A "superstrain" of HIV, first discovered in the US, is finding a foothold this side of the Atlantic. The new strain - known as "type E" - appears to target heterosexuals and is endemic in Asia, where most HIV positive people are heterosexual. Last year doctors at the Harvard School of Public Health (HSPH) in the US found that the strain is more adept at infecting cells that line the vagina and tip of the penis than other HIV substypes. According to a report on the HSPH's work in the New Scientist, the "type E" strain could present a serious threat to the heterosexual population.