ETIDIOH - NEW

Abstract Influenza A viruses (IAVs) are prime examples of emerging viruses in humans and animals. IAV circulation in domestic animals poses a pandemic risk as it provides new opportunities for zoonotic infections. The recent emergence of H5N1 IAV in cows and subsequent spread over multiple states within the USA, together with reports of spillover infections in humans, cats and mice highlight this issue. The horse is a domestic animal in which an avian-origin IAV lineage has been circulating for >60 years . In 2018/19, a Florida Clade 1 (FC1) virus triggered one of the largest epizootics recorded in the UK , which led to the replacement of the Equine Influenza Virus (EIV) Florida Clade 2 (FC2) lineage that had been circulating in the country since 2003. We integrated geographical, epidemiological, and virus genetic data to determine the virological and ecological factors leading to this epizootic. By combining newly-sequenced EIV complete genomes derived from UK outbreaks with existi...

Abstract Background .  Sudan virus (SUDV) has caused multiple outbreaks in Uganda over the past two decades, leading to significant morbidity and mortality . The recent outbreaks in 2022 and 2025 highlight the ongoing threat posed by SUDV and the challenges in its containment. This study aims to characterize the epidemiological patterns and phylogenomic evolution of SUDV outbreaks in Uganda, identifying key factors influencing transmission and disease severity.  Methods .  We conducted a retrospective observational study analyzing epidemiological and genomic data from SUDV outbreaks in Uganda between 2000 and 2025. Epidemiological data were collected from official sources, including the Ugandan Ministry of Health and the World Health Organization, supplemented with reports from public health organizations. Genomic sequences of SUDV were analyzed to investigate viral evolution and identify genetic variations associated with pathogenicity and transmissibility.  Results...

Abstract Determining the incubation period of Oropouche virus disease can inform clinical and public health practice . We analyzed data from 97 travel-associated cases identified by the Centers for Disease Control and Prevention (n = 74) or the GeoSentinel Network (n = 13) and 10 cases from published literature . Using log-normal interval-censored survival analysis, we estimated the median incubation period to be 3.2 (95% CI 2.5–3.9) days . Symptoms developed by 1.1 (95% CI 0.6–1.5) days for 5% of patients, 9.7 (95% CI 6.9–12.5) days for 95% of patients, and 15.4 (95% CI 9.6–21.3) days for 99% of patients . The estimated incubation period range of 1–10 days can be used to assess timing and potential source of exposure in patients with Oropouche symptoms. For patients with symptom onset >2 weeks after travel , clinicians and public health responders should consider the possibility of local vectorborne transmission or alternative modes of transmission. Source: US Centers for Disease C...

ABSTRACT The outbreak of H5N1 in dairy cattle in United States revealed challenges in identification and management of a novel disease . The virus showed an exceptional ability to spread between farms and among cows within a farm. The impact of the virus on dairy cattle varied from nonclinical to severe clinical signs and death. Many dairy producers did not report clinical signs in their cows or test for the virus. Cats and peridomestic birds on many affected dairies died from viral exposure . Dairy workers showed signs of conjunctivitis , which was confirmed to be due to H5N1. With the disease affecting multiple species and showing efficient cow-to-cow transmission , the situation only worsened. There was a negative impact on the relationships among dairy producers, dairy workers, poultry producers, and veterinarians, in which professional and personal relationships were severed and some experienced loss of employment. The regulatory response varied by geographic location, and in some...

Abstract Highly Pathogenic Avian Influenza (HPAI) is a prominent candidate for a future human pandemic arising from a zoonotic spillover event . Its best-known strain is H5N1 , with South- or South-East Asia a likely location for an initial outbreak. Such an outbreak would be initiated through a primary event of bird-to-human infection, followed by sustained human-to-human transmission . Early interventions would require the extraction, integration and interpretation of epidemiological information from the limited and noisy case data available at outbreak onset. We studied the implications of a potential zoonotic spillover of H5N1 influenza into humans. Our simulations used BharatSim , an agent-based model framework designed primarily for the population of India , but which can be tuned easily for others. We considered a synthetic population representing farm-workers (primary contacts) in a farm with infected birds. These primary contacts transfer infections to secondary (household) co...

