Skip to main content

The #Swiss national #program for #surveillance of #influenza A viruses in #pigs and #humans: genetic variability and zoonotic transmissions from 2010 – 2022

Image
By G.M.

Abstract

Influenza A viruses (IAV) are likely candidates for pandemics. This report summarizes the results of the Swiss national program for surveillance of influenza viruses in pigs and transmissions to humans between 2010 and 2022. Challenges and optimization options in the program are discussed. Nasal swabs or lung tissue samples from pigs with influenza-like signs (e.g. fever, cough) were screened by real-time RT-PCR for swine influenza virus (SIV) genomes, including that of the 2009 pandemic strain A(H1N1)pdm09; positive samples were subtyped for H1, N1, H3 and N2 by RT-PCR and Sanger sequencing. In parallel, humans with influenza-like symptoms and recent contact to diseased pigs were asked to self-sample themselves with a nasal swab. Human swabs were tested for IAV and positive swabs further subtyped to identify potential cross-species transmission between swine and humans. In the pigs, SIV was detected in 375 of 674 farm visits. H1N1 is the only subtype detected in Swiss pigs so far. The (H1N1)pdm09 strain (HA clade 1A) was only detected in seven out of 375 SIV positive farm visits. Phylogenetic analyses from partial hemagglutinin (HA) and neuraminidase (NA) genome sequences indicate that the remaining pigs were infected with the Eurasian avian lineage (HA clade 1C), which is predominant in swine in Europe. The Swiss H1N1 strains form distinct clusters within HA clades 1C.2.1 and 1C.2.2 and seem to evolve comparably slowly. Infection of humans with SIV was identified in five cases. Sequence analysis assigned the five viruses to the Eurasian avian lineage (C), clades 1C.2.1 and 1C.2.2. There was no evidence for sustained human-to-human transmission. Although no critical IAV variants seem to have emerged so far in Switzerland, further surveillance of influenza viruses at the swine-human interface is of major importance.

Source: MedRxIV, https://www.medrxiv.org/content/10.1101/2025.01.28.24319114v1

_____

Labels:

Comments

Post a Comment

Popular posts from this blog

#USA, Novel #Influenza A #H5N1 Virus: One Pediatric Case in #California {FluView}

By G.M.
 {Excerpt} One confirmed human infection with influenza A(H5) virus was reported to CDC this week. To date, human-to-human transmission of influenza A(H5) virus has not been identified in the United States. This case was reported by the California Department of Public Health and occurred in a child less than 18 years old with no known contact with influenza A(H5N1) virus-infected animals or humans . The investigation into the source of infection for this case is ongoing , and no human-to-human transmission has been identified. A specimen from the individual was tested at a public health laboratory using the CDC influenza A(H5) assay before being sent to CDC for further testing. The specimen was positive for influenza A(H5) virus using diagnostic RT-PCR at CDC. Additional analysis including genetic sequencing is underway. In response to this detection, additional case investigation and contact monitoring are being conducted by public health officials in California. There have now be...
Post a Comment
Read more »

#USA, Two more #human cases of #H5N1 #birdflu reported in #California

By G.M.
Two cases of bird flu have been reported in San Joaquin County, California, local health officials said. According to a press release issued Friday and reported by the Sacramento Bee , health officials with San Joaquin County Public Health Services said both cases were farm workers who were exposed to infected animals . Both people are showing mild symptoms and are recovering, officials said, adding that there are 34 total confirmed cases across California. In a warning posted on Facebook, health officials said bird flu was “spreading in several farms such as poultry and cattle” and urged residents to take precautions to prevent the spread of the disease. Precautions include the use of protective equipment when handling poultry, dairy cattle or other animals that may be infected, and when handling raw and unpasteurized milk. (...) There are currently 60 confirmed cases of bird flu in the country . While most of the cases are in California , other states with confirmed cases include Col...
Post a Comment
Read more »

#PuertoRico - High pathogenicity avian #influenza #H5N1 viruses (#poultry) (Inf. with) - Immediate notification

By G.M.
Highly pathogenic avian influenza (HPAI) H5N1 clade 2.3.4.4b was confirmed on one poultry premises in Culebra Municipality, Puerto Rico . This is the first confirmed case of HPAI in poultry from Puerto Rico. Full genotyping confirms the virus as a reassortant of the A3 genotype with North American wild bird lineage viruses ( AM PB2, PA, NP ). Comparisons of the virus to other recent detections from wild birds and North America reports are in progress. The USDA Animal and Plant Health Inspection Service (APHIS), in conjunction with State Animal Health and Wildlife Officials, are conducting comprehensive epidemiological investigations and enhanced surveillance in response to the HPAI H5N1 related events. Source: WOAH,  https://wahis.woah.org/#/in-review/6185 _____
Post a Comment
Read more »