Search Results (133)

Foot and mouth disease (FMD) is a highly contagious transboundary viral disease affecting livestock, causing significant economic losses. This sero-epidemiological study investigated FMD distribution and associated risk factors in cattle and buffaloes along the Pakistan–Afghanistan border. A total of 800 serum samples were collected from cattle (n = 610) and buffaloes (n = 190) and tested for antibodies against FMD viral structural proteins (SP) and non-structural proteins (NSP) using ELISA. Overall, 35.25% (282/800) of samples were NSP-positive, indicating natural infection. Serotype-specific analysis showed serotype O as the most prevalent (66.1%), followed by serotype A (50%) and Asia-1 (32%). Cattle exhibited higher FMD prevalence (37%; 95% CI: 33–40) than buffaloes (30%; 95% CI: 23–37). Significant spatial variations in SP and NSP Seroprevalence were observed across different areas. Risk factor analysis identified male sex, young age (1–2 years), crossbred and exotic breeds, summer season, large herd size, smallholders subsistence production systems, poor body condition, and animal movement as factors associated with significantly higher (p < 0.05) FMD circulation. These findings indicate that FMD is highly endemic in the border region and highlight the critical need for government-led mass vaccination campaigns, targeted risk-based surveillance, and stringent movement control to mitigate disease spread. Implementation of such control strategies is essential to safeguard livestock health and protect the regional economy from substantial losses. Full article

Oropouche virus (OROV) is an emerging arthropod-borne virus in the Americas that has evolved from a pathogen historically restricted to forest environments into an increasingly important regional and international public health concern. Despite decades of documented circulation, the true burden of OROV infection remains substantially underestimated, largely because of frequent misdiagnosis and the high proportion of asymptomatic or subclinical infections. This review synthesizes current evidence on the historical emergence, epidemiology, transmission dynamics, and clinical features of OROV, with a particular focus on populations at increased risk due to biological susceptibility, environmental exposure, and limited access to healthcare. Drawing on seroepidemiological data, we demonstrate that OROV transmission is far more widespread than routine surveillance suggests and examine how factors such as age, pregnancy, immune status, underlying health conditions, occupational exposure, and healthcare accessibility interact to influence disease risk and detection. Although multiple vaccine platforms have shown promise in preclinical studies, progress toward clinical development remains constrained by limited immunological evidence, shortcomings of available animal models, diagnostic uncertainty, and structural barriers in endemic regions. We propose that future OROV vaccine development prioritize population-specific needs rather than focusing solely on technological platforms, and that effective prevention will require integrating vaccination with strengthened surveillance, improved diagnostics, and equitable delivery systems. Full article

Equine trypanosomosis remains an important veterinary concern in regions where horses play a significant economic and cultural role. In Kazakhstan, comprehensive nationwide data on the seroepidemiological status of equine trypanosomes are limited. The aim of this study was to assess the serological distribution of equine trypanosomosis across all administrative regions of Kazakhstan using complement fixation testing (CFT). A total of 6065 equine serum samples were collected from seventeen regions between 2023 and 2025. Antibodies against members of the Trypanozoon subgenus were detected using a WOAH-recommended CFT protocol. Overall seropositivity was 4.73%, with substantial regional variation ranging from 0% to 16.52%. Statistically significant differences in seroprevalence were observed between regions (p < 0.001), and mixed-effects modelling indicated considerable regional clustering. PCR testing of seropositive samples did not confirm the presence of Trypanosoma equiperdum, while one sample tested positive for Trypanosoma evansi. These findings suggest that CFT seropositivity reflects exposure to equine trypanosomes rather than confirmed dourine infection. Given the inability of CFT to reliably distinguish between T. equiperdum and T. evansi, species-level attribution remains uncertain. This study provides the first nationwide overview of serological reactivity to equine trypanosomes in Kazakhstan. The results highlight regional heterogeneity in antibody detection and underscore the need for expanded molecular surveillance and improved species-specific diagnostic tools to clarify the epidemiological status of equine trypanosomosis in the country. Full article

