Clinical Diagnosis and Differentiation Diagnosis

The main subtypes discovered up to now that may infect human beings include H5N1, H5N6, H7N1, H7N2, H7N3, H7N4, H7N7, H7N9, H9N2, and H10N8, among which subtypes H5N1 and H7N9 with high mortality are particularly worthy of much attention. Human infected with different subtypes of influenza viruses differ greatly in clinical manifestations [1], which are correlated mainly to the virulence of these subtypes. Conjunctivitis is the main manifestation of those infected with subtype H7N7. Those infected with H5N1 or H7N9 usually have severe disease with high mortality, in contrast to those infected with H9N2 who manifest milder clinical symptoms of probably upper respiratory infection, or even no symptom in some patients.