Search Results (99)

Wildlife serves as a significant reservoir for various pathogens transmissible to domestic animals and humans. Vector-borne diseases represent an increasing concern in Europe, affecting both animal and human health. This pilot study investigated the circulation of endemic and emerging vector-borne viruses in wild ungulates in Hungary, utilizing a One Health approach. Serum samples were obtained from European fallow deer (Dama dama), red deer (Cervus elaphus), and roe deer (Capreolus capreolus) during routine national game management activities between 2020 and 2023. Samples were analyzed for antibodies against the Bluetongue virus (BTV), West Nile virus (WNV), and Epizootic hemorrhagic disease virus (EHDV) using ELISA and neutralization tests. The results revealed a WNV seroprevalence of 22.3% in fallow deer and 31.8% in red deer, while BTV seroprevalence was 2.5% in fallow deer. All samples were negative for EHDV antibodies. These findings confirm the circulation of WNV and BTV in Hungarian wild ungulates. While the study’s design precludes statistical analysis due to non-random sampling, it demonstrates the potential of integrating wild ungulate serosurveillance into disease monitoring programs, leveraging established wildlife management activities for a cost-effective and complementary approach to One Health surveillance, particularly considering the ongoing spread of EHDV in Europe and the importance of BTV serotype monitoring for effective vaccination strategies. Full article

Community-based serosurveillance for emerging zoonotic viruses can provide a powerful and cost-effective measurement of cryptic spillovers. Betacoronaviruses, including SARS-CoV, SARS-CoV-2 and MERS-CoV, are known to infect bats and can cause severe respiratory illness in humans, yet remain under-surveyed in high-risk populations. This study aimed to determine the seroprevalence of betacoronaviruses in an occupational cohort in contact with bats before and after the emergence of SARS-CoV-2. Serum samples from pre- and post-COVID-19 pandemic were screened using antigen-based multiplex microsphere immunoassays (MMIAs) and a multiplex surrogate virus neutralization test (sVNT). Pre-pandemic samples showed no SARS-CoV-2 antibodies, while post-pandemic samples from vaccinated participants displayed binding and neutralizing antibodies against SARS-CoV-2 and a related bat CoV. Furthermore, one participant (1/237, 0.43%) had persistent antibodies against MERS-CoV in 2017, 2018 and 2021 but was seronegative in 2023, despite reporting no history of traveling abroad or severe pneumonia. The observed sustained antibody levels indicate a possible exposure to MERS-CoV or a MERS-CoV-like virus, although the etiology and clinical relevance of this finding remains unclear. Ongoing surveillance in high-risk populations remains crucial for understanding virus epidemiology and mitigating zoonotic transmission risk. Full article

Background/Objectives: This study mapped antibody dynamics across three COVID-19 vaccination rounds (primary course, first, and second booster with BNT162b2) in Belgian nursing home residents (NHRs). Methods: Within a national SARS-CoV-2 serosurveillance study (February 2021–September 2022) across Belgian nursing homes, dried blood spots were collected, on which anti-spike SARS-CoV-2 IgG antibodies were quantified by ELISA in international units/mL (IU/mL). Sociodemographic data were collected at the study start and infection history and vaccination data at each sampling round. Results: Infection-naïve NHRs had low antibody levels after primary course vaccination (geometric mean concentration (GMC) 292 IU/mL, 95% confidence interval (95% CI): 197–432), but increased tenfold after first booster (GMC 2168 IU/mL, 95% CI: 1554–3027). While antibodies among NHRs significantly declined within six months after primary vaccination (p < 0.0001), they remained stable for nine months post-booster (p > 0.05). Among primary vaccine non-responders, 92% (95% CI: 82–97%) developed antibodies after the first booster (GMC 594 IU/mL, 95% CI: 416–849), though tenfold lower than initial responders (GMC 4642 IU/mL, 95% CI: 3577–6022). Conclusions: These findings demonstrate that NHRs require tailored vaccination, prioritizing repeated immunization to improve serological outcomes in poor responders such as infection-naive NHRs. Regular immune monitoring could aid in implementing evidence-based vaccine strategies, ensuring optimal protection for vulnerable populations against SARS-CoV-2 and other infectious threats. Full article

