The attack of bird flu and its mutant viruses is coming. The flu they cause scientists called a seal. They also warn against strains from southern China that no one is immune to. Learn what the symbols H1N1, H3N2, H3N8, B – Brisbane and Phuket hide. And what do Poles, French and Americans think about the viruses awaiting us?
The 2016/2017 season promises to be interesting. And it’s not about fashion trends, but those of interest to virologists. The largest American government agency dealing with viral diseases – Center for Disease Control, announces: this year’s season will be dominated by A / California / 7/2009 (H1N1), A / Hong Kong / 4801/2014 (H3N2) and type B viruses – B / Brisbane / 60/2008 (Victoria line) and B / Phuket / 3073/2013 (Yamagata line).
Virus Trojan Horse
What does this mean in practice? Flu risk at medium level. But for the past two seasons, scientists in Europe have been afraid of an attack of “something more”, and when this “more” is not coming, we can almost hear their sigh of relief. Americans, Americans – they are far away. Unfortunately, also those who are closer to us – viral disease experts from the Swedish government agency SMI say it’s for sure – the flu epidemic is coming. In fact, he is already knocking at the gates of Europe. And what is most worrying, scientists are not able to predict which type of virus will attack the most, because there are several candidates for the role of the “Trojan horse”.
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Flu in Polish
Last year’s 2015/2016 flu season in Poland was tough. It ended up with a whopping 140 deaths from the flu, and we were dying from it until May 7 this year. Another sad record was also broken: by May 22, the National Institute of Public Health had recorded 3,6 million cases of flu, or 9 percent. more than in the record season 2014/2015 and 1,250 million cases more than in the season 2013/2014. As many as 16 100 people were admitted to hospitals, which is 38 percent more than a year earlier. The dominant strain was the A / H1N1.1 virus.
Meanwhile, during the recent expert debate “Flu Forum 2016”, prof. Lidia Brydak, director of the National Influenza Center of the National Institute of Public Health-PZH in Warsaw, stated: “The number of influenza infections and deaths caused by this disease is significantly underestimated in Poland.” Prof. Brydak claims that such a small percentage of the population is vaccinated in our country (only 3,4 percent of us last season). And that it is impossible that with such a small number of vaccinated people so few deaths from the flu. All the more so as flu also occurs after the flu season between January and March. The post-season flu has certainly hit 30 people this year in May and June, and the last flu was reported to official statistics on August 29.
Incorrect diagnosis
According to the Polish Press Agency, Dr. hab. Agnieszka Mastalerz-Migas from the Chair and Department of Family Medicine at the Medical University of Wrocław, such an understatement is very likely indeed. And its reason may be not only the low percentage of vaccinated people. Also the fact that Poles like to disregard flu as a disease and doctors do not like to report it due to bureaucratic procedures.
So only 1,4 percent of doctors officially detect the flu. In the 2015/2016 season, they sent a total of 8,5 thousand. samples to be tested. This proves that the epidemiological data from Poland are reliable. So what do doctors “diagnose” instead of flu? Dr hab. Agnieszka Mastalerz-Migas says that most often they enter a cold instead of the flu in the patient’s records, and if, for example, due to complications of influenza, severe pneumonia results in death, the death certificate includes pneumonia, which led to circulatory and respiratory failure .
Some Polish experts believe that the situation could only improve by introducing free vaccinations for all those who have no contraindications for vaccinations, or at least for all retirees. What do those who observe our struggle with flu from overseas? US scientists from the CDC noted something disturbing: they believe this year’s flu vaccine is less effective than those introduced in previous years, especially in Europe and the US. In its recommendations for the 2016/2017 season, the CDC admitted that the LAIV 4 intranasal vaccine, used especially in children and adolescents, is simply not effective. Why? This question was decided not by the Americans, not by the Swedes, but by the French. According to scientists from the famous French Institute Pasteur, dealing with infectious diseases, the problem is that Europe and North America are attacked by new strains of the flu virus. It shows up towards the end of the season and is not yet highly invasive, and if it is, it is usually too late to include it in a vaccine.
