The World of Viruses is Constantly Evolving and Bringing Us New Surprises
The last decade has been marked by the emergence of new, as well as re-emerging human pathogens responsible for various infectious diseases. Viruses, especially those of zoonotic origin that originate in the wild, are demanding significant attention—and rightly so. This group of viruses currently accounts for 70% of infectious diseases in the human population, with many using animal organisms as vectors (e.g., ticks, mosquitoes) to transport and infect the human body. Human-vector interactions are becoming increasingly common, particularly due to ongoing urbanization, encroachment into previously uninhabited areas, population migration, increasing travel, shrinking distances, and climate change. In the following text, we will look at some specific examples.
Little-Known Posaviruses: They Can't Do Without Viral Helpers
The viral world is incredibly diverse and variable. Due to mutation mechanisms, nothing in this area is truly constant, and research continually brings us new insights. Recently, information from nine Japanese institutions, which have been collectively researching the group of posaviruses for a long time, has come to light. These are little-known viruses, unclassified in the viral system, which are similar to the group of picornaviruses (which can cause, for instance, aseptic meningitis, encephalitis, hepatitis, conjunctivitis, or heart disease).
Posaviruses have been found in both various vertebrates and invertebrates. Japanese scientists have identified eleven different viruses found in the feces of domestic pigs so far. Further analyses revealed that they are a related group of viruses found not only in pigs but also among rats. Several of these viruses can also occur in humans. It is also noteworthy that these viruses apparently need another viral helper for their survival and reproduction in the host organism, as they are not fully equipped with the mechanism for capturing and entering the host's cells.
Medusavirus: Newly Discovered Inhabitant of Hot Springs
In April of last year, a study from Japanese institutions was published, which reported the discovery of a previously unknown large virus found in hot springs in Japan. Scientists named it medusavirus, and it has now been fully morphologically described and its genetic information has been read. Based on this data, it appears that its host in nature is most likely amoebas. It is assumed that more related representatives of this family will gradually be found, which will be grouped into a new viral family.
Czech Contribution: How Viruses and Leishmaniasis are Related
Czech scientists, in collaboration with foreign institutions, have described the discovery of a new virus in connection with their long-term research on leishmaniasis. The virus found in protozoa responsible for causing leishmaniasis was named Leptomonas pyrrhocoris ostravirus 1.
Leishmaniasis is a parasitic disease that occurs in several forms, the most severe being visceral leishmaniasis or black fever. The disease is caused by parasitic protozoa that attack the human liver and spleen, causing them to swell and gradually lose their function. The patient suffers from high fevers, weight loss, and anemia. If not treated, the patient dies.
Don't Forget About 'Traditional' and Seemingly Researched Threats
Despite the fact that these and many other individual pieces of information and news coming in recent months and years from the field of viral research often appear as 'mega-news,' especially in lay media, the importance of not underestimating well-known viral pathogens and the classic anti-epidemic measures remains undeniable. Primarily, these are classic respiratory viral infections, which still account for more than 4 million deaths annually, as well as millions of hospitalizations, very often in developing countries. 'Just' the cause of various respiratory system infections with the potential for epidemic spread is about 200 viral pathogens from families such as Orthomyxoviridae, Paramyxoviridae, Picornaviridae, Coronaviridae, Adenoviridae, and Herpesviridae. Incidentally, the current situation regarding the spread of a new type of coronavirus from Wuhan, China, in January 2020 is just another example of these facts.
Programs focused on the prevention and control of diseases like malaria, dengue, chikungunya, and Japanese encephalitis are also extremely important, even though their causes are very well researched. However, the epidemiology of these diseases has its specifics and differences due to various ecological conditions, vector characteristics, and economic, socio-cultural, and behavioral factors also play a role.
It is an undeniable fact that viral pathogens hold significant epidemic or pandemic threats, and therefore we must continuously pay increased attention to them.
(boš)
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