Articles from Emerging Infectious Diseases

The global resurgence of measles is a major public health concern. After the success of its Expanded Programme on Immunization, Bangladesh experienced a measles resurgence in 2026. The country faced major setbacks after measles vaccination coverage declined because of political instability, discontent among field-level staff, change in procurement policy, COVID-19–related service disruptions, and delayed supplementary immunization campaigns. During March 15–September 13, 2026, Bangladesh reported 170,638 suspected and 20,006 confirmed measles cases, including 919 deaths among suspected and 100 deaths among laboratory-confirmed cases. The outbreak disproportionately affected unvaccinated and underimmunized children. Political turmoil during 2024–2025 disrupted vaccine procurement, delayed mass vaccination campaigns, weakened the health workforce, and compromised financial and logistic continuity. Simultaneously, disruptions in vitamin A supplementation and worsening child malnutrition amplified disease severity. To prevent future resurgence, immunization programs must be depoliticized, supported by buffer vaccine stocks, strengthened through microlevel surveillance, and integrated with nutrition and primary healthcare services.

As measles elimination unravels across the Americas, Europe, and the Western Pacific, Japan is experiencing a resurgence of measles; the World Health Organization had verified elimination of measles in Japan in 2015. By epidemiologic week 20 of 2026, a total of 498 cases had been reported, exceeding every full-year total since 2020. Median case-patient age has fallen to 26 years, shifting the burden from a generation who received single-dose measles vaccinations to younger cohorts caught between successive vaccination-policy transitions. Among case-patients with a documented 2-dose vaccination history, more than half experienced modified measles, an attenuated, easily missed illness that delays diagnosis and isolation. As mass gatherings concentrate global travel, Japan has become a sentinel for the fragility of measles elimination, including in countries that consider elimination status secure. Surveillance shows importation-driven resurgence; the shift in genotype profile from D8 to B3 predominance back to D8 enabled tracking of source countries.

Subacute sclerosing panencephalitis (SSPE) is a delayed, almost uniformly fatal complication of measles. The Philippines had measles outbreaks in 2010–2011, 2013, and 2018–2019; the last was the largest in the World Health Organization Western Pacific Region. Published SSPE data from the Philippines end in 2015. We reviewed all 20 children admitted with SSPE to a tertiary pediatric hospital in Quezon City during 2007–2022 and estimated year of measles infection. Median patient age was 6.2 years at hospital admission and 0.7 years at reported measles illness. Five (25.0%) of 20 admissions occurred in 2022, and estimated infection dates placed 4 patients within the 2018–2019 outbreak; all were admitted during 2020–2022. Given the multiyear latency of SSPE, additional cases might emerge over coming years. Reported measles history could not be established in one quarter of patients. Strengthened measles surveillance and sustained 2-dose vaccination coverage are needed.

Metastatic infection after Candidozyma auris candidemia remains poorly characterized. We retrospectively studied patients with C. auris candidemia at a tertiary hospital in Spain during 2016–2024. Of 108 patients, 24 (22.2%) experienced metastatic infections; endocarditis was most frequent (7.4%), followed by osteoarticular infection, meningitis, and hepatosplenic infection (3.7% each). In multivariable Fine–Gray regression, a cardiac device or prosthetic valve was independently associated with metastatic infection (subdistribution hazard ratio [HR] 2.89 [95% CI 1.21–6.91]), although that association was attenuated in a sensitivity analysis restricted to echocardiographed patients. Persistent candidemia showed a higher, nonsignificant risk for metastatic infection in the day-5 landmark analysis (subdistribution HR 2.67 [95% CI 0.86–8.32]). Metastatic infection was associated with increased deaths in time-dependent analyses at 60 days (adjusted HR 2.21 [95% CI 1.04–4.67]) and 90 days (adjusted HR 2.26 [95% CI 1.09–4.67]). Our findings support echocardiography in patients with intracardiac devices.