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 ≥...

Highlights •  A large B19V French outbreak of an unexpected magnitude occurred, with a monthly rate that has reached 21.4%. •  During this outbreak, 50% of infected pregnant women exhibited fetal complications. •  Phylogenetic analysis revealed the co-circulation of several B19V lineages of genotype 1a, the main epidemic lineage of which emerged in 2017. Abstract Background The human parvovirus B19 (B19V) infections cycle occurs in 3- to 4-year periods and is responsible for benign childhood erythema infectiosum . It is also associated with transient aplastic crisis in patients with underlying hemolytic diseases and with severe fetal sometimes fatal infection . This study investigated the epidemiological, clinical and molecular characteristics of an unusually large 2023-2024 outbreak of B19V. Methods . Laboratory-confirmed cases were retrospectively and prospectively recorded at the Clermont-Ferrand University Hospital, France , between January, 2018 and November, 2023 an...

Abstract Background   The ongoing H5N1 panzootic in mammals has amplified zoonotic pathways to facilitate human infection . Characterising key epidemiological parameters for H5N1 is critical should it become widespread.  Aim   To identify and estimate critical epidemiological parameters for H5N1 from past and current outbreaks, and to compare their characteristics with human influenza subtypes and the 2003 Netherlands H7N7 outbreak .  Methods   We searched PubMed, Embase, and Cochrane Library for systematic reviews reporting parameter estimates from primary data or meta-analyses. To address gaps, we searched PubMed and Google Scholar for studies of any design providing relevant estimates. We estimated the basic reproduction number for the outbreak in the US and the 2003 Netherlands H7N7 outbreak. In addition we estimated the serial interval for H5N1 using data from previous household clusters in Indonesia . We also applied a branching process model to simulate t...

Summary Background Latin America has been experiencing an Oropouche virus (OROV) outbreak of unprecedented magnitude and spread since 2023–24 for unknown reasons. We aimed to identify risk predictors of and areas at risk for OROV transmission. Methods In this multidisciplinary, laboratory-based, modelling study, we retrospectively tested anonymised serum samples collected between 2001 and 2022 for studies on virus epidemiology and medical diagnostics in Bolivia, Brazil, Colombia, Costa Rica, Ecuador, and Peru with nucleoprotein-based commercial ELISAs for OROV-specific IgG and IgM antibodies. Serum samples positive for IgG from different ecological regions and sampling years were tested against Guaroa virus and two OROV glycoprotein reassortants (Iquitos virus and Madre de Dios virus) via plaque reduction neutralisation testing (PRNT) to validate IgG ELISA specificity and support antigenic cartography. Three OROV strains were included in the neutralisation testing, a Cuban OROV isolate...

Abstract The continuous spread of highly pathogenic avian influenza H5 viruses poses significant challenges, particularly in regions with high poultry farm densities where conventional control measures are less effective. Using phylogeographic and phylodynamic tools , we analysed virus spread in Southwestern France in 2020-21, a region with recurrent outbreaks. Following a single introduction, the virus spread regionally, mostly affecting duck farms , peaking in mid-December with a velocity of 27.8 km/week and an effective reproduction number between farms (Re) of 3.8, suggesting the virus can spread beyond current control radii. Transmission declined after late December following preventive culling. Farm infectiousness was estimated around 9 days. Duck farm density was the main driver of virus spread and we identified farm density and proximity thresholds required to maintain effective control (Re < 1). These findings offer actionable guidance to support regional biosecurity and to...

Abstract We modeled the impact of initiating one-dose influenza vaccination at 3 months vs 6 months after declaration of a pandemic over a 1-year timeframe in the US population. Three vaccine effectiveness (VE) and two pandemic severity levels were considered, using an epidemic curve based on typical seasonal influenza epidemics. Vaccination from 3 months with a high, moderate, or low effectiveness vaccine would prevent ~95%, 84%, or 38% deaths post-vaccination, respectively, compared with 21%, 18%, and 8%, respectively following vaccination at 6 months, irrespective of pandemic severity. While the pandemic curve would not be flattened from vaccination from 6 months , a moderate/high effectiveness vaccine could flatten the curve if administered from 3 months. Overall, speed of initiating a vaccination campaign is more important than VE in reducing the health impacts of an influenza pandemic. Preparedness strategies may be able to minimize future pandemic impacts by prioritizing rapid v...