Background: Measles remains a global public health threat despite the availability of an effective vaccine and substantial progress toward elimination in many countries. Outbreaks in highly vaccinated settings suggest that waning vaccine-induced immunity, particularly among adults, may create silent susceptibility gaps capable of sustaining viral transmission. Aim: To evaluate age- and cohort-specific patterns of measles-specific antibody levels in Mexican adults and to examine evidence suggesting lower vaccine-induced antibody levels in younger vaccinated cohorts. Methods: A cross-sectional seroepidemiological study was conducted among 302 voluntary blood donors aged 18–70 years. Demographic, clinical, and vaccination data were collected through structured interviews. Serum anti-measles-virus (MV) IgG levels were quantified using a commercial ELISA. Antibody concentrations were analyzed according to age, sex, vaccination history, self-reported measles infection, and historical vaccination strategies. Multivariate linear models were applied to identify factors associated with IgG levels. Results: Anti-MV IgG seropositivity (>200 mIU/mL) was 67.2%, with a geometric mean concentration (GMC) of 270.43 mIU/mL. A positive correlation was observed between age and antibody levels (r_s = 0.161, p = 0.005). Individuals born before the introduction of the measles vaccine (pre-1970) had significantly higher GMCs (1096.63 mIU/mL) than younger cohorts. A history of natural infection tended to be associated with higher antibody levels (GMC: 428.38 vs. 257.24 mIU/mL; p = 0.051). In multivariate analysis, historical vaccination strategy emerged as the primary factor associated with antibody levels, whereas age alone was not significant. Conclusions: Cohort-specific differences in measles IgG levels suggest generational patterns of immunity and are consistent with diminished vaccine-induced antibody levels in younger adults in the absence of natural boosting. These findings highlight the importance of ongoing serological surveillance in post-elimination settings and underscore the need for targeted public health interventions. Full article

Background/Objectives: Tick-borne encephalitis (TBE) is the most important tick-borne viral central nervous system (CNS) infection in Europe and Asia. Since the introduction of a vaccine in Austria in the late 1970s, sero-epidemiological studies on the true incidence of tick-borne encephalitis virus (TBEV) infection in the population have been difficult, because it was not possible to distinguish between vaccine- and infection-induced antibodies. The goal of our study has been to analyze the sero-epidemiology of TBEV infections, vaccination protection rate, and manifestation index of the disease in the region of interest. Methods: Applying a newly developed anti-TBEV-NS1-IgG assay and the neutralization test, the protection and infection rates in blood donors of the Austrian Federal State of Upper Austria.It is one of the first areas in Austria, where the TBEV vaccine had been rolled out and broadly used. Samples from blood donors of all districts of the Federal State of Upper Austria were screened for anti-TBEV-IgG. Positive sera were differentiated for infection- and vaccine-induced antibodies. The results were matched with donor age, gender, and geographical origin. Results: 2162 samples were analyzed. A total of 87.0% of the blood donors tested showed anti-TBEV-IgG related to past TBEV vaccination. Within the unvaccinated group, a total of 13.3% of male and 9.9% of female blood donors exhibited anti-TBEV-NS1-IgG, indicating a past TBEV infection. The anti-TBE-NS1-IgG seroprevalence was determined at 74/100,000 for the whole population and at 594/100,000 in the non-vaccinated population. The manifestation index (MI) was calculated at 2.8%. The MI is defined as the probability or percentage of infected individuals who develop clinical symptoms of a disease. Conclusions: Our data provide evidence of a continuing high risk of TBEV infection in the Federal state of Upper Austria. The non-vaccinated population has an eightfold higher infection prevalence compared to the whole population. The MI of TBEV for severe infection seems lower as detailed in previous reports. Full article

Background: Rickettsioses disproportionately affect vulnerable populations and are frequently misdiagnosed as other febrile illnesses in Yucatan, the Mexican state with the greatest diversity of Rickettsia spp. Although significant seroprevalence has been reported in rural communities, the last population-based study was conducted over two decades ago, despite environmental and social changes that have likely increased transmission risk. This study aimed to estimate the seroprevalence of spotted fever group (SFG) and typhus group (TG) of Rickettsia in an endemic area of southeastern Mexico. Methods: A cross-sectional analytical study was conducted among 390 participants. Indirect immunofluorescence was used to detect IgG antibodies against SFG and TG of Rickettsia. Sociodemographic characteristics of participants, along with environmental and community-level variables from their regions of residence, were analyzed. Results: The overall seroprevalence of both Rickettsia groups was 31.2%. Higher maximum temperatures were associated with an increase in Rickettsia seroprevalence (PR = 4.18; 95% CI: 3.40–5.14), while higher population density was associated with a decrease in seroprevalence (PR = 0.97; 95% CI: 0.96–0.98). Conclusions: Rickettsia seroprevalence in Yucatan remains high and is shaped by both environmental and demographic factors. These findings highlight the need to strengthen surveillance and prevention strategies that integrate ecological and social determinants within a One Health framework. Full article

