The H5N1 virus has created a situation of “animal pandemic” that began in the late 1990s in Southeast Asia and this disease is considered endemic in countries such as Vietnam or China, he explains. Nacho de Blas, researcher in veterinary epidemiology at the University of Zaragoza.
Migratory waterfowl carry all four strains of flu awhich has led to its spread among birds, which has already reached Central and South America.
The researcher recalls that since 2005, when the spread of the disease in animals gained strength, “some very sporadic cases of zoonotic jump to humans began to be reported.”
According to data from the World Health Organization, between 2003 and March 2022 there have been 864 human casesand 456 deaths, and the researcher has specified that although it is a “very virulent” disease and with a high lethality for humans, “it is very, very little contagious.”
Cases of infection They have occurred, “above all, due to very, very close coexistence with sick animals or due to very inadequate handling of them” according to the expert.
“This virus can pass to humans as well as to other mammals, although it is not something easy, but it must be followed and, above all, closely monitor, as has been done for some time, possible infections in pigs”, which for De Blas are the “big problem”.
The zoonotic jump (from animals to people) “is complicated” because the receptors to which the influenza A virus binds are different in birds and in humans.
However, the pig, which is kept “monitored”, has both types of receptors, so there is the possibility that it could be infected simultaneously with N5H1 and with another pig or human virus.
This coinfection could generate -he points out- a recombination of viruses and that the result is a virus that can be very contagious or virulent for humans.
The fundamental risk is recombination in pigs, where co-infections can occur resulting in a virus that is contagious to humans.
The “fundamental risk” is the recombination in pigswhile in the rest of mammals “it is very rare” that this scenario occurs.
The pig is considered as “a glass of mixtures or a shaker. When coinfections occur, viruses recombine and that is where there is a very high risk of a virus emerging that complicates our lives.
De Blas remembers the H1N1 emerged in 2009 and which was also an influenza A virus as a result of a multiple recombination of avian viruses of Eurasian origin, North American swine and humans. A virus that “fortunately was not too virulent” and that now circulates “normally”.
outbreaks among mammals
The spread of avian influenza among not only wild birds but also on farms is a matter to be monitored and constitutes, “above all, a sanitary problem for birds”, as well as an economic one due to supply problems and higher prices for eggs and eggs. poultry meat that is causing in various countries.
H5N1 outbreaks have also multiplied in recent weeks between mammals such as mink, otters, foxes and sea lions, a phenomenon that the World Health Organization (WHO) already described on the eighth day as worrisome and that should be monitored.
The researcher says that “normally, this virus is highly adapted” to birds and although mammals can become infected, contact has to be very close.
This does not mean that there have been cases in foxes, skunks, bears or pumas in the United States, or the death of hundreds of seals in the Caspian Sea, a transmission that would occur not only because carnivorous mammals prey on infected birds, but also because contagion between them.