A woman diagnosed with an advanced HIV infection may have caught it by sharing manicure equipment with a cousin who didn't realise she was HIV-positive

A 22-year-old woman was diagnosed with HIV after having her nails done using shared manicure equipment.

Doctors say the case, detailed in a medical journal, has revealed a new form of transmission for the virus.

However the researchers warned that transmission through shared manicure equipment is a 'very rare event' and the risks of infection from new sources are still very low.

When diagnosed, the woman was found to have advanced HIV, according to the report in the journal AIDS Research and Human Retroviruses.

But she had none of the usual risk factors for acquiring the virus, which is most commonly caught by having sex without a condom.

It can also be passed on by sharing infected needles and other injecting equipment, and from an HIV-positive mother to her child during pregnancy, birth and breastfeeding.

However, the woman did report having shared manicure instruments years before with a cousin who was later found to be HIV-positive.

Blood analysis suggested the woman contracted the virus around ten years ago.

Further genetic analysis of the viruses from both patients suggested it came from a common ancestor, indicating the possibility HIV was transmitted through the manicure instruments.

Dr Brian Foley, of the HIV Sequence Database at the Los Alamos National Laboratory, said the case should not make people scared of contact with people with the virus, as the risk of infection is very low.

He said: 'HIV is not transmitted by casual contact, such as sharing eating utensils, or drinking from the same water glass.

'This transmission of HIV by shared manicure equipment is a very rare event that should serve not to make people fear HIV or contact with HIV-infected people.'

However, the case could promote caution around sharing items which may contain blood, he added.

He said: 'It should make people aware that sharing any utensils with possible blood-blood contact, such as needles used for drugs, tattoos, or acupuncture can result in transmission of viruses such as hepatitis C (HCV) and HIV.

The HIV virus (pictured) is most commonly caught by having sex without a condom. It can also be passed on by sharing infected needles and other injecting equipment, and from an HIV-positive mother to her child during pregnancy, birth and breastfeeding

'In addition, there are other common viruses and bacteria that can also be spread by sharing equipment without proper disinfection between users.'

HIV is transmitted from one person to another through bodily fluids including blood, blood, semen, rectal fluids, vaginal fluids and breast milk.

It must enter directly into a person's bloodstream through an injection with a needle or syringe, or come in contact with damaged tissue, or a mucous membrane.

Mucous membranes can be found inside the mouth, the vagina, the opening of the penis, and the rectum.

Dr Michael Brady, Medical Director at Terrence Higgins Trust, echoed that this is a rare case.

He said: 'This is a highly unusual case. It is often very difficult to be certain as to the source of an HIV infection – especially one that happened over a decade ago – and it is hard to imagine how HIV could be caught from manicure equipment.