Risk Factors For Seropositivity Research Articles

Coxiella burnetii (Q fever) exposure in wildlife professionals.

Although occupational exposure to Coxiella burnetii has been studied previously, the zoonotic risk in wildlife environments remains unclear and has yet to be fully established. Accordingly, the present study aimed to serologically assess professionals with daily contact with free-living and captive wildlife in Paraná State, Brazil, along with the potential associated risk factors for C. burnetii exposure. Overall, 25 out of 309 (8.1%) wildlife professionals were seropositive, including 6/54 (11.1%) national and 7/125 (5.6%) state park employees, 6/92 (6.5%) zookeepers, and 6/38 (15.8%) animal service workers, with titers ranging from 32 to 128. No statistical association was found between seropositivity and associated risk factors, including the working location. Our results differ from those of previous studies in Brazil, which found 8/893 (0.9%) indigenous, 1/18 (5.5%) police officers, and 44/200 (22.0%) former Black slaves to be seropositive. This study is the first serological investigation of C. burnetii among park rangers, zookeepers, and animal service workers in Brazil, showing no statistically significant risk factors for seropositivity. As the seroprevalence in this study was higher than that in previous surveys of healthy (asymptomatic) human populations, C. burnetii exposure may also be an occupational risk for wildlife professionals owing to their contact with the natural environment in Brazil.

Twenty Years of Lyme Borreliosis in the Netherlands: Temporal Trends in Seroprevalence and Risk Factors.

Lyme borreliosis (LB) is not notifiable in many European countries, and the patchwork of surveillance strategies in Europe perpetuates knowledge gaps. In the Netherlands, LB incidence has been estimated from recurring general practitioner surveys since the 1990s. To complement the incidence data, this study aimed to estimate the prevalence of antibodies against Borrelia burgdorferi sensu lato in the general population of the Netherlands in 1995/1996, identify risk factors for seropositivity, and compare these findings to data from 2016/2017 to identify temporal trends. Sera from participants (n = 8041, aged 0-80 years) in a cross-sectional nationwide surveillance study were assessed for the presence of antibodies against B. burgdorferi s.l., using a screening ELISA and immunoblot confirmation. Risk factors associated with seropositivity were evaluated using multivariable analysis. A significant difference in weighted seroprevalence was observed between 1995/1996 (2.8%) and 2016/2017 (4.3%). In both cohorts, the seroprevalence was significantly higher among men than among women, and increased with age and tick bite frequency. The upward trend in age-specific seropositivity in individuals over 50 was steeper in 2016/2017 than in 1995/1996, possibly due to improved fitness among contemporary elderly, allowing increased outdoor activities. This study highlights significant trends in the seroprevalence of B. burgdorferi s.l. antibodies in the general population of the Netherlands over 20 years. The doubling of seroprevalence underscores the increasing burden of LB, and the importance of continued surveillance. Targeted interventions, particularly for elderly populations, may help raise awareness to the risks of tick bites and reduce the growing disease burden and societal costs associated with LB.

Seroprevalence of SARS-CoV-2 infection in pediatric patients in a tertiary care hospital setting.

Globally, cases of children's coronavirus disease 2019 (COVID-19) have been reported since the pandemic started. Most children have an asymptomatic or mild infection. Therefore, the incidence rate of COVID-19 in children might have been underestimated. This study aimed to determine (1) the seroprevalence (and seroconversion rates) of COVID-19, including associated risk factors, in pediatric patients visiting hospitals; and (2) the immunological responses to COVID-19. This was a prospective, cross-sectional study. Patients aged 0-18 years who visited the hospital from September 2020 to February 2022 were included. Demographic, clinical, and laboratory data were reviewed. A total of 1,443 pediatric patients were enrolled. Of these, 323 (22.6%) had a history of COVID-19. In the pre-Delta period, the seroprevalence increased from 4.1% to 70.6% in all included patients and from 0.5% to 10% in patients without a known history of COVID-19 compared with the Delta-Omicron period. The seroconversion rate was 6.8% (19 per 100 person-years) in pediatric patients with COVID-19. Risk factors for COVID-19 seropositivity were respiratory symptoms, being in an outpatient department setting, and infection during the Delta-Omicron period. Exposure to household members with confirmed COVID-19 was a risk factor for seropositivity and seroconversion. Infection during the Delta-Omicron period and testing conducted >2 weeks after the onset of symptoms was associated with spike immunoglobulin (Ig) M and spike and nucleocapsid IgG, respectively. High nucleocapsid IgG levels were associated with pneumonia in pediatric patients with COVID-19. Pediatric patients exposed to household members with COVID-19 and respiratory symptoms should be tested for COVID-19. Nucleocapsid IgG can be used as a surrogate marker to identify patients who may have experienced pneumonia from COVID-19 and as a screening tool for the COVID-19 outbreak, regardless of COVID-19 vaccination status.