Insect-borne viruses may account for a significant proportion of non-malaria and non-bacterial febrile illnesses in Liberia. Although the presence of many arthropod vectors has been documented, the collective burden of arbovirus infections and baseline pre-existing immunity remains enigmatic. Our goal was to determine the seroprevalence of arbovirus exposure across the country using a resource-sparing, multiplex immunoassay to determine IgG responses to immunodominant antigens. 532 human serum samples, from healthy adults, collected from 10 counties across Liberia, were measured for IgG reactivity against antigens of eight common flavi-, alpha-, and orthobunya/nairoviruses suspected to be present in West Africa. Approximately 32.5% of our samples were reactive to alphavirus (CHIKV) E2, ~7% were reactive separately to West Nile (WNV) and Zika virus (ZIKV) NS1, while 4.3 and 3.2% were reactive to Rift Valley Fever virus (RVFV) N and Dengue virus-2 (DENV-2) NS1, respectively. Altogether, 21.6% of our samples were reactive to ≥1 flavivirus NS1s. Of the CHIKV E2 reactive samples, 8.5% were also reactive to at least one flavivirus NS1, and six samples were concurrently reactive to antigens of all three arbovirus groups, suggesting a high burden of multiple arbovirus infections for some participants. These insights suggest the presence of these four arbovirus families in Liberia with low and moderate rates of flavi- and alphavirus infections, respectively, in healthy adults. Further confirmational investigation, such as mosquito surveillance or other serological tests, is warranted and should be conducted before initiating additional flavivirus vaccination campaigns. The findings of these studies can help guide healthcare resource mobilization, vector control, and animal husbandry practices. Full article

Query fever (Q fever) causes huge economic and agricultural losses through congenital effects such as late abortions, stillbirths, and dead or weak offspring in infected livestock and wildlife. Due to limited data on Q fever in small ruminants (sheep and goats) in South Africa, this cross-sectional study aimed to determine the sero- and molecular prevalence of C. burnetii in small ruminants in farms of the North West province. Testing using ELISA showed a 33.96% seropositivity with no significant risk factors. Molecular detection using PCR showed a 61.11% frequency of detection, with higher detection in goats (36.51%) than in sheep (24.60%). There were significant differences in C. burnetii PCR detection between seasons of the year (p = 0.001). Sequence analysis of PCR products showed similarity to the C. burnetii transposase gene, validating the PCR results. A fair correlation between the ELISA and PCR results was observed, suggesting agreement between serology and PCR detection. This study also shows a high prevalence of C. burnetii by both serology and PCR on farms in the North West province of South Africa. As such, extension of such surveillance programs to other provinces in South Africa, as well as inclusion of C. burnetii detection tests, to resolve abortion or stillbirth cases, need to be considered. Full article

Tick-borne encephalitis virus (TBEV) is an emerging pathogen that initially causes flu-like symptoms and can progress to central nervous system (CNS) infections. Tick-borne encephalitis (TBE) is an endemic disease in southern coastal counties with regular human cases, while the causative agent, TBEV, is prevalent in ticks in most of the coastal regions of Norway. This study was aimed to understand TBEV infection status across Norway including both TBE endemic and non-endemic areas. For this, we analyzed a total of 1940 residual serum samples from 19 counties of Norway (as of 2016). The samples were initially screened by ELISA, followed by virus neutralization tests for TBEV confirmation. We found a similar TBEV seroprevalence of 1.7% in TBE endemic and 1.6% in non-endemic areas. Since TBE cases are only reported from endemic regions, our findings suggest a potential subclinical or asymptomatic infection and underdiagnosis in non-endemic areas. Notably, only 43% of the ELISA-positive samples were confirmed by virus neutralization tests indicating that not all ELISA positives are true TBEV infections. Additionally, 137 samples of patients presenting with symptoms of CNS infections from a non-endemic area were included. Of these samples, 11 ELISA-positive samples were analyzed for cross-reactivity among flaviviruses. Cross-reactivity was detected with Dengue virus, West Nile Virus, and non-specific reactions. This underscores the importance of using multiple diagnostic tests to confirm TBEV infections. None of the patients with CNS infection was found to be TBE positive, and in the whole cohort, we found a low TBEV seroprevalence of 0.7%. Full article

