Lunar Occultations Observed in Japan and Lunar Limb Profiles Derived

Lunar occultation observations are useful in refining lunar limb profiles, which will be used for the analysis of solar eclipse observations to detect the variation of the solar diameter, and in detecting the possible errors of the Hipparcos proper motion system. Many lunar occultations have been observed in Japan. Some of the results are shown in this paper to encourage people in the world to observe more lunar occultations with better accuracies.

A 3-D Shape Model of (704) Interamnia from Its Occultations and Lightcurves

A 3-D shape model of the sixth largest of the main belt asteroids, (704) Interamnia, is presented. The model is reproduced from its two stellar occultation observations and six lightcurves between 1969 and 2011. The first stellar occultation was the occultation of TYC 234500183 on 1996 December 17 observed from 13 sites in the USA. An elliptical cross section of (344.6 ± 9.6 km) × (306.2 ± 9.1 km), for position angle P = 73.4 ± 12.5° was fitted. The lightcurve around the occultation shows that the peak-to-peak amplitude was 0.04 mag. and the occultation phase was just before the minimum. The second stellar occultation was the occultation of HIP 036189 on 2003 March 23 observed from 39 sites in Japan and Hawaii. An elliptical cross section of (349.8 ± 0.9 km) × (303.7 ± 1.7 km), for position angle P = 86.0 ± 1.1° was fitted. A companion of 8.5 mag. of the occulted star was discovered whose separation is 12 ± 2 mas (milli-arcseconds), P = 148 ± 11°. A combined analysis of rotational lightcurves and occultation chords can return more information than can be obtained with either technique alone. From follow-up photometric observations of the asteroid between 2003 and 2011, its rotation period is determined to be 8.728967167 ± 0.00000007 hours, which is accurate enough to fix the rotation phases at other occultation events. The derived north pole is λ2000 = 259 ± 8°, β2000 = -50 ± 5° (retrograde rotation);the lengths of the three principal axes are 2a = 361.8 ± 2.8 km, 2b = 324.4 ± 5.0 km, 2c = 297.3 ± 3.5 km, and the mean diameter is D = 326.8 ± 3.0 km. Supposing the mass of Interamnia as (3.5 ± 0.9) × 10-11 solar masses, the density is then ρ = 3.8 ± 1.0 g·cm-3.

Eclipses and Occultations of Galilean Satellites Observed at Yunnan Observatory in 2003

We describe and analyze observations of mutual events of Galilean satellites made at the Yunnan Observatory in February 2003 from CCD imaging for the first time in China. Astrometric positions were deduced from these photometric observations by modelling the relative motion and the photometry of the involved satellites during each event.

Early colorectal cancer screening–no time to lose

In this editorial,we comment on the article entitled“Stage at diagnosis of colorectal cancer through diagnostic route:Who should be screened?”by Agatsuma et al.Colorectal cancer(CRC)is emerging as an important health issue as its incidence continues to rise globally,adversely affecting the quality of life.Although the public has become more aware of CRC prevention,most patients lack screening awareness.Some poor lifestyle practices can lead to CRC and symptoms can appear in the early stages of CRC.However,due to the lack of awareness of the disease,most of the CRC patients are diagnosed already at an advanced stage and have a poor prognosis.

Genetic diversity and occult hepatitis B infection in Africa: A comprehensive review

BACKGROUND Occult hepatitis B infection(OBI)is a globally prevalent infection,with its frequency being influenced by the prevalence of hepatitis B virus(HBV)infection in a particular geographic region,including Africa.OBI can be transmitted th-rough blood transfusions and organ transplants and has been linked to the development of hepatocellular carcinoma(HCC).The associated HBV genotype influences the infection.AIM To highlight the genetic diversity and prevalence of OBI in Africa.METHODS This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines and involved a comprehensive search on PubMed,Google Scholar,Science Direct,and African Journals Online for published studies on the prevalence and genetic diversity of OBI in Africa.RESULTS The synthesis included 83 articles,revealing that the prevalence of OBI varied between countries and population groups,with the highest prevalence being 90.9%in patients with hepatitis C virus infection and 38%in blood donors,indicating an increased risk of HBV transmission through blood transfusions.Cases of OBI reactivation have been reported following chemotherapy.Genotype D is the predominant,followed by genotypes A and E.CONCLUSION This review highlights the prevalence of OBI in Africa,which varies across countries and population groups.The study also demonstrates that genotype D is the most prevalent.