Exploring Histoplasma species seroprevalence and risk factors for seropositivity in The Gambia's working equid population: Baseline analysis of the Tackling Histoplasmosis project dataset.

Exposure rates to Histoplasma species, the causative agent of equine epizootic lymphangitis (EL), are unknown amongst working equids in The Gambia. The primary aims of this study were to estimate anti-Histoplasma antibody seroprevalence in the equid population in rural The Gambia and to explore risk factors for seropositivity. A nationwide cross-sectional study was conducted (February-July 2022), representing baseline measurements of a longitudinal cohort study. Horses (n = 463) and donkeys (n = 92) without EL signs were recruited in 18 study sites. Following informed owner consent, equid clinical and management data were recorded. Blood samples were collected by jugular venepuncture, and sera were subject to the IMMY Latex Agglutination Histoplasma test (LAT). Seropositivity risk factors were explored by multi-level, multivariable logistic regression analysis. Study site and household variance were described using a latent-variable approach. Whole blood DNA extractions were subject to nested ITS-PCR to detect Histoplasma capsulatum var. farciminosum (HCF), and agreement with LAT results was measured using Cohen's kappa statistic. Anti-Histoplasma antibody seroprevalence in horses and donkeys was 79.9% [95% confidence interval (CI) 76.0-83.5%] and 46.7% (95% CI 36.3-57.4%), respectively. In horses, two multivariable models explained the maximum amount of data variability. Model 1 demonstrated increased odds of seropositivity in mares [odds ratio (OR) = 2.90 95% CI 1.70-4.95, p < 0.001] and decreased odds in horses <2.5 years (OR = 0.46 95% CI 0.22-0.95, p = 0.04; reference: ≥4.5 years). Model 2 demonstrated increased odds in horses recruited during the rainy season (OR = 2.03 95% CI 1.08-3.84, p = 0.03) and those owned by farmers reporting previous EL in their equids (OR = 1.87 95% CI 1.04-3.37, p = 0.04). Decreased odds were measured in horses <2.5 years (OR = 0.37 95% CI 0.18-0.78, p = 0.01) and horses reported to transport firewood (OR = 0.45 95% CI 0.28-0.74, p = 0.001). On multivariable analysis of donkeys, decreased odds of seropositivity were demonstrated amongst donkeys owned by households which also owned horses (OR = 0.23 95% CI 0.06-0.85, p = 0.03). HCF infection prevalence in horses and donkeys was 22.0% (n = 102/463, 95% CI 18.3-26.1%) and 5.4% (n = 5/92, 95% CI 1.8-12.2%), respectively. No significant agreement was measured between LAT and nested ITS-PCR results (κ < 0.00). High Histoplasma spp. exposure was demonstrated amongst equids in The Gambia. Investigation of risk factors, including equid husbandry and management strategies, as well as geoclimatic variations, is warranted. Outcomes may inform sustainable and equitable EL control strategies in The Gambia and comparable settings worldwide.

Anti-filarial antibodies are sensitive indicators of lymphatic filariasis transmission and enable identification of high-risk populations and hotspots

ObjectivesCirculating filarial antigen (Ag) is used by elimination programs to monitor lymphatic filariasis (LF) transmission; however, antifilarial antibodies (Ab) may be more sensitive than Ag for detecting LF. Our objectives were to describe Ab seroprevalence, identify risk factors for Ab seropositivity, investigate age-specific associations between Ag and Ab, and evaluate geographic clustering of seropositivity. MethodsCommunity-based serosurveys of participants aged ≥5 years were conducted in 35 primary sampling units (PSUs). Ag-positivity was detected using Alere™ Filariasis Test Strips and Ab-seropositivity using multiplex bead assays. Seroprevalence was adjusted for study design. ResultsOf 3795 participants (range:5-90 years), adjusted prevalence for Ag, Bm14 Ab, Wb123 Ab, and Bm33 Ab were 3.7% (n=117), 20.3% (n=583), 32.2% (n=987), and 51.0% (n=1659), respectively. Male sex, older age, and residents of suspected hotspots had higher odds of seropositivity to all seromarkers. Seroprevalence was lower in 5-9-year-olds vs ≥10-year-olds (P<0.001). Clustering was significantly higher in households (intra-cluster correlation for Ag:0.45; Bm14 Ab:0.32; Bm33 Ab:0.31; Wb123 Ab:0.29) compared to PSUs or region. ConclusionsAbs enabled identification of risk factors for seropositivity and geographical clustering to inform targeted interventions for LF programmes. Further research is needed to define Ab thresholds for active versus past infection and elimination targets.

Serological and molecular survey of Toxoplasma gondii infection and associated risk factors in urban cats in Kunming, Southwest China.

Toxoplasma gondii (T. gondii) is a worldwide zoonotic parasite that can infect almost warm-blood animals, including humans, which seriously affect the health of host. Cats are known to be the only definitive host of T. gondii and continuously excrete highly infectious oocysts. This parasite carried by the companion animals leads to a great public health risk. However, there is little information on epidemiology of T. gondii in urban cats in Kunming, Southwest China. In the present study, a total of 231 serum and fecal samples were collected in Kunming aera, and then seroprevalence of T. gondii IgG antibodies in serum and molecular investigation in feces were analyzed to elucidate T. gondii infection in urban cats. The results revealed that 168 of 231 cats (72.7%) were positive for T. gondii antibodies, and 1 of 74 cat feces (1.4%) also showed a positive PCR for T. gondii DNA. The positive fecal sample was sequenced and then phylogenetically analyzed, and the isolate of T. gondii in the present study was closely related to T. gondii strain CN. In addition, the food, water and age of cats were identified as the risk factor for seropositivity. Overall, our findings indicate the widespread occurrence of T. gondii infection in urban cats in Kunming, Southwest China and identify food, water and age are the risk factors associated with T. gondii infection, which can provide effective information for developing strategies to prevent and control this zoonosis.

Prevalence and risk factors for HPV seropositivity and anogenital DNA positivity among men who have sex with men: a repeated cross-sectional study

ObjectivesThis study aimed to assess associations of potential risk factors with human papillomavirus (HPV) seropositivity among men who have sex with men (MSM) and compare these to risk factors for anal and penile (HPV) deoxyribonucleic acid (DNA)-positivity in the same study population. MethodsSeropositivity and anal and penile HPV DNA-positivity were determined for seven high-risk HPV genotypes for MSM aged 16-24 years participating in Papillomavirus Surveillance among STI clinic Youngsters in the Netherlands (PASSYON) 2009-2021. Logistic regression models were conducted to assess risk factors for seropositivity, anal and penile HPV DNA-positivity. ResultsOverall, 1019 MSM were included. HPV-16 and -18 were most common for serology, and anal and penile HPV DNA-positivity. Although no clear similarities were observed for most risk factors for HPV seropositivity and anal or penile DNA positivity, receptive anal intercourse (RAI) was the strongest associated risk factor for both seropositivity (‘RAI ever’ adjusted odds ratio [aOR] 3.50, 95% confidence interval [CI] 1.56-7.88; ‘RAI previous 6 months’ aOR 2.17, 95% CI 1.44-3.26) and anal DNA-positivity (‘RAI previous 6 months’ aOR 1.67, 95% CI 1.09-2.56). ConclusionsOur study is suggestive of site-specific immune response after HPV infection; RAI might lead to anal HPV infections and consequently to seroconversion. Finally, as the two genotypes that are most oncogenic and preventable by all HPV vaccines were most common, our results underline the importance of gender-neutral vaccination.

