Abstract
Given the serious threat to public health, early and accurate diagnosis of H5N1 infection is critical for effective clinical management, disease containment and infection control measures. Since re-emerging in 2003, avian H5N1 has maintained a steady global advance from the epicentre in South-East Asia, infecting wild birds and poultry, spreading into Europe and parts of Africa. Viral evolution has led to significant genetic variation among H5N1 viruses, associated with increased virulence and an expanded mammalian host-range. Numerous lineages, HA clades and subclades have been described, with recent isolates clustering into two distinct clades: clade 1 and the more diverse clade 2. Moreover, the ability of H5N1 to directly transmit from infected birds to humans following close contact, although a rare event, has been repeatedly demonstrated in more than 270 cases with an approximate case fatality of 50–60 % (). Although H5N1 remains an avian virus not yet adapted to transmission between humans, there is concern that small genetic changes may significantly alter the pandemic potential of this virus, allowing it to emerge as the next influenza pandemic strain. Highly sensitive, specific and rapid tests for H5N1 detection are therefore essential to control the threat to human health posed by this zoonotic infection. In view of the genetic diversity, molecular assays capable of detecting a wide range of circulating H5N1 variants are essential.