Clinicopathological features,psychological status,and prognosis of 33 patients with occult breast cancer

BACKGROUND Occult breast cancer(OBC)has traditionally been considered to be a carcinoma of unknown primary origin with a favorable prognosis and can be treated as stage II-III breast cancer.Due to the small number of cases and limited clinical experience,treatments vary greatly around the world and no standardized treatment has yet been established.AIM To investigate the clinicopathological features,psychological status and prognostic features of patients with OBC.METHODS The clinicopathological data of 33 OBC patients diagnosed and treated in the Affiliated Hospital of Xuzhou Medical University and Xuzhou Central Hospital from November 2015 to November 2022 were retrospectively analyzed.The psychological status of OBC patients was evaluated by the Self-rating Anxiety Scale and Self-rating Depression Scale.Patients’emotions,stress perception and psychological resilience were evaluated by the Positive and Negative Affect Schedule,the Chinese Perceived Stress Scale,and the Connor-Davidson Resilience Scale(CD-RISC),respectively.Patient survival was calculated using the Kaplan-Meier method,and survival curves were plotted for analysis with the log-rank test.Univariate and multivariate survival analyses were performed using the Cox regression model.RESULTS The 33 OBC patients included 32 females and 1 male.Of the 33 patients,30(91%)had axillary tumors,3(9%)had a neck mass as the primary symptom;18(54.5%)had estrogen receptor-positive tumors,17(51.5%)had progesterone receptor-positive tumors,and 18(54.5%)had Her-2-positive tumors;24(72.7%)received surgical treatment,including 18 patients who underwent modified radical mastectomy,1 patient who underwent breast-conserving surgery plus axillary lymph node dissection(ALND),and 5 patients who underwent ALND alone;12 patients received preoperative neoadjuvant therapy.All 30 patients developed anxiety and depression,with low positive affect scores and high negative affect scores,accompanied by a high stress level and poor psychological resilience.There were no differences in the psychological status of patients according to age,body mass index,or menopausal status.The overall survival and disease-free survival(DFS)of all the patients were 83.3%and 55.7%,respectively.Univariate analysis demonstrated that the initial tumor site(P=0.021)and node stage(P=0.020)were factors that may affect patient prognosis.The 5-year DFS rate of OBC patients who received radiotherapy was greater(P<0.001),while the use of different surgical methods(P=0.687)had no statistically significant effect on patient outcomes.Multivariate analysis revealed that radiotherapy(P=0.031)was an independent prognostic factor.Receiving radiotherapy had a significant effect on the CD-RISC score(P=0.02).CONCLUSION OBC is a rare breast disease whose diagnosis and treatment are currently controversial.There was no significant difference in the efficacy of other less invasive surgical procedures compared to those of modified radical mastectomy.In addition,radiotherapy can significantly improve patient outcomes.We should pay attention to the psychological state of patients while they receive antitumor therapy.

Yeats’s Ideals:Women Old and Young

William Butler Yeats ranks among the most widely admired and intensively studied poets of the 20th century.This paper intends to explore the women who have exerted the most critical influences upon Yeats,namely Gonne,Lady Gregory,and Georgie Hyde-Lees.Even in Yeats’s poetry involved with symbolism,it is worth noting that his employment of symbols has used these women as the archetypes,and that the historical context rendered Yeats’s representations of them in his poetry all the more interesting.

