Avian flu, the first death in the world from human contagion in Mexico: risk of new pandemic?

The first person to be victim of is Mexican H5N2 avian flu in the world. The confirmation came yesterday through laboratory tests by the World Health Organization. The 59-year-old man died in April, but was already suffering from other pathologies.

The WHO specified in a note that this case does not change the risk level for avian influenza in the population, considered “Bass”. Mexico said bird flu was not the cause of the man's death.

Outbreaks have broken out around the world, cases monitored

In Mexico, the presence of avian H5N2 has caused at least three recent outbreaks in poultry farms. It is not yet clear how the man contracted the infection, as there are no reports of exposure to animals in his case. The victim's family members and contacts have tested negative for different flu strains, but serological tests are currently underway to check for the presence of a past infection.

The H5N2 virus involved in the Mexican case it is not present in Europe, including Italy, and does not match the strain known as “highly pathogenic” H5N1, which is of concern to scientists. The latter strain, designated B3.13 by the United States Department of Agriculture, also affected cattle in the United States for the first time in history, causing an epidemic that affected 83 herds in 9 states.

According to the latest report from the European Food Safety Authority dated December 2023-March 2024, Human infections with avian influenza remain rare and no human-to-human transmission had been observed until that time. In addition to the three workers who fell ill in the United States, the report mentions five cases of human H5N1 infections in Cambodia (with one death) and seven in China (with two victims), caused by avian strains H5N6, H9N2 and H10N5 (this is the first time human contagion for this strain is observed).

Avian flu, WHO advises against drinking raw milk

This epidemic is being monitored closely due to the proximity of the animals to humans and because the virus was found in a wide range of dairy products on the market, in wastewater in Texas, in raw milk and in muscle tissue from a diseased cow, according to analyzes conducted by the U.S. Food and Drug Administration. This suggests a possible underestimation of real cases due to the presence of probable asymptomatic subjects in livestock and perhaps also in humans.

“In all countries people should consume pasteurized milk because the virus was detected in raw milk in the United Statesbut preliminary tests show that pasteurization kills it,” said the WHO director general, Tedros Adhanom Ghebreyesus. His words confirm what had already been stated previously by the United States Department of Agriculture which maintained that “the detection of viral RNA does not in itself pose a health risk to consumers and we expect to find this genetic material residue if the virus was in raw milk and was inactivated by the pasteurization process to inactivate pathogens.”

This data, combined with the report that avian influenza has infected numerous cats and mammals of 60 different species (the latest reported species being mice, with 11 identified in New Mexico), have raised concerns about the possibility that the H5N1 strain could “jump” and spread more widely, finding an efficient means of transmitting from person to person. This scenario is considered a possible prelude to the next flu pandemic, as many experts fear.

The situation in Italy: H5N1 has never been detected in Europe

In Europe and Italy, the situation regarding the H5N1 strain of avian influenza presents some peculiarities.

According to data from the Italian Ministry of Health updated to April 2024, it has been confirmed a single outbreak of avian influenza highly pathogenic in a poultry farm in February this year. In the period between March and December 2023, however, 11 outbreaks were reported. In the European context, in the same period of time, 88 outbreaks of avian influenza were identified in poultry and 175 in wild birds, in a total of 23 countries. The virus has affected mammals only in Finland, where cases have been recorded on fur farms.

Although this strain is widespread in the avian fauna of all continents, with reports even in remote places such as Antarctica, currently in Europe the overall number of detections of the “highly pathogenic” virus in birds is significantly lower than in previous years, as reported in the EFSA report.

As for the cattleit is not the H5N1 strain has never been detected in Europe, not even in the past. Currently, a verification activity is being carried out with serological tests among cattle in European countries where the virus has circulated more in the past, such as in Italy, Germany and France. So far, results have been negative, suggesting low spread of the virus among cattle in these regions.

Fabrizio Pregliasco, professor of Hygiene at the University of Milan and director of the Irccs Galeazzi Hospital – Sant'Ambrogio in Milan, however, expresses concern about the first human death in the world caused by the new strain of avian influenza A/H5N2, underlining the need to be prepared to avoid situations similar to those that occurred with Covid-19. Regarding the case of the woman who died in Mexico, Pregliasco observes that there is still no clarity: “From the information available, it appears that the victim did not have contact with infected animals. We could therefore find ourselves faced with a possible human-to-human contagion“.

A task force opened in Emilia-Romagna to fight pandemics

After the Covid emergency, many now fear the arrival of new pandemics; in recent months, in addition to cases of avian flu, cases of Dengue have also been found in humans. For this reason Emilia-Romagna has activated a task force which will lead to identifying and recognizing the virus after two days.

“We can't say for sure what this virus will be,” he explains Vittorio Sambri, professor, microbiologist and head of the analysis laboratory of Pievesestina (Cesena) for infectious diseases in the Emilia-Romagna region, “even if statistically we expect it to be a new influenza virus. We don't even know when it will arrive, but the experience with Covid-19 has taught us the importance of being ready, and now we are.”

The Romagna Local Health Authority, following the national pandemic plan, has developed an updated regional plan which clearly defines the actions to take and responsibilities in the event of a new pandemic. Over the last three months, exercises have been conducted involving all the actors who could be involved in the management of a new emergency, simulating different scenarios to improve general preparedness.

These exercises included preparation for the potential need for new masks and an increase in beds in intensive care. Thanks to the funds from the National Plan for complementary investments of the Pnrr, managed by the Emilia-Romagna Region, the laboratories are now much better equipped than in the pre-Covid-19 period. New technologies, developed with millionaire investments, allow us to quickly identify new viruses and establish rapid diagnostic tests within 48/72 hours.