#Serological #Surveillance of Avian #Influenza Virus #H9N2 Subtype in #Occupational Populations Exposed to #Poultry Environment in #China During 2018–2023

 

Abstract

Background

Avian influenza virus (AIV) H9N2 has a major role in the emergence of influenza pandemic. We assessed the risk of AIV H9N2 to the human population and public health.

Method

The hemagglutination inhibition method was used to screen for hemagglutinin antibodies. Microneutralization tests were performed to confirm neutralizing antibodies against the AIV H9N2 subtype. Real-time polymerase chain reaction was conducted to detect the H9 subtype in environmental samples. GraphPad Prism software was used for mapping, and STATA software was used for statistical analysis.

Results

The nationwide seroprevalence among these populations was 0.76%. Seroprevalence was compared across regions, genders, and occupational exposure sites. The seroprevalence rates for males and females showed no significant difference. Significant differences were found across regions and occupational exposure environments (P < .05). The south and southwest regions had the highest seroprevalence rates at 1.58% and 1.38%, respectively. The highest seroprevalence was observed in individuals exposed to live poultry market (1.51%). Significant regional differences in H9 nucleic acid positive rates (NAPRs) were found (P < .05), with the southwest and central regions showing the highest rates at 25.99% and 24.35%, respectively. H9 NAPR in live poultry markets (LPMs), farms, and slaughterhouses varied significantly by region (P < .05).

Conclusions

Poultry-related environments have become a key factor in AIV H9N2 infection among occupational populations. Exposure to LPM showed the highest seroprevalence among occupational groups. The distribution characteristics of H9N2 across different poultry environments increased the risk of infection in occupationally exposed populations.

Source: 

Link: https://academic.oup.com/ofid/article/13/4/ofag144/8537381

____

#MERS #Coronavirus–Specific T-Cell Responses in Dromedary #Camel #Abattoir #Workers in #Nigeria Suggests Frequent Zoonotic #Spillover

 

Abstract

Middle East respiratory syndrome coronavirus (MERS-CoV) is assessed to have high pandemic risk, and dromedary camels are the source of zoonotic spillover. More than 75% of MERS-CoV–infected dromedary camels are found in Africa, but no zoonotic disease has been reported from Africa where there is little awareness of MERS-CoV as a potential cause of respiratory disease. Antibody responses are a poor indicator of mild infection. We found that 47 of 60 (78%) dromedary camel abattoir workers in Kano, Nigeria, had MERS-CoV–specific T-cell responses while none of 18 controls did, suggesting that zoonotic infection is common in camel-exposed individuals in Africa.

Source: 

Link: https://academic.oup.com/jid/advance-article-abstract/doi/10.1093/infdis/jiag095/8504072?redirectedFrom=fulltext

____

Serological and viral #prevalence of #Oropouche virus (OROV): A systematic review and meta-analysis from 2000–24 including #human, #animal, and #vector #surveillance studies

 

Abstract

Background

Oropouche virus (OROV) is an emerging arbovirus primarily transmitted by biting midges and is increasingly recognized as a public health threat in Central and South America. With over 11,000 confirmed cases reported in 2024, a ten-fold increase from the previous year, its transmission dynamics and true burden remain poorly understood due to diagnostic challenges and fragmented surveillance systems.

Objective

This systematic review and meta-analysis (SRMA) synthesizes OROV prevalence data in humans and summarizes the available data for vectors and animal hosts sampled between 2000 and 2024 to provide updated estimates and identify key surveillance gaps.

Methods

We systematically searched Web of Science, PubMed, Embase, Medline, and LILACS for OROV seroprevalence and viral prevalence studies in human, insect, and animal populations, published up to September 12, 2024. The review protocol was registered with PROSPERO (CRD42024551000). Studies were extracted in duplicate, and data were meta-analyzed using generalized linear mixed-effects models. Risk of bias was appraised using a modified Joanna Briggs Institute checklist.

