Fiocruz identifies a new strain of influenza virus in Brazil

Researchers of the Oswaldo Cruz Institute (IOC/Fiocruz) have identified a new strain of the influenza virus in a patient in the city of Ibiporã, in the southern state of Paraná. Analysis have pointed to the presence of the influenza virus A(H1N2)v, which causes infection in pigs. The case was reported to the Ministry of Health, which then notified the World Health Organization (WHO), according to the international health regulation. All records of human infection by new viral subtypes must be notified, as mutations in these micro-organisms may lead to person-to-person dissemination, with pandemic potential.

An alert issued by the WHO informs that 26 cases of infection by the A(H1N2)v influenza virus have been recorded since 2005, and most patients had only mild symptoms. In Brazil, one case was recorded in 2016. There is no evidence of transmission of these viral strains between people. Virologist Marilda Siqueira, chief of the Respiratory Viruses and Measles Laboratory of the IOC, a reference for respiratory viruses in Brazil and responsible for identifying variations of influenza virus in Brazil, states that the new finding is no reason for concern. “Cases like this are identified in different countries over time. It does not mean this will turn into a pandemic. Control measures are the same as those for airborne infections in general, such as washing your hands often and, in the event of respiratory symptoms, seek medical treatment for a better assessment of the clinical situation”, she clarifies.

The patient from Ibiporã has already recovered and required no hospitalization; she reported flu-like symptoms in mid April. When seeking medical care, a sample was collected from her respiratory tract as part of the routine actions of the national influenza surveillance system. The Central Laboratory of Public Health of Paraná (Lacen-PR) identified an influenza A virus of an unknown subtype, and sent the sample to the Respiratory Viruses and Measles Laboratory of the IOC, where the micro-organism was then identified. Siqueira emphasizes that the finding, right in the midst of the Covid-19 pandemic, which is already overloading health services and the country’s network of laboratories, shows Brazil’s response capacity.

“In the middle of a coronavirus pandemic that is impacting all levels of healthcare, we still work within the protocols, and were able to identify a new variation of the influenza virus. This shows the rapid response capacity that our country can provide to control influenza, thanks to a great effort by the Ministry of Health, the Secretaries of Health, the Public Health Central Laboratories (Lacens), and institutions such as IOC/Fiocruz, Evandro Chagas Institute (IEC), and Adolfo Lutz Institute (IAL)”, says Siqueira.

Once influenza viruses occur in different animal species, the appearance of new variations may take place either by mutations of the viral genoma or through recombination between micro-organisms of different species. Using genetic sequencing, researchers have learned that the new virus strain had RNA segments associated to viruses detected in pigs and humans.

“The virus identified in Paraná is characterized as a new variant because it has genetic configurations that differ from those of other influenza A viruses (H1N2), including the strain detected in Brazil in 2016. Thanks to the genomic sequencing, we observed that segments H and N of the new variant were associated to viruses that had previously been circulating among humans and pigs. We also detected internal genes associated to the influenza A virus (H1N1), which has been around since 2009”, states Paola Cristina Resende, researcher of the Respiratory Viruses and Measles Laboratory of IOC/Fiocruz.

According to the WHO, human infections by swine flu virus occur mainly through contact with infected animals or infected environments. The specific case in Ibiporã is still being investigated, but it is possible that the patient was infected in the swine slaughterhouse where she works. In that same period, another employee reported influenza symptoms, but no samples were collected at the time. The ongoing epidemiological and laboratorial investigation has not found evidence of other cases of infection. “We will continue with the analysis, but so far there is no evidence that transmission has occurred”, emphasizes Siqueira.