Population-based Seroprevalence Study Research Articles

Logistics Workers Are a Key Factor for SARS-CoV-2 Spread in Brazilian Small Towns: Case-Control Study.

BackgroundData on how SARS-CoV-2 enters and spreads in a population are essential for guiding public policies.ObjectiveThis study seeks to understand the transmission dynamics of SARS-CoV-2 in small Brazilian towns during the early phase of the epidemic and to identify core groups that can serve as the initial source of infection as well as factors associated with a higher risk of COVID-19.MethodsTwo population-based seroprevalence studies, one household survey, and a case-control study were conducted in two small towns in southeastern Brazil between May and June 2020. In the population-based studies, 400 people were evaluated in each town; there were 40 homes in the household survey, and 95 cases and 393 controls in the case-control study. SARS-CoV-2 serology testing was performed on participants, and a questionnaire was applied. Prevalence, household secondary infection rate, and factors associated with infection were assessed. Odds ratios (ORs) were calculated by logistic regression. Logistics worker was defined as an individual with an occupation focused on the transportation of people or goods and whose job involves traveling outside the town of residence at least once a week.ResultsHigher seroprevalence of SARS-CoV-2 was observed in the town with a greater proportion of logistics workers. The secondary household infection rate was 49.1% (55/112), and it was observed that in most households (28/40, 70%) the index case was a logistics worker. The case-control study revealed that being a logistics worker (OR 18.0, 95% CI 8.4-38.7) or living with one (OR 6.9, 95% CI 3.3-14.5) increases the risk of infection. In addition, having close contact with a confirmed case (OR 13.4, 95% CI 6.6-27.3) and living with more than four people (OR 2.7, 95% CI 1.1-7.1) were also risk factors.ConclusionsOur study shows a strong association between logistics workers and the risk of SARS-CoV-2 infection and highlights the key role of these workers in the viral spread in small towns. These findings indicate the need to focus on this population to determine COVID-19 prevention and control strategies, including vaccination and sentinel genomic surveillance.

Development of Zika NS1 ELISA methodology for seroprevalence detection in a cohort of Mexican patients in an endemic region

BackgroundZika (ZIKV) is a mosquito-borne virus that has caused multiple outbreaks in Americas. The early and accurate diagnosis of ZIKV is the key to minimize the health burden imposed on the infected patients. Many commercial ZIKV diagnosis kit are available based on ZIKV envelope antigen with varying sensitivity and specificity. ObjectiveThe aim of this study was to develop sensitive ELISA methodology based on recombinant ZIKV NS1 and NS1 β-ladder antigens for seroprevalence detection in a cohort of patients in an arbovirus endemic Mexican region in comparison to a commercial kit. Study designWe obtained serum samples from 60 patients presenting with febrile illness and from 10 healthy donors in Michoacán state in 2016–2017. These samples were screened for ZIKV by RT-PCR and used to develop NS1 based ELISA and compared to a commercial kit. ResultsOur results indicate that both ZIKV sNS1 and β-ladder-based ELISA can reliably detect anti-ZIKV NS1 antibodies in infected patients, relevant for the serodiagnosis of ZIKV. Determination of antibody titers showed that it offered higher sensitivity than a commercially available ZIKV ELISA. Over 90% seropositivity against ZIKV for the febrile patients was detected in Lázaro Cárdenas which is an arbovirus endemic region while lower seropositivity was observed in the healthy volunteers in Morelia (non-endemic area). ConclusionWe conclude that our simple and sensitive in-house NS1 based ELISA used in this study has excellent sensitivity, is easy to use and can provide fast results suitable for larger population-based seroprevalence studies in the future.

SARS-CoV-2 population-based seroprevalence studies in Europe: a scoping review

ObjectivesWe aimed to review SARS-CoV-2 seroprevalence studies conducted in Europe to understand how they may be used to inform ongoing control strategies for COVID-19.DesignScoping review of peer-reviewed publications and manuscripts...

