Emerging Infectious Diseases

La Crosse virus (LACV) causes the majority of pediatric arboviral encephalitis cases in the United States, with Ohio historically reporting the highest incidence of LACV neuroinvasive disease (LACV-ND). To identify county-level risk factors, we analyzed two decades (2003-2023) of Ohio surveillance data across all 88 counties using spatial statistical methods. Land-use correlation screening identified deciduous forest cover ({rho} = 0.36, adjusted p = 0.006) and pasture/hay cover ({rho} = 0.37, a...

In November 2025, a traveler from Cuba tested positive for chikungunya virus upon arrival to Mexico. The virus belonged to the East-Central-South-African lineage, clustering with a clade prevalent in Brazil. Ten years after the last chikungunya epidemic in Mexico, strengthened surveillance is required to anticipate transmission of this emergent lineage.

BackgroundAustralia is experiencing its worst syphilis epidemic in decades, driven by two distinct outbreaks -- a heterosexual epidemic disproportionately affecting Aboriginal and Torres Strait Islander communities in northern Australia, and a predominantly MSM-associated epidemic in urban centres. We examined the spatial dynamics of this dual epidemic, including geographic clustering, service accessibility associations, and COVID-19 impacts. MethodsWe analysed publicly available aggregate surv...

BackgroundYellow fever virus (YFV) is transmitted by mosquitoes among humans and non-human primates (NHPs) in South America. The 2024-25 yellow fever (YF) outbreak was notable for its spread into new areas, including the department of Tolima in Colombias Andean region. We investigated the eco-epidemiology of human and NHP YF cases to understand the patterns and drivers of the Tolima outbreak. MethodsWe collected spatiotemporal, sociodemographic, and mortality data on human YF cases in Tolima, a...

Strengthening in-country sequencing capacity generated 28 Lassa virus genomes from human clinical cases, expanding our knowledge of Lassa fever in Guinea. Phylogeographic analysis revealed cross-border exchange between Liberia and the NZerekore region, and a Sierra Leone introduction into the Gueckedou area. Enhanced genomic surveillance is crucial to guide future public health actions.

BackgroundViral hemorrhagic fevers (VHFs) remain a major public health threat in resource-limited settings. The 2014-2016 Ebola virus disease epidemic exposed critical gaps in laboratory preparedness and diagnostic capacity in most-at-risk countries, including Guinea. Sustainable in-country laboratory capacity is essential for early detection and rapid response to VHF outbreaks, including Lassa fever. MethodsA long-term laboratory capacity-strengthening programme was implemented in Guinea, comb...

BackgroundHeartland virus (HRTV) is an emerging tick-borne virus capable of causing severe illness and death. The burden of disease is likely underestimated due to limited seroprevalence studies, lack of commercially available diagnostic tests, and an overlapping clinical syndrome with more commonly diagnosed bacterial diseases such as spotted fever group rickettsiosis or ehrlichiosis. MethodsActive surveillance for Heartland virus disease was conducted at a large academic center from March to ...

Household transmission of EV-D68 was identified in 35 of 1040 households (3.4%) in the Pacific Northwest between 2022-2024, with an estimated secondary attack rate of 15%. Sequences from within households clustered closely with 0 to 2 pairwise nucleotide differences (median 1) between cases 6-14 days apart (median 7).

BackgroundsFollowing an increase in mpox clade Ib cases in several African countries, the World Health Organization recognized mpox as a public health emergency of international concern, highlighting the need for reliable and accessible diagnostic tools. As several mpox clades are co-circulating in endemic countries, the analytical sensitivity of diagnostic assays should be evaluated for all of them in a comparative manner. MethodsThis study evaluated the analytical sensitivity of three rapid t...

We summarize an outbreak of N. gonorrhoeae ST16676 associated with disseminated gonococcal infections (DGIs) in Minnesota, USA in 2025. This novel strain replaced ST11184 as the predominant sequence type circulating among DGI cases in the state, encoded a porB1a allele, and carried a tetracycline resistance gene on a mobilizable plasmid.

