A new HIV pandemic is “a real possibility,” one of the world’s leading authorities on infectious disease has said, warning that a rise of drug resistant strains of the virus could “reverse progress made since the 1980s” in combating the disease. Professor Jeremy Farrar said that “the spectre of drug-resistant HIV” threatened to have “a huge impact” in the next 20 years, if drugs which have made vast improvements to the life expectancy of patients since the 1990s become less effective. Professor Farrar, director of the leading research foundation the Wellcome Trust in the UK, said that it was “inevitable” that resistance to HIV would increase because it was a virus which could easily mutate. Antiretroviral drugs currently used to treat HIV have been so successful that people living with the virus can expect to live healthy, active lives if they have access to the drugs and adhere to their regime. While hailing the “incredible” progress made since the 1980s in treating HIV, Professor Farrar said that resistance to first resort drugs, and also some second and third resort, drugs had already occurred and that drug options for the virus were not “limitless.” “It is not unreasonable that a HIV pandemic could return.” he said. “The possibility of a resistantly-driven HIV pandemic is quite real.”