Seroprevalence of SARS-CoV-2 in the West Bank region of Palestine: a cross-sectional seroepidemiological study

ObjectivesSeroprevalence rates are important indicators to the epidemiology of COVID-19 and the extent of the pandemic given the existence of asymptomatic cases. The purpose of this study is to assess...

Changes in SARS-CoV-2 Spike versus Nucleoprotein Antibody Responses Impact the Estimates of Infections in Population-Based Seroprevalence Studies.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific antibody responses to the spike (S) protein monomer, S protein native trimeric form, or the nucleocapsid (N) proteins were evaluated in cohorts of individuals with acute infection (n = 93) and in individuals enrolled in a postinfection seroprevalence population study (n = 578) in Switzerland. Commercial assays specific for the S1 monomer, for the N protein, or within a newly developed Luminex assay using the S protein trimer were found to be equally sensitive in antibody detection in the acute-infection-phase samples. Interestingly, compared to anti-S antibody responses, those against the N protein appear to wane in the postinfection cohort. Seroprevalence in a "positive patient contacts" group (n = 177) was underestimated by N protein assays by 10.9 to 32.2%, while the "randomly selected" general population group (n = 311) was reduced by up to 45% relative to the S protein assays. The overall reduction in seroprevalence targeting only anti-N antibodies for the total cohort ranged from 9.4 to 31%. Of note, the use of the S protein in its native trimer form was significantly more sensitive compared to monomeric S proteins. These results indicate that the assessment of anti-S IgG antibody responses against the native trimeric S protein should be implemented to estimate SARS-CoV-2 infections in population-based seroprevalence studies.IMPORTANCE In the present study, we have determined SARS-CoV-2-specific antibody responses in sera of acute and postinfection phase subjects. Our results indicate that antibody responses against viral S and N proteins were equally sensitive in the acute phase of infection, but that responses against N appear to wane in the postinfection phase where those against the S protein persist over time. The most sensitive serological assay in both acute and postinfection phases used the native S protein trimer as the binding antigen, which has significantly greater conformational epitopes for antibody binding compared to the S1 monomer protein used in other assays. We believe these results are extremely important in order to generate correct estimates of SARS-CoV-2 infections in the general population. Furthermore, the assessment of antibody responses against the trimeric S protein will be critical to evaluate the durability of the antibody response and for the characterization of a vaccine-induced antibody response.

Severe acute respiratory syndrome-coronavirus-2 seroprevalence study in Pimpri-Chinchwad, Maharashtra, India coinciding with falling trend - Do the results suggest imminent herd immunity?

COVID-19 is a public health concern currently demanding continuous efforts to understand its epidemiology. Pimpri-Chinchwad township with a population of over 25 lakhs is located in Maharashtra, one of the worst affected states in India. After the incidence peaked in the township in mid-September 2020, cases started declining even as lockdown restrictions were eased. A seroprevalence study was conducted to understand the transmission dynamics of the pandemic in this region. We carried out a population-based seroprevalence study for IgG antibodies for severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) among 5000 residents 12 years and above selected by the cluster random sampling. We selected 50 clusters in slums, 80 clusters in tenements, and 70 clusters from housing societies. The field work for collection of samples was carried out from October 07 to October 17, 2020. We used kit from Abbott (SARS-CoV-2 IgG), which employs chemiluminescent microparticle immunoassay technology. The prevalence of IgG antibodies was expressed as point estimates with 95% confidence intervals (CIs). These were weighted for areas and cluster effect and further adjusted for test performance. The overall seropositivity for IgG was 34.04% (95% CIl 31.3%-36.8%). Slum dwellers had 40.9% positivity rate (95% CI 37.0%-44.7%), those in tenements 41.2% (95% CI 37.7%-44.8%) and people living in housing societies had 29.8% positivity (95% CI 25.8%-33.8%). A considerable proportion of population had encountered the novel coronavirus approaching partial, if not complete, herd immunity, which may partly explain the declining trend in spite of easing of lockdown restrictions.

