Viral evolution refers to the genetic changes that a virus accumulates during its lifetime which can arise from adaptations in response to environmental changes or the immune response of the host. Influenza A virus is one of the most rapidly evolving microorganisms. Its genetic instability may lead to large changes in its biological properties, including changes in virulence, adaptation to new hosts, and even the emergence of infectious diseases with a previously unknown clinical course. Genetic variability makes it difficult to implement effective prophylactic programs, such as vaccinations, and may be responsible for resistance to antiviral drugs. The aim of the review was to describe the consequences of the variability of influenza viruses, mutations, and recombination, which allow viruses to overcome species barriers, causing epidemics and pandemics. Another consequence of influenza virus evolution is the risk of the resistance to antiviral drugs. Thus far, one class of drugs, M2 protein inhibitors, has been excluded from use because of mutations in strains isolated in many regions of the world from humans and animals. Therefore, the effectiveness of anti-influenza drugs should be continuously monitored in reference centers representing particular regions of the world as a part of epidemiological surveillance.

Congenital cytomegalovirus (CMV) infection is the most common intrauterine viral infection with a significant impact on the foetus and newborn. Current diagnostic practice includes serological testing for specific antibodies, but there are no global screening protocols. Maternal CMV screening is often performed in conjunction with antenatal ultrasound. While most infections are asymptomatic, severe cases can lead to long-term disability or death. Antiviral therapies, mainly ganciclovir and valganciclovir, are reserved for symptomatic patients, especially those with central nervous system involvement. Although effective, these treatments are associated with significant side effects such as neutropenia and hepatotoxicity. Foscarnet and cidofovir are used as alternatives, but their efficacy and safety require further study in paediatric patient populations. The effectiveness of passive prophylaxis is still uncertain. The lack of universally accepted guidelines for diagnosis, treatment, and prevention and the risk of serious side effects highlight the need for continued research. This review evaluates current therapeutic strategies, discusses their efficacy and associated risks, and highlights the need for innovative approaches to improve outcomes for affected neonates.

Introduction and objective: For centuries influenza has been one of the most prevalent viral infectious diseases and still remains an important cause of morbidity and mortality in many regions of the world, including Poland. The aim of the study was presentation of the scope of problems...