Opisthorchis Felineus Infection is a Risk Factor for Cholangiocarcinoma in Western Siberia: A Hospital-based Case-control Study.

BACKGROUND: Cholangiocarcinoma (CCA), a fatal bile duct cancer, has a high incidence in Western Siberia, Russian Federation. In addition, Opisthorchis felineus, a bile duct-dwelling trematode liver fluke is highly endemic. Closely related species have been shown to be cancerogenic agents in Asia. We therefore examined the association between O felineus infection and CCA in Western Siberia. METHODS: We conducted a hospital-based, individually matched case-control study between January 2017 and August 2020 in Tomsk Oblast and Khanty-Mansiysk Autonomous Okrug, Yugra, Russian Federation. Histologically confirmed CCA patients (cases) were compared with matched age, sex, and place of residence hospital controls. The examination of study participants included the diagnosis of current and past O felineus infection, abdominal ultrasonographical assessment, physical examination, and interview on exposures to potential risk factors. RESULTS: We identified 40 patients with CCA and 160 controls. Exposures to O felineus infection was strongly associated with CCA (odds ratio [OR], 3.9; 95% confidence interval [CI], 1.4-10.8; P = .008). Also, cases reported more often that they were currently or in the past were infected by O felineus compared with controls (OR, 4.03; 95% CI, 1.7-9.5; P = .001). Furthermore, cases reported river fish consumption and fishing habits significantly more often than controls (OR, 5.5; 95% CI, 1.5-19.8; P = .009 and OR, 3.3; 95% CI, 1.4-7.7; P = .005). CONCLUSIONS: The study results revealed a strong significantly increased risk for CCA development in O felineus-infected individuals. Elaboration of the guidelines on screening programs for early CCA diagnosis, prevention, and treatment is socially important in endemic regions.

A randomized trial assessing the efficacy, immunogenicity, and safety of vaccination with live attenuated varicella zoster virus-containing vaccines: ten-year follow-up in Russian children.

In Russia, a universal varicella vaccination (UVV) program has not been implemented, and varicella vaccination coverage is low. We assessed the efficacy, antibody persistence, and safety of one- and two-dose varicella vaccination schedules in Russian children with a ten-year follow-up period, as part of an international phase IIIB, observer-blind, randomized, controlled trial (NCT00226499). Children aged 12-22 months were randomized (3:3:1) to receive two doses of tetravalent measles-mumps-rubella-varicella vaccine (V2 group), one dose trivalent measles-mumps-rubella (MMR) vaccine and one dose of varicella vaccine (V1 group), or two doses of MMR vaccine (V0 [control] group), 42 days apart. Main study outcomes were: vaccine efficacy (VE) against confirmed varicella cases, anti-varicella zoster virus (VZV) seropositivity rates and geometric mean concentrations, and reporting of (serious) adverse events ([S]AEs). The total vaccinated cohort in Russia comprised 1000 children; 900 were followed up until study end (year [Y] 10). VE estimates against confirmed varicella (Y10) were 92.4% in the V2 group and 74.7% in the V1 group. Anti-VZV seropositivity rates remained ≥99.4% in the V2 group and ≥89.7% in the V1 group from day 42 post-vaccination 2 until Y10. Occurrence of (un)solicited AEs and SAEs was similar across groups and confirmed the safety profile of the vaccines. No vaccination-related SAEs or deaths were reported. These results are consistent with the global trial results, i.e., the highest VE estimates observed following the two-dose schedule compared to the one-dose schedule. These data may inform decision-making related to potential implementation of a UVV program.

What is the context?Varicella is a common childhood disease caused by the highly contagious varicella zoster virus.Varicella vaccines have been used for more than three decades.A large clinical trial conducted in ten countries assessed the efficacy and safety of one dose of monovalent varicella vaccine or two doses of combined varicella vaccine (MMRV). The enrolled children were also followed up for a ten-year period to evaluate the persistence of the immune response and the long-term efficacy of the vaccine.What is new?Here, we present the long-term efficacy, immunogenicity, and safety results in the cohort of children enrolled in Russia, as part of the global ten-year follow-up study. We found that:The monovalent and combined vaccines reduced the number of varicella cases.The MMRV two-dose regimen displayed higher efficacy in preventing varicella of all severities compared to the one-dose regimen.The immune response conferred by the vaccine persisted up to ten years post-vaccination.No vaccination-related deaths occurred, and no safety concerns were raised.What is the impact?Vaccination against varicella resulted in long-term protective efficacy and antibody persistence over ten years post-vaccination in Russian children.Although one-dose varicella vaccination was effective at protecting against varicella, a two-dose schedule provided a more complete protection. This could inform health policy decisions regarding the implementation of varicella vaccination in routine immunization program in Russia.