Very High Relative Seroprevalence of Anti--SARS-CoV-2 Antibodies Among Communities in Bangui, Central African Republic

Background: Large-scale population-based seroprevalence studies of SARS-CoV-2 are essential to characterize the cumulative incidence of SARS-CoV-2 infection and to extrapolate the prevalence of presumptive immunity at the population level.Objective: The objective of our survey was to estimate the cumulative population immunity for COVID-19 and to identify individual characteristics associated with a positive serostatus.Method: This was a clustered cross-sectional study conducted from July 12 to August 20, 2021, in households in the city of Bangui, the capital of the Central African Republic. Information regarding demographic characteristics (age, gender, and place of residence), comorbidities (chronic diseases) was collected. A venous blood sample was obtained for each participant to determine the level of total anti-SARS-CoV-2 antibodies using a WANTAI SARS-CoV-2 Ab ELISA kit.Results: All up, 799 participants were surveyed. The average age was 27 years, and 45·8% of the respondents were male (sex ratio: 0.8). The overall proportion of respondents with a positive serostatus was 74·1%. Participants over 20 years of age were twice as likely to have a positive serostatus, with an OR of 2.· ·2 (95% CI: [1·6, 3·1]).Interpretation: The results of this survey revealed a high cumulative level of immunity in Bangui, thus indicating a significant degree of spread of SARS-CoV-2 in the population. The public health implications of this high level of immunity to SARS-CoV-2 in the population remain to be determined.Funding Information: This study was funded by the French Ministry for Europe and Foreign Affairs through the REPAIR COVID-19-Africa project coordinated by the Pasteur International Network association.Declaration of Interests: All authors declare no competing interests.Ethics Approval Statement: This study was authorised by the Ministry of Health of the Central African Republic (N° 603/MSPP/DIRCAB/CMRF-21) and by the Ethics and Scientific Committee of the University of Bangui (N°09/UB/FACSS/IPB/CES/20). Informed and signed consent was obtained from each participant.

Seroprevalence, spatial dispersion and factors associated with flavivirus and chikungunya infection in a risk area: a population-based seroprevalence study in Brazil

BackgroundThe State of Ceará, in Northeastern Brazil, suffers from a triple burden of arboviruses (dengue, Zika and chikungunya). We measured the seroprevalence of chikungunya, dengue and Zika and its associated factors in the population of Juazeiro do Norte, Southern Ceará State, Brazil.MethodsA cross-sectional study of analytical and spatial analysis was performed to estimate the seroprevalence of dengue, Zika and chikungunya, in the year 2018. Participants were tested for IgM and IgG against these three viruses. Those with IgM and/or IgG positive tests results were considered positive. Poisson regression was used to analyze the factors associated with positive cases, in the same way that the spatial analysis of positive cases was performed to verify whether the cases were grouped.ResultsOf the 404 participants, 25.0% (103/404) were positive for CHIKV, 92.0% (373/404) for flavivirus (dengue or Zika) and of these, 37.9% (153/404) samples were classified as probable dengue infection. Of those who reported having had an arbovirus in the past, positive CHIKV cases had 58.7% arthralgia (PR = 4.31; 95% CI: 2.06–9.03; p = 0.000) mainly in the hands, ankles and feet. Age over 60 years had a positive association with cases of flavivirus (PR = 1.29; 95% CI: 1.09–1.54; p = 0.000). Fever, muscle pain, joint pain and skin rash were the most reported symptoms (46.1, 41.0, 38.3 and 28.41%, respectively). The positive cases of chikungunya and dengue or Zika were grouped in space and the city center was most affected area.ConclusionsFour years after the introduction of CHIKV, where DENV has been in circulation for over 30 years, 1/4 of the population has already been exposed, showing the extent of the epidemic. The measured prevalence was much higher than that reported by local epidemiological surveillance.

Immunity to Hepatitis-A virus: A nationwide population-based seroprevalence study from Iran

BackgroundThe mortality rate of acute Hepatitis A increases from 0.1% in the children to 1.2%, in the adults. Hepatitis A is efficiently prevented by HAV-vaccine, but the strategy for distributing this vaccine among countries is dependent on their level of immunity to HAV. This study aimed to detect the level of immunity to HAV in Iran. MethodsIn this population-based seroprevalence study, 5419 participants from 12 of provinces of Iran, including 57 urban and 120 rural areas were chosen through a multi-stage cluster random sampling. Participants were interviewed by filling checklists and 3 cc of blood sample was obtained from each of them. IBM SPSS statistics V.21 software was used for univariable and multivariable analysis of data. ResultsMean of age of Interviewees was 26.4 ± 16 years, ranging from 1 to 94 years with a male to female ratio 1.02. Overall, 3603 (66.5%) of subjects were seropositive for HAV-IgG. Among the age groups, 41.1% of children by the age 15 years and 82.6% of adults around 30 years old were immune to HAV. The Mid-point age of population immunity was 21 years. Residents of the borders of the country, people who had less access to the safe water or sanitary toilet, individuals with low socioeconomic status and persons who were a member of dense families had the most probability of seropositivity. ConclusionsThis study showed that Iran is among HAV low endemic countries and vaccination against HAV is recommended only in the high-risk population, including patients with chronic liver diseases, patients with coagulopathy, travelers to the high endemic areas, and homosexuals. Establishment of national HAV surveillance system, concerning of health system about the occurrence of the HAV outbreaks, implementation of harm reduction strategies, improving economic indices and sanitation and access to the safe water in the deprived regions is recommended.

Third national biobank for population-based seroprevalence studies in the Netherlands, including the Caribbean Netherlands

BackgroundThis paper outlines the methodology, study population and response rate of a third large Dutch population-based cross-sectional serosurvey carried-out in 2016/2017, primarily aiming to obtain insight into age-specific seroprevalence of vaccine-preventable diseases to evaluate the National Immunization Programme (NIP). In addition, Caribbean Netherlands (CN) was included, which enables additional research into tropical pathogens.MethodsA two-stage cluster sampling technique was used to draw a sample of Dutch residents (0–89 years) (NS), including an oversampling of non-Western migrants, persons living in low vaccination coverage (LVC) areas, and an extra sample of persons born in Suriname, Aruba and the former Dutch Antilles (SAN). A separate sample was drawn for each Caribbean island. At the consultation hours, questionnaires, blood samples, oro- and nasopharyngeal swabs, faeces, − and only in the Netherlands (NL) saliva and a diary about contact patterns – were obtained from participants. Vaccination- and medical history was retrieved, and in CN anthropometric measurements were taken.ResultsIn total, blood samples and questionnaires were collected from 9415 persons: 5745 (14.4%) in the NS (including the non-Western migrants), 1354 (19.8%) in LVC areas, 501 (6.9%) SAN, and 1815 (23.4%) in CN.ConclusionsThis study will give insight into protection of the population against infectious diseases included in the NIP. Research based on this large biobank will contribute to public health (policy) in NL and CN, e.g., regarding outbreak management and emerging pathogens. Further, we will be able to extend our knowledge on infectious diseases and its changing dynamics by linking serological data to results from additional materials collected, environmental- and pharmacological data.

Association between seroprevalence of measles and various social determinants in the year following a measles outbreak in Turkey

ObjectivesDespite an ongoing measles elimination programme, a measles outbreak occurred in 2013 in Turkey. Population-based seroprevalence studies are needed to determine seronegativity and explore the reasons for this outbreak. This study aimed to explore the seroprevalence of measles and its association with various social determinants in a provincial population in Turkey in the year following a measles outbreak. Study designCross-sectional study. MethodsThis study was conducted in Manisa Province in 2014 in a sample of 1740 people aged >2 years. The dependent variable was the seroprevalence of measles. Independent variables were sex, age, migration, household size, household density, income, education level, existence of chronic disease and occupational class. Blood samples were collected from participants at family health centres. The presence of specific measles antibodies in serum samples was determined using an anti-measles virus IgG enzyme-linked immunosorbent assay test. Chi-squared test and logistic regression analysis were performed. ResultsOverall, data from 1250 people were analysed. The seroprevalence of measles in the whole study population was 82.2% (95% confidence interval 80.0–84.2). Seroprevalence was 55.4% among subjects aged 2–9 years, 48.7% among subjects aged 10–19 years, 74.1% among subjects aged 20–29 years and 93.6% among subjects aged 30–39 years (P < 0.01). Seroprevalence in subjects aged >40 years was >95%. The lowest seroprevalence was found in primary school children (40.2%), followed by those below the age for primary education (69.8%) and secondary school graduates (75.1%). The prevalence of measles seronegativity was not associated with any of the social determinants when adjusted for age. ConclusionsThe seroprevalence of measles was lower than expected in the study population and was particularly low in subjects aged <30 years of age despite previous vaccination. Seroprevalence was not associated with social determinants of health that confirmed either an even distribution of virus exposure or fair access to vaccination services. However, the current seroprevalence cannot be sufficiently effective to reach the measles elimination targets, suggesting that it may be necessary to re-evaluate the need for an extra dose of measles vaccine.

Chlamydia trachomatis Pgp3 Antibody Population Seroprevalence before and during an Era of Widespread Opportunistic Chlamydia Screening in England (1994-2012).

BackgroundOpportunistic chlamydia screening of <25 year-olds was nationally-implemented in England in 2008 but its impact on chlamydia transmission is poorly understood. We undertook a population-based seroprevalence study to explore the impact of screening on cumulative incidence of chlamydia, as measured by C.trachomatis-specific antibody.MethodsAnonymised sera from participants in the nationally-representative Health Surveys for England (HSE) were tested for C.trachomatis antibodies using two novel Pgp3 enzyme-linked immunosorbent assays (ELISAs) as a marker of past infection. Determinants of being seropositive were explored using logistic regression among 16–44 year-old women and men in 2010 and 2012 (years when sexual behaviour questions were included in the survey) (n = 1,402 women; 1,119 men). Seroprevalence trends among 16–24 year-old women (n = 3,361) were investigated over ten time points from 1994–2012.ResultsIn HSE2010/2012, Pgp3 seroprevalence among 16–44 year-olds was 24.4% (95%CI 22.0–27.1) in women and 13.9% (11.8–16.2) in men. Seroprevalence increased with age (up to 33.5% [27.5–40.2] in 30–34 year-old women, 18.7% [13.4–25.6] in 35–39 year-old men); years since first sex; number of lifetime sexual partners; and younger age at first sex. 76.7% of seropositive 16–24 year-olds had never been diagnosed with chlamydia. Among 16–24 year-old women, a non-significant decline in seroprevalence was observed from 2008–2012 (prevalence ratio per year: 0.94 [0.84–1.05]).ConclusionOur application of Pgp3 ELISAs demonstrates a high lifetime risk of chlamydia infection among women and a large proportion of undiagnosed infections. A decrease in age-specific cumulative incidence following national implementation of opportunistic chlamydia screening has not yet been demonstrated. We propose these assays be used to assess impact of chlamydia control programmes.

Malaria epidemiology in central Myanmar: identification of a multi-species asymptomatic reservoir of infection

BackgroundThe spread of artemisinin-resistant Plasmodium falciparum is a global health concern. Myanmar stands at the frontier of artemisinin-resistant P. falciparum. Myanmar also has the highest reported malaria burden in Southeast Asia; it is integral in the World Health Organization’s plan to eliminate malaria in Southeast Asia, yet few epidemiological data exist for the general population in Myanmar.MethodsThis cross-sectional, probability household survey was conducted in Phyu township, Bago Region (central Myanmar), during the wet season of 2013. Interviewers collected clinical and behavioural data, recorded tympanic temperature and obtained dried blood spots for malaria PCR and serology. Plasmodium falciparum positive samples were tested for genetic mutations in the K13 region that may confer artemisinin resistance. Estimated type-specific malaria PCR prevalence and seroprevalence were calculated, with regression analysis to identify risk factors for seropositivity to P. falciparum. Data were weighted to account for unequal selection probabilities.Results1638 participants were sampled (500 households). Weighted PCR prevalence was low (n = 41, 2.5%) and most cases were afebrile (93%). Plasmodium falciparum was the most common species (n = 19. 1.1%) and five (26%) P. falciparum samples harboured K13 mutations. Plasmodium knowlesi was detected in 1.0% (n = 16) and Plasmodium vivax was detected in 0.4% (n = 7). Seroprevalence was 9.4% for P. falciparum and 3.1% for P. vivax. Seroconversion to P. falciparum was 0.003/year in the whole population, but 16-fold higher in men over 23 years old (LR test p = 0.016).DiscussionThis is the first population-based seroprevalence study from central Myanmar. Low overall prevalence was discovered. However, these data suggest endemic transmission continues, probably associated with behavioural risk factors amongst working-age men. Genetic mutations associated with P. falciparum artemisinin resistance, the presence of P. knowlesi and discrete demographic risk groups present opportunities and challenges for malaria control. Responses targeted to working-age men, capable of detecting sub-clinical infections, and considering all species will facilitate malaria elimination in this setting.

Prevalence and predictors of hepatitis B in Jeddah City, Saudi Arabia: a population-based seroprevalence study.

Despite solid preventive strategies to reduce the risk of hepatitis B virus (HBV) infection, recent reports about its prevalence and predictors are lacking in several Saudi cities at the community level. This study aimed to assess the seroprevalence of HBV and to identify the most important predictors among the Saudi population in Jeddah city, Saudi Arabia. A cross-sectional study was conducted among 5,584 Saudi people attending primary health-care centers in Jeddah city during 2012/2013. Sociodemographic and hepatitis-related data were collected. HBV was diagnosed by ELISA test. The seroprevalence of HBV was estimated, and appropriate statistical analyses were performed, including univariate and multivariable regression analyses. The seroprevalence of HBV was 2.2% (95% CI = 1.82-2.58) in the studied participants. The prevalence was higher among non-governmental workers (3.5%), male participants (3.4%) and those aged ≥ 25 years (2.4%). The most important predictors for increasing the risk of HBV in this study were HBV contacts, male sex, history of dental procedures and blood transfusion. The significant positive risks associated with these predictors were 3.3, 2.5, 2.0 and 1.65, respectively. HBV vaccination, on the other hand, was associated with a significant risk reduction of 88% (OR = 0.12; 95% CI = 0.03-0.51). The seroprevalence of HBV was relatively low among the Saudi population in Jeddah city reflecting the actions taken by health authorities to control HBV infection. However, more efforts, particularly in relation to health education programmes, strict control of blood banks and dental clinics, are still needed.

Seroprevalence of Burkholderia pseudomallei among Adults in Coastal Areas in Southwestern India.

BackgroundAlthough melioidosis, is an important disease in many Southeast Asian countries and Australia, there is limited data on its prevalence and disease burden in India. However, an increase in case reports of melioidosis in recent years indicates its endemicity in India.Aims and methodsA population-based cross-sectional seroprevalence study was undertaken to determine the seroprevalence of B. pseudomallei by indirect haemagglutination assay and to investigate the associated risk determinants. Subjects were 711 adults aged 18 to 65 years residing in Udupi district, located in south-western coast of India.Key resultsOverall, 29% of the study subjects were seropositive (titer ≥20). Females were twice as likely to be seropositive compared to males. Rates of seroprevalence were similar in farmers and non-farmers. Besides gardening, other factors including socio-demographic, occupational and environmental factors did not show any relationship with seropositive status.Major conclusionsThere is a serological evidence of exposure to B. pseudomallei among adults in India. While the bacterium inhabits soil, exposure to the agent is not limited to farmers. Non-occupational exposure might play an important role in eliciting antibody response to the bacterium and may also be an important factor in disease causation.

Population-Level Persistence of Immunity 2 Years After the PsA-TT Mass-Vaccination Campaign in Mali.

Background. In 2010, Africa's first preventive meningococcal mass vaccination campaign was launched using a newly developed Neisseria meningitidis group A (NmA) polysaccharide–tetanus toxoid conjugate vaccine, PsA-TT (MenAfriVac), designed specifically for the meningitis belt. Given PsA-TT's recent introduction, the duration of protection against meningococcal group A is unknown.Methods. We conducted a household-based, age-stratified seroprevalence survey in Bamako, Mali, in 2012, 2 years after the vaccination campaign targeted all 1- to 29-year-olds. Randomly selected participants who had been eligible for PsA-TT provided a blood sample and responded to a questionnaire. Sera were analyzed to assess NmA-specific serum bactericidal antibody titers using rabbit complement (rSBA) and NmA-specific immunoglobulin G (IgG) by enzyme-linked immunosorbent assay. The proportion of participants putatively protected and the age group- and sex-specific rSBA geometric mean titers (GMTs) and IgG geometric mean concentrations (GMCs) were determined.Results. Two years postvaccination, nearly all of the 800 participants (99.0%; 95% confidence interval [CI], 98.3%–99.7%) maintained NmA-specific rSBA titers ≥8, the accepted threshold for protection; 98.6% (95% CI, 97.8%–99.4%) had titers ≥128, and 89.5% (95% CI, 87.4%–91.6%) had titers ≥1024. The rSBA GMTs were significantly higher in females than in males aged <18 years at vaccination (P < .0001). NmA-specific IgG levels ≥2 µg/mL were found in 88.5% (95% CI, 86.3%–90.7%) of participants.Conclusions. Two years after PsA-TT introduction, a very high proportion of the population targeted for vaccination maintains high antibody titers against NmA. Assessing the duration of protection provided by PsA-TT is a priority for implementing evidence-based vaccination strategies. Representative, population-based seroprevalence studies complement clinical trials and provide this key evidence.

Seroepidemiology of Epstein−Barr virus and cytomegalovirus among Israeli male young adults

PurposeTo assess the seroprevalence and seroconversion of Epstein−Barr virus (EBV) and cytomegalovirus (CMV) Immunoglobulin G (IgG) antibodies and identify associated socioeconomic and smoking variables among male young adults in Israel, to explore health disparities and aid prevention efforts. MethodsA population-based seroprevalence study of EBV and CMV IgG antibodies in a systematic sample of Israeli males upon recruitment to mandatory military service during 1994–2004. Associations between socioeconomic and smoking variables and the seroprevalence of EBV/CMV were evaluated, controlling for possible confounders. A subset of seronegative subjects was assessed for seroconversion upon discharge from military service. ResultsOverall seroprevalence rates were 87% for EBV and 59% for CMV. An association between the seroprevalence of EBV and CMV was observed. Seroconversion was 56% for EBV as compared with 31% for CMV. Lower paternal education was found to be associated with both EBV and CMV seroprevalence. Lower socioeconomic status, North African origin, and urban residence were found to be associated with CMV seropositivity, as was smoking for EBV seropositivity. ConclusionsSocioeconomic disparities exist in the seroprevalence rates of CMV and EBV among Israeli male young adults. The results of the study could aid public health efforts and determine target populations when a vaccine becomes available.

Seroprevalence of HBV and HCV markers among young adult males in the Air Force in Florianópolis, South Brazil

We investigated the prevalence of hepatitis B virus (HBV) and hepatitis C virus (HCV) serological markers of infection in young adults from the metropolitan region of Florianópolis who were conscripts of the Air Base of Florianópolis in the state of Santa Catarina, Brazil. A population-based cross-sectional seroprevalence study was conducted with 371 young males during a one year period starting in June 2009. Demographic characteristics, socio-economic characteristics and possible risk factors to HBV and HCV were assessed. Blood samples were analyzed for HBsAg, anti-HBc, anti-HCV and anti-HBs through automated microparticle enzymatic immunoassays (Abbott®, AxSYM System, Wiesbaden, Germany). None of the participants showed positivity to HBsAg or anti-HCV. The prevalence of anti-HBc was 1.6% (95% CI 0.6 - 3.5), and the prevalence of anti-HBs was 40.7% (95% CI 35.7 - 45.9). Unsafe sex was associated with positive anti-HBc in a bivariate analysis. There was a very low prevalence of past HBV infection and no cases of past HCV infection in a young adult population in the metropolitan region of Florianópolis. The very low prevalence of markers of infection and risk factors indicates a very optimistic future with respect to HBV and HCV infection in this population.

National Estimates of Seroincidence and Seroprevalence for Herpes Simplex Virus Type 1 and Type 2 Among US Military Adults Aged 18 to 29 Years

While population-based seroprevalence studies of herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) are widespread, seroincidence studies are largely limited to select or high-risk populations. The US military offers a potential population to derive national seroincidence rate estimates for young adults (ages 18-29). We used banked, longitudinal serum specimens collected in a cohort of 1094 military personnel aged 18 to 30 years who served between 1989 and 2005 to estimate national HSV-1 and HSV-2 seroincidence and seroprevalence for the young, adult military population, weighted according to the US Census. Serum was tested with indirect ELISA (enzyme-linked immunosorbent assay). Estimated national seroincidence rates for the US young, adult military population were 9.1 per 100 person-years (95% confidence interval: 4.6-13.5) for HSV-1 and 6.2 (95% confidence interval: 3.1-9.3) for HSV-2. Female sex and black race were associated with significantly higher HSV-2 seroconversion rates. Our estimated HSV1/2 seroprevalences were comparable to US national data provided by National Health and Nutrition Examination Surveys' serosurveys except for non-Hispanic blacks and Hispanics. Although these US 2000 Census-weighted estimates of HSV-1 and HSV-2 seroincidence apply only to young, military adults, they nonetheless supply, to our knowledge, the only national figures that might be used to predict US national HSV1/2 seroincidence in young adults. Thus, we believe that our findings in this military population can be used to inform the planning of HSV-1 and 2 prevention measures in the general, young-adult US population.

Prevalence of hepatitis B virus infection and carriage after nineteen years of vaccination program in the Western Brazilian Amazon

Reductions in the prevalence of hepatitis B virus (HBV) infection and carriage, decreases in liver cancer incidence, and changes in patterns of liver dysfunctions are described after hepatitis B vaccination. We conducted a population-based seroprevalence study aimed at estimating the HBV prevalence and risk of infection in the rural area of Lábrea following nineteen years of HBV vaccination. Half of the subjects showed total anti-HBc of 52.1% (95% CI 49.6-54.7). The HBsAg prevalence was 6.2% (95% CI 5.1-7.6). Multivariate analysis showed an inverse association between HBV infection and vaccination (OR 0.62; 95% CI 0.44-0.87). HBsAg remained independently associated with past hepatitis (OR 2.44; 95% CI 1.52-3.89) and inversely to vaccination (OR 0.43; 95% CI 0.27-0.69). The prevalence of HBeAg among HBsAg-positive individuals was 20.4% (95% CI 12.8-30.1), with the positive subjects having a median age of 11 years (1-46) p=0.0003. We demonstrate that HBV infection is still an important public health issue and that HBV vaccination could have had better impact on HBV epidemiology. If we extrapolate these findings to other rural areas in the Brazilian Amazon, we can predict that the sources of chronic infected patients remain a challenge. Future studies are needed regarding clinical aspects, molecular epidemiology, surveillance of acute cases, and risk groups.