Middle East respiratory syndrome coronavirus (MERS-CoV) is a persistent zoonotic and epidemic threat. We analyzed 807 publicly available human- and camel-derived MERS-CoV genomes collected during 2012–2024 to assess global genomic surveillance. Most sequences originated from Saudi Arabia and the United Arab Emirates. Major gaps in surveillance persist across Africa and South and Central Asia despite large camel populations, active trade, and evidence of viral circulation. Phylogenetic analysis confirmed predominance of clade B in the Arabian Peninsula and clade C in East Africa, consistent with regional patterns. We identified uneven sampling, incomplete metadata, and long delays between sample collection and public sequence submission, often spanning years. Those limitations reduce the value of genomic data for timely situational awareness. Integrating genomic with population and trade data supports timelier, more representative, and coordinated One Health surveillance for MERS-CoV but reveals major blind spots.

Post–COVID-19 pandemic Mycoplasma pneumoniae resurgences have occurred globally and have been particularly severe in Taiwan. We conducted a multicenter study to assess M. pneumoniae trends in children. Compared with the 2019 peak, 2024 data revealed a doubling of incidence (546/100,000 population), a 2.2-fold increase in intensive care unit admissions (10.9/100,000 population), and a 13.7-fold surge in central nervous system complications (6.1/100,000 population). In a 2023–2024 prospective cohort (n = 226), intensive care unit admission risk factors were neutrophils >7,000/μL (adjusted odds ratio [aOR] 6.2 [95% CI 1.3–29.9]), platelets >400 × 10³/μL (aOR 12.5 [95% CI 2.7–57.9]), pleural effusion (aOR 9.7 [95% CI 1.6–58.1]), and central nervous system involvement (aOR 27.9 [95% CI 4.1–188.3]). Phylogenetic analysis of 698 genomes demonstrated that 4 emerging subclades replaced pre–COVID-19 lineages by mid-2024; 1 subclade was associated with severe outcomes, highlighting evolving resistant, neurotropic lineages and calling for enhanced surveillance.

Accurate knowledge of microbial etiology is essential for optimizing spinal fusion surgical site infection (SSI) management, yet contemporary national data in the United States, particularly prevalence and factors associated with gram-negative infections, remain poorly understood. We conducted a cross-sectional analysis of US data reported to the Centers for Disease Control and Prevention National Healthcare Safety Network (2021–2022) to characterize the microbiology of spinal fusion SSI and identify factors associated with gram-negative infection. Among 7,187 cases, gram-negative organisms caused 31.5% (n = 2,265) of SSIs. Older age, female sex, higher body mass index, longer operative times, higher American Society of Anesthesiologists class, lumbar involvement, inpatient surgery, and emergent and trauma surgeries were independently associated with gram-negative infections relative to monomicrobial Staphylococcus aureus infections. Our findings might inform future studies focusing on high-risk cohorts as targets for expanded gram-negative prophylactic regimens. Clinicians can use risk profiles to guide empiric gram-negative antibiotic coverage in treating SSIs.

We conducted a retrospective, population-based laboratory surveillance study during May 2023–December 2025 in Alberta, Canada, to characterize adult invasive enterovirus and parechovirus infections and to identify groups at high risk for those infections. Of 15,621 samples tested, 162 (1.0%) were virus positive, of which 51 (31.5%) samples from 39 patients indicated invasive infections. Cerebrospinal fluid, blood, and cardiac tissue were the most frequent virus-positive specimens. The invasive enterovirus and parechovirus incidence rate was 0.37 cases/100,000 person-years; rates were higher in patients <50 versus >50 years of age (incidence rate ratio 8.2; p<0.001). The annual incidence rates were 0.20–0.56 cases/100,000 person-years; rates appeared higher in 2025 than in 2024 (incidence rate ratio 2.1; p = 0.11). Severe disseminated enterovirus infection occurred in 2 patients who received ocrelizumab. Continuous surveillance and ongoing optimization of enterovirus and parechovirus detection assays is essential for comprehensive public health tracking.

