[Various sides of influenza. Part II--epidemiology, influenza surveillance and prophylaxis].

Influenza viruses cause epidemics and pandemics. Animal reservoir for influenza viruses and repeatedly occurring human infections with avian influenza viruses since 1997 indicate that there is a real threat of pandemic, but it is no possible to predict when this outbreak begins. Every year 330-990 millions of people are ill due to influenza worldwide. In Poland there are registered from a few hundred to few millions of cases and suspected cases of influenza each epidemic season. WHO coordinates the international Global Influenza Surveillance Network consisting of international WHO reference centres for influenza in London, Atlanta, Tokyo, Melbourne and 115 national influenza centres in 86 countries all over the world. One of such National Influenza Centers is located in Poland at the National Institute of Hygiene in Warsaw Influenza surveillance provides information on the currently circulating strains of influenza viruses, including new variants and their spreading that allows to choose appropriate strains to include into the vaccine for the next epidemic season. Regional influenza surveillance networks also exist, as the European Influenza Surveillance Scheme (EISS). The epidemic season 2004/2005 was the first season when the integrated system of virological and epidemiological surveillance SENTINEL started to work in Poland, according to EISS indications. In this system there are included the selected family physicians representing the entire country, Voivodship Sanitary-Epidemiological Stations and the National Influenza Center. Data obtained by the SENTINEL system are then forwarded to EISS and WHO. Widely available way of prophylaxis against influenza is vaccination. Inactivated influenza vaccines prevent illness in 70%-90% healthy adults under 65 and in children. They also prevent post-influenza complications. Attenuated nasal influenza vaccines are registered to use in Russia and the United States. In Poland, vaccinations against influenza are considered in the Program of the Preventive Vaccinations as recommended since 1994. Vaccination against influenza is especially recommended for people who highly risk occurrence of post-influenza complications as well as for some groups of people due to epidemiological indications. Vaccine is administered before epidemic season, but it is also possible during the epidemic season when virus already circulates in the population. There are performed studies to improve currently vaccines, e.g. studies on the safe adjuvants (aluminium, MF59, virosoms), DNA vaccines, use of hemagglutinins and neuraminidase obtained by genetic recombination and expression in insect cells, studies on the production of influenza vaccines in the cell culture MDCK and Vero instead of currently used chicken embryos. There are available specific antiviral-antiinfluenza drugs of new generation: oseltamivir and zanamivir that are neuraminidase inhibitors and old generation drugs: amantadine and rimantadine that are inhibitors of M2 protein.