Seroprevalence and molecular detection of foot and mouth disease virus in cattle in selected districts of Wolaita Zone, Southern Ethiopia

Foot and mouth disease (FMD) is a highly contagious, endemic, and acute viral cattle ailment that causes major economic damage in Ethiopia. Although several serotypes of the FMD virus have been detected in Ethiopia, there is no documented information about the disease's current serostatus and serotypes circulating in the Wolaita zone. Thus, from March to December 2022, a cross-sectional study was conducted to evaluate FMDV seroprevalence, molecular detection, and serotype identification in three Wolaita Zone sites. A multistage sample procedure was used to choose three peasant associations from each study region, namely Wolaita Sodo, Offa district, and Boloso sore district. A systematic random sampling technique was employed to pick 384 cattle from the population for the seroprevalence research, and 10 epithelial tissue samples were purposefully taken from outbreak individuals for molecular detection of FMDV. The sera were examined using 3ABC FMD NSP Competition ELISA to find antibodies against FMDV non-structural proteins, whereas epithelial tissue samples were analyzed for molecular detection using real-time RT-PCR, and sandwich ELISA was used to determine the circulating serotypes. A multivariable logistic regression model was used to evaluate the associated risk variables. The total seroprevalence of FMD in cattle was 46.88% (95% CI 41.86–51.88), with Wolaita Sodo Town having the highest seroprevalence (63.28%). As a consequence, multivariable logistic regression analysis revealed that animal age, herd size, and interaction with wildlife were all substantially related to FMD seroprevalence (p < 0.05). During molecular detection, only SAT-2 serotypes were found in 10 tissue samples. Thus, investigating FMD outbreaks and identifying serotypes and risk factors for seropositivity are critical steps in developing effective control and prevention strategies based on the kind of circulating serotype. Moreover, further research for animal species other than cattle was encouraged.

Histoplasma seropositivity and environmental risk factors for exposure in a general population in Upper River Region, The Gambia: A cross-sectional study

Robust surveillance of Histoplasma species is warranted in endemic regions, including investigation of community-level transmission dynamics. This cross-sectional study explored anti-Histoplasma antibody seroprevalence and risk factors for exposure in a general population in Upper River Region (URR), The Gambia.Study participants were recruited (December 2022–March 2023) by random household sampling across 12 Enumeration Areas (EAs) of URR. A questionnaire and clinical examination were performed; exploring demographic, clinical and environmental risk factors for Histoplasma exposure. One venous blood sample per participant was subject to IMMY Latex Agglutination Histoplasma test to determine presence of a recent IgM response to Histoplasma. Seropositivity risk factors were explored by multi-level, multivariable logistic regression analysis.The study population (n = 298) aged 5–83 years, demonstrated a positively skewed age distribution and comprised 55.4% females. An apparent seroprevalence of 18.8% (n = 56/298, 95% CI 14.5–23.7%) was measured using the LAT. A multivariable model demonstrated increased odds of Histoplasma seropositivity amongst female participants (OR = 2.41 95% CI 1.14–5.10); and participants reporting involvement in animal manure management (OR = 4.21 95% CI 1.38–12.90), and management of domestic animals inside the compound at night during the dry season (OR = 10.72 95% CI 2.02–56.83). Increasing age (OR = 0.96 95% CI 0.93–0.98) was associated with decreased odds of seropositivity. Clustering at EA level was responsible for 17.2% of seropositivity variance.The study indicates frequent recent Histoplasma exposure and presents plausible demographic and environmental risk factors for seropositivity. Histoplasma spp. characterisation at this human-animal-environment interface is warranted, to determine public health implications of environmental reservoirs in The Gambia.The study was supported by Wellcome Trust (206,638/Z/17/Z to CES) and a University of Liverpool-funded PhD studentship (to TRC).

Hunting for Answers: Assessing Brucella spp. Seroprevalence and Risks in Red Deer and Wild Boar in Central Portugal.

Between 2016 and 2023, a cross-sectional study was conducted in the central region of Portugal in order to better understand the epidemiology and public health risks resulting from the handling and consumption of game animals infected with Brucella spp. The seroprevalence and risk factors for Brucella spp. seropositivity were evaluated. Antibodies against Brucella spp. were determined using a commercial enzyme-linked immunosorbent assay (ELISA) according to the manufacturer's instructions. Results showed that in the 650 serum samples collected from red deer (n = 298) and wild boars (n = 352) in Portugal, 21.7% (n = 141; 95% CI: 18.6-25.1%) tested positive. Wild boar had a significantly higher prevalence (35.5%; 95% CI: 30.5-40.8%) than red deer (5.4%, 95% CI: 3.1-8.6%; p ≤ 0.001). Risk factors for seropositivity were investigated using multivariable logistic regression models. The odds of being seropositive was 8.39 (95% CI: 4.75-14.84; p ≤ 0.001) times higher in wild boar than in red deer. Correlations between sex, age, body condition, and seropositivity could not be observed. The higher seroprevalence in wild boar suggests that this species may primarily contribute to the Brucella spp. ecology in central Portugal.

The seroprevalence of toxocariasis and related risk factors in children in Ho Chi Minh City, Vietnam: results from a school-based cross-sectional study.

Children are especially vulnerable to Toxocara infection and its severe complications; however, there have not been any published data on the disease prevalence and treatment effectiveness in the population of Vietnamese children. This study was conducted to determine the prevalence of toxocariasis and explore factors associated with Toxocara infection in children aged 3-15 y in Ho Chi Minh City, Vietnam. We conducted a cross-sectional study using a multistage cluster sampling approach in public schools. Blood samples were collected, and toxocariasis cases were confirmed, based on a history of contact with dogs/cats and positive anti-Toxocara antibody detection via ELISA. We calculated the percentage of seropositive children across gender, grade levels, districts and caregiver education. Multiple regression models were employed to identify potential risk factors. Anti-Toxocara antibodies were found in 14.2% of the 986 children studied. Significant variations in seropositivity were observed across grade levels, districts and caregiver education levels. Multivariable analysis identified caregiver education, contact with dogs/cats and improper handling of pet feces as seropositivity risk factors. This was the first community-based prevalence study of toxocariasis in a pediatric population in Vietnam. Implementation of preventive measures such as public education, routine fecal examinations and chemotherapeutic treatment of animals is highly recommended.

Schistosomiasis Seroprevalence among Children Aged 0-14 Years in Nigeria, 2018.

The first nationally representative, population-based study of schistosomiasis seroprevalence in Nigeria was conducted using blood samples and risk-factor data collected during the 2018 Nigeria HIV/AIDS Indicator and Impact Survey (NAIIS). Schistosomiasis seroprevalence was estimated by analyzing samples for reactivity to schistosome soluble egg antigen (SEA) in a multiplex bead assay; NAIIS survey data were assessed to identify potential risk factors for seropositivity. The SEA antibody data were available for 31,459 children aged 0 to 14 years. Overall seroprevalence was 17.2% (95% CI: 16.3-18.1%). Seropositive children were identified in every age group, including children < 5 years, and seroprevalence increased with increasing age (P < 0.0001). Several factors were associated with increased odds of seropositivity, including being a boy (odds ratio [OR] = 1.34, 95% CI: 1.24-1.45), living in a rural area (OR = 2.2, 95% CI: 1.9-2.5), and animal ownership (OR = 1.67, 95% CI: 1.52-1.85). Access to improved sanitation and drinking water sources were associated with decreased odds of seropositivity (OR = 0.52, 95% CI: 0.47-0.58 and OR = 0.53, 95% CI: 0.47-0.60, respectively) regardless of whether the child lived in a rural (sanitation: adjusted odds ratio [aOR] = 0.7, 95% CI: 0.6-0.8; drinking water: aOR = 0.7, 95% CI: 0.6-0.8) or urban area (sanitation: aOR = 0.6, 95% CI: 0.5-0.7; drinking water: aOR = 0.5, 95% CI: 0.4-0.6), highlighting the importance of these factors for schistosomiasis prevention and control. These results identified additional risk populations (children < 5 years) and a new risk factor (animal ownership) and could be used to monitor the impact of control programs.

SARS-CoV-2 seropositivity among healthcare professionals in a rural state.

