As health officials worldwide step up monitoring of suspected cases of the H5N1 avian influenza virus (bird flu), two companies are developing a "lab on a chip" that will be able to identify the lethal virus strain in the field in about an hour. However, the devices won't be ready for market until the fourth quarter, in time for the next flu season, the companies said.There are three types of flu virus: A, B and C, of which only types A and B affect humans. Only the type A viruses pose a threat of a pandemic, according to the World Health Organization, and within that category, the H5N1 strain is considered among the most dangerous. Identifying the presence of H5N1 without long delays for laboratory processing will allow health care workers to respond more effectively to outbreaks.European semiconductor manufacturer STMicroelectronics is working with a Singaporean medical diagnostics company, Veredus Laboratories, to develop the chip, which will use STMicro's In-Check lab-on-chip system to identify whether viruses in a sample are of type A or B, and whether the H5N1 strain is present.In-Check is a plastic slide, about 75 millimeters by 25 mm, containing a microscopic laboratory with its own plumbing, pumps and temperature controls. STMicro etches the laboratory components onto the slide in the same way it makes silicon chips.To use the lab, medical workers place a droplet of a sample on the slide. Traces of DNA in the droplet are copied using the polymerase chain reaction (PCR), and those copies are pumped to other areas of the chip for matching against particular DNA profiles, such as those of the flu viruses. A match causes the appropriate part of the chip to fluoresce. Processing the sample takes about an hour, after which the results can be obtained in seconds with a portable optical reader, according to STMicro.The slides will allow field workers to quickly identify particular flu subtypes where patients are cared for, the companies said. Today, medical staff face a choice between faster, bedside tests which indicate the presence of a virus but don't specifically identify the lethal strain, or more precise testing which typically requires sending samples away to a laboratory.