Chronic hepatitis B and occult infection in chemotherapy patients-evaluation in oncology and hemato-oncology settings:The CHOICE study

BACKGROUND Reactivation of hepatitis B virus(HBV)infection is a well-known risk that can occur spontaneously or following immunosuppressive therapies,including cancer chemotherapy.HBV reactivation can cause significant morbidity and even mortality,which are preventable if at-risk individuals are identified through screening and started on antiviral prophylaxis.AIM To determine the prevalence of chronic HBV(CHB)and occult HBV infection(OBI)among oncology and hematology-oncology patients undergoing chemo-therapy.METHODS In this observational study,the prevalence of CHB and OBI was assessed among patients receiving chemotherapy.Serological markers of HBV infection[hepatitis B surface antigen(HBsAg)/anti-hepatitis B core antigen(HBc)]were evaluated for all patients.HBV DNA levels were assessed in those who tested negative for HBsAg but positive for total anti-HBc.RESULTS The prevalence of CHB in the study cohort was determined to be 2.3%[95%confidence interval(95%CI):1.0-4.2].Additionally,the prevalence of OBI among the study participants was found to be 0.8%(95%CI:0.2-2.3).CONCLUSION The findings of this study highlight the importance of screening for hepatitis B infection in oncology and hematology-oncology patients undergoing chemotherapy.Identifying individuals with CHB and OBI is crucial for implementing appropriate antiviral prophylaxis to prevent the reactivation of HBV infection,which can lead to increased morbidity and mortality.

Occult pancreaticobiliary reflux is a pathogenic factor of some benign biliary diseases and gallbladder cancer

Background:Pancreaticobiliary maljunction(PBM)is a well-known high-risk factor for biliary malignant tumors because of constant pancreaticobiliary reflux(PBR).However,the impact of occult pancreaticobiliary reflux(OPR),which is characterized by high bile amylase levels in individuals with anatomically normal pancreaticobiliary junction,on biliary diseases remains unclear.The aim of this study was to assess the correlation between OPR and biliary diseases.Methods:We enrolled 94 consecutive patients with normal pancreaticobiliary junction and primary biliary diseases confirmed by magnetic resonance cholangiopancreatography.We prospectively collected patients’bile samples and measured bile amylase levels.We investigated the incidence of OPR and the difference in bile amylase levels among these patients and assessed the correlation between high bile amylase levels(HBAL)and benign or malignant biliary diseases,as well as the OPR risk factors.Results:The incidence of OPR was 36.6%in patients with benign biliary diseases,26.7%in those with cholangiocarcinoma and 62.5%in those with gallbladder cancer.The median bile amylase level tended to be higher in patients with gallbladder cancer than in those with benign biliary diseases,but there was no significant difference(165.5 IU/L vs.23.0 IU/L,P=0.212).The prevalence of an HBAL with bile amylase levels of 1000-7500 IU/L was similar in patients with gallbladder cancer and benign biliary diseases.However,the incidence of HBAL with bile amylase levels greater than 7500 IU/L was significantly higher in patients with gallbladder cancer than in those with benign biliary diseases(37.5%vs.4.2%,P=0.012).Multivariate logistic regression analysis revealed that choledocholithiasis was an independent risk factor for OPR.Conclusions:OPR can occur in benign and malignant biliary diseases,and it may be a pathogenic factor for some benign biliary diseases and a high-risk factor for gallbladder cancer.There is a correlation between choledocholithiasis and OPR.

Supply and quality of colonoscopy according to the characteristics of gastroenterologists in the French population-based colorectalcancer screening program