We evaluated SARS-CoV-2 anti-nucleocapsid (anti-N) seroconversion and seroreversion rates, risk factors associated with SARS-CoV-2 seroconversion, and COVID-19 risk perceptions among academic healthcare center employees in a rural state. Among employees aged ≥18 years who completed a screening survey (n = 1,377), we invited all respondents reporting previous COVID-19 (n = 85; 82 accepted) and a random selection of respondents not reporting previous COVID-19 (n = 370; 220 accepted) to participate. Participants completed surveys and provided blood samples at 3-month intervals (T0, T3, T6, T9). We used logistic regression to identify risk factors for seropositivity at T0. The cohort was primarily direct patient caregivers (205/302; 67.9%), white (278/302; 92.1%), and female (212/302; 70.2%). At T0, 86/302 (28.4%) participants were seropositive. Of the seronegative participants, 6/198 (3.0%), 6/183 (3.3%), and 14/180 (7.8%) had seroconverted at T3, T6, and T9, respectively. The overall seroreversion rate was 6.98% at T9. At T0, nursing staff (odds ratio [OR], 2.37; 95% confidence interval [CI], 1.08, 5.19) and being within six feet of a non-household member outside of work (OR, 2.91; 95% CI, 1.02, 8.33) had significantly higher odds of seropositivity. Vaccination (OR, 0.05; 95% CI, 0.02, 0.12) and face mask use (OR, 0.36; 95% CI, 0.17, 0.78) were protective. The seroconversion and seroreversion rates were low among participants. Public health and infection prevention measures implemented early in the COVID-19 pandemic - vaccination, face mask use, and social distancing - were associated with significantly lower odds of SARS-CoV-2 seropositivity among participants.

HIV Sero-Status and Risk Factors of Sero-Positivity of HIV Exposed Children Below Two Years of Age at Mityana General Hospital in Mityana District, Uganda

The aim of this study was to identify the factors linked to HIV serostatus and the risks of HIV positivity among children under two years old exposed to HIV at Mityana General Hospital in Mityana district, Uganda. This was a cross-sectional descriptive survey utilizing quantitative data from administered questionnaires and routine service data obtained from the mother’s HIV care card and the exposed infant clinical chart. Data analysis was performed using Epi Info version 7.2.4 for entry and Stata version 16 for analysis. Descriptive statistics characterized both infant and mother traits. Logistic regression was employed to determine the factors associated with HIV serostatus. Among the 102 mother–infant pairs recruited, most mothers were between 25–34 years old (53/102, 52.0%), married (67/102, 65.7%), had attained at least primary education (49/102, 48.1%), and were involved in farming for their livelihood (89/102, 87.3%). The HIV prevalence among the infants stood at 8.8%. In the bivariate analysis, factors such as place of delivery (OR = 4.6, 95% CI: 1.340-9.413, p = 0.003), normal delivery (OR = 4.7, 95% CI:0.682-5.522, p= &lt;0.001), poor adherence to ART (OR=3.11, 95% CI: 0.983-8.344, p=0.026), and the mothers’ level of education (OR=6.2, 95% CI: 3.00-14.476, p= &lt;0.001) were associated with HIV-positive outcomes in infants below two years old. This study underscores that 8.8% of children under 2 years attending Mityana General Hospital are HIV-infected due to exposure from their mothers. Factors contributing to this burden include maternal non-adherence to ART, delivery in facilities lacking PMTCT protocols, maternal education levels, and the absence of prophylaxis administration to exposed infants, collectively propagating HIV transmission among these infants. Keywords: Pediatric HIV, Mother-to-child transmission, HIV serostatus, Infants below 2 years.

Trends in Chlamydia trachomatis IgG seroprevalence in the general population of the Netherlands over 20 years

ObjectivesTo report sex and age-specific Chlamydia trachomatis (Ct) seroprevalence estimates in the general population of the Netherlands between 1996 and 2017 and identify risk factors associated with Ct seropositivity.MethodsParticipants (n=5158,...

Prevalence and Risk Factors for Hepatitis E Virus in Wild Boar and Red Deer in Portugal.