Hypervirulent Klebsiella pneumoniae (hvKp) is an emerging cause of invasive infection, but clinical relevance of a 5-biomarker genotypic definition remains unclear. We analyzed 207 episodes of K. pneumoniae bloodstream infection at a tertiary hospital in Japan during 2022–2024. We defined hvKp by PCR detection of all 5 biomarkers: rmpA, rmpA2, iucA, iroB, and peg-344. Overall, hvKp accounted for 14% (28/207) of episodes. Abscess complications occurred in 61% (17/28) of hvKp episodes and 13% (23/179) of classical K. pneumoniae episodes. hvKp case-patients had longer median hospitalization (28 vs. 14 days) and duration of antimicrobial drug treatment (43 vs. 14 days) than those with classical K. pneumoniae. Most (9/10) sequence type 23 hvKp episodes involved abscesses. Short-read whole-genome sequencing detected CTX-M–type extended-spectrum β-lactamase genes in 11% (3/28) of hvKp isolates, representing 1.4% (3/207) of all K. pneumoniae episodes. The 5-biomarker definition delineated a clinically distinct subgroup, demonstrating its value for genomic surveillance of emerging hvKp.

Of 1,289 measles case-patients during April 2025–March 2026 in Jerusalem, Israel, 11 children died, a measles-specific mortality rate of 1.1 deaths/100,000 population. The measles-specific mortality rate among children <5 years of age was 7.7 deaths/100,000 population but 80.1 deaths/100,000 population in 6 neighborhoods populated by ultraorthodox Jews, a 47% measles-attributed death fraction.

We evaluated the probability of needing public health actions against trachoma in Esmeraldas Province, Ecuador, by estimating seroconversion rates of Chlamydia trachomatis plasma gene protein 3 IgG in children. Seroconversion rates suggest high probability of the need for public health interventions in rural communities and motivate further assessment.

Cross-reactive SARS-CoV-2–specific antibodies could compromise the specificity of MERS-CoV serology, potentially leading to misclassification of infection history. SARS-CoV-2 exposure induced MERS-CoV antibodies primarily targeting the conserved S2 domain, with occasional neutralizing capacity. Combining MERS-CoV S1 binding with neutralization, however, limited the influence of SARS-CoV-2–induced cross-reactivity on MERS-CoV serology.

Highly pathogenic avian influenza A(H5Nx) viruses, particularly clade 2.3.4.4b, pose substantial global health risks. We combined and piloted 2 duplex reverse transcription digital PCRs to discriminate between avian and seasonal influenza viruses in wastewater. This approach enabled rapid, strain-specific detection to reduce ambiguity in environmental surveillance for influenza viruses.

We report 2 cases of asymptomatic Dirofilaria microfilaremia in humans in Sri Lanka, detected during night blood surveillance for lymphatic filariasis in 2025. Partial sequence of microfilarial cytochrome c oxidase 1 gene revealed that both infections were caused by the novel species D. asiatica, originally described in Hong Kong as Candidatus D. honkongensis.

Filarial nematodes cause significant illness worldwide, including lymphatic and subcutaneous filariases in tropical regions. Dirofilaria asiatica is a recently described canine filarioid increasingly implicated in zoonotic human infections. Here, we report a patent infection in a child in Sri Lanka who had persistent microfilaraemia after 2 rounds of diethylcarbamazine treatment.

We describe a fatal Rickettsia parkeri rickettsiosis case in a 3-year-old boy in Georgia, USA, receiving chemotherapy for B-cell acute lymphoblastic leukemia, hospitalized with febrile neutropenia. Plasma microbial cell-free DNA sequencing confirmed the diagnosis. This report highlights the need to maintain suspicion for tickborne diseases in immunocompromised hosts in some settings.

We evaluated the transmission dynamics of dengue virus (DENV) during 2010–2025 in Ceará State, Brazil. Ceará has been a dengue hyperendemic region, where all 4 DENV serotypes co-circulate, predominantly DENV-1 and DENV-2, and where DENV-3 was recently reintroduced. Our findings provide an epidemiologic baseline for postlicensure dengue vaccine evaluation.