Hepatitis E virus (HEV) is an important cause of acute and chronic hepatitis worldwide, transmitted primarily through waterborne exposure and zoonotic foodborne pathways. In recent years, shellfish have attracted growing attention as a potential vehicle for HEV transmission. This interest is driven by epidemiological observations linking shellfish consumption to human HEV infection and by repeated detection of HEV RNA in bivalve mollusks across multiple geographic regions. This review critically evaluates the current evidence by integrating epidemiological data, environmental and food surveillance studies, and mechanistic insights into viral accumulation in shellfish. Signals from outbreak investigations, observational studies, seroepidemiological surveys, and case reports suggest that shellfish may contribute to HEV exposure. However, these findings are largely associative, methodologically heterogeneous, and limited by the absence of explicit documentation of raw or undercooked shellfish consumption in many cases. To date, no study has recovered infectious HEV from shellfish, nor has any established molecular epidemiological linkage between shellfish-derived HEV and human infections. Mechanistic knowledge from norovirus and hepatitis A virus demonstrates that bivalves can bioaccumulate enteric viruses through filter feeding, yet HEV-specific processes governing viral binding, persistence, and infectivity within shellfish remain poorly defined. Surveillance data reveal marked geographic variation in HEV RNA detection among shellfish species and production areas. Overall, existing evidence supports shellfish as a biologically plausible but unconfirmed source of HEV exposure. Addressing key knowledge gaps—particularly through direct infectivity assessments and high-resolution molecular linkage studies—will be essential to determine the public health significance of shellfish within the broader ecology of HEV transmission. Full article

We assessed the prevalence of three helminthic zoonoses—echinococcosis, fasciolosis and the taeniosis/cysticercosis complex—among residents of the Chucuito Health Network (Puno Health Region, Peru) over four years (2018–2021). Sera (n = 910) were analysed by ELISA to detect pathogen-specific antibodies, following national protocols. Echinococcosis predominated, whereas fasciolosis and taeniosis/cysticercosis occurred at comparatively low levels. Prevalence ranged from 4.4–9.2% for echinococcosis, 1.1–4.9% for fasciolosis, and 1.1–2.7% for taeniosis/cysticercosis across the four years. Prevalence varied significantly between years, with a notable upsurge in echinococcosis in 2021. These findings underscore the need for integrated control and prevention measures grounded in a One Health framework that recognises the interconnections between human, animal and environmental health. Priority actions include strengthened health education programmes, improved hygiene and sanitation practices, and enhanced rural health infrastructure, alongside coordinated epidemiological surveillance and environmental management. Such measures are essential to mitigate the burden of zoonotic disease in vulnerable high-Andean communities. Full article

Introduction: Seroprevalence of antibodies for vaccine-preventable diseases (VPDs), due to vaccination or previous infection, can provide a more accurate estimate of immunity compared to vaccination coverage data alone. This study aimed to examine the seroepidemiology and spatial distribution of VPD seroprevalence in Samoa in 2018 and 2019. Methods: Dried blood spot (DBS) samples were collected from two nationally representative community-based surveys of participants aged ≥5 years from the Surveillance and Monitoring to Eliminate Lymphatic Filariasis and Scabies from Samoa (SaMELFS) project. DBSs were tested using multiplex bead assays (MBAs) to detect antibodies against measles, rubella, diphtheria, and tetanus. Seroprevalence was estimated at the national and primary sampling unit (PSU) levels, and cluster analysis was completed using SaTScan. Results: Overall, 8394 valid MBA results were analysed across 35 PSUs. The highest overall seroprevalence was observed for tetanus (91.0%; 95% CI: 90.2–91.7), followed by diphtheria (83.7%; 95% CI: 82.7–84.7), rubella (79.3%; 95% CI: 78.2–80.3), and measles (45.8%; 95% CI: 44.8–46.9) with substantial heterogeneity across PSUs. Clusters of seronegativity to measles (relative risk [RR]: 1.16, p < 0.001) and diphtheria (RR: 1.16, p < 0.001) were also identified. Conclusions: These findings demonstrate significant variation in seroprevalence and pockets of low population immunity to multiple VPDs, highlighting the key advantage of an integrated rather than siloed approach. The relatively high seroprevalence to rubella suggests potential community transmission, emphasising the need to strengthen congenital rubella surveillance and improve vaccination coverage. Identifying low immunity to VPDs can provide an early warning to potential outbreak risk and support the Ministry of Health to target public health interventions in higher-risk areas. Full article

