Two rare cases of family HIV transmission between adults reported

Two similarly unusual but unconnected cases of HIV transmission within two Australian families are reported in the September 5th issue of AIDS, providing a sobering reminder that HIV can occasionally be acquired by surprising routes. These also appear to be the first reports of one adult family member infecting another that involve a source patient with unrecognised HIV infection.

The first concerned a 16 year-old girl and her 18 year-old sister who shared a bathroom at their family home. The younger sister became aware of her HIV infection after donating blood in 1999. She had never had sex, nor any other risk-factor for acquiring HIV, and both of her parents were HIV antibody negative. The elder sister was subsequently found to be HIV antibody positive, and recalled having symptoms of seroconversion illness (severe ‘glandular fever’) in January 1997, one month after her first ever sexual encounter, with a Russian man.

Subsequent HIV analysis found that both younger and elder sister were infected with ‘Russian-type’ subtype A, which is very rare in Australia, and env and RT sequencing were strikingly similar, leading to the conclusion that the elder sister had infected the younger. The only risk factor ascertained by rigourous personal interviews with both sisters and their parents was their occasional sharing of the same razor for shaving body hair.

The second case concerned a 55 year-old woman and her son, in his early thirties. The mother first became aware of her HIV infection after donating blood in 1997. She had been married for 25 years, and reported no sexual partners during that period other than her husband, who was found to be HIV antibody negative. Their teenage daughter was also HIV antibody negative. The son had been living in Thailand and reported occasional unprotected sex during his time there. He moved home for six months in December 1996, and during that time had active psoriasis.

Subsequent HIV analysis found that both mother and son were infected with subtype E (CRF01_AE), which is common in Thailand and extremely rare in Australia, leading the authors to conclude that the son had infected the mother. The only risk factor for the mother acquiring HIV from her son appeared to be applying topical therapy (lotion or creme) to her son’s psoriasis lesions, which were reported to be dry and did not bleed.

Although no route of transmission for either of these cases was conclusively identified, the authors cite a previous case report of razor sharing as a prior possible source of HIV infection. However, applying lotion to dry psoriasis lesions has never previously been identified as a possible source of HIV infection.

The accuracy of the history of the second case is somewhat muddied by the fact that the son declined a face-to-face interview, agreeing only to answer questions in writing. Additionally, the son also had hepatitis C co-infection, suggesting to the authors that he may have had an undisclosed history of injecting drug use.

Since the authors relied totally on self-report, the actual routes of transmission may have been missed or unrecognised and the conclusions reached here do not in any way represent a significant risk factor for acquiring HIV, which is primarily a sexually transmitted infection.