We analyzed 919 Streptococcus pyogenes isolates from laboratory-confirmed streptococcal toxic shock syndrome cases in Japan during 2023–2024. Post–COVID-19 resurgence was driven by expansion of M1_UK (49.8%) and emerging M1_13SNPs (37.4%) lineages, replacing ancestral M1_global. M1_13SNPs were associated with younger patient age and higher death rates in unadjusted analyses.

In 2025, a respiratory disease outbreak occurred among camels in Kazakhstan. We detected Middle East respiratory syndrome coronavirus by using quantitative reverse transcription PCR in 38 symptomatic camels, demonstrating active circulation in Central Asia. Our findings highlight the need for enhanced surveillance to assess zoonotic transmission risk.

Whole-genome sequencing strengthens tuberculosis surveillance, but incomplete lineage schemes can misclassify isolates. We developed Pathotypr, an alignment-free tool for assemblies and reads, using 2,145 markers derived from 26,813 genomes. Across 88,071 samples, Pathotypr improved concordance, expanded uncommon lineage coverage, and detected resistance markers, supporting molecular epidemiology and public health surveillance.

We detected influenza A virus antibodies in plasma collected from East Greenland polar bears during subsistence hunts in 2024 (3/14 [21%]) and 2025 (6/14 [43%]). Four bears from 2025 had antibodies for the globally emerging highly pathogenic avian influenza virus H5 clade 2.3.4.4b, consistent with survival after exposure.

We report on an immunocompromised patient in southeast France who sought care for fever, knee arthritis, and skin erythema. Blood and joint samples were positive for Spiroplasma turonicum, an intracellular gram-negative bacterium generally found in plants, insects, and ticks. Clinicians should be aware of possible S. turonicum infection in immunocompromised patients.

A renal transplant recipient in India receiving trimethoprim/sulfamethoxazole prophylaxis experienced fever, hemoptysis, and neurologic deficits. The diagnosis was pulmonary aspergillosis and disseminated nocardiosis caused by trimethoprim/sulfamethoxazole–resistant Nocardia. Antimicrobial drug therapy led to complete clinical and radiological resolution after 6 months. This case highlights a resistant breakthrough Nocardia pathogen in a transplant recipient.

The results of an outbreak investigation of pneumonic plague conducted in the plague-endemic district of Fenoarivobe, Madagascar, revealed a familial cluster of plague. Transmission was aided by intrahousehold contact or gatherings and was amplified by delayed plague treatment, highlighting the need for early diagnosis and rapid initiation of appropriate therapy.

Nationwide surveillance in Bangladesh during April 2–May 27, 2026, identified a total of 67,079 suspected and 8,834 confirmed measles cases across 8 administrative divisions. Among suspected cases, 472 deaths were reported, and 88 deaths were reported among confirmed cases. Despite high reported vaccine coverage, transmission persisted amid residual immunity gaps. Vaccine stockouts, discontinued vaccination campaigns, and coverage overestimation likely contributed to Bangladesh’s largest recorded measles outbreak.

Crimean-Congo hemorrhagic fever (CCHF) during pregnancy is associated with severe maternal and fetal complications, but evidence remains limited to heterogeneous case reports. We synthesized patient-level data from published and unpublished cases identified through systematic database searches and direct collaboration with centers in CCHF-endemic areas. We harmonized patient-level clinical, laboratory, obstetric, treatment, and outcome data for 55 pregnancies. The maternal mortality rate was 28.8% (15/52), and fetal loss occurred in 57.4% (31/54) of cases. Maternal mortality rates increased with advancing gestation, reaching 31.3% in the third trimester, but fetal loss was highest (85.7%) in the first trimester. Ribavirin treatment during the third trimester was associated with lower observed maternal mortality rates (odds ratio 0.33, 95% CI 0.13–0.84; p = 0.031). Our findings highlight gestational age–specific risks of CCHF and support the need for standardized management protocols and strengthened CCHF surveillance during pregnancy in endemic regions.