Serological surveillance of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) antibodies is important to monitor population COVID-19 immunity. Dried blood spots (DBS) are a valuable method for serosurveys, particularly in remote settings and in children. We compared the measurement of SARS-CoV-2 spike-specific IgG in paired blood samples collected using standard venepuncture (serum) and the hemaPEN^® microsampling DBS device from children and adults. A total of 83 participants (10 months to 65 years of age), comprising COVID-positive and -negative participants, were recruited. Paired serum and DBS samples were assayed for SARS-CoV-2 receptor-binding domain (RBD) and Spike (S1) antibodies using an established in-house ELISA. RBD and S1 IgG concentrations of paired hemaPEN DBS eluates and serum samples were compared using a non-parametric Wilcoxon matched-pairs signed ranked test. A Pearson’s correlation was used for RBD and S1 IgG concentrations and the level of agreement between the hemaPEN DBS eluates and serum samples was assessed by Bland–Altman analysis. A total of N = 41 adults (36 COVID-positive and 5 COVID-negative), and N = 42 children (37 COVID-positive, and 5 COVID-negative) have paired serum and DBS assayed. We found moderate to strong correlations between paired hemaPEN DBS eluates and serum SARS-CoV-2 IgG antibodies for RBD (r = 0.9472, p < 0.0001) and S1 proteins (r = 0.6892, p < 0.0001). Similar results were observed in both adult and paediatric populations. No significant differences in S1-specific IgG levels were observed in hemaPEN DBS samples stored for up to 35 weeks at room temperature. Eluted hemaPEN samples showed high specificity and sensitivity (100% and 89.89%, respectively) compared with serum. The use of the microsampling hemaPEN device for DBS sample collection is a feasible approach for assessing SARS-CoV-2 antibodies for serosurveillance studies, particularly in remote settings and in children. Full article

Integrated serological surveillance (serosurveillance) involves testing for antibodies to multiple pathogens (or species) simultaneously and can be achieved using multiplex bead assays (MBAs). This systematic review aims to describe pathogens studied using MBAs, the operational implementation of MBAs, and how the data generated were synthesised. In November and December 2023, four databases were searched for studies utilising MBAs for the integrated serosurveillance of infectious diseases. Two reviewers independently screened and extracted data regarding the study settings and population, methodology, seroprevalence results, and operational implementation elements. Overall, 4765 studies were identified; 47 were eligible for inclusion, of which 41% (n = 19) investigated multiple malaria species, and 14% performed concurrent surveillance of malaria in combination with other infectious diseases (n = 14). Additionally, 14 studies (29%) investigated a combination of multiple infectious diseases (other than malaria), and seven studies examined a combination of vaccine-preventable diseases. Haiti (n = 8) was the most studied country, followed by Ethiopia (n = 6), Bangladesh (n = 3), Kenya (n = 3), and Tanzania (n = 3). Only seven studies were found where integrated serosurveillance was the primary objective. The synthesis of data varied and included the investigation of age-specific seroprevalence (n = 25), risk factor analysis (n = 15), and spatial analysis of disease prevalence (n = 8). This review demonstrated that the use of MBAs for integrated surveillance of multiple pathogens is gaining traction; however, more research and capabilities in lower- and middle-income countries are needed to optimise and standardise sample collection, survey implementation, and the analysis and interpretation of results. Geographical and population seroprevalence data can enable targeted public health interventions, highlighting the potential and importance of integrated serological surveillance as a public health tool. Full article

Reproducibly assessing malaria exposure is critical for force health protection for military service members deployed to malaria-endemic regions as well as for civilians making public health decisions and evaluating malaria eradication efforts. However, malaria disease surveillance is challenged by under-reporting, natural immunity, and chemoprophylaxis, which can mask malaria exposure and lead to an underestimation of malaria prevalence. In this study, we determined the feasibility of using a serosurveillance-based approach to measure Anopheles vector exposure, Plasmodium sporozoite exposure, and blood-stage parasitemia using a multiplex serological panel. We tested post-deployment samples obtained from U.S. service members returning from regions with malaria risk to assess the potential of this serosurveillance panel. The results identified that some service members had anti-CSP antibody levels comparable to those found in endemic populations, suggesting exposure to sporozoites while those individuals were on chemoprophylaxis. We also observed isolated cases of anti-MSP1 levels that were as high as those observed in endemic populations and in CHMI studies, suggesting possible cases of clinical or subclinical parasitemia. The study demonstrated the feasibility of implementing a multiplex serology approach for conducting serosurveillance for Anopheles vector exposure and Plasmodium parasite exposure in samples collected following military deployments and its potential to support public health policies. Full article

Bluetongue (BT) is considered endemic in the southern states of India, with sporadic incidences reported from the northern, western and central parts of India. However, the eastern and north-eastern states of India have not experienced active disease so far. In the recent past, an extensive sero-epidemiological investigation was carried out in the eastern and north-eastern Indian states. With the aim of getting updated and refined estimates of positivity rates, the sero-surveillance data were analyzed using the Markov chain Monte Carlo (MCMC) method to calculate the positivity rates of various species across different states and agro-climatic zones. The posterior positivity distribution helped in accurately estimating the seroprevalence of bluetongue virus (BTV) among different species and regions. The MCMC method was applied for the first time in a BTV seroprevalence analysis that enhanced our understanding of infection dynamics, guided targeted interventions and supported better decision-making in bluetongue disease control, prevention and disease preparedness. This exercise is quite pertinent in the context of the recent upsurge of newer BTV strains, e.g., BTV-3 and BTV-8, in the western world. In short, as a powerful computational tool, MCMC could be used for accurate seroprevalence estimation, species-specific insights, regional analysis, enhanced decision-making and epidemiological insights for bluetongue. Full article

A newly formatted enzyme-linked immunosorbent assay (ELISA) for the detection of antibodies to bluetongue virus (BTV) was developed and validated for bovine and ovine sera and plasma. Validation of the new sandwich ELISA (sELISA) was achieved with 949 negative bovine and ovine sera from BTV endemic and non-endemic areas of Australia and 752 BTV positive (field and experimental) sera verified by VNT and/or PCR. The test diagnostic sensitivity (DSe) and diagnostic specificity (DSp) were 99.70% and 99.20%, respectively, for bovine sera, and 97.80% and 99.50%, respectively, for ovine sera. Comparable diagnostic performances were noted for the sELISA compared to four competition ELISAs. While the sensitivity of the sELISA remained unaffected by BTV-15 positive sera, the cELISAs were not as sensitive. BTV-15 is endemic to Australia, and early warning depends on sensitive diagnoses of all serotypes: endemic or incurring. The sELISA failed to discriminate against epizootic hemorrhagic disease virus (EHDV) antibodies, the most serologically related orbivirus to BTV. The ACDP cELISA and the IDEXX kit showed cross-reactivity with some EHDV serotypes, with the least cross-reactive being the VMRD and the IDVet kits. Cross-reactivities, however, were also detected in sera raised experimentally from 10 isolates of the 21 known non-BTV orbiviruses. In this case, the sELISA was the least affected, followed equally by the VMRD and IDVet kits, and the IDEXX kit and the ACDP cELISA were the least discriminatory. In addition to exclusivity assessment of the ELISAs, an inclusivity assessment was made for all ELISAs using well characterized reference sera positive for antibodies to all serotypes BTV-1 to BTV-24. Full article

Background: Serosurveillance of epidemic cerebrospinal meningitis (ECM) in healthy individuals is crucial for assessing disease risk and evaluating the effectiveness of vaccinations. However, this practical work is rare in China. Methods: We conducted cross-section serosurveillance in Guangzhou, Zhanjiang, and Heyuan in Guangdong Province, measuring Anti-Nm IgG with serogroups A, C, Y, and W, and analyzed the trends using a generalized additive model (GAM). Results: During 2019–2022, 7752 participants were included. The overall antibody positivity rate for serogroups A, C, Y, and W were 60.75%, 15.51%, 32.83%, and 14.56%, respectively. High Anti-Nm IgG was in children aged 0–5 and 5–10 years old. Geometric mean concentrations (GMCs) of Anti-Nm IgG were higher and correlated positively with vaccine doses compared with unvaccinated individuals. The GMC showed a consistent decrease trend in the vaccinated and a U-shaped curve in populations. The declined rates of GMC were 1.59 (95% CI: 1.03, 2.14) µg/mL, 1.65 (95% CI: 1.28, 2.03), 0.62 (95% CI: 0.22, 1.03), and 0.31 (95% CI: 0.08, 0.53) µg/mL per year for serogroups A, C, Y, and W, respectively. Conclusions: There were differences in antibody positivity rate and GMC for the four serogroups of ECM in the healthy individuals of Guangdong Province, with serogroup A showing the highest, and the demographic differences highlighted the high seroprevalence of Neisseria meningitidis in younger people. The variable prevalence rates among serogroups A, C, Y, and W and the observed decline in antibody titers underscore the need for adjustments in the immunization program targeting the meningococcal vaccine. Full article

Toxoplasma gondii is an intracellular protozoan parasite of veterinary and public health importance. Infection may lead to abortion in susceptible pregnant animals and women, and potentially fatal health complications in immunocompromised individuals. In this study, we aimed to provide an update on the seroprevalence of, and risk factors for, T. gondii antibodies in cattle from Qena, southern Egypt. Additionally, we investigated if raw milk and serum samples from the same animals reacted similarly in a commercial ELISA, thus potentially reducing the invasiveness of future serosurveillance studies. Cattle serum samples (n = 362) from three locations in the Qena governorate (Qena, Qus, and Al Waqf cities), of both sexes and different ages were collected. From most dairy cows, a corresponding milk sample (n = 154) was additionally obtained. We found that the overall seroprevalence in serum samples was 9.1% (33/362). Increasing age was the sole risk factor identified in our study among all tested parameters (location, age, sex, lactating yes or no). Thus, older cattle (more than 3 years old) exhibited significantly higher rates of T. gondii antibodies (11.7%; p = 0.033, odd ratio = 4.3) in comparison to animals younger than 1 year (2.9%). In the corresponding serum and milk samples, the prevalence was 12.3% (19/154) in serum samples, and 9.7% (15/154) in milk samples, respectively. A high correlation was observed between the two sample types with a concordance of 97.4%, a kappa value of 0.87, and a Pearson r correlation coefficient of 0.85. When the serum ELISA was taken as the gold standard, the milk ELISA had the following characteristics: sensitivity (78.9%), specificity (100%), positive predictive value (100%), negative predictive value (97.1%), and area under the receiver operating characteristic (ROC) curve (0.6, p = 0.0011). In this study, we confirmed the frequent occurrence of T. gondii antibodies in cattle in southern Egypt and demonstrated that non-invasive milk samples may be used instead of serum samples for seroprevalence studies in dairy cows. Full article

Influenza A virus (IAV) is a multi-host pathogen maintained in water birds and capable of spillover into humans, wildlife, and livestock. Prior research has focused on dabbling ducks as a known IAV reservoir species, yet our understanding of influenza dynamics in other water birds, including gulls, is lacking. Here, we quantify morphological and environmental drivers of serological (antibody detection by ELISA) and virological (viral RNA detection by PCR) prevalence in two gull species: ring-billed (Larus delawarensis) and Franklin’s (Leucophaeus pipixcan) gulls. Across 12 months and 10 locations, we tested over 1500 gulls for influenza viral RNA, and additionally tested antibody levels in nearly 1000 of these. We find substantial virus prevalence and a large, nonoverlapping seroprevalence, with significant differences across age and species classifications. The body condition index had minimal explanatory power to predict (sero)positivity, and the effect of the surrounding environment was idiosyncratic. Our results hint at a nontrivial relationship between virus and seropositivity, highlighting serological surveillance as a valuable counterpoint to PCR. By providing indication of both past infections and susceptibility to future infections, serosurveillance can help inform the distribution of limited resources to maximize surveillance effectiveness for a disease of high human, wildlife, and livestock concern. Full article

Ruminant abortion events cause economic losses. Despite the importance of livestock production for food security and the livelihoods of millions of people in the world’s poorest communities, very little is known about the scale, magnitude, or causes of these abortions in Africa and Asia. The aim of this review was to determine the current status of surveillance measures adopted for ruminant abortigenic pathogens in Africa and Asia and to explore feasible surveillance technologies. A systematic literature search was conducted using PRISMA guidelines for studies published between 1 January 1990 and 1 May 2024 that reported epidemiological surveys of abortigenic pathogens Africa and Asia. A meta-analysis was used to estimate the species-specific sero-prevalence of the abortigenic agents and the regions where they were detected. In the systematic literature search, 39 full-text manuscripts were included. The most prevalent abortigenic pathogens with sero-prevalence greater than 10% were BHV-1, Brucella, Chlamydia abortus, Neospora caninum, RVFV, and Waddlia chondrophila in cattle, BVDV in sheep, and RVFV and Toxoplasma gondii in goats in Africa. In Asia, Anaplasma, BHV-1, Bluetongue virus, Brucella, and BVDV were prevalent in cattle, whereas Mycoplasma was important in goats and sheep. Full article