Welcome to the winter edition of pH7, which focuses on the world pandemic of HIV/Aids. According to Public Health Laboratory Service estimates, the UK is set to see a 25 per cent rise in new HIV diagnoses. The evidence also appears to show that many of these people were infected relatively recently. HIV, says Dr Kevin Fenton, head of the HIV division at PHLS, is a "current, not historical, problem". The good news is, he adds, that because of the introduction of new screening procedures, over 100 HIV infections were prevented in newborn babies in 2001. However in the third world - as our cover story reveals - many children are not so fortunate. Of the 13 million children orphaned by Aids, the majority live in sub-Saharan Africa. And although only around 15 per cent of these children are actually infected with the virus, they face a harrowing and uncertain future.

Thank you to the Village Trust and HopeHIV for the use of their photographs. A special thanks goes to ActionAid for permission to use the cover image featuring Miriam Kalule, a 71 year-old widow responsible for five orphans in her hut in Namulonge, near Kampala in Uganda. The photograph, by Guideon Mendel, is taken from his book, A Broken Landscape.