Results

We included 71 articles reporting serological or viral prevalence of OROV across nine countries. Between 2000–2024, pooled human seroprevalence among individuals with febrile illness or suspected of Oropouche infection was 12.6% [95% CI 5.3-26.9%] across four South American countries and seroprevalence of 1.1% [95% CI 0.5-2.3%] was observed in asymptomatic groups. Viral prevalence among individuals with febrile illness or suspected of Oropouche infection was 1.5% [0.8-3.0%] across seven South American countries and Haiti. Most studies used convenience sampling and RT-PCR or hemagglutination assays. In vector populations, positive OROV prevalence in Aedes aegypti and Culex quinquefasciatus was reported in two of 18 sources, while 10.0% and 7.5% animal host prevalence was reported in dogs and cattle, respectively. We found high risk of bias in 11.3% of studies in our critical appraisal, with most animal, human, and vector studies falling in the moderate risk of bias range.

Conclusions

Despite rising numbers of OROV reported cases, prevalence estimates remain limited by sparse surveillance and variable methodology. This review highlights the urgent need for standardized serological assays, community-based studies, and expanded surveillance in animal and vector reservoirs. A One Health approach is essential to monitor OROV transmission and inform regional preparedness efforts.

Source: 

Link: https://journals.plos.org/plosntds/article?id=10.1371/journal.pntd.0013340

____

#Serological evidence of concurrent #Lassa virus and #SARS-CoV-2 #exposure in #Ghana- a cross-sectional study

 

Abstract

Background

The COVID-19 pandemic has exposed vulnerabilities in infectious disease surveillance, especially in West Africa where endemic viruses including Lassa fever persist. The overlapping clinical symptoms of these two infections create diagnostic challenges and the possibility of undetected co-infections.

Methods

A retrospective cross-sectional study was conducted using archived serum samples from a nationwide SARS-CoV-2 seroprevalence survey in Ghana. 434 samples across six regions were tested for SARS-CoV-2 total antibodies (IgG/IgM) using the WANTAI ELISA kit and Lassa virus IgG using ReLASV Pan-Lassa-NP-IgG ELISA.

Results

SARS-CoV-2 antibody prevalence was 64.29% (n = 279) and Lassa virus IgG prevalence was 20.28% (n = 88). Of the cohort of subjects who were seropositive for SARS-CoV-2, 20.79% were also seropositive for LASV IgG. Multivariate analysis revealed household size as a strong risk factor of dual exposure. Individuals from medium-sized households (4–6 persons) (aOR = 8.78, 95% CI: 1.18–65.56, p = 0.034) and large households (≥ 7 persons) (aOR = 12.90, 95% CI: 1.99–83.40, p = 0.007) had significantly increased odds of dual seropositivity compared to small households. Regional variations were observed, with Greater Accra showing significantly lower odds of dual seropositivity (aOR = 0.13, 95% CI: 0.03–0.51, p = 0.004) compared to Ashanti Region.

Conclusion

This study provides serological evidence of SARS-CoV-2 and Lassa virus concurrent exposure in Ghana during the COVID-19 pandemic. This finding suggests large household size as a key driver of dual viral exposure and calls for integrated surveillance systems and targeted interventions in large household settings to reduce concurrent transmission of viruses with pandemic potential.

Source: 

Link: https://link.springer.com/article/10.1186/s12879-025-12385-1

____

Local and introduced #lineages drive #MERS-CoV #recombination in Egyptian #camels

 

ABSTRACT

Dromedary camels are the primary reservoir for Middle East respiratory syndrome coronavirus (MERS-CoV), a zoonotic coronavirus responsible for sporadic human infections. While clade B predominates in the Arabian Peninsula and is frequently linked to zoonotic outbreaks and household secondary transmission, clade C circulates primarily in African camels, with limited evidence of human infections. The extent of MERS-CoV transmission, genetic diversity, and cross-species potential in North Africa remains poorly characterized. Here, we investigate MERS-CoV incidence, seroprevalence, and genomic recombination in dromedary camels and sympatric livestock across slaughterhouses and farms in Egypt. MERS-CoV was detected in 12% of camels sampled at slaughterhouses, with no evidence of infection in cattle, buffalo, sheep, or goats. Seroprevalence was higher in slaughtered camels (79%) than camels on farms (12%). Phylogenetic analyses of MERS-CoV genomes obtained from dromedary camels revealed an introduction of clade B into Egypt, originating from the Arabian Peninsula. Furthermore, we identified recombination events between clades B and C, in addition to events within each clade. This included at least one clade C virus that acquired multiple genomic regions from the newly introduced clade B viruses. These findings suggest that newly introduced MERS-CoV strains can recombine with locally circulating viruses, generating novel variants with potential zoonotic implications and challenging assumptions of limited cross-regional exchange. Enhanced surveillance, targeted control measures, and a One Health approach are crucial to mitigating MERS-CoV transmission and the emergence of recombinant strains.