BACKGROUND Since its complete roll-out in 2009,the French colorectal cancer screening program(CRCSP)experienced 3 major constraints[use of a less efficient Guaiac-test(gFOBT),stopping the supply of Fecal-Immunochemical-Test kits(FIT),and suspension of the program due to the coronavirus disease 2019(COVID-19)]affecting its effectiveness.AIM To describe the impact of the constraints in terms of changes in the quality of screeningcolonoscopy(Quali-Colo).METHODS This retrospective cohort study included screening-colonoscopies performed by gastroenterologists between Jan-2010 and Dec-2020 in people aged 50-74 living in Ile-de-France(France).The changes in Quali-colo(Proportion of colonoscopies performed beyond 7 mo(Colo_7 mo),Frequency of serious adverse events(SAE)and Colonoscopy detection rate)were described in a cohort of Gastroenterologists who performed at least one colonoscopy over each of the four periods defined according to the chronology of the constraints[gFOBT:Normal progress of the CRCSP using gFOBT(2010-2014);FIT:Normal progress of the CRCSP using FIT(2015-2018);STOP-FIT:Year(2019)during which the CRCSP experienced the cessation of the supply of test kits;COVID:Program suspension due to the COVID-19 health crisis(2020)].The link between each dependent variable(Colo_7 mo;SAE occurrence,neoplasm detection rate)and the predictive factors was analyzed in a two-level multivariate hierarchical model.RESULTS The 533 gastroenterologists(cohort)achieved 21509 screening colonoscopies over gFOBT period,38352 over FIT,7342 over STOP-FIT and 7995 over COVID period.The frequency of SAE did not change between periods(gFOBT:0.3%;FIT:0.3%;STOP-FIT:0.3%;and COVID:0.2%;P=0.10).The risk of Colo_7 mo doubled between FIT[adjusted odds ratio(aOR):1.2(1.1;1.2)]and STOPFIT[aOR:2.4(2.1;2.6)];then,decreased by 40%between STOP-FIT and COVID[aOR:2.0(1.8;2.2)].Regardless of the period,this Colo_7 mo’s risk was twice as high for screening colonoscopy performed in a public hospital[aOR:2.1(1.3;3.6)]compared to screening-colonoscopy performed in a private clinic.The neoplasm detection,which increased by 60%between gFOBT and FIT[aOR:1.6(1.5;1.7)],decreased by 40%between FIT and COVID[aOR:1.1(1.0;1.3)].CONCLUSION The constraints likely affected the time-to-colonoscopy as well as the colonoscopy detection rate without impacting the SAE’s occurrence,highlighting the need for a respectable reference time-tocolonoscopy in CRCSP.

Submandibular solid-cystic mass as the first and sole manifestation of occult thyroid papillary carcinoma: A case report

BACKGROUND Occult thyroid papillary carcinoma(OTPC)is typically characterized by initial presentation with cervical lymph node metastasis and can be detected through ultrasound.However,the initial and sole manifestation was a submandibular solid-cystic mass.High-frequency ultrasound,enhanced multislice computed tomography(CT)scan,and thyroid function tests revealed no abnormalities,which is relatively uncommon.CASE SUMMARY A 24-year-old Chinese female,who studied at a university in Shandong Province,presented to the clinic in June 2019 with a right submandibular mass that she had noticed 2 mo earlier.Clinical examination revealed a 2-cm,nontender,movable solid-cystic mass in the submandibular region,with no palpable thyroid mass observed.Ultrasonography revealed a 2.0 cm×1.1 cm solid-cystic mass in the right submandibular region,and the thyroid gland showed no abnormalities.CT scan and 131I whole body follow-up scan showed that there were no abnormalities in the thyroid.However,cytology and pathology showed papillary tumor cell clusters,consistent with papillary thyroid carcinoma.Thus,we performed total thyroidectomy and right neck lymph node dissection.The pathology revealed the thyroid was detected as classical thyroid micropapillary carcinoma,and lymph nodes of levels VI central and levels II,III,IV,V on the right side showed no tumor metastasis.The patient was followed up for 2 years without significant recurrence.CONCLUSION The presentation of a submandibular solid-cystic mass as the primary and solitary indication of OTPC is relatively uncommon.Fine needle aspiration is advised for evaluating neck masses.

Tumor-Specific Histo-Blood Group Antigens: Apropos of Two Cases

Cancer cells with immunogenic properties having altered protein glycosylation, modified blood group substances have been widely studied. Due to the genetic instability occurring during carcinogenesis the glycosyltransferases may suffer from posttranslation sequence modification. The author describes 2 autopsy cases, where in the background of the unusual metastatic tumor presentation, incompatible blood group antigenic determinants have been demonstrated using blood group specific lectins and monoclonal antibodies (mAb). In the first case, reported here, a 10-year-old girl developed an acute myeloid leukemia and died in a septic endotoxin shock after successful cytostatic treatment of a juvenile signet ring cell cancer of her colon. At autopsy there were no signs of tumor except bilateral apple-sized mucinous ovarian (Krukenberg) metastases. While she had erythrocyte phenotype of blood group A, the signet ring adenocarcinoma cells expressed blood group B incompatible antigenic determinants with lectin/mAb. In the second case, the autopsy of a 78-year-old female resulted in no macroscopic tumor sign except a moderately enlarged, ham hard spleen. Light microscopy revealed adenocarcinomatous infiltration in the splenic sinusoids. The patient had blood group O, while the metastatic cells in the spleen reacted with Breast Carcinoma Antigen (BioGenex) and incompatible anti-B Banderiaeasimplicifolia agglutinin I and anti-B mAb. It proved to be a case of an occult, completely regressed breast cancer. Based on these observations the expression of tumor specific incompatible blood group antigens might occur from time to time, mostly in adenocarcinomas. Accordingly, blood group-based specific immuno-oncotherapy could be considered in some cancer cases.