Influenza A(H3N2) subclade K virus was detected in Canada early in the 2025/26 influenza season, bearing an antigenic transition in the hemagglutinin (HA) glycoprotein. Analysis of 396 HA sequences from Canada showed antigenic divergence from 2025/26 influenza vaccine strains, consistent with partial mismatch. Phylodynamic analysis revealed sustained pre-vaccine transmission without clear post-vaccine expansion. Phylogenetic and phylogeographic analyses indicated interprovincial mixing within a ...

ObjectiveWest Nile virus lineage 2 (WNV-2) is a growing public health concern in Europe causing West Nile fever or West Nile neuroinvasive disease (WNND) with substantial morbidity and mortality; however, genomic data from Southern Italy are limited despite recent expansion of autochthonous transmission. The aim of the study was to characterise the phylogenetic and molecular features of the WNV-2 strain responsible for the first autochthonous human infection reported in Calabria (2023), and two ...

BackgroundElimination of Plasmodium vivax is challenging due to its dormant liver stages (hypnozoites), which can reactivate weeks or months after the primary infection, causing relapses and ongoing transmission of the parasite. Despite these challenges, P. vivax clinical case numbers have declined over the past decade in Cambodia. We used parasite genotyping to assess whether the decline in case numbers was reflected in parasite diversity and relatedness as a proxy to transmission. MethodsGeno...

BACKGROUNDOn 14 August 2024, WHO Director-General declared a public health emergency of international concern (PHEIC) following a sharp increase in mpox cases linked to the emergence of monkeypox virus (MPXV) clade Ib. We characterise imported and autochthonous cases of MPXV clade I reported in the WHO European Region since August 2024. METHODSBetween 14 August 2024 and 23 November 2025, we collected key information of MPXV clade I infections reported by member states of the WHO European Region...

BackgroundPlasmodium vivax is the predominant cause of malaria in South Asia. P. vivax cases have fallen over the past decade, but cross-border transmission remains a major challenge to elimination. Genetic data can generate valuable insights into transmission; however, until now, only low-resolution data have been available from Nepal, Bhutan and Bangladesh. We piloted high-resolution genotyping using a new microhaplotype (multiallelic) assay to monitor P. vivax transmission across borders. Me...

BackgroundMpox has spread to 35 countries in Africa, yet many face challenges achieving nationwide PCR-based testing due to cost and limited access in remote and rural areas. Point-of-care antigen-based rapid diagnostic tests (AgRDTs) may help improve diagnostic access. ObjectivesTo evaluate the diagnostic accuracy of five mpox AgRDTs manufactured by Beijing Hotgen Biotech (China), Contipharma (Belgium), Hangzhou Testsea Biotechnology (China), Guangdong Wesail Biotech (China), and NG Biotech (F...

We evaluated the BOSCH Vivalytic MPXV assay using serial dilutions of monkeypox virus clade Ib, a new offshoot of clade I identified in 2023. The assay detected viral DNA down to [~]100 copies/mL demonstrating comparable analytical sensitivity to our in-house reference PCR and to other commercial platform-based mpox molecular assays.

Several African countries experienced a surge in acute hemorrhagic conjunctivitis (AHC) cases in 2024. Investigations in Kenya, Mayotte and Tanzania identified coxsackievirus A24 variant (CV-A24v) as the causative agent. To date, limited genomic data exist to elucidate the sources, epidemiology, and evolution of CV-A24v in Africa. We generated 245 CV-A24v genomes from samples collected between January and September 2024 in coastal Kenya. Phylogenetic analysis showed that these viruses belonged t...

The measles outbreak in Jalisco, Mexico (January-February 2026) experienced vigorous sustained transmission with an exponential growth rate = 0.10 (95% CI: 0.10-0.11) per day, doubling time = 6.3 days (95% CI: 6.3-6.9), yielding the effective reproduction number at 3.34 (95% CI: 3.16-3.54), with elevated incidence among infants and young adults.

Individuals with occupational exposure to swine may have disproportionate risk for zoonosis with swine influenza A virus (IAV). To evaluate human antibody responses, sera or plasma from swine veterinarians, swine farm employees, and the general population were tested by hemagglutination inhibition (HI) assays against representative swine and human seasonal influenza vaccine strains. HI data were analyzed by antigenic cartography to assess strain relationships, and reproduction number modeling to...