First chickens tried to kill us all, then pigs, and now ...

In something completely unconnected with our intended theme for the next issue, a previously unknown virus that killed four of the five people it struck in an outbreak in South Africa last year has been identified as part of a family of viruses humans can catch from rats.

The virus, named Lujo, is an arenavirus that over nine days caused rash, fever, muscle pain, diarrhoea, severe bleeding, vomiting, organ failure and death, said Nivesh Sewlall, who treated the first patient at Johannesburg's Morningside MediClinic Hospital.

Which, fast on the back of piggy sniffles, is a little worrying. Other animal-derived diseases such as Ebola have failed to spread widely because while it is extremely infectious and incredibly deadly, it has only so far affected isolated areas and presents symptoms and then kill its victims so quickly that outbreaks can be contained. SARS, similarly, only becomes a problem in certain conditions.

The high death rate for Lujo is worrying, though the conditions in which its victims became infected, and their medical histories may well be a significant factor - just as many of the deaths from swine flu have been from people with previous, though sometimes unidentified, medical issues.