Influenza: etiology, epidemiology and complications

Greta Reikertaitė1, Ilona Šakuro1 

1 Lithuanian University of Health Sciences Medical Academy Faculty of medicine, Kaunas, Lithuania


Influenza is an acute respiratory tract infection which spreads through the air via aerosol droplets. It is dangerous because of possible complications, such as pneumonia, myocarditis, worsening of other non-infectious conditions like asthma or congestive heart failure. Influenza poses a high risk to pregnant women, children, people aged 65 and older, also to people with chronic diseases. According to the institute of hygiene, there were 41078 patients diagnosed with influenza (14.32 cases per 1000 residents) in 2016, the majority of the patients were women (N=21747; 52.94%). In 2017 36443 people were diagnosed with influenza (12.88 cases per 1000 residents), the majority of cases were observed in women (N=19231; 52.77%). In 2018 there were 66454 influenza cases in the country (23,72 cases per 1000 residents), the majority of which were female patients (N=35849; 53.95%). In 2013 complications caused by influenza resulted in 28 deaths in Lithuania (0.98 deaths per 100000 residents), in 2017 it was 14 deaths (0.49 deaths per 100000 residents) and in 2018 that number was 24 (0.86 deaths per 100000 residents). According to the Centre for Communicable Diseases and AIDS in 2019 forty municipalities began collecting data about influenza-related hospitalizations for influenza season of 2019-2020. By the end of the 4th week of 2020, 99 people were hospitalized due to influenza, of whom 71 were children and 28 were adult patients. One hospitalized person was pregnant. Seven people required intensive therapy. During 2019-2020 influenza season one death was registered Vaccines are one of the most effective measures used to prevent sickness and complications. It is recommended to vaccinate annually before the influenza season. For various reasons, a substantial part of society remains unvaccinated each year.

Keywords: influenza, influenza complications.