Western equine encephalitis virus (WEEV) reemerged in Argentina during 2023–2024, raising public health concerns and posing a potential threat to blood transfusion safety. We assessed the effect of WEEV circulation on the blood supply by implementing responsive, community-informed interventions within a regional hemovigilance system, including epidemiologic mapping, enhanced donor selection criteria, and alphavirus-specific nucleic acid testing. Among 637 donors residing in outbreak-affected areas, we detected 1 asymptomatic viremic donor. Phylogenetic analysis showed that the viral sequence clustered within the contemporary South American outbreak lineage, consistent with ongoing regional transmission. Those findings demonstrate silent WEEV circulation among blood donors and highlight the critical role of donor surveillance as a sentinel system for emerging arboviruses. Hemovigilance provides valuable insights into viral circulation in the broader population, underscoring the need to integrate molecular surveillance into routine blood bank practices to strengthen transfusion safety and public health preparedness.

Trichinella spp. nematodes are parasites that can cause trichinellosis in humans after consumption of infected, undercooked meat. A November 2024 trichinellosis outbreak in western North Carolina, USA, resulted in 3 cases (2 probable, 1 confirmed), all linked to undercooked bear jerky. In total, 6 persons consumed the implicated meat (attack rate 50%). Molecular testing identified Trichinella spiralis in leftover meat from the same bear. This outbreak provides evidence of changing trichinellosis patterns. Low-cost safety measures and prevention efforts regarding safe wild game preparation are needed to avoid future outbreaks.

Anaplasmosis, an emerging tickborne zoonosis, infrequently involves the central nervous system, and cerebrospinal fluid (CSF) profiles of anaplasmosis remain poorly characterized. We conducted a multisite retrospective study of patients hospitalized with anaplasmosis during November 1, 2014–November 29, 2024, in Minnesota and Wisconsin, USA, a hyperendemic region. Included patients had anaplasmosis confirmed by PCR on blood samples, exhibited neurologic symptoms, and had lumbar puncture procedures. Ten hospitalized patients met inclusion criteria, 6 with meningitis, 3 with meningoencephalitis, and 1 with encephalitis. CSF findings were within reference ranges for 5 patients; 4 patients demonstrated mild lymphocytic pleocytosis, but glucose and protein levels were within reference ranges. One patient underwent a traumatic lumbar puncture resulting in neutrophilic pleocytosis. CSF abnormalities did not correlate with neurologic severity, suggesting a cytokine-mediated process rather than direct central nervous system infection. All patients rapidly improved with doxycycline, highlighting the need for early recognition and empiric therapy for anaplasmosis.

Diagnosis of coccidioidomycosis is challenging and requires a high index of clinical suspicion. We estimated the incidence and duration of, and risk factors associated with, diagnostic delays and missed opportunities in the diagnosis of coccidioidomycosis. We conducted a retrospective analysis of health insurance claims data in the United States during 2001–2022 included in the Merative MarketScan Databases. Using a case-crossover design and a bootstrapping approach, we estimated the number of excess visits for coccidioidomycosis-related symptoms before diagnosis. We also evaluated potential factors associated with delay. We estimated that almost 60% of patients experienced >1 missed opportunity for diagnosis; the average diagnostic delay was 29.69 (95% CI 28.25–31.18) days. Missed opportunities were predominantly observed in outpatient settings (73%) and were significantly associated with older age, rural residence, underlying pulmonary conditions, and prescriptions for antibiotics or inhalers. Diagnostic delays for coccidioidomycosis are common, and addressing such delays could improve clinical outcomes.

Snowshoe hare virus (SSHV) is an arbovirus in the California serogroup known to circulate throughout Canada and northern latitudes of the United States. The clinical spectrum of SSHV infection ranges from asymptomatic or mild febrile illness to neuroinvasive disease; neuroinvasive disease occurs more often in children and young adults. We describe a cluster of confirmed and probable SSHV meningoencephalitis cases in 3 children from Whistler, British Columbia, Canada, in the summer of 2024. We highlight the shared epidemiology, clinical manifestations, serologic diagnostic methods, and outcomes for the cases. All 3 children acquired the infection locally and made a full recovery. This case series suggests underrecognized SSHV infection prevalence that warrants enhanced surveillance and review of existing diagnostic algorithms. California serogroup viruses, including SSHV, should be recognized as a potential cause of neuroinvasive disease in North America during mosquito season, particularly when initial diagnostic testing is inconclusive.

