Seroprevalence Of Antibodies Research Articles

Seroprevalence of Hepatitis E among Blood Donors in Calabar

Context: Hepatitis E virus is one of the reemerging pathogens of global concern with an increased risk of transmission by transfusion of blood and blood products. However, this has not been studied in our environment. Aim: The aim is to study the seroprevalence of HEV transmission by potential blood donors in Calabar. Materials and Methods: This is a cross-sectional study conducted at the UCTH Calabar. A total of 187 potential donors were enrolled. Serum IgM and IgG HEV antibodies were done on 182 donors. IgM and IgG HEV antibodies were measured using an enzyme-linked immunosorbent assay. Data generated were analyzed using the statistical package for social sciences IBM SPSS version 23. Results: One hundred and eighty-two participants in the study with a male-to-female ratio of 2.1:1; a mean age and standard deviation of 28.1 ± 5–7 years; 63.7%, 31.9%, and 4.4% of the study population were first-time, regular, and lapsed donors, respectively. Also, 57.1%, 41.8%, and 1.1% of the subject were voluntary, replacement, and remunerated donors; respectively. Fifty percent of the subjects were HEV seropositive, out of which 8.79% were positive for IgM-only anti-HEV antibodies, 86.81% were positive for IgG-only anti-HEV antibodies, and 7.69% were positive for both anti-HEV IgM/IgG antibodies. Conclusion: There is a high seroprevalence of HEV (IgM and IgG) among potential blood donors in Calabar. IgM antibodies reflect acute infections which may be subclinical as in our study population while IgG reflects past infection. The relatively high seroprevalence of IgM antibodies obtained in the index study has serious implications for transfusion safety, especially for the immunocompromised persons in the region.

Seroprevalence of Echinococcus IgG antibodies in a tertiary care center: a 5-year study and literature review

Abstract Background: Cystic echinococcosis (CE), also known as hydatid disease, is a global zoonotic infection resulting from the larval stage of Echinococcus granulosus tapeworms. This condition manifests as single or multiple cystic growths in various bodily organs such as the liver, lungs, kidneys, etc. Materials and Methods: A retrospective analysis was conducted on all sample records within the microbiology laboratory register or microbiology database of the parasitology section, spanning from January 2017 to December 2021. The objective was to ascertain the seroprevalence of echinococcosis. Through enzyme-linked immune sorbent assay, 200 samples were examined to detect the presence of anti-hydatid immunoglobulin G (IgG). Results: Among the individuals tested for CE IgG antibodies, a greater seroprevalence was evident in female patients (42.7%) compared to males (32.5%). In 2017, the observed seroprevalence stood at 36%; in 2021, it escalated to 55.5%. It signifies a noteworthy surge of 20% in seropositivity over the last 5 years. Conclusion: The study’s findings highlight a substantial correlation between age, gender, and the prevalence of CE in northern India. Furthermore, the research revealed a progressive incline in seropositivity rates among patients from North India.

Postinfectious and Postvaccinal Humoral Immune Response to SARS-CoV-2 in Adults: Qualitative and Quantitative Assessment

Relevance. Serological studies play an important role in assessing the spread of SARS-CoV-2 and formation of post-infection and post-vaccination immune response.The Aims aim of the study was a comparative assessment of seroprevalence and concentration of antibodies to SARS-CoV-2 at 3–6 months after infection or vaccination.Materials & Methods. For the presence of total IgM and IgG antibodies to RBD fragment of the SARS-CoV-2 S protein, the blood sera of 1331 people aged 18-70 years were examined, of which 334 had COVID-19 3–6 months before the study, 305 did not have COVID-19 and were vaccinated (using Sputnik V, Russia, or Sinopharm, PRC) 3–6 months before the study, 692 people were not ill and were not vaccinated. A quantitative assessment of IgG antibodies to the full-size S-protein of SARS-CoV-2 was performed for 435 samples.Results. The proportion of seropositive individuals 3–6 months after COVID-19 or after vaccination did not differ: 92.5% and 93.8% of the corresponding group had antibodies. Among the non-ill and unvaccinated, 45.7% also had specific antibodies, which indicates a high level of asymptomatic infection with SARS-CoV-2. The group of vaccinated was also examined immediately before the introduction of the vaccine, and 39.7% of them already had specific antibodies due to asymptomatic infection with SARS-CoV-2. The median concentration of antibodies in the group of COVID-19 was statistically significantly higher than in asymptomatically infected (50.9 AE/ml versus 29.1 AE/ml). The largest proportion of seropositive individuals (100.0%) and the highest concentration of antibodies (110 AE/ml) were detected in the group of vaccinated who had pre-existing antibodies.Conclusion. Infection with the SARS-CoV-2 is characterized by a high frequency of subclinical course. Asymptomatic infection induced a weaker immune response compared to symptomatic COVID-19 or vaccination. Hybrid immunity caused by natural infection with SARS-CoV-2 and subsequent vaccination was the most persistent and pronounced.

Prevalence of Antibodies to COVID-19 Due to Infection or Vaccination in US Adults.

-Determine the seroprevalence of SARS-CoV-2 infection and vaccination in a population applying for life insurance. -This is a cross-sectional study of 2584 US life insurance applicants, to determine the seroprevalence of antibodies to COVID-19. This convenience sample was selected on two consecutive days April 25-26, 2022. -For COVID-19, 97.3% are seropositive, and 63.9% have antibodies to nucleocapsid protein, a marker of prior infection. An additional, 33.7% have been vaccinated with no serologic evidence of infection. -Serum and urine samples from a nationwide group of insurance applicants for routine risk assessment were collected. The examination of applicants typically occurs, in their homes, their place of employment, or a clinic. The paramedic exam occurs 7-14 days after the insurance application. Before the exam, an office assistant calls the applicant and inquires if they have been in contact with a person with SARS-CoV-2, been ill within the last 2 weeks, felt sick, or recently had a fever. If the applicant answers yes, the exam is rescheduled. Before sample collection, the applicant reads and signs a consent form to release medical information and testing. Next, the examiner records the applicant's blood pressure, height, and weight. Then, a blood and a urine sample are collected and sent with the consent form to our laboratory via Federal Express. On April 25-26, 2022, we tested 2584 convenience samples from adult insurance applicants for the presence of antibodies to nucleocapsid and spike proteins from SARS-CoV-2. As a standard practice, we reported the client-specified test profile results to our life insurance carriers. In contrast, the COVID-19 test results were only available to the authors. Patient and Public Involvement.-There was no patient involvement in study design, reporting of results, or journal publication selection. There was patient consent to publish de-identified study results. No public involvement occurred in the creation or completion of the study. The authors thank the participants in this study for approving the use of their blood samples to further society's understanding of the SARS-CoV-19 pandemic. Ethics Review.-Western Institutional Review Board reviewed the study design and determined it to be exempt under the Common Rule and applicable guidance. Therefore, it is exempt under 45 CFR § 46.104(d)(4) from using de-identified study samples for epidemiologic investigation, WIRB Work Order #1-1324846-1. In addition, all test subjects had signed a consent allowing research of their blood and urine samples with the removal of personally identifiable information. -The combined seroprevalence for antibodies to nucleocapsid, a marker of prior infection, and antibodies to spike protein, an indicator of either previous infection or vaccination, was 97.3%. Higher infection rates occur in younger vs older age groups, with a non-statistical difference for vaccinated and acquired natural immunity. For the age group 16-84, the total estimated seroprevalence of COVID-19 in the US is 249 million cases. -The US population has widespread immune resistance to current variants of COVID-19 due to prior infection or vaccination. The infectivity of new variants and silent disease, independent of previous infection or vaccination, are the driving force behind the sporadic increase in clinical SARS-CoV-2 cases.

Humoral immune responses to inactivated COVID-19 vaccine up to 1 year in children with chronic hepatitis B infection.

Inactivated SARS-CoV-2 vaccination has recently been approved for children aged 3-17 years in China. However, data on long-term humoral responses to inactivated vaccines in children with chronic hepatitis B (CHB) are still limited. In this prospective observational study, CHB children after primary inactivated SARS-CoV-2 vaccines were recruited consecutively and followed up for 1 year. CHB adults from another cohort study (NCT05007665) were used as a control. The receptor-binding domain IgG antibody (anti-RBD-IgG), neutralizing antibody (NAb), neutralization against Omicron (BA2.12.1, BA.4 and BA.5), and memory B -cell (MBC) responses were evaluated. Overall, 115 CHB children and 351 CHB adults were included in this analysis. The antibody titers decreased over the first ~180 days and then plateaued up to 1 year in CHB children. However, lower and faster declines in antibody responses were observed in CHB adults. Interestingly, the seroprevalence of antibodies was still high after over 8 months in CHB children (anti-RBD-IgG [90%] and NAbs [83%]). However, neutralization against Omicron subvariants was significantly reduced in CHB children (-3.68-fold to -8.60-fold). Notably, neutralization against the BA.5 subvariant was obviously diminished in CHB children compared with adults. Moreover, CHB children had similar RBD-specific MBCs but higher RBD-specific atypical MBCs compared with adults. Inactivated vaccination could elicit more robust and durable antibody responses to the wild-type SARS-CoV-2 strain in CHB children than in CHB adults but showed inferior responses to Omicron subvariants (especially to the BA.5 strain). Hence, new Omicron-related or all-in-one vaccines are needed immediately for CHB children.

Influence of the SARS-CoV-2 Omicron (B.1.1.529) variant and booster vaccine doses on the seroprevalence of specific IgG antibodies in the staff of the Slovak Academy of Sciences

The presented seroprevalence study focused on specific antibodies to the SARS-CoV-2 virus is the second survey conducted among SAS employees. Its realization enabled monitoring of the impact of booster vaccination doses and the spread of the Omicron variant in a defined group of people. The total seropositivity of the involved SAS employees in autumn 2022 was 96.04%. In the group of vaccinated participants (1,189) the seropositivity rate was 99.5%, while among unvaccinated participants (176) it was 72.73%. By October 2022, when the study was conducted, 65.05% (888) of the participants have had a positive PCR/Ag test for SARS-CoV-2 at least once. Based on the presence of antibodies against the nucleoprotein (NCP) of SARS-CoV-2 it was proven, that 27.39% of participants (25.12% of vaccinated; 51.22% of non-vaccinated) who have never had a positive PCR/Ag test for SARS-CoV-2, overcame the COVID-19. According to self-assessment of the disease course, it was shown that a severe course occurred in 6.31% of the participants who overcame the disease without prior vaccination and in 1.44% of the participants who overcame COVID-19 after completing the baseline vaccination scheme. The most significant finding of the study is the evidence of significantly lower levels of specific antibodies after overcoming the Omicron variant of SARS-CoV-2, and thus its reduced immunogenicity compared to ancestral virus and earlier variants of concern.

High seroprevalence of hepatitis E virus (HEV) in South Transdanubia, Hungary (2010-2022).

Hepatitis E virus (HEV) is an increasingly recognized etiological agent of acute, chronic and extrahepatic human infections with primarily zoonotic origin in Europe. Limited numbers of comprehensive population-based studies are available related to HEV seroepidemiology, especially from Central Europe.The aim of this study was to investigate the seroprevalence and trends of total and IgM antibodies against HEV in different age groups in the population of South Transdanubia, Hungary, within a thirteen years long period between the years 2010 and 2022.We retrospectively analysed the serological test results of HEV total and HEV IgM antibodies carried out by ELISA technique using Dia.Pro (Diagnostic Bioprobes, Italy) kit from serum samples collected from patients with or without hepatitis between January 1, 2010 and December 31, 2022.The number of tested samples (∑6,996 for total antibody and ∑6,582 for IgM) increased during the study period. The average HEV total and the IgM antibody seropositivities were 33% (2,307/6,996 samples) and 9.6% (642/6,582 samples), respectively, in the study population. The HEV total antibody seropositivity varied in different age groups between 3.9% (age group 1-5 years) and 58.6% (86-90 years) and showed an increasing positivity by age. At the age groups >50 years, nearly half (43%) of the population had antibodies against HEV. The HEV IgM positivity had an increasing trend of up to 13.9% in the age group 81-85 years.High HEV total and IgM antibody seroprevalence were detected in South Transdanubia, Hungary, confirming that this region is highly endemic for HEV infections in Europe.

Evidence of Rift Valley Fever Virus Circulation in Livestock and Herders in Southern Ghana.

Rift Valley fever (RVF) is a re-emerging zoonotic disease of domestic ruminants and humans. While neighbouring countries have reported outbreaks of RVF, Ghana has not yet identified any cases. The aim of this study was to determine whether RVF virus (RVFV) was circulating in livestock and herders in the southern part of Ghana, to estimate its seroprevalence, and to identify associated risk factors. The study surveyed 165 livestock farms randomly selected from two districts in southern Ghana. Serum samples of 253 goats, 246 sheep, 220 cattle, and 157 herdsmen were tested to detect IgG and IgM antibodies against RVFV. The overall seroprevalence of anti-RVF antibodies in livestock was 13.1% and 30.9% of farms had RVFV seropositive animals. The species-specific prevalence was 24.1% in cattle, 8.5% in sheep, and 7.9% in goats. A RVFV IgG seroprevalence of 17.8% was found among the ruminant herders, with 8.3% of all herders being IgM positive. RVFV was shown, for the first time, to have been circulating in southern Ghana, with evidence of a recent outbreak in Kwahu East; however, it was clinically undetected despite significant recent human exposure. A One Health approach is recommended to better understand RVF epidemiology and socio-economic impact in Ghana.

Seroprevalence of Chlamydia abortus in Anestrous Cattle of Nawalpur and Chitwan District, Nepal

Chlamydia abortus are gram negative coccoid, obligate intracellular zoonotic bacteria responsible for abortion and other reproductive problems in dairy cattle. This leads to sub-fertility and infertility in cattle thereby causing significant economic losses to dairy farmers. However, the status of Chlamydia abortus in Nawalpur and Chitwan districts, which are the dairy pockets of Nepal, are poorly understood. The objective of this study was to determine the seroprevalence of antibodies to Chlamydia abortus in anestrous dairy cattle of Nawalpur and Chitwan districts in relatively low risk winter season. In total, 92 cattle serum (Nawalpur (n= 27) and Chitwan (n= 65) samples were collected from April 2018 to May 2019 and tested using a Chlamydia abortus specific indirect ELISA kit to evaluate the seropositivity status of cattle. Results showed that only 2 (2.17%) cattle were seropositive for Chlamydia abortus. Both the positive cattle were Jerseys from Nawalpur area with a history of abortion. The ages of the seropositive cattle were 3 and 4 years. In conclusion, there was a low seroprevalence of C. abortus in dairy cattle of Nawalpur and Chitwan districts. The presence of this bacterium suggests that it is likely to be a cause of unidentified abortion in dairy cattle in Nepal. We suggest screening dairy animals for C. abortus infection to minimize this risk.

Translated article] SARS-CoV-2 Infection in Patients With or at Risk for Venereal Infections: Incidence and Associated Factors in a Sexual Health Clinic

Background and objectiveSARS-CoV-2 is more easily spread by close contact, which is inherent to sexual intercourse. People with, or at risk for, sexually transmitted infections (STIs) may therefore have higher rates of COVID-19. The aim of this study was to estimate SARS-CoV-2 antibody seroprevalence in people seen at a dedicated STI clinic, compare our findings to the estimated seroprevalence in the local general population, and study factors associated with SARS-CoV-2 infection in this setting. Material and methodsCross-sectional observational study including consecutive patients older than 18 years of age who had not yet been vaccinated against COVID-19 and who underwent examination or screening at a dedicated municipal STI clinic in March and April 2021. We ordered rapid SARS-CoV-2 serology and collected information on demographic, social, and sexual variables, STI diagnoses, and history of symptoms compatible with SARS-CoV-2 infection. ResultsWe studied 512 patients (37% women). Fourteen (24.2%) had a positive SARS-CoV-2 test. Variables associated with positivity were use of FFP2 masks (odds ratio 0.50) and a higher-than-average number of sexual partners (odds ratio 1.80). Use of FFP2 masks was not randomly distributed in this sample. ConclusionsSexually active members of the population in this study had a higher incidence of SARS-CoV-2 infection than the general population. The main route of infection in this group appears to be respiratory, linked to close contact during sexual encounters; sexual transmission of the virus is probably limited.

Dengue and COVID-19 Co-circulation in the Peruvian Amazon: A Population-Based Study.

The COVID-19 pandemic affected the main Amazon cities dramatically, with Iquitos City reporting the highest seroprevalence of anti-SARS-CoV-2 antibodies during the first COVID-19 wave worldwide. This phenomenon raised many questions about the possibility of a co-circulation of dengue and COVID-19 and its consequences. We carried out a population-based cohort study in Iquitos, Peru. We obtained a venous blood sample from a subset of 326 adults from the Iquitos COVID-19 cohort (August 13-18, 2020) to estimate the seroprevalence of anti-dengue virus (DENV) and anti-SARS-CoV-2 antibodies. We tested each serum sample for anti-DENV IgG (serotypes 1, 2, 3, and 4) and SARS-CoV-2 antibodies anti-spike IgG and IgM by ELISA. We estimated an anti-SARS-CoV-2 seroprevalence of 78.0% (95% CI, 73.0-82.0) and an anti-DENV seroprevalence of 88.0% (95% CI, 84.0-91.6), signifying a high seroprevalence of both diseases during the first wave of COVID-19 transmission in the city. The San Juan District had a lower anti-DENV antibody seroprevalence than the Belen District (prevalence ratio, 0.90; 95% CI, 0.82-0.98). However, we did not observe these differences in anti-SARS-CoV-2 antibody seroprevalence. Iquitos City presented one of the highest seroprevalence rates of anti-DENV and anti-SARS-CoV-2 antibodies worldwide, but with no correlation between their antibody levels.

Changes in SARS-CoV-2 seroprevalence and population immunity in Finland, 2020–2022

ABSTRACT Studying the prevalence of SARS-CoV-2 specific antibodies (seroprevalence) allows for assessing the impact of epidemic containment measures and vaccinations and estimating the number of infections regardless of viral testing. We assessed antibody-mediated immunity to SARS-CoV-2 induced by infections and vaccinations from April 2020 to December 2022 in Finland by measuring serum IgG to SARS-CoV-2 nucleoprotein (N-IgG) and spike glycoprotein from randomly selected 18–85-year-old subjects (n = 9794). N-IgG seroprevalence remained at <7% until the last quartile (Q) of 2021. After the emergence of the Omicron variant, N-IgG seroprevalence increased rapidly and was 31% in Q1/2022 and 54% in Q4/2022. Seroprevalence was highest in the youngest age groups from Q2/2022 onwards. We did not observe regional differences in seroprevalence in 2022. We estimated that 51% of the Finnish 18–85-year-old population had antibody-mediated hybrid immunity induced by a combination of vaccinations and infections by the end of 2022. In conclusion, major shifts in the COVID-19 pandemic and resulting population immunity could be observed by serological testing.

Seroprevalence of COVID-19 antibodies in babies born to COVID positive or suspected mothers and their outcome

Background &amp; Objective: COVID-19 infection has been the most researched topic since its emergence in 2019. Little is known about the vertical transmission of this disease and its effects on the babies of the infected mothers in our country. We evaluated the antibody titers of babies born to COVID-19 positive or suspected COVID mothers and observed the immediate and short-term outcome of such babies. We share our experience of 43 babies born to known or suspected COVID positive mothers in a tertiary care hospital in Karachi, Pakistan. Methodology: It was a cross-sectional study conducted in the departments of gynecology/obstetrics and the pediatrics of Memon Medical Institute Hospital, Karachi. Cases delivered during December 2020 till May 2021 were included in this study. Mothers known or suspected COVID positive were included and their newborn babies were screened for antibody titer. Babies were followed up for any sign of the disease for six months. Results: Out of a total of 547 deliveries conducted in our hospital during the study period, PCR test was performed amongst 43 suspected mothers and 41 (95.34%) came out to be positive on PCR, while two mothers had antibodies in their blood, so were included in the study. The antibody titer was positive in 17 (39.53%) of babies of all PCR positive mothers, and 41.46% of the babies of all confirmed COVID positive mothers. Conclusion: The results of our study conclude that the babies of a fair proportion of all the COVID affected women exhibited a good antibody response, and no disease manifestation was noticed in them for six months after birth. Key words: COVID-19; Vertical transmission; Antibody titers Citation: Aijaz N, Bham SQ, Hassan F, Huda N, Kauser S, Sharif UHA. Seroprevalence of COVID-19 antibodies in babies born to COVID positive or suspected mothers and their outcome. Anaesth. pain intensive care 2023;27(3):332−337. DOI: 10.35975/apic.v27i3.2003 Received: September 19, 2022; Reviewed: November 30, 2022; Accepted: April 4, 2023

Monitoring for Equine Viral Arteritis has decreased its prevalence in European breeding sires

Equine viral arteritis (EVA) can induce a persistent carrier state in stallions and shedding of the virus with semen can spread EVA and cause abortions in seronegative pregnant mares. In the early 1990s, obligatory testing for EVA of stallions used for artificial insemination was implemented within the European Union (Council Directive 92/65/EEC). In addition, vaccination programs for young stallions and exclusion of carrier stallions from certain breed registry events were implemented in Warmblood sport horses. Information on the efficacy of these actions on the prevalence of EVA in reproductively active stallions are not yet available in Europe. This study retrospectively analyzed results of serological and virus antigen testing for EVA in sires (n=308, one sample set per sire, EVA-vaccination status unknown) of different age and breed referred to the Centre for Artificial Insemination of Vetmeduni Vienna for semen preservation between 2001 and 2021. For analysis, stallions were grouped by age (1-3, 4-10, 11-16, >16 years) and breed. The EVA antibody titer was determined by serum neutralization test and semen was analyzed for EVA virus by PCR and/or virus isolation test. Statistical analysis was performed by chi2-test, Kruskal-Wallis test or Mann-Whitney U-test using the IBM SPSS 28.0 statistics software. Of 308 stallions tested, 14.9% (n=46) were EVA seropositive and in 12 stallions EVAvirus was detected in semen (26% of seropositive and 3.8% of all tested stallions, respectively). The incidence of seropositive stallions (22% of sires tested during 2001-05 to 4.1% during 2016-21) and of stallions shedding EVA virus via semen (8.5% of all serologically tested stallions 2001-05 to 1.4% during 2016-21) decreased over time (p<0.05). No difference among breeds with regard to occurrence of seropositive stallions was detected. There was a tendency towards more Standardbred and Lipizzaner stallions (14% and 13%, respectively) shedding EVA virus in semen compared to all other breeds (<3%, p=0.074 among groups). Differences in the seroprevalence of EVA antibodies existed among stallions from different age groups (p<0.01) with the highest percentage of seropositive stallions in 11-16 year-stallions (45.7%). No differences among age groups with regard to virus shedding existed. The EVA antibody titer increased with age (p<0.01), reflecting a higher possibility of repeated virus challenge in older stallions. Antibody titer was not associated with carrier state. In conclusion, monitoring of stallions for EVA in combination with vaccination programs resulted in a decrease of the prevalence of seropositive and virus-shedding stallions during the past 20 years in a European stallion population and can therefore be considered successful.