IMPORTANCE

This study highlights the importance of monitoring Middle East respiratory syndrome coronavirus (MERS-CoV) in dromedary camels, which are the main animal source of this virus that can occasionally infect humans. While most human cases have been linked to strains in the Arabian Peninsula, this research focused on Egypt, where the virus is less understood. Among surveyed dromedary camels and associated livestock, a significant number of camels at slaughterhouses were infected, and many had antibodies showing past exposure. Importantly, we discovered that a strain common in the Arabian Peninsula had recently entered Egypt and mixed genetically with local strains. This mixing, or recombination, can lead to new virus versions that may pose new risks to humans. The findings challenge the belief that MERS-CoV strains in different regions do not interact and highlight the need for stronger monitoring and prevention strategies. A One Health approach, linking animal, human, and environmental health, is key to managing future risks.

Source: 

Link: https://journals.asm.org/doi/full/10.1128/jvi.00641-25?af=R

____

The #epidemiology of #chikungunya virus in #Brazil and the potential #impact of #vaccines: a mathematical modelling study

 

Summary

Background

The first chikungunya virus (CHIKV) vaccine is now licensed in Brazil, the country that reports the most cases of CHIKV globally; however, the optimal use of the vaccine remains unclear owing to a poor understanding of CHIKV epidemiology and population immunity. We aimed to combine the distribution of cases and deaths reported since 2014 with seroprevalence studies to inform mathematical models that estimate the underlying rates of infection by state and year, and the underlying patterns of disease and death by age and sex.

Methods

We quantified the annual CHIKV infection and disease burden between 2014 and 2024 in each of the 27 federative units of Brazil using a mathematical model in a Bayesian framework that integrated serological surveys (n=12) and confirmed CHIKV disease cases (n=488 234) and CHIKV deaths (n=1719) reported between January, 2014, and September, 2024. Using this base, we estimated the potential impact of a vaccine over the period 2025–29 had the population been vaccinated before the 2025 season, evaluating different roll-out strategies.

Findings

We found that 18·3% (95% credible interval 16·5–20·3) of the Brazilian population has been infected since 2014, with the highest risk concentrated in the northeast and southeast. Overall, 1·13% (1·07–1·19) of infections were detected by surveillance systems, with an increasing probability of symptoms with age and greater risk of symptoms in females. Vaccinating 40% of the population older than 12 years (73 million doses), and assuming a vaccine efficacy of 70% against infection and 95% against disease, would avert up to 1·6 million (0·5–3) cases and 198 (61–359) deaths over the next 5 years.

Interpretation

Despite widespread circulation, most of Brazil remains susceptible to infection. CHIKV vaccination has the potential to substantially reduce disease burden.

Funding

CEPI.

Source: 

Link: https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(25)00605-X/fulltext?rss=yes

____

Serological #Evidence of Exposure to Eurasian-Lineage HPAI #H5N1 Clade 2.3.4.4b in Wild #Mammals in #Ohio, #USA, 2024–2025

 

