There are 4 types of influenza viruses, types A, B, C and D. Influenza A and B viruses circulate and cause seasonal epidemics of disease. Influenza A viruses are further classified into subtypes according to the combinations of the proteins on the surface of the virus. Currently circulating in humans are subtype A(H1N1) and A(H3N2) influenza ...

2025年1月7日 · Influenza viruses are constantly changing, with new strains appearing often. A person's first flu infection gives some long-term protection against similar strains of flu. But the vaccines offered each year are made to match the flu virus strains that are most likely to …

2010年5月13日 · Avian influenza viruses survive in bird faeces and secretions for up to 4 weeks, depending on virus type, waste type, temperature and other environmental conditions. Influenza viruses can be inactivated by disinfectants, such as those containing chlorine or hypochlorite, or alcohols, and destroyed by temperatures above 70 °C.

2024年10月16日 · Seasonal influenza is an acute respiratory infection caused by influenza viruses which circulate in all parts of the world. It is characterized by a sudden onset of fever, cough (usually dry), headache, muscle and joint pain, severe malaise (feeling unwell), sore throat and a runny nose. The cough can be severe and can last two or more weeks.

Influenza B and C viruses mainly affect humans, whereas influenza A viruses infect a range of mammalian and avian species. Only type A and B cause human disease of any concern. Influenza virus is transmitted primarily by droplets or respiratory secretions of infected persons.

2009年11月27日 · Influenza is usually mild and uncomplicated and most people recover without medical treatment. However infection with influenza may occasionally cause severe disease and death, particularly among the elderly, pregnant women, very young children and persons with certain medical conditions (including chronic heart, lung, kidney, liver, blood or ...

2023年10月3日 · Other avian influenza viruses have resulted in sporadic human infections. For swine influenza viruses, risk factors include close proximity to infected pigs or visiting locations where pigs are exhibited. Sporadic human infections with swine influenza viruses of the A(H1) and A(H3) subtypes have also been detected. Diagnosis

2024年10月16日 · However, zoonotic influenza viruses - animal influenza viruses that may occasionally infect humans through direct or indirect contact - can cause disease in humans ranging from a mild illness to death. Birds are the natural hosts for avian influenza viruses. After an outbreak of A(H5N1) virus in 1997 in poultry in Hong Kong SAR, China, since ...

Since 2004, influenza A(H5N1), A(H9N2) and other subtypes of influenza viruses have also been taken into consideration by GISRS for pandemic preparedness purposes. The development of high yield candidate vaccine viruses is a complex process, involving collaboration of laboratories involved in developing reassortants and WHO Collaborating ...

Influenza viruses are constantly changing, and can infect both humans and animals (birds, pigs, horses). There are several types (namely A, B and C) and subtypes of the Influenza virus. In India, both seasonal influenza and avian influenza (in …