Evaluating the Efficacy of Fecal Occult Blood Test and Tumor Marker Combined Screening for Colorectal Cancer

Objective:To analyze the screening effectiveness of combining the fecal occult blood test with tumor marker detection for colorectal cancer.Methods:A total of thirty patients with colorectal cancer and thirty patients with benign colon hyperplasia who received treatment from January 2020 to January 2023 were selected.These patients were assigned to the observation group and the control group,respectively.All patients in both groups underwent both fecal occult blood tests and tumor marker detection.The levels of tumor markers between the two groups were compared,the tumor marker levels in different stages were assessed within the observation group,and the positive detection rates for single detection and combined detection were compared.Results:The levels of various tumor markers in the observation group were significantly higher than those in the control group(P<0.05).Furthermore,as the Duke stage increased within the observation group,the levels of various tumor markers also increased(P<0.05).The positive detection rate of the combined test was notably higher than that of single detection(P<0.05).Conclusion:Combining the fecal occult blood test with tumor marker detection in colorectal cancer screening can significantly improve the overall detection rate.

急性区域性隐匿性外层视网膜病变误诊为视神经视网膜病变1例

急性区域性隐匿性外层视网膜病变（acute zonal occult outer retinopathy,AZOOR）是一组急性发作、眼底表现不明显,以单个或多个区域视网膜外层功能障碍为特征的症候群。其早期可仅表现为视力下降,传统的检测手段,如眼底彩色照相、视野、视网膜电图及荧光素眼底血管造影（FFA）等在AZOOR的诊断及随访中均存在一定的局限性易误诊、漏诊。

Electron content near the lunar surface using dual-frequency VLBI tracking data in a single lunar orbiter mission

In VLBI observations of Vstar, a subsatellite of the Japanese lunar mission SELENE, there were opportunities for lunar grazing occultation when Vstar was very close to the limb of the Moon. This kind of chance made it possible to probe the thin plasma layer above the Moon＇s surface as a meaningful by-product of VLBI, by using the radio occultation method with coherent radio waves from the S/X bands. The dual-frequency measurements were carried out at Earth-based VLBI stations. In the line-of-sight direction between the satellite and the ground-based tracking station where VLBI measurements were made, the effects of the terrestrial ionosphere, interplanetary plasma and the thin lunar ionosphere mixed together in the combined observables of dual-frequency Doppler shift and phase shift. To separate the variation of the ionospheric total electron content （TEC） near the surface of the Moon from the mixed signal, the influences of the terrestrial ionosphere and interplanetary plasma have been removed by using an extrapolation method based on a short-term trend. The lunar TEC is estimated from the dual-frequency observation for Vstar from UT 22：18 to UT 22：20 on 2008 June 28 at several tracking stations. The TEC results obtained from VLBI sites are identical, however, they are not as remarkable as the result obtained at the Usuda deep space tracking station.

Genetic variation of occult hepatitis B virus infection

Occult hepatitis B virus infection(OBI), characterized as the persistence of hepatitis B virus(HBV) surface antigen(HBs Ag) seronegativity and low viral load in blood or liver, is a special form of HBV infection. OBI may be related mainly to mutations in the HBV genome, although the underlying mechanism of it remains to be clarified. Mutations especially within the immunodominant "α" determinant of S protein are "hot spots" that could contribute to the occurrence of OBI via affecting antigenicity and immunogenicity of HBs Ag or replication and secretion of virion. Clinical reports account for a large proportion of previous studies on OBI, while functional analyses, especially those based on full-length HBV genome, are rare.

Systematic review of colorectal cancer screening guidelines for average-risk adults: Summarizing the current global recommendations

AIM To summarize and compare worldwide colorectal cancer(CRC) screening recommendations in order to identify similarities and disparities.METHODS A systematic literature search was performed using MEDLINE, EMBASE, Scopus, CENTRAL and ISI Web of knowledge identifying all average-risk CRC screening guideline publications within the last ten years and/or position statements published in the last 2 years. In addition, a hand-search of the webpages of National Gastroenterology Society websites, the National Guideline Clearinghouse, the BMJ Clinical Evidence website,Google and Google Scholar was performed. RESULTS Fifteen guidelines were identified. Six guidelines were published in North America, four in Europe, four in Asia and one from the World Gastroenterology Organization. The majority of guidelines recommend screening average-risk individuals between ages 50 and 75 using colonoscopy(every 10 years), or flexible sigmoidoscopy(FS, every 5 years) or fecal occult blood test(FOBT, mainly the Fecal Immunochemical Test, annually or biennially). Disparities throughout the different guidelines are found relating to the use of colonoscopy, rank order between test, screening intervals and optimal age ranges for screening. CONCLUSION Average risk individuals between 50 and 75 years should undergo CRC screening. Recommendations for optimal surveillance intervals, preferred tests/test cascade as well as the optimal timing when to start and stop screening differ regionally and should be considered for clinical decision making. Furthermore, local resource availability and patient preferences are important to increase CRC screening uptake, as any screening is better than none.

New strategies for colorectal cancer screening

Colorectal cancer (CRC) is still one of the leading causes of cancer-related death in Western countries, despite major improvements in its treatment. The dramatically high social and economic impact of CRC on human health makes the identification of a reliable screening tool of paramount importance. Current screening methods, such as the fecal occult blood test and colonoscopy do not adequately meet the ideal requisites of a screening test because, even if they are effective, they are limited first by too low specificity and sensitivity, or second by high invasiveness, costs and risk. Nowadays extended efforts are made by researchers to look for more reliable and effective screening tests based on a systems biology approach, using biological samples easily available, such as urine, breath, serum and feces. The effectiveness and reliability of several new attempts to screen these patients by non-invasive analysis of their biological samples using genomic (genetic and epigenetic alteration), transcriptomic (miRNA), proteomic (cancer-related antigens, new antibodies against tumor-associated antigens, mutated proteins) and metabolomic (volatile organic metabolites) methods are discussed in this review. Among the most interesting new screening tools, fecal fluorescent long-DNA, fecal miRNA and metabolomic evaluation in breath and/ or serum seem to be most promising.

Occult infection related hepatitis B surface antigen variants showing lowered secretion capacity

AIM:To elucidate the molecular mechanisms underlying hepatitis B virus(HBV)occult infection of genotype C.METHODS:A total of 10 types of hepatitis B surface antigen(HBs Ag)variants from a Korean occult cohort were used.After a complete HBV genome plasmid mutated such that it does not express HBs Ag and plasmid encoding,each HBs Ag variant was transiently co-transfected into Hu H-7 cells.The secretion capacity and intracellular expression of the HBV virions and HBs Ags in their respective variants were analyzed using real-time quantitative polymerase chain reaction assays and commercial HBs Ag enzyme-linked immunosorbent assays,respectively.RESULTS:All variants exhibited lower levels of HBs Ag secretion into the medium compared with the wild type.In particular,in eight of the ten variants,very low levels of HBs Ag secretion that were similar to the negative control were detected.In contrast,most variants(9/10)exhibited normal virion secretion capacities comparable with,or even higher than,the wild type.This provided new insight into the intrinsic nature of occult HBV infection,which leads to HBs Ag sero-negativeness but has horizontal infectivity.Furthermore,most variants generated higher reactive oxidative species production than the wild type.This finding provides potential links between occult HBV infection and liver disease progression.CONCLUSION:The presently obtained data indicate that deficiency in the secretion capacity of HBs Ag variants may have a pivotal function in the occult infections of HBV genotype C.

Occult hepatitis B virus infection and blood transfusion

Transfusion-transmitted infections including hepatitis B virus(HBV) have been a major concern in transfusion medicine. Implementation of HBV nucleic acid testing(NAT) has revealed occult HBV infection(OBI) in blood donors. In the mid-1980 s, hepatitis B core antibody(HBc) testing was introduced to screen blood donors in HