A 16-year review of seroprevalence studies on measles and rubella

The determination of the seroprevalence of vaccine-preventable diseases is critical in monitoring the efficacy of vaccination programmes and to assess the gaps in population immunity but requires extensive organisation and is time and resource intensive. The results of the studies are frequently reported in peer-reviewed scientific, government and non-government publications. A review of scientific literature was undertaken to advise the development of WHO guidelines for the assessment of measles and rubella seroprevalence. A search of the National Library of Medicine’s PubMed online publications using key words of ‘measles’, ‘rubella’, combined with ‘serosurvey’, ‘seroprevalence’, ‘immunity’ and ‘population immunity’ was conducted. A total of 97 articles published between January 1998 and June 2014 were retrieved, 68 describing serosurveys for measles and 58 serosurveys for rubella, conducted in 37 and 36 different countries respectively. Only 13 (19%) and 8 (14%) respectively were UN classified “least developed countries”. The study sample varied markedly and included combinations of male and female infants, children, adolescents and adults. The study sizes also varied with 28% and 33% of measles and rubella studies respectively, having greater than 2000 participants. Microtitre plate enzyme immunoassays were used in 52 (76%) measles studies and 40 (69%) rubella studies. A total of 39 (57%) measles and 44 (76%) rubella studies reported quantitative test results. Seroprevalence ranged from 60.8% to 95.9% for measles and 53.0% to 99.3% for rubella studies. The review highlighted that infants lost maternally-acquired immunity within 9 months of birth and were unprotected until vaccination. Two groups at higher risk of infection were identified: young adults between the ages of 15 and 30 years and immigrants.     

Hepatitis B surface antigen seroprevalence among pre- and post-vaccine cohorts in Cambodia, 2017

Background: Hepatitis B virus (HBV) infection is highly endemic in most low income countries including Cambodia. This nationwide serosurvey was conducted to assess the impact of hepatitis B vaccination and to determine whether Cambodia met the WHO regional 2017 target of hepatitis B surface antigen (HBsAg) seroprevalence less than 1% in five-year-old children.Methods: A cross-sectional multi-stage cluster survey was conducted among children born during 2010–2012 and their mothers in Cambodia. HBsAg prevalence was estimated by rapid point-of-care testing, and demographic data, including vaccination history, was collected. Vaccine coverage in children and the prevalence of HBsAg among children and mothers was calculated taking into account the complex survey design. Factors associated with children’s failure to receive timely (within 24 h) vaccination were analysed by multivariate logistic analysis.Findings: A total of 2,520 children 5–7 years old and 2,028 mothers were recruited. In total, 78.4% of children received hepatitis B vaccination birth-dose (HepB-BD); of these, 58.7% were administered ≤ 24 h. Birth at home or “other” location were independent risk factors for children’s failure to receive timely HepB-BD. Overall HBsAg seroprevalence was 4.39% (95%CI: 3.53%–5.45%) among mothers and 0.56% (95%CI: 0.32%–0.98%) among children. The prevalence among children without hepatitis B vaccination was 4.62% (95%CI: 1.31%–14.97%). Among children with a HBsAg-positive mother, prevalence was 10.11% (95%CI: 5.41%–18.11%).Interpretation: Having achieved the 2017 target of less than 1% HBsAg prevalence among 5 years old children, Cambodia can now focus on eliminating mother-to-child transmission of HBV. Moreover, the high HBsAg prevalence among mothers suggests that routine screening with proper linkage to care and treatment is needed. Strengthening measures to improve vaccination coverage further and eliminate mother-to-child transmission by coordinated programming with other services offering additional HBV interventions will help move towards the global goal of hepatitis B elimination by 2030.Funding: As per sources of funding.     

Hepatitis E: An Underdiagnosed,Emerging Infection in Nonendemic Regions

Although hepatitis E virus (HEV) is the primary cause of enterically transmitted acute hepatitis and jaundice in developing countries, locally acquired HEV infections are increasing in nonendemic countries. As such, HEV is emerging as an underdiagnosed cause of infection. This report describes three clinically variable cases of HEV infection with unusual clinical presentations. These cases highlight the fact that HEV should be considered in the differential diagnosis of patients with unexplained hepatitis (acute or chronic) with or without extrahepatic manifestations. HEV should also be considered in patients with persistently elevated liver enzymes who have not travelled to known HEV-endemic regions. Lack of knowledge among physicians and an absence of standardized diagnostic tests may result in increased morbidity and mortality from HEV infection.     

Serologic evidence for human ehrlichiosis in Africa

Human ehrlichiosis is a recently recognized rickettsial disease. It is caused byEhrlichia chaffeensis, an intraleucocytic Gram-negative, obligate intracellular bacterium, grouped within the genusEhrlichiae. Most human cases of ehrlichiosis have been diagnosed in the USA. Two cases have been reported outside of the USA, one in Europe and one in Africa. From 1 January to 30 June 1992, 765 sera from blood donors or other asymptomatic subjects in 8 African countries, including Ivory Coast, Burkina Faso, Mali, Central African Republic, Angola, Zimbabwe, Mozambique and Commores Islands, were tested by indirect immunofluorescence for the presence ofE. chaffeensis antibodies. Positive sera were confirmed by Western immunoblotting. Only two of 765 sera tested were positive. One serum obtained from Burkina Faso had an IgG titer of 1:200 and one from Mozambique had an IgG titer of 1:80. Human ehrlichiosis seems to occur infrequently in Africa, although many more sera from additional African countries need to be evaluated.     

Assessment of poliovirus antibody seroprevalence in polio high risk areas of West Africa

We conducted a serological survey of anti-polio antibodies in polio high-risk areas of Mali, Guinea and Cote d’Ivoire to assess risk of future poliovirus outbreaks.Random community sampling of children 6–11 and 36–48 months-old was conducted; neutralizing antibodies against poliovirus were detected using microneutralization assay.We analysed 1059/1064 (99.5%) of enrolled children. Seroprevalence to poliovirus type 1 (PV1) across all age groups and locations ranged between 92 and 100%, for PV2 it was 77–100%, and 89–95% for PV3. PV2 seroprevalence in the younger age group in Guinea and Cote d’Ivoire was <80%. History of <4 polio vaccine doses and acute malnutrition were associated with seronegativity (OR = 2.1 CI95% = 1.5–3.1, OR = 1.8 CI95% = 1.1–3.3 respectively).The risk of poliovirus outbreak following importation is low because of high population immunity to PV1, however, due to large cohort of PV2 seronegative children any future detection of vaccine-derived poliovirus type 2 requires urgent response to arrest rapid spread.     

Changes in cytomegalovirus seroprevalence in pregnant Japanese women—A 10-year single center study

BackgroundHuman cytomegalovirus (CMV) causes congenital infections during pregnancy, and seroepidemiological data are important for estimating the risk of infection. However, only a few reports of CMV seroprevalence exist for pregnant Japanese women.ObjectivesThe purpose of this study was to assess CMV seroprevalence in pregnant Japanese women.Study designThis cross-sectional study involved pregnant Japanese women who delivered from 2003 to 2012 at our hospital (n = 15,616). Among these women, 14,099 (90.3%) underwent tests for the presence of CMV IgG. Those with an equivocal test result were excluded (n = 195) from this analysis, leaving a study sample of 13,904 Japanese pregnant women. The prevalence of CMV IgG was also assessed by calendar year, age, and parity.ResultsThe overall CMV IgG prevalence rate was 66.0%. CMV IgG prevalence significantly decreased over the course of 10 years from 2003 to 2012 (from 69.9% in 2003 to 65.2% in 2012) (p < 0.001). Adjusted odds ratios for CMV IgG positivity in women aged <25, 25–30, 35–40, and >40 years were 1.66 (95%CI: 1.25–2.20), 1.20 (95%CI: 1.07–1.35), 1.16 (95%CI: 1.07–1.26), and 1.44 (95%CI: 1.28–1.62), respectively, compared to women aged 30–35 years. Adjusted odds ratios for CMV IgG positivity for a parity of 1, 2, and ≥3 were 1.14 (95%CI: 1.06–1.23), 1.52 (95%CI: 1.32–1.77), and 2.54 (95%CI: 2.69–3.84), respectively, compared to nulliparous women.ConclusionWe found that 34% of pregnant Japanese women were susceptible to CMV infection. Calendar year, maternal age, and parity were significantly associated with changes in CMV seroprevalence among this population.     

Prevalencia de la infección por el VHC en un área sanitaria de Madrid: el primer paso para la microeliminación

ObjectiveTo estimate the prevalence of HCV infection in the general population of a health area through an intervention in Primary Care, differentiating between new diagnoses and infections previously diagnosed but not treated.MethodsParticipants were selected through a risk assessment questionnaire, with all those who gave at least one affirmative answer and all those over 50 years of age undergoing a rapid test. Positive tests were confirmed in the lab by determination of anti-HCV antibodies by chemiluminescent microparticle immunoassay and determination of viraemia.ResultsOf the 7,991 participants, 36.2% presented a positive HCV risk questionnaire. 4,717 tests were performed, finding an anti-HCV percentage of 0.65% in the screened population, with 0.46% of active infections. Among the individuals with a positive test result, 51.9% had a known prior diagnosis but had not received treatment, because they were not aware of it or were not linked to the health system, and 19.2% had a positive result for the first time. The prevalence of hidden infection was higher in men, those over 50 years of age and people from Eastern Europe.ConclusionWe found a prevalence of active infections higher than recently described nationwide, and a higher percentage of newly diagnosed infections than recent similar studies in other areas. These differences justify the need to perform local assessments of the prevalence of HCV infection in each of the health areas where it is planned to implement and monitor a microelimination programme.     

The economic impact of prenatal varicella immunity among pregnant women in Alberta

In light of the changing epidemiology of varicella, we sought to examine varicella antibody levels in the prenatal population in the Canadian province of Alberta. All prenatal varicella screening tests performed between August 1, 2002 and February 2, 2014 (454,592) were included in this study. Test results, demographics and vaccination status were examined to identify varicella seroprevalence and correlates for being seronegative. An overall seroprevalence for varicella of 95.8% was found across all pregnancy screenings. Significant independent correlates of seronegativity included younger age (AOR: 4.72 (95% CI: 3.87–5.77) for <20 years of age vs. >40 years of age) and having immigrated to Alberta from Africa or Asia (AOR: 4.55 (95% CI: 4.10–5.05) and AOR: 5.83 (95%CI; 5.48–6.19), respectively). Women who were initially seronegative for varicella antibodies and who received both postnatal vaccination and post-vaccination prenatal screening (2566) were examined to assess seroconversion. 66.3% of women who were tested up to six months post-vaccination were seropositive, however only 36.9% of women tested after 36 months were seropositive. Finally, 40.9% of all prenatal varicella specimens tested were deemed redundant, i.e. women had either a history of (1) ⩾2 doses of varicella vaccine, (2) varicella infection, or (3) a previous positive varicella serology. Eliminating this redundant screening could provide an estimated $96,000 in savings annually in laboratory and Public Health follow-up costs alone. As the number of women with vaccine-derived immunity through universal childhood vaccination increase in the prenatal population, screening methods may need to adapt to ensure varicella immunity is accurately conducted and assessed.     

Seroprevalencia de infección frente a SARS-CoV-2 en trabajadores de la salud en un hospital monográfico pediátrico en Madrid (España)

IntroductionAs of 30 April 2020, 203.715 SARS-CoV-2 infections had been reported in Spain, 54.486 in Madrid, 21.4% were health care workers. Our objective is to determine seroprevalence of COVID-19 among workers in a monographic pediatric hospital.MethodsBetween April13^th and 30^th, 1.523 health workers were recruited to be tested for SARS-CoV-2 serology screening (All Test®) and they answered a questionnaire with demographic, epidemiological and clinical information and previous exposure to COVID-19.FindingsOne thousand two hundred ninety two (84.8%) were tested. Positive serology (IgM and/or IgG) to SARS-CoV-2 was found in 17.2% (222/1.292), in 15.5% (201/1.292) if only IgG was considered. Median age was 44±13 years, 73% were female. The 33.8% (75/222) were asymptomatic. Eighty one had a previous positive rRT-PCR. The 14% (32/222) referred a family contact.ConclusionSerology prevalence for SARS-CoV-2 in workers of a pediatric hospital was higher than in general population. Many of them had an unnoticed infection.