Blastomyces urine antigen testing is a sensitive blastomycosis diagnostic method, but its utility for active case identification during outbreaks is unknown. We evaluated urine antigen testing for identifying blastomycosis cases during a 2023 outbreak at a Michigan, USA, paper mill and assessed demographic and clinical factors associated with test positivity. Approximately 2 months after the outbreak was recognized, we collected work and health information for 603 employees; 95% (n = 578) underwent urine antigen testing and 9% (n = 52) tested positive, including 25 previously undetected cases. Blastomycosis-like symptoms were associated with test positivity (p<0.001), but 10% of employees with positive results were asymptomatic. Recent hospitalization for blastomycosis was associated with test positivity (p = 0.02) and higher antigen levels. Further research into urine antigen testing is needed clarify its suitability for detecting mild and asymptomatic infections during outbreak investigations. Urine antigen testing had high acceptability among employees and effectively identified additional cases.

Reports of ocular manifestations of Lyme disease (LD) are uncommon, and signs and symptoms may be overlooked by physicians. We conducted a retrospective case series of ocular LD reported during 1988–2025. Among 27 published reports in PubMed, we noted that, in 38 cases, the most common ocular manifestation was uveitis, representing 45% of cases, followed by optic neuritis and cranial nerve palsies (including trochlear and abducens). Not all cases met Centers for Disease Control and Prevention surveillance guidelines for LD, given that some case reports were published before the current guidelines. Cases that provided microbiologic proof were 2 anterior uveitis cases, 1 case of anterior uveitis with abducens’s nerve palsy, 1 case of intermediate uveitis, and 1 case of intranuclear ophthalmoplegia. Ocular LD can have a broad variety of manifestations; therefore, physicians should be aware of those manifestations and obtain microbiologic proof for a more definitive diagnosis and epidemiologic value when possible.

Group A Streptococcus (GAS) causes a variety of diseases in humans but is not widely appreciated as a cause of meningitis. During 1997–2022, ten sites participating in the Active Bacterial Core Surveillance network in the United States identified GAS meningitis cases. We calculated annual incidence and case-fatality rates (CFRs) for 320 of those cases and determined antimicrobial resistance by whole-genome sequencing. Annual incidence of GAS meningitis ranged from 0.02 to 0.07 cases/100,000 persons. Children <1 year of age had the highest average annual incidence, 0.23 cases/100,000 children. GAS meningitis had a higher CFR (19.4%) than meningitis caused by group B Streptococcus, Streptococcus pneumoniae, Neisseria meningitidis, or Haemophilus influenzae. Clindamycin resistance among GAS meningitis isolates increased from 3.2% during 1997–2002 to 17.7% during 2018–2022. Clinicians should be aware that meningitis is an uncommon but severe manifestation of invasive GAS and has a higher CFR than more established meningitis etiologies.

A previous study demonstrated noninferior efficacy of 4-month rifapentine/moxifloxacin regimen for tuberculosis (TB) treatment compared with the standard regimen. We analyzed pregnancy outcomes of women who became pregnant during the study. Among 740 women, 97 (13.1%) became pregnant. Of 102 pregnancies (in 97 participants), 30 (29.4%) participants were exposed to study drugs. Fetal loss was reported for 3/13 (23.1%) in the control regimen, 1/9 (11.1%) in the rifapentine/moxifloxacin regimen, and 1/8 (12.5%) in the rifapentine regimen. Among 21 live births in exposed pregnancies (7 in each arm), 1 infant with a congenital anomaly was reported in a participant on the rifapentine regimen. Among women receiving a short rifapentine/moxifloxacin regimen for tuberculosis who became pregnant, we observed no elevated rates of fetal losses or congenital anomalies.