Hepatitis E virus (HEV) is a zoonotic foodborne virus with an annual infection prevalence of 20 million human cases, which seriously affects public health and economic development in both developed and developing countries. To better understand the epidemiology of HEV in Central Portugal, a cross-sectional study was conducted from 2016 to 2023 with sera samples from wild ungulates. The seroprevalence and risk factors for HEV seropositivity were evaluated in the present study. Specifically, antibodies against HEV were determined by a commercial enzyme-linked immune-sorbent assay (ELISA). Our results show that in the 650 sera samples collected from 298 wild red deer and 352 wild boars in Portugal, 9.1% red deer and 1.7% wild boar were positive for antibodies to HEV. Regarding age, the seropositivity in juvenile wild ungulates was 1.3%, whereas it was 7.2% in adults. Logistic regression models investigated risk factors for seropositivity. The odds of being seropositive was 3.6 times higher in adults than in juveniles, and the risk was 4.2 times higher in red deer than in wild boar. Both wild ungulate species were exposed to HEV. The higher seroprevalence in red deer suggests that this species may make a major contribution to the ecology of HEV in Central Portugal. Further research is needed to understand how wildlife affects the epidemiology of HEV infections in Portugal.

Inactivated SARS-CoV-2 booster vaccine enhanced immune responses in patients with chronic liver diseases

Chronic liver disease (CLD) entails elevated risk of COVID-19 severity and mortality. The effectiveness of the booster dose of inactivated SARS-CoV-2 vaccine in stimulating antibody response in CLD patients is unclear. Therefore, we conducted a cross-sectional study involving 237 adult CLD patients and 170 healthy controls (HC) to analyze neutralizing antibodies (NAbs) against SARS-CoV-2 prototype and BA.4/5 variant, anti-receptor binding domain (RBD) IgG, and total anti-SARS-CoV-2 antibodies. Serum levels of the total anti-SARS-CoV-2 antibodies, anti-RBD IgG and inhibition efficacy of NAbs were significantly elevated in CLD patients after the booster dose compared with the pre-booster dose, but were relatively lower than those of HCs. Induced humoral responses decreased over time after booster vaccination. The neutralization efficiency of the serum against BA.4/5 increased but remained below the inhibition threshold. All four SARS-CoV-2 antibodies, including total anti-SARS-CoV-2 antibodies, anti-RBD IgG and NAbs against prototype and BA.4/5, were lower in patients with severe CLD than those with non-severe CLD. After booster shot, age and time after the last vaccine were the risk factors for seropositivity of NAb against BA.4/5 in CLD patients. Additionally, white blood cell counts and hepatitis B core antibodies were the protective factors, and severe liver disease was the risk factor associated with seropositivity of total anti-SARS-CoV-2 antibodies. Overall, our data uncovered that antibody responses were improved in CLD patients and peaked at 120 days after the booster vaccines. All antibodies excepting total anti-SARS-CoV-2 antibodies declined after peak. CLD patients exhibited impaired immunologic responses to vaccination and weakened NAbs against BA.4/5, which hindered the protective effect of the booster shot against Omicron prevalence. Cellular immune responses should be further evaluated to determine the optimal vaccine regimen for CLD patients.

Seroprevalence and associated risk factors of brucellosis, Rift Valley fever and Q fever among settled and mobile agro-pastoralist communities and their livestock in Chad.

Brucellosis, Rift Valley fever (RVF) and Q fever are zoonoses prevalent in many developing countries, causing a high burden on human and animal health. Only a few studies are available on these among agro-pastoralist communities and their livestock in Chad. The objective of our study was to estimate brucellosis, RVF and Q fever seroprevalence among Chadian agro-pastoralist communities and their livestock, and to investigate risk factors for seropositivity. We conducted a multi-stage cross-sectional serological survey in two rural health districts, Yao and Danamadji (966 human and 1041 livestock (cattle, sheep, goat and equine) samples)). The true seroprevalence were calculated applying a Bayesian framework to adjust for imperfect diagnostic test characteristics and accounting for clustering in the study design. Risk factors for each of the zoonotic diseases were estimated using mixed effects logistic regression models. The overall prevalence for brucellosis, Q fever and RVF combined for both regions was estimated at 0.2% [95% credibility Interval: 0-1.1], 49.1% [%CI: 38.9-58.8] and 28.1% [%CI: 23.4-33.3] in humans, and 0.3% [%CI: 0-1.5], 12.8% [%CI: 9.7-16.4] and 10.2% [%CI: 7.6-13.4] in animals. Risk factors correlating significantly with the respective disease seropositivity were sex for human brucellosis, sex and Q fever co-infection for animal brucellosis, age for human Q fever, species and brucellosis co-infection for animal Q fever, age and herd-level animal RVF seroprevalence within the same cluster for human RVF, and cluster-level human RVF seroprevalence within the same cluster for animal RVF. In Danamadji and Yao, Q fever and RVF are notably seroprevalent among agro-pastoralist human and animal communities, while brucellosis appears to have a low prevalence. Correlation between the seroprevalence between humans and animals living in the same communities was detected for RVF, highlighting the interlinkage of human and animal transmissible diseases and of their health, highlighting the importance of a One Health approach.