Abstract

The Goose/Guandong lineage of highly pathogenic avian influenza virus [A/Goose/Guangdong/1/1996(H5N1)] is the progenitor of the currently circulating Eurasian-lineage highly pathogenic avian influenza H5N1 clade 2.3.4.4b and has been the most consequential highly pathogenic avian influenza lineage globally. Despite increased reports of infections, the extent of exposure and role of wild mammals in the ecology and transmission dynamics of the virus remains poorly understood. We surveyed wild mammals in Ohio, United States to investigate the potential spillover of highly pathogenic H5N1 avian influenza clade 2.3.4.4b. While no active infections—defined as positive results indicative of viral replication and potential propagation—were detected by swab-based molecular tests, serological assays revealed antibodies against multiple avian influenza virus antigens in raccoons and opossums. Specifically, antibodies to avian influenza virus nucleoprotein were detected in 54.9% (n = 61) of samples using enzyme-linked immunosorbent assay; antibodies to Eurasian-lineage highly pathogenic avian influenza H5 clade 2.3.4.4b and North American low pathogenic avian influenza H5 were detected in 43.2% (n = 48) and 22.5% (n = 25) of samples, respectively, using virus neutralization assays; and antibodies to avian influenza virus neuraminidase were detected in 44.1% (n = 49) of samples using enzyme-linked lectin assay. All seropositive animals were sampled at Ohio marshes with previously confirmed highly pathogenic avian influenza H5N1 detections in waterfowl. These findings suggest prior exposure of wild mammals to these viruses without mortality events. Wild mammals may play an intermediary role in the mammalian adaptation of avian influenza A viruses. Therefore, ongoing surveillance of wild mammals is crucial for assessing the risk to public health.

Source: Viruses, https://www.mdpi.com/1999-4915/17/10/1388

____

#Genetic and Serological Analysis of #H7N3 Avian #Influenza Viruses in #Mexico for #Pandemic #Risk Assessment

 

Abstract

Avian influenza A viruses pose ongoing threats to human and animal health, with H7 subtypes causing outbreaks globally. In Mexico, highly pathogenic H7N3 viruses have circulated in poultry since 2012, causing sporadic human infections. Here we analyzed genetic markers in hemagglutinin sequences from Mexican H7N3 isolates and conducted serological assays on human populations with poultry exposure. Our results show conserved avian-like receptor binding sites, thus limiting human adaptation, alongside antigenic drift and acquisition of glycosylation sites likely driven by vaccination. Serological testing of 1103 individuals revealed no detectable antibodies against H7N3, indicating a naïve population. Phylogenetic analyses revealed multiple virus clades circulating regionally. These findings suggest that while current H7N3 viruses have limited capacity for sustained human transmission, the lack of population immunity underscores the importance of continued surveillance and risk assessment to mitigate potential pandemic threats.

Source: Viruses, https://www.mdpi.com/1999-4915/17/10/1376

____

First serological #evidence of equine #coronavirus and #SARS-CoV-2 in #horses in North #Africa

 

Abstract

Viral diseases cause significant economic losses within the equine population. Horses are susceptible to equine coronavirus (ECoV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), although only ECoV has been associated to clinical disease. The aim of this study was to investigate, for the first time in Algeria, the seroprevalence of ECoV and SARS-CoV-2 antibodies and the prevalence of ECoV infection in horses. In 2022, a total of 299 serum samples was collected from horses aged 1 to 27 years. Serological analysis for the presence of ECoV and SARS-CoV-2 was performed using a validated in-house and a commercially available ELISA, respectively. In addition, fecal samples of these animals were tested for the presence of ECoV RNA by RT-qPCR. SARS-CoV-2-ELISA positive sera with high S/P ratios and negative samples close to the doubtful threshold were retested using a virus neutralization test (VNT). The seroprevalence of ECoV and SARS-CoV-2 in the tested horses was 63.5% (190/299) and 4.3% (13/299), respectively. Among CoVs-seropositive horses, six were seropositive for both ECoV and SARS-CoV-2, thus 6/10 sera were VNT positive, including two ELISA-negative samples for SARS-CoV-2. ECoV seroprevalence varied according to age, breed and sex. None of the fecal samples tested positive for ECoV. Antibodies against SARS-CoV-2 were confirmed by VNT in six samples (2%). One SARS-CoV-2-positive serum tested by ELISA and confirmed through VNT was cytotoxic for VERO cells. This study is the first to report the circulation of ECoV and SARS-CoV-2 in the Algerian horse population. Further studies are necessary to isolate and obtain molecular characterisation of ECoV and SARS-CoV-2 from horses in Algeria.