Bulgarian relief
However, this state of affairs can easily change. In January 2015 in Bulgaria, in the village of Konstantinovo, in the Kameno region near Burgas, the Bulgarian Food Safety Agency (BFSA) detected an outbreak of the H7N9 virus, or avian flu, a strain suspected of being able to infect humans – potentially capable of transmission from animals. Dr Georgi Mitev, the head of the BFSA, told the Bulgarian media that 21221 birds from 105 farms had been killed then, and that it was enough for a year: so far no new outbreaks of the virus have been identified, although “this does not mean that they will not appear in the 2015/2016 season”. If so, the virus has an open road, to war-torn Ukraine on the one hand, and to the Balkans – on the other.
Scientists also expect the Manitoba / Ontario strain of the H5N9 virus known from the 1966 epidemic to return to North America and Canada in the spring. This strain would not be as invasive as H7N9, but an epidemic caused by it would have a harder time extinguishing as the virus is more resistant.
Chinese invasion
The hidden danger is H3N8 – a completely new virus. It appeared for the first time on the American side of the Atlantic, on the coast closest to Europe – in New England. He ransacked herds of common seals, killing 160 animals. At that time, scientists isolated a new strain from the virus, showing the same mutation of the key protein that was revealed in the highly pathogenic H5N1 avian influenza virus strain (revealed in Poland in 2006). It was H3N8, and it was found at the time that it could already infect through the air, transmitting itself as easily as seasonal flu viruses. Resistance to this strain has only been found in a few fishermen in the area – city dwellers have not yet acquired any immunity to it.
Changes in both H5N1 and H3N8 concern two mutations of the main protein, which is haemagglutinin (HA) and the PB2 gene. The HA protein is carried on the surface of the virus and allows it to attach to the attacked cell. A mutation in PB2 indicates increased virulence manifested by more severe disease symptoms. Both of these mutations allow the virus to transmit itself via droplets.
Both H5N1 and H3N8 are the so-called Atlantic viruses belonging to the Atlantic Ocean basin. The latter may not be new – experts from the CDC believe that broadcast by horses and dogs caused a great epidemic in 1880, which killed tens of thousands of Americans and Europeans, and the death rate in rural areas was 52-60 percent. However, the second, very important area where influenza viruses are created is Asia, especially southern China. Joint research by scientists from the Chinese Academy of Sciences and the University of Cambridge allowed to state that there are 20 new strains of the influenza virus there. Within a few years, 5 of them may become invasive, with no one having immunity to them, and the risk of causing not so much an epidemic as a global pandemic is assessed as “high”. On the WHO map, the circulation of influenza viruses for the current seasons indicates that Asian viruses will rather reach us.
How does the vaccine work?
The flu vaccine is made up of three main types of inactive influenza viruses and epidemic viruses that allow the immune system to understand them. And they mutate rapidly, with single amino acid changes occurring in the surface protein envelope of seasonal influenza viruses every 2-3 years.
This amino acid exchange takes place at 7-8 sites, and it is enough to trick the immune system into ceasing to recognize the virus. All amino acid exchanges occur in the so-called binding site – the field where the virus adheres to the attacked cell. In the case of people with reduced immunity, a virus with only 4 amino acid changes in the protein envelope is sufficient for infection. There are also extensive changes to the areola, occurring in 12–130 locations. They are associated with changes in the hemagglutinin and in the PB2 gene, which creates a completely new strain and type of virus. This means that it is necessary to update the catalogs of virus strains that will be included in the vaccine at least twice a year.
Such rapid changes in the virus envelope as detected by an international research team, led by Dr. Bjorn Koel from the Erasmus Medical Center in the Netherlands and prof. Derek Smith of the University of Cambridge, means you need to get vaccinated, even if the vaccine is less effective. In the case of an infection with a changed virus, the flu is then easy to get through and it is not threatening with complications or even life-threatening.