Immunological non-inferiority of a new fully liquid presentation of the MenACWY-CRM vaccine to the licensed vaccine: results from a randomized, controlled, observer-blind study in adolescents and young adults.

A fully liquid MenACWY-CRM vaccine presentation has been developed, modifying the meningococcal serogroup A (MenA) component from lyophilized to liquid. The safety and immunogenicity of the liquid presentation at the end of the intended shelf-life (aged for 24 or 30 months) were compared to the licensed lyophilized/liquid presentation. This multicenter, randomized (1:1), observer-blind, phase 2b study (NCT03433482) enrolled adolescents and young adults (age 10-40 years). In part 1, 844 participants received one dose of liquid presentation stored for approximately 24 months or licensed presentation. In part 2, 846 participants received one dose of liquid presentation stored for approximately 30 months or licensed presentation. After storage, the MenA free saccharide (FS) level was approximately 25% and O-acetylation was approximately 45%. The primary objective was to demonstrate non-inferiority of the liquid presentation to licensed presentation, as measured by human serum bactericidal assay (hSBA) geometric mean titers (GMTs) against MenA, 1-month post-vaccination. Immune responses against each vaccine serogroup were similar between groups. Between-group ratios of hSBA GMTs for MenA were 1.21 (part 1) and 1.11 (part 2), with two-sided 95% confidence interval lower limits (0.94 and 0.87, respectively) greater than the prespecified non-inferiority margin (0.5), thus meeting the primary study objective. No safety concerns were identified. Despite reduced O-acetylation of MenA and increased FS content, serogroup-specific immune responses induced by the fully liquid presentation were similar to those induced by the licensed MenACWY-CRM vaccine, with non-inferior anti-MenA responses. The safety profiles of the vaccine presentations were similar.

Opisthorchis felineus infection, risks, and morbidity in rural Western Siberia, Russian Federation.

BACKGROUND: The liver fluke, Opisthorchis felineus, is widely distributed throughout Europe and large parts of the Russian Federation. In Western Siberia, information about opisthorchiasis is lacking although infection may lead to severe liver and bile duct diseases. We aimed to assess the current prevalence of O. felineus infection along with associated risk factors and morbidity in rural Western Siberia. METHODS: We conducted a community-based, cross-sectional study in the rural Shegarskiy district, Tomsk Oblast, Russian Federation. All household members (≥ 7 years) present on the survey day were enrolled (n = 600). Two stool samples per person were examined for helminth eggs, using PARASEP (DiaSys Ltd, UK). The number of eggs per gram (EPG) of feces was recorded. Each study participant was interviewed to determine risk factors, using a pre-tested questionnaire. An abdominal ultrasonography examination of liver and bile ducts was performed with a mobile, high resolution ultrasound device. In total, 488 persons completed assessments (two stool samples, completed questionnaires); of those, 436 individuals had an ultrasonography (US) examination. RESULTS: We observed a prevalence of O. felineus infection of 60.2%. Significant risk factors for infection were the consumption of river fish (odds ratio from adjusted analysis [aOR] 2.4, 95% CI 1.52-3.95, p<0.001), particularly stock fish (OR from multivariable analysis [mOR] 3.2, 95% CI 2.63-3.80, p<0.001), smoked fish (mOR 1.5, 95% CI 1.24-1.72, p<0.001), frozen fish (mOR 1.6, 95% CI 1.29-2.02, p<0.001), and raw fish (mOR 1.4, 95% CI 1.05-1.84, p = 0.02); and fishing activities (mOR 1.2, 95% CI 1.03-1.43, p = 0.019). Women had a higher risk of infection than men. Infection was associated positively with age and negatively with socio-economic status. The respondents' general awareness of opisthorchiasis was quite high (93.2%), but their knowledge about infection transmission and prevention was insufficient. Children aged 7-18 years old had a lower level of awareness compared to adults. The abdominal ultrasonography results demonstrated a strong association between O. felineus infection and gallbladder stones (mOR 2.8, 95% CI 1.33-6.04, p = 0.007) and periductal fibrosis of intrahepatic bile ducts (mOR 1.9, 95% CI 1.08-3.46, p = 0.026). CONCLUSION: O. felineus infection is highly prevalent in rural regions of Western Siberia, and associated with severe hepatobiliary pathology. Identified risk factors will be used to develop a comprehensive targeted O. felineus infection control program.

Case Report: Two Cases of Cholangiocarcinoma in Patients with Opisthorchis felineus Infection in Western Siberia, Russian Federation.

Cholangiocarcinoma (CCA) is a cancer with high mortality owing to its aggressiveness and resistance to therapy. The liver flukes of the Opisthorchiidae family have been recognized as risk factors of CCA. Opisthorchis felineus infection occurs in Western Siberia, the biggest endemic area in the Russian Federation, and is associated with chronic inflammation of the bile ducts, which may be linked to severe hepatobiliary morbidity. We report two cases of confirmed CCA who had a chronic O. felineus infection. Both cases presented unspecific symptoms at the onset of the disease, a stage when severe pathological changes already had occurred. Both patients were living in endemic areas but did not receive any antihelminthic treatment. This report underlines the need for assessment of O. felineus infection as a causative factor of CCA. The results will provide further arguments for control of O. felineus in the Russian Federation.

Opisthorchis felineus infection prevalence in Western Siberia: A review of Russian literature.

In this study we reviewed Russian scientific literature (scientific publications, book chapters, monographs) published between 1 January 1979 and 31 August 2015 from two sources: Main database of the Russian Scientific Electronic Library (eLIBRARY, http://elibrary.ru/), and the Scientific Medical Library of Siberian State Medical University (http://medlib.tomsk.ru/). Specifically, the review details the infection prevalence of Opisthorchis felineus (O. felineus) in Western Siberia, Russian Federation. From the primary key words screening, 1591 records were identified from which 32 Russian-language publications were relevant. The lowest O. felineus infection rate of 0.4% was reported in Tatarstan Republic, and the highest reached 83.9% in the Khanty-Mansiysk Autonomous Okrug. The infection prevalence was lower in children than in adults and increased with age. O. felineus infection was detected more often in indigenous population than in migrants. Infection intensity in western regions (Permskaya, Bryanskaya Oblast) was low and varied from 15 to 336 eggs per gram stool (epg), while in endemic regions it reached more than 2000 epg. In some settlements the mean intensity infection was 5234 epg. The high rates of intensity were registered in regions with a high prevalence of infection. Based on obtained data, a map of O. felineus infection prevalence in Western Siberia was developed. After mapping the results, the highest prevalence was detected in Tyumenskaya Oblast with over 60%, while the Tomskaya Oblast had the lowest prevalence at fewer than 19.0%. Khanty-Mansiysk Autonomus Okrug, Altaiskii Krai, Novosibirskaya Oblast and Omskaya Oblast had an average level of O. felineus infection of 20-39%. According to the results of the review, Western Siberia must be considered as highly endemic region for opisthorchiasis in the Russian Federation. The development of a control program specific for the Russian community is warranted.

Opisthorchis felineus infection and cholangiocarcinoma in the Russian Federation: A review of medical statistics.

Opisthorchis felineus (O. felineus) occurs in Western Siberia and many other parts of the Russian Federation (RF). The true extent of its distribution is not known. Chronic infection may lead to severe hepatobiliary morbidity. According to surgical and experimental reports, long-term infestation might significantly increase the risk for cholangiocarcinoma (CCA). To date, no association between O. felineus infection and CCA has been demonstrated. The objective of this study was to review existing health data on the incidence of O. felineus infection and on the incidence of CCA in the RF. We reviewed the official medical statistics on reported O. felineus infection and CCA in 83 political/geographical units of the RF, covering the period January 2011-December 2013. Annual incidence data were obtained from Rospotrebnadzor and from official medical statistics. We calculated the average annual incidence of infection and cancer. The average annual incidence of O. felineus was 24.7±9.0 cases per 100,000 population. The highest incidence was observed in Khanty-Mansiysk district (599.7 cases per 100,000 population per year). In 27 geographical units, no O. felineus cases were reported. The incidence of liver and intrahepatic bile duct cancers was 4.8±0.2 cases per 100,000 population; the highest rate was reported in Sakha Republic and Tomsk Oblast (14.5 and 9.3 cases per 100,000 population), and the lowest in Yamalo-Nenets Autonomous Okrug (0.9 cases per 100,000 population). O. felineus incidence was not associated with the mean annual incidence of liver and intrahepatic bile duct cancers (r=0.20, p=0.07). This study documents the importance of opisthorchiasis in certain endemic areas and presents the best available data on associations between O. felineus infection and liver/intrahepatic bile duct cancers in RF. The findings support the need to implement a public health control programme against liver fluke infections and to increase the availability of anthelmintic treatment. Further studies are warranted to assess the contribution of opisthorchiasis to the CCA in RF.