Oz virus, an emerging tick-borne thogotovirus, has been reported to cause fatal human infection in Japan. However, its ecology and geographic distribution remain largely unknown. In this study, we developed a double-antigen sandwich enzyme-linked immunosorbent assay (DAgS ELISA) for detecting Oz virus antibodies in animals and used it to conduct a seroepidemiological survey of wild boars (Sus scrofa) in Miyazaki Prefecture, Japan. Recombinant Oz virus nucleoprotein was expressed in E. coli and used as both the capture and detection antigen. Relative to the neutralization test, the DAgS ELISA showed a sensitivity of 72.2%, a specificity of 88.2%, and an overall concordance rate of 79.0%. We used this assay to examine 1045 wild boar serum samples collected between November 2022 and May 2025, finding a seroprevalence of 33.5%. The seroprevalence did not significantly differ by sex, age, or region, but showed significant seasonal variation, peaking in summer (p < 0.0001). Oz virus RNA was detected by quantitative RT-PCR in one serum sample (0.09%). Phylogenetic analysis of the partial Oz virus glycoprotein gene showed that this strain shared 98.8% nucleotide identity with the EH8 strain, which was the first Oz virus isolate obtained from ticks in Ehime Prefecture. These findings suggest that wild boars in Miyazaki are frequently exposed to Oz virus and that ticks in the region harbor the virus. However, no human cases have been reported to date. The DAgS ELISA developed in this study provides a practical tool for serological surveillance in animals. Continuous monitoring of animal populations is warranted to clarify the epidemiology of Oz virus in the region and to identify potential reservoir species. Full article

Background/Objectives: Understanding the seroepidemiology of P. falciparum antibody responses is essential for assessing the acquisition of natural immunity and may guide interventions that impact the acquisition of immunity against malaria in endemic areas. This study assessed the association between antigen-specific IgG responses and protection against P. falciparum infection in children from Burkina Faso. Methods: Children aged 1.5 to 12 years were followed using cross-sectional and longitudinal approaches. IgG responses to 16 P. falciparum antigens were measured using a multiplex assay and analyzed by age group and malaria infection status. Associations between antibody levels and clinical malaria risk were assessed using incidence rate ratios (IRRs), and predictive performance of antibody combinations was evaluated using ROC analysis. Results: IgG responses to AMA1, CSP, and MSP2 CH150 showed weak but significant positive correlation with age. Children aged 5–12 years had higher antibody levels than younger children aged 1.5–5 years. Uninfected children had higher levels of antibodies to EBA181 RIII-V, Rh5.1, and SEA1, while infected children had elevated AMA1 and MSP2 CH150. Anti-GLURP R2 and anti-Rh5.1 antibodies were associated with reduced malaria risk (adjusted IRR = 0.52 and 0.40, respectively). The antibody combination of AMA1, GLURP R2, and Etramp5 Ag1 showed the best predictive performance (AUC = 0.70). Conclusions: This study underlines the value of less-studied antibodies (Etramp5 Ag1, Rh5.1, HSP40 Ag1) for diagnosing and protecting against malaria, opening up prospects for the development of more effective tests and targeted vaccine approaches. The variability of responses according to age and infection status calls for further studies to optimize prevention strategies. Full article

Oz virus (OZV), an emerging negative-sense single-stranded RNA virus classified under the family Orthomyxoviridae and genus Thogotovirus, was first isolated from Amblyomma testudinarium ticks in Ehime Prefecture, Japan, in 2013. Moreover, a single fatal case in an elderly individual, suspected to be associated with OZV infection, was reported in Ibaraki Prefecture in 2023. Given these circumstances, this study was conducted to investigate the molecular epidemiology and seroepidemiology of OZV in Ibaraki Prefecture, Japan. From April to November 2023, a total of 2430 ticks were collected at 19 sites. The OZV RNA was detected in one A. testudinarium nymph. Additionally, among 934 wild boar serum samples collected between 2019 and 2023, one sample tested positive for OZV RNA. Neutralizing antibody assays revealed that 243 samples (26.0%) obtained from wild boars were seropositive, indicating widespread exposure among wild boars. Antibody prevalence and titers were highest in the central–western mountainous region, suggesting an active transmission hotspot. Sequence analysis of the OZV viral RNA detected from one tick sample and one wild boar serum revealed that a 212 bp fragment of segment 4 and a 261 bp fragment of segment 5 were 100% identical to a human-derived strain isolated in the same prefecture, suggesting the circulation of a single viral lineage within the local environment. These findings represent the first report demonstrating the circulation of OZV in the natural environment in Ibaraki Prefecture, implicating A. testudinarium as the principal vector and wild boars as a potential source of OZV infection These results suggest that OZV should be considered a potential emerging zoonotic pathogen. Further seroepidemiological studies among residents are warranted to assess the risk of human infection in the region. Full article

Brucella canis is a neglected zoonotic pathogen associated with canine reproductive disorders and emerging public health concerns. This study presents the first nationwide systematic review and meta-analysis of Brucella spp. in Portugal, integrated with a 13-year retrospective seroepidemiological investigation (2013–2025) of B. canis in dogs across mainland Portugal and Insular Autonomous Regions. Among 132 canine serum samples, a seropositivity of 23.48% was observed using an immunochromatographic assay confirmed by indirect immunofluorescence (IFAT). Significant associations were identified with seasonality (p < 0.001) and breed (p = 0.001), while sex and age were not statistically significant. Municipal-level analysis revealed marked heterogeneity, with Trofa showing the highest seropositivity (58.82%) and a pooled odds ratio of 11.28 (95% CI: 2.90–43.94; p < 0.001). In parallel, meta-analyses of published data estimated a pooled seroprevalence of 2.42% in animals (95% CI: 1.79–3.13) and 10.57% in humans (95% CI: 8.80–12.47), underscoring the broader burden of Brucella spp. exposure in Portugal. These findings suggest underdiagnosis of canine brucellosis and highlight the need for enhanced surveillance in high-risk breeds and regions. The study reinforces the importance of integrated One Health strategies to improve early detection, control, and prevention of B. canis infection in both veterinary and public health contexts. Full article

Leptospirosis is a zoonotic disease caused by Leptospira spp., with over 250 serovars classified into 24 serogroups. Control measures depend on understanding serovar-specific epidemiology, yet the microscopic agglutination test (MAT) is only serogroup specific, and classification is complicated by cross-reactivity. While MAT is the reference standard for leptospirosis serodiagnosis and seroepidemiological studies, factors influencing serogroup cross-reactivity remain poorly characterized. We investigated the relationship between age, antibody titer, and serogroup diversity among seropositive individuals in a population-based serosurvey in the Dominican Republic. Between June and October 2021, we conducted a multistage national serosurvey, enrolling 6683 participants across 134 clusters. MAT was performed on sera from 2091 participants in two provinces using a 20-serovar panel. MAT positivity was defined as titers ≥ 1:100. Generalized Additive Models were used to assess associations between age, maximum titer, and serogroup diversity. Of 2091 tested samples, 237 (11.3%) were seropositive. Older individuals and those with higher titers reacted to a greater number of serogroups (p = 0.005 and p < 0.0001, respectively). However, mean maximum titer decreased with age, suggesting that broader serogroup reactivity in older individuals reflects cumulative exposure rather than higher titers. Maximum titer was the strongest predictor of serogroup breadth, while gender, study region, and urban/rural setting were not significant. Overall, our findings demonstrate that serogroup cross-reactivity in MAT was significantly influenced by antibody titer and prior exposure, with older individuals displaying broader serogroup reactivity despite lower titers. These findings highlight key considerations for interpreting MAT results in seroepidemiological studies and underscore the limitations of MAT in serogroup-level classification. Full article

Due to possible congenital infections, cytomegalovirus (CMV) remains a significant public health concern in childbearing-aged and pregnant women. We analyzed the spatial, temporal, and age-related trends in CMV seroepidemiology in Croatia over 10 years. A total of 2838 childbearing-aged and pregnant women, aged 16–45 years, tested between 2015 and 2024 were included in the study. CMV IgM/IgG antibodies were detected using a commercial ELISA. IgM/IgG-positive samples were tested for IgG avidity. CMV IgG antibodies were detected in 2006 (70.6%) of participants. No significant differences were observed between 2015–2019 and 2020–2024 (72.0% vs. 69.8%), while yearly differences were of borderline significance, ranging from 62.4 to 77.3%. The overall seropositivity increased progressively with age from 49.6% in the 16–20 age group to 77.5% in the 36–40 age group. Significant regional differences in IgG seroprevalence were observed: 68.6% in the City of Zagreb/Northern Croatia, 78.5% in Pannonian Croatia, and 71.9% in Adriatic Croatia, while differences between settlement types were not significant. IgG seroprevalence was higher in women with an unfavorable obstetric history (85.3%) than in non-pregnant women and those with a normal pregnancy (70.6% and 66.5%, respectively). IgM antibodies were detected in 278 (9.8%) of participants. Acute infections were more common in younger participants, with rates decreasing from 13.6% in the youngest age group to 6.7% in the oldest. Logistic regression showed that age was a significant predictor of both IgG and IgM positivity. Region and obstetric history were significant predictors of IgG seropositivity, while settlement was a significant predictor of IgM seropositivity. Full article