Abstract Understanding the transmission routes of high-pathogenicity avian influenza (HPAI) is crucial for developing effective control measures to prevent its spread. In this context, windborne transmission , the idea that the virus can travel through the air over considerable distances, is a contentious concept and, documented cases are rare. Here, though, we provide genetic evidence supporting the feasibility of windborne transmission . During the 2023-24 HPAI season, molecular surveillance identified identical H5N1 strains among a cluster of unrelated commercial farms about 8 km apart in the Czech Republic . The episode started with the abrupt mortality of fattening ducks on one farm and was followed by disease outbreaks at two nearby high-biosecurity chicken farms. Using genetic, epizootiological, meteorological and geographical data , we reconstructed a mosaic of events strongly suggesting wind was the mechanism of infection transmission between poultry in at least two independen...

Abstract Background For decades after the identification of mpox in humans in the Democratic Republic of Congo (DRC) in 1970, the disease was largely confined to the rural areas of Central and West Africa and thus did not garner broad attention. On August 13, 2024, mpox was declared a Public Health Emergency of Continental Security (PHECS) by the Africa Centers for Disease Control and Prevention (Africa CDC), a notice that was followed the next day by a declaration of a Public Health Emergency of International Concern (PHEIC) by the World Health Organization. Methods In this study we analyzed all mpox cases and deaths , based on clinical or laboratory diagnosis, that were reported to the Africa CDC from January 1, 2022, to October 30, 2024, to identify temporal variations, geographic distributions, and epidemiologic trends. Results From January 1, 2022, to August 18, 2024, a total of 45,652 mpox cases were clinically diagnosed and laboratory-confirmed in 12 African countries . These ca...

Summary Background DR Congo has the highest global burden of mpox , a disease caused by infection with the monkeypox virus . The incidence has risen since 1980, but recent analyses of epidemiological trends are lacking. We aimed to describe trends in suspected and confirmed mpox cases in DR Congo using epidemiological and laboratory mpox surveillance data collected from 2010 to 2023, and provide insights that can better inform the targeting and monitoring of control strategies. Methods We analysed aggregated national epidemiological surveillance data and individual-level laboratory data from 2010 to 2023. We calculated incidence based on suspected cases, case-fatality ratios, and percentage of laboratory-confirmed cases and assessed geospatial trends. Demographic and seasonal trends were investigated using generalised additive mixed models. Findings Between Jan 1, 2010, and Dec 31, 2023, a total of 60 967 suspected cases and 1798 suspected deaths from mpox were reported in DR Congo ( c...

Abstract We present a stochastic metapopulation transmission model that simulates the spread of H5N1 avian influenza through individual dairy cows in 35,974 dairy herds in the continental United States . Transmission is enabled through the movement of cattle between herds , as indicated from Interstate Certificates of Veterinary Inspection (ICVI) data. We estimate the rates of under-reporting by state and present the anticipated rates of positivity for cattle tested at the point of exportation over time. We investigate the likely impact of intervention methods to date on the underlying epidemiological dynamics, demonstrating that current interventions have had insufficient impact , preventing only a mean 175.2 reported outbreaks. Our model predicts that the majority of the disease burden is, as of January 2025, concentrated within West Coast states , due to the network of cattle movements and distribution of the respective dairy populations . We quantify the extent of uncertainty in th...

Abstract The generation time , representing the interval between infections in primary and secondary cases , is essential for understanding and predicting the transmission dynamics of seasonal influenza , including the real-time effective reproduction number (Rt). However, comprehensive generation time estimates for seasonal influenza, especially since the 2009 influenza pandemic, are lacking. We estimated the generation time utilizing data from a 7-site case-ascertained household study in the United States over two influenza seasons, 2021/2022 and 2022/2023. More than 200 individuals who tested positive for influenza and their household contacts were enrolled within 7 days of the first illness in the household. All participants were prospectively followed for 10 days, completing daily symptom diaries and collecting nasal swabs, which were then tested for influenza via RT-PCR. We analyzed these data by modifying a previously published Bayesian data augmentation approach that imputes in...