Serological Markers of Exposure to Plasmodium falciparum and Plasmodium vivax Infection in Southwestern Ethiopia.

As malaria control and elimination efforts ramp up in Ethiopia, more sensitive tools for assessing exposure to coendemic Plasmodium falciparum and Plasmodium vivax are needed to accurately characterize malaria risk and epidemiology. Serological markers have been increasingly explored as cost-effective tools for measuring transmission intensity and evaluating intervention effectiveness. The objectives of this study were to evaluate the efficacy of a panel of 10 serological markers as a proxy for malaria exposure and to determine underlying risk factors of seropositivity. We conducted cross-sectional surveys in two sites of contrasting malaria transmission intensities in southwestern Ethiopia: Arjo in Oromia Region (low transmission) and Gambella in Gambella Regional State (moderate transmission). We measured antibody reactivity against six P. falciparum (AMA-1, CSP, EBA175RIII-V, MSP-142, MSP-3, RH2ab) and four P. vivax (DBPII[Sal1], EBP2, MSP-119, RBP2b) targets. We used mixed effects logistic regressions to assess predictors of seropositivity. Plasmodium spp. infection prevalence by quantitative polymerase chain reaction was 1.36% in Arjo and 10.20% in Gambella. Seroprevalence and antibody levels against all 10 antigens were higher in Gambella than in Arjo. We observed spatial heterogeneities in seroprevalence across Arjo and smaller variations across Gambella. Seroprevalence in both sites was lowest against PfCSP and highest against PfAMA-1, PfMSP-142, and PvMSPS-119. Male sex, age, and agricultural occupation were positively associated with seropositivity in Arjo; associations were less pronounced in Gambella. Our findings demonstrate that seroprevalence and antibody levels to specific Plasmodium antigens can be used to identify high-risk groups and geographical areas where interventions to reduce malaria transmission should be implemented.

Horses as Sentinels for the Circulation of Flaviviruses in Eastern-Central Germany.

Since 2018, autochthonous West Nile virus (WNV) infections have been regularly reported in eastern-central Germany. While clinically apparent infections in humans and horses are not frequent, seroprevalence studies in horses may allow the tracing of WNV and related flaviviruses transmission, such as tick-borne encephalitis virus (TBEV) and Usutu virus (USUV), and consequently help to estimate the risk of human infections. Hence, the aim of our study was to follow the seropositive ratio against these three viruses in horses in Saxony, Saxony Anhalt, and Brandenburg and to describe their geographic distribution for the year 2021. In early 2022, i.e., before the virus transmission season, sera from 1232 unvaccinated horses were tested using a competitive pan-flavivirus ELISA (cELISA). In order to estimate the true seropositive ratio of infection with WNV, TBEV, and USUV for 2021, positive and equivocal results were confirmed by a virus neutralization test (VNT). In addition, possible risk factors for seropositivity using questionnaires were analyzed using logistic regression based on questionnaires similar to our previous study from 2020. In total, 125 horse sera reacted positive in the cELISA. Based on the VNT, 40 sera showed neutralizing antibodies against WNV, 69 against TBEV, and 5 against USUV. Three sera showed antibodies against more than one virus, and eight were negative based on the VNT. The overall seropositive ratio was 3.3% (95% CI: 2.38-4.40) for WNV, 5.6% (95% CI: 4.44-7.04) for TBEV, and 0.4% (95% CI: 0.14-0.98) for USUV infections. While age and number of horses on the holding were factors predicting TBEV seropositivity, no risk factors were discovered for WNV seropositivity. We conclude that horses are useful sentinels to determine the flavivirus circulation in eastern-central Germany, as long as they are not vaccinated against WNV.