Source: Veterinary Research Communications, https://link.springer.com/article/10.1007/s11259-025-10928-0

____

Avian #Influenza #Surveillance Among Migratory #Birds, #Poultry, and #Humans Around Nansi Lake, #China, 2021–2024

Abstract

Avian influenza A viruses (AIVs) pose a significant pandemic threat due to their cross-species transmission potential. However, AIV surveillance at the critical “migratory birds–poultry-exposed population” interface remains limited. Between 2021 and 2024, we implemented a prospective One Health surveillance program around Nansi Lake, monitoring AIVs in migratory birds, poultry, and environmental samples, as well as serological investigations against representative AIVs among migratory birds or poultry-exposed subjects. AIVs were detected in 2.1% (30/1417) of migratory bird samples and 10.2% (100/978) of poultry samples. Among these, we identified ten highly pathogenic avian influenza (HPAI) H5 subtype viruses, one HPAI H7N9 virus, and five low pathogenic avian influenza (LPAI) H9N2 viruses. Phylogenetic analysis revealed evidence of frequent genomic reassortment events involving H5 subtype viruses among migratory birds, poultry, and humans. Serological investigation also suggested that both migratory birds and the poultry-exposed population had a higher risk of getting AIV infection than the general control population, especially against the H9N2 virus. Our study emphasizes the importance of strengthening continuous prospective surveillance of AIVs among migratory birds, poultry, and their exposed individuals to prevent and control potential outbreaks.

Source: Viruses, https://www.mdpi.com/1999-4915/17/8/1117

____

Potential #impacts of 2.3.4.4b highly pathogenic #H5N1 avian #influenza virus #infection on Snow #Goose (Anser caerulescens) movement #ecology

Abstract

While wild waterfowl are known reservoirs of avian influenza viruses and facilitate the movement of these viruses, there are notable differences in the response to infection across species. This study explored differential responses to infection with highly pathogenic avian influenza in Snow Geese (Anser caerulescens) located in the California Central Valley. Though H5 antibody prevalence was high across years among birds sampled in the winter (75% in both years via hemagglutination inhibition), these values were even higher among birds sampled in summer that failed to migrate (i.e., August 2023 = 100% and August 2024 = 93% via hemagglutination inhibition). Birds that failed to migrate were also generally lighter than birds sampled in the winter and presented notable damage to cerebrum and cerebellum. In December 2022, a single individual positive for infection with H5N1 at the time of sampling indicated reduced movement during the 14 days following sampling but completed spring migration comparably with uninfected conspecifics. However, while no birds were actively infected during sampling and marking in 2023, two marked geese departed for migration late and one did not migrate at all. Additional banded birds marked in August have been reencountered in scenarios ranging from hunter harvest at a different site over a year later to found dead shortly after banding. Our data indicate that Snow Geese infected with HPAI have the potential to express variable outcomes following infection with highly pathogenic H5N1, ranging from rapid recovery within a migratory season to death. These data also suggest that the abnormal failure of some Snow Geese to migrate from the Central Valley is likely driven by HPAI infection.

Source: PLoS One, https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0328149

____

Hunting-training #dogs & companion dogs in #Netherlands are frequently exposed to highly pathogenic avian #influenza #H5 & human #H1N1 virus, 2021–2023

Highlights

• High seropositivity in dogs to highly pathogenic avian influenza (HPAI) H5 virus in the Netherlands during HPAI H5 endemicity in wild birds.

• HPAI H5-seropositivity higher in hunting-training dogs than companion dogs. 

• HPAI H5-seropositivity in hunting-training dogs associated with recent bird contact in/near water.

• High seropositivity in dogs to human H1N1pdm2009 influenza A virus (IAV).

• H1N1pdm2009-seropositivity higher in companion dogs than hunting-training dogs.

Abstract

Dogs are susceptible to the currently circulating highly pathogenic avian influenza (HPAI) H5 and human H1N1pdm2009 (pandemic H1N1) viruses, yet little is known about the extent to which dogs are exposed to both these viruses. Here we investigated HPAI H5 and human H1N1pdm2009 virus exposure in domestic dogs–including dogs that participated in hunting-training–and investigated lifestyle factors associated with HPAI H5 virus exposure. We screened sera from 538 dogs, sampled between 2021 and 2023, for influenza A virus antibodies, using ELISA and hemagglutination inhibition assays (HAIs). We analyzed lung tissue and (naso)pharyngeal swabs for influenza A viruses using RT-qPCR. Seropositivity to HPAI H5 virus was more frequent (13.3 %) in hunting-training dogs than in companion dogs with unknown bird contact (3.7 %). In contrast, seropositivity to H1N1pdm2009 was more frequent in companion dogs (7.1 %) than in hunting-training dogs (0.7 %). Based on owner questionnaires, seropositivity to HPAI H5 by ELISA in hunting-training dogs was significantly associated with recent bird contact in/near water (odds ratio 6.9). No influenza A viruses were detected in 207 necropsy dogs and 180 (hunting) dogs. Our findings suggest that dogs are frequently exposed to zoonotic influenza A viruses, and we recommend dog owners to avoid dog contact with sick/dead birds.

Source: OneHealth, https://www.sciencedirect.com/science/article/pii/S2352771425001703?via%3Dihub

____

#Seroprevalence of #H9N2 and #H5 avian #influenza in mixed-species #poultry #farms in Northern #Benin

ABSTRACT

Avian influenza is one of the major threats to poultry and human health in northern Benin, while mixed-species farming systems increase the risks of viral transmission. The present study estimated the seroprevalence of avian influenza subtypes H9N2 and H5 in indigenous chickens and guinea fowls in the Atacora and Donga regions. A total of 300 birds including 191 indigenous chickens and 109 guinea fowls, from six districts were sampled through a cross-sectional survey using systematic random sampling. Hemagglutination inhibition assay was used to detect antibodies, revealing an overall H9N2 seroprevalence of 41%, with 17.5% of samples testing positive for H5. The seroprevalence of H9N2 was notably higher in guinea fowls (51.81% in Atacora and 52% in Donga) compared to chickens (34.95% in Atacora and 34.83% in Donga). H5 antibodies were found only in guinea fowls in Atacora (46.66%). The study also found that farms with both chickens and guinea fowls had a significantly higher odds ratio for H9N2 positivity (OR = 4.25, p < 0.001) compared to chicken-only farms. The results underscore the importance of mixed-species systems in the transmission of avian influenza, suggesting that targeted surveillance and biosecurity measures are essential for controlling the spread of these viruses.

Source: Journal of Immunoassay and Immunochemistry, https://www.tandfonline.com/doi/full/10.1080/15321819.2025.2496480

____

#Risk #assessment of 2024 #cattle #H5N1 using age-stratified #serosurveillance data

ABSTRACT

The highly pathogenic avian influenza virus A(H5N1) clade 2.3.4.4b has caused a human outbreak in North America since March 2024. Here, we conducted a serosurveillance study to determine the risk of A(H5N1) clade 2.3.4.4b (2024 cattle H5N1) to general population. In the initial screening of 180 serum specimens encompassing all age groups, 2.2% (4/180) had detectable neutralizing antibody (nAb) titers against reverse genetics-derived 2024 cattle H5N1, with all collected from older adults aged ≥60 years old. Further screening showed that 4.2% (19/450) of adults aged ≥60 years old had detectable nAb titers against the 2024 cattle H5N1. 80% (4/5) serum specimens with nAb titer of ≥40 had detectable HI titer, and there was a positive correlation between nAb titer and HA binding (r = 0.3325, 95% confidence interval 0.2477 to 0.4123; P < 0.0001). The nAb titer against seasonal H1N1 virus was 4.2-fold higher for ≥60 years old individuals with detectable H5N1 nAb titer than those ≥60 years old ones without (geometric mean titer: 89.3 [95% CI 42.9-185.7]) vs 21.3 [95% CI 17.3-26.1], P < 0.0001), but there was no statistically significant difference between H5N1 and H3N2 nAb titer. There was no difference in demographics, comorbidities and clinical frailty scores between individuals with detectable H5N1 nAb and those without. Our findings suggest that most individuals lack nAb response against 2024 cattle H5N1 and there is an urgency to develop and evaluate H5N1 vaccine or prophylactic monoclonal antibodies. Immune imprinting may be responsible for the cross neutralization between H5N1 and H1N1 among older adults.

Source: Emerging Microbes and Infections, https://www.tandfonline.com/doi/full/10.1080/22221751.2025.2497304

____

Detection of #antibodies against #influenza A viruses in #cattle

ABSTRACT

Unexpected outbreaks caused by the H5N1 highly pathogenic avian influenza virus (HPAIV) in dairy cows in the United States (US) have raised significant veterinary and public health concerns. When and how the H5N1 HPAIV was introduced into dairy cows and the broader epidemiology of influenza A virus (IAV) infections in cattle in the US remain unclear. Herein, we performed a retrospective study to screen more than 1,700 cattle serum samples collected from different bovine breeds in the US from January 2023 to May 2024 using an enzyme-linked immunosorbent assay (ELISA) targeting the nucleoprotein (NP) to detect IAV infections, and the positive samples were further tested by hemagglutination inhibition (HI) assay. Results showed that 586 of 1,724 samples (33.99%) from 15 US states were seropositive by the NP ELISA assay, including 78 samples collected in 2024 and 508 samples collected in 2023. Moreover, the HI assay revealed that 45 of these ELISA-positive samples were positive to human seasonal H1N1 and H3N2 and swine H3N2 and H1N2 viruses, and some were positive to two or three tested IAVs. Surprisingly, none of these ELISA-positive samples were HI positive for the circulating bovine H5N1 strain. Our results demonstrate that IAVs other than H5N1 can infect cattle, infections are not limited to dairy cows, and that bovine infections with swine and human IAVs have occurred prior to the H5N1 outbreaks. All results highlight the value in monitoring IAV epidemiology in cattle, as the viruses might adapt to cattle and/or reassort with the currently circulating H5N1 HPAIV, increasing risk to humans.

IMPORTANCE

Influenza A virus (IAV) is an important zoonotic pathogen that can infect different species. Although cattle were not historically considered vulnerable to IAV infections, an unexpected outbreak caused by H5N1 highly pathogenic avian influenza virus in dairy cows in the United States (US) in early 2024 has raised significant concerns. When and how the virus was introduced into dairy cows and the wider impact of IAV infections in cattle in the US remain unclear. Our retrospective serological screen provided evidence of human and swine H1 and H3 IAV infections in different cattle breeds in addition to dairy cows, although no H5N1 infection was detected. Our results underline the necessity to monitor IAV epidemiology in cattle, as reassortment of IAVs from different species may occur in cattle, generating novel viruses that pose threats to public and animal health.

Source: Journal of Virology, https://journals.asm.org/doi/full/10.1128/jvi.02138-24?af=R

____

#Seroprevalence of Highly Pathogenic Avian #Influenza A(#H5) Virus #Infections Among Bovine #Veterinary #Practitioners — #USA, September 2024

Summary

-- What is already known about this topic?

- Highly pathogenic avian influenza (HPAI) A(H5) virus infections have been detected in humans exposed to infected dairy cattle.

-- What is added by this report?

- Public health officials conducted a serosurvey among 150 bovine veterinary practitioners. Three practitioners had evidence of recent infection with HPAI A(H5) virus, including two without exposures to animals with known or suspected HPAI A(H5) virus infections and one who did not practice in a U.S. state with known HPAI A(H5) virus–infected cattle.

-- What are the implications for public health practice?

- These findings suggest the possible benefit of systematic surveillance for rapid identification of HPAI A(H5) virus in dairy cattle, milk, and humans who are exposed to cattle to ensure appropriate hazard assessments.

Abstract

The current outbreak of highly pathogenic avian influenza (HPAI) A(H5) clade 2.3.4.4.b viruses, genotype B3.13, among dairy cattle was first detected in March 2024 (1), with human cases of HPAI A(H5) among dairy farm workers identified beginning in April (2). Farm workers and bovine veterinary practitioners working with HPAI A(H5) virus–infected cattle are at increased risk for HPAI A(H5) exposure; in the current outbreak, most human infections with HPAI A(H5) have been mild and were detected through enhanced surveillance of persons working with affected animals (2).

Source: Morbidity and Mortality Weekly Report, https://www.cdc.gov/mmwr/volumes/74/wr/mm7404a2.htm?s_cid=mm7404a2_w

_____

Are we serologically prepared against an avian #influenza #pandemic and could seasonal flu #vaccines help us?

ABSTRACT

The current situation with H5N1 highly pathogenic avian influenza virus (HPAI) is causing a worldwide concern due to multiple outbreaks in wild birds, poultry, and mammals. Moreover, multiple zoonotic infections in humans have been reported. Importantly, HPAI H5N1 viruses with genetic markers of adaptation to mammals have been detected. Together with HPAI H5N1, avian influenza viruses H7N9 (high and low pathogenic) stand out due to their high mortality rates in humans. This raises the question of how prepared we are serologically and whether seasonal vaccines are capable of inducing protective immunity against these influenza subtypes. An observational study was conducted in which sera from people born between years 1925–1967, 1968–1977, and 1978–1997 were collected before or after 28 days or 6 months post-vaccination with an inactivated seasonal influenza vaccine. Then, hemagglutination inhibition, viral neutralization, and immunoassays were performed to assess the basal protective immunity of the population as well as the ability of seasonal influenza vaccines to induce protective responses. Our results indicate that subtype-specific serological protection against H5N1 and H7N9 in the representative Spanish population evaluated was limited or nonexistent. However, seasonal vaccination was able to increase the antibody titers to protective levels in a moderate percentage of people, probably due to cross-reactive responses. These findings demonstrate the importance of vaccination and suggest that seasonal influenza vaccines could be used as a first line of defense against an eventual pandemic caused by avian influenza viruses, to be followed immediately by the use of more specific pandemic vaccines.

Source: mBio, https://journals.asm.org/doi/10.1128/mbio.03721-24

_____

#Risk #assessment of 2024 #cattle #H5N1 using age-stratified #serosurveillance data

ABSTRACT

The highly pathogenic avian influenza virus A(H5N1) clade 2.3.4.4b has caused a human outbreak in North America since March 2024. Here, we conducted a serosurveillance study to determine the risk of A(H5N1) clade 2.3.4.4b (2024 cattle H5N1) to general population. In the initial screening of 180 serum specimens encompassing all age groups, 2.2% (4/180) had detectable neutralizing antibody (nAb) titers against 2024 cattle H5N1, with all collected from older adults aged ≥60 years old. Further screening showed that 5.0% (15/300) of adults aged ≥70 years old had detectable nAb titers against the 2024 cattle H5N1. All serum specimens with nAb titer of ≥40 had detectable HI titer, and there was a positive correlation between nAb titer and HA binding (r=0.3311, 95% confidence interval 0.2264 to 0.4283; P<0.0001). The nAb titer against seasonal H1N1 virus was 3.9-fold higher for patients with detectable H5N1 nAb than those without (geometric mean titer: 108.5 [95% CI 56.3-209.1] vs 27.9 [95% CI 21.0-37.0], P=0.0039), but there was no statistically significant difference between H5N1 and H3N2 nAb titer. There was no difference in demographics, comorbidities and clinical frailty scores between individuals with detectable H5N1 nAb and those without. Our findings suggest that most individuals lack nAb response against 2024 cattle H5N1 and there is an urgency to develop and evaluate H5N1 vaccine or prophylactic monoclonal antibodies. Immune imprinting may be responsible for the cross neutralization between H5N1 and H1N1 among older adults.

Source: MedRxIV, https://www.medrxiv.org/content/10.1101/2024.12.23.24319580v1

______