[Influenza diagnostics in patient with leukemia suspicion]

Influenza is a seasonal viral disease, with the peak of morbidity occurring in Poland between January and March. It is estimated that up to 70% of respiratory infections during the season is caused by this virus. Influenza virus infection poses an ultimate threat to the elderly > or = 65 years old and chronically ill, in whom postinfluenzal complications--including viral pneumonia and secondary bacterial pneumonia--cause from 0.1% to 0.4% deaths annually. Influenza also triggers off from 5% to 7% cases of nosocomial infections in these patients. Among three influenza types being human pathogens only influenza A and B have clinical and diagnostic significance. Type C causes mild respiratory infections, usually in children. Out of the viruses circulating in our region the most pathogenic is A/H3N2 subtype that causes more severe infections, an increased number of hospitalizations and higher mortality than A/ H1N1 or B viruses. Lack of pathognomonic symptoms makes difficult a case definition-based diagnosis and draws an attention to key role of laboratory diagnostics for respiratory infections. It has an essential significance in high-risk patients not vaccinated against influenza giving an opportunity to use antiviral drugs of the new generation as oseltamivir.