Seroprevalence and risk factors of bovine fasciolosis in the municipalities of Colombia.

Bovine fasciolosis is a reemerging neglected disease with a worldwide distribution caused by the trematode Fasciola spp., which parasitize various hosts. Bovine fasciolosis is responsible for large economic losses in the bovine livestock sector. This study aimed to estimate the seroprevalence and risk factors of bovine fasciolosis in the municipalities of Colombia. This was a descriptive cross-sectional study with simple random sampling conducted on 1140 cattle from the municipalities of Chiquinquirá, San Miguel de Sema, and Ubaté for a duration of 3 months. Serum samples were processed using the commercial Fasciola hepatica Antibody Test Kit IDEXX® Fasciolosis Verification (IDEXX, United States), which identified immunoglobulin G antibodies for gf2 antigen purified from Fasciola extracts. The f2 antigen is extremely immunogenic and highly specific for F. hepatica. An epidemiological survey was performed to record variables related to the sampled animals and herd management practices. Data were processed using the statistical program Epi Info® (Centers for Disease Control and Prevention; Atlanta, Georgia). The prevalence ratio was estimated to evaluate the association between fasciolosis and the hypothesized causal factors and the significance of this association using Pearson's Chi-square test. Finally, a logistic regression model was developed. The overall seroprevalence was 72.3%. The seroprevalence was 83.9% (323/385) in Chiquinquirá, 68.17% (257/377) in Ubaté, and 64.55% (244/378) in San Miguel de Sema. The seroprevalence was higher in male animals in Chiquinquirá and in female animals in San Miguel de Sema and Ubaté. Similarly, sex showed a statistically significant association with disease prevalence in Ubaté. The highest prevalence was found in cattle aged >2 years. The Holstein breed showed maximum seroprevalence in Chiquinquirá (p ≤ 0.05) and San Miguel de Sema, whereas crossbreed showed higher seroprevalence in Ubaté. Similarly, in Chiquinquirá, the association between the seroprevalence of fasciolosis and the presence of other species was statistically significant (95% confidence interval [CI]: 0.9601-3.4944; p = 0.0448). In Ubaté, the disease presentation was also associated with pasture rental (95% CI: 0.4047-1.0023; p = 0.003) and attendance to livestock expositions (95% CI: 0.2313-1.0636; p = 0.044). However, in San Miguel de Sema, water from the stream showed a statistically significant association with disease presentation (95% CI: 0.5209-1.0985; p = 0.00649785). Female sex and diarrhea occurrence were considered risk factors for fasciolosis. A high seroprevalence of antibodies to Fasciola spp. was detected in cattle in the study municipalities, indicating a high parasite distribution in these areas. Female sex and diarrhea were established as risk factors associated with fasciolosis in Ubaté and San Miguel de Sema, respectively. Further, research is necessary to establish prevention and control programs against parasitosis.

Healthcare personnel at non–acute-care facilities are at risk of COVID-19 from workplace and community exposures

Background: Healthcare personnel (HCP) working in non–acute-care facilities are at high risk of COVID-19. We sought to determine SARS-CoV-2 seroprevalence, and analyzed behaviors and activities related to COVID-19 acquisition in this cohort. Methods: Between May and June 2021, HCP were enrolled at a skilled nursing facility and a memory care facility in St. Louis, Missouri. Data regarding demographics, prior SARS-CoV-2 testing, symptoms consistent with COVID-19 in the previous 6 months, COVID-19 vaccination, personal protective equipment (PPE) use, and COVID-19 exposures were collected via survey. Blood specimens were obtained to determine SARS-CoV-2 nucleocapsid IgG antibody seroprevalence (Abbott Laboratories). Study protocol was approved by the Washington University Institutional Review Board. Results: The survey was completed by 74 HCP. 82% of participants were female, and 31% reported &gt;10 years of healthcare experience. The overall SARS-CoV-2 seropositivity rate was 8.9% (5 HCP). Of the surveyed HCP, 50% reported symptoms concerning for COVID-19 in the prior 6 months. Headache (38%), fatigue (35%) and fever (27%) were the most common self-reported symptoms. Among symptomatic HCP, only 35% sought medical care for these symptoms. All HCP reported having taken at least 1 COVID-19 test prior to study enrollment. Of note, 18.9% (14 HCP) had a self-reported prior positive SARS-CoV-2 PCR test, of whom 9 HCP were seronegative. All seronegative HCP with a self-reported history of COVID-19 reported infection &gt;3 months before study participation. Completion of a primary COVID-19 vaccination series was reported by 86% of HCP. Known exposure to COVID-19 at work was reported by 28% of HCP. When asked about PPE at the time of workplace exposure, N95 mask use was reported by 81%, gloves by 57%, gowns by 33%, face shields by 29% and surgical masks by 14%. Known specific exposure to COVID-19 outside work was reported by 31% of HCP. Conclusions: One year after the initial COVID-19 pandemic impacted the St. Louis region, HCP at non–acute-care facilities had a SARS-CoV-2 seroprevalence of 8.9%. Similar frequency of exposures were reported from both the workplace and community, with high rates of PPE use at the workplace. HCP in such settings remain at high risk of COVID-19 exposure from workplace and community exposures. Ongoing efforts are needed to maintain PPE use to prevent SARS-CoV-2 transmission within non–acute-care facilities, and continue access to timely COVID-19 screening for HCP.Disclosure: None

Prevalence of Antibodies to COVID-19 Due to Infection or Vaccination in US Adults.

-Determine the seroprevalence of SARS-CoV-2 infection and vaccination in a population applying for life insurance. -This is a cross-sectional study of 2584 US life insurance applicants, to determine the seroprevalence of antibodies to COVID-19. This convenience sample was selected on two consecutive days April 25-26, 2022. -For COVID-19, 97.3% are seropositive, and 63.9% have antibodies to nucleocapsid protein, a marker of prior infection. An additional, 33.7% have been vaccinated with no serologic evidence of infection. -Serum and urine samples from a nationwide group of insurance applicants for routine risk assessment were collected. The examination of applicants typically occurs, in their homes, their place of employment, or a clinic. The paramedic exam occurs 7-14 days after the insurance application. Before the exam, an office assistant calls the applicant and inquires if they have been in contact with a person with SARS-CoV-2, been ill within the last 2 weeks, felt sick, or recently had a fever. If the applicant answers yes, the exam is rescheduled. Before sample collection, the applicant reads and signs a consent form to release medical information and testing. Next, the examiner records the applicant's blood pressure, height, and weight. Then, a blood and a urine sample are collected and sent with the consent form to our laboratory via Federal Express. On April 25-26, 2022, we tested 2584 convenience samples from adult insurance applicants for the presence of antibodies to nucleocapsid and spike proteins from SARS-CoV-2. As a standard practice, we reported the client-specified test profile results to our life insurance carriers. In contrast, the COVID-19 test results were only available to the authors. Patient and Public Involvement.-There was no patient involvement in study design, reporting of results, or journal publication selection. There was patient consent to publish de-identified study results. No public involvement occurred in the creation or completion of the study. The authors thank the participants in this study for approving the use of their blood samples to further society's understanding of the SARS-CoV-19 pandemic. Ethics Review.-Western Institutional Review Board reviewed the study design and determined it to be exempt under the Common Rule and applicable guidance. Therefore, it is exempt under 45 CFR § 46.104(d)(4) from using de-identified study samples for epidemiologic investigation, WIRB Work Order #1-1324846-1. In addition, all test subjects had signed a consent allowing research of their blood and urine samples with the removal of personally identifiable information. -The combined seroprevalence for antibodies to nucleocapsid, a marker of prior infection, and antibodies to spike protein, an indicator of either previous infection or vaccination, was 97.3%. Higher infection rates occur in younger vs older age groups, with a non-statistical difference for vaccinated and acquired natural immunity. For the age group 16-84, the total estimated seroprevalence of COVID-19 in the US is 249 million cases. -The US population has widespread immune resistance to current variants of COVID-19 due to prior infection or vaccination. The infectivity of new variants and silent disease, independent of previous infection or vaccination, are the driving force behind the sporadic increase in clinical SARS-CoV-2 cases.

Seroprevalence of Toxoplasma gondii IgG and IgM antibodies and associated risk factors among pregnant women consulted in three health centers in Dschang, Cameroon

BackgroundToxoplasmosis is a zoonosis caused by Toxoplasma gondii, an obligate intracellular protozoan responsible for one of the most common congenital infections in the world. This study aimed to determine the seroprevalence and risk factors associated with toxoplasmosis in pregnant women consulted in three health centers in the city of Dschang. MethodsThis study was a cross-sectional study that was conducted, with a total of 242 participants. A questionnaire was administered after obtaining the free and informed consent of the participants. Blood sample was collected to assay IgG and IgM antibodies specific to Toxoplasma gondii using the enzyme-linked immunosorbent assay (ELISA) kit, and potential risk factors were evaluated with the administration questionnaire using a binary logistic regression model. Statistical significance was measured at P < 0.05. ResultsThe overall seroprevalence of toxoplasmosis was 82.7%,with a seroprevalence of toxoplasma IgG of 62.8% (152), that of IgM at 11.6% (28) and that of IgG/IgM at 8.3% (20). The Saint Vincent Paul Hospital had a seroprevalence of 43.8% IgG and 8.7% IgM; followed by the Dschang District Hospital (11.6% IgG and 2.1% IgM). The seroprevalence of toxoplasma IgG (35.5%) and IgM (6.2%) was higher in multiparous pregnant women, and in the group of women who performed their first toxoplasmosis serology in the first trimester of pregnancy, 70 (28.9%), 9 (3.7%) respectively for IgG and IgM. The multivariate logistic regression analysis showed that the possession of a cat at home or its presence in the neighborhood, the consumption of undercooked or uncooked meat and having a history of blood transfusion were found to be statistically significant risk factors associated with toxoplasmosis seroprevalence among pregnant women. ConclusionThe present study revealed a high seroprevalence of toxoplasmosis. Given this high seroprevalence, screening for toxoplasmosis in women of childbearing age should be encouraged.

A longitudinal study of SARS-CoV-2 antibody seroprevalence and mitigation behaviors among college students at an Arkansas University

Objective: Assess university students’ SARS-CoV-2 antibody seroprevalence and mitigation behaviors over time. Participants: Randomly selected college students (N = 344) in a predominantly rural Southern state. Methods: Participants provided blood samples and completed self-administered questionnaires at three timepoints over the academic year. Adjusted odds ratios and 95% confidence intervals were estimated from logistic regression analyses. Results: SARS-CoV-2 antibody seroprevalence was 18.2% in September 2020, 13.1% in December, and 45.5% in March 2021 (21% for those with no vaccination history). SARS-CoV-2 antibody seroprevalence was associated with large social gatherings, staying local during the summer break, symptoms of fatigue or rhinitis, Greek affiliation, attending Greek events, employment, and using social media as the primary COVID-19 information source. In March 2021, seroprevalence was associated with receiving at least one dose of a COVID-19 vaccination. Conclusion: SARS-CoV-2 seroprevalence was higher in this population of college students than previous studies. Results can assist leaders in making informed decisions as new variants threaten college campuses.

Seroepidemiology of Lassa virus in pregnant women in Southern Nigeria: A prospective hospital-based cohort study.

There is limited epidemiological evidence on Lassa fever in pregnant women with acute gaps on prevalence, infection incidence, and risk factors. Such evidence would facilitate the design of therapeutic and vaccine trials and the design of control programs. Our study sought to address some of these gaps by estimating the seroprevalence and seroconversion risk of Lassa fever in pregnant women. We conducted a prospective hospital-based cohort between February and December 2019 in Edo State, Southern Nigeria, enrolling pregnant women at antenatal clinic and following them up at delivery. Samples were evaluated for IgG antibodies against Lassa virus. The study demonstrates a seroprevalence of Lassa IgG antibodies of 49.6% and a seroconversion risk of 20.8%. Seropositivity was strongly correlated with rodent exposure around homes with an attributable risk proportion of 35%. Seroreversion was also seen with a seroreversion risk of 13.4%. Our study suggests that 50% of pregnant women were at risk of Lassa infection and that 35.0% of infections might be preventable by avoiding rodent exposure and conditions which facilitate infestation and the risk of human-rodent contact. While the evidence on rodent exposure is subjective and further studies are needed to provide a better understanding of the avenues of human-rodent interaction; public health measures to decrease the risk of rodent infestation and the risk of spill over events may be beneficial. With an estimated seroconversion risk of 20.8%, our study suggests an appreciable risk of contracting Lassa fever during pregnancy and while most of these seroconversions may not be new infections, given the high risk of adverse outcomes in pregnancy, it supports the need for preventative and therapeutic options against Lassa fever in pregnancy. The occurrence of seroreversion in our study suggests that the prevalence obtained in this, and other cohorts may be an underestimate of the actual proportion of women of childbearing age who present at pregnancy with prior LASV exposure. Additionally, the occurrence of both seroconversion and seroreversion in this cohort suggests that these parameters would need to be considered for the development of Lassa vaccine efficacy, effectiveness, and utility models.