relatively recent technological innovation. The initiative is supported by the US government and the UN Population Fund.

But while this peer-provided HIV counselling and testing has increased the number of people tested from key populations, it has not detected a significant number of new HIV cases. In 2014, there were only about 150 confirmed cases.

To improve their efforts to find more people living with HIV, implementation partners are starting to retool the programme to intensify outreach to people at the highest risk within each key population, using geographical hotspot mapping information.

Says Ly: "The plan is to modify the outreach guidelines to the population at highest risk and intensify targeted outreach activity, as well as active case management, to register and retain the people who were found to be HIV positive to ensure they receive treatment."

There were an estimated 34,000 entertainment workers in Cambodia in 2014, working in a range of places, including hotels, karaoke bars, beer gardens, casinos and massage parlours. Unprotected sexual relations with male customers can place some women at higher risk of HIV.

"Some go out with customers without using a condom correctly and consistently. And they sometimes also use drugs together, sharing needles and syringes, which increases their risk of exposure," says Molika.

As part of her job with the Smartgirl programme, she informs entertainment workers about health, sexually transmitted diseases including HIV and contraceptive methods.

When the group counselling session ends, Molika breaks away and in a separate room welcomes Mao Soma.

The two women talk quietly with a tray full of cotton swabs, vials and bandages laid out on the table before them. Molika has been trained to provide pre- and post-HIV test counselling and to conduct a rapid finger prick test.

While Mao Soma winces as the needle pricks her finger, the procedure is over fast. Within 15 minutes, there is a result.

"HIV testing lies at the foundation of the region's response to HIV," says Steve Kraus, UNAids director for the regional support team for Asia and the Pacific.

"Only if people know their status can we reach our global goal of ending the Aids epidemic as a public health threat in the region."

Saya Oka is regional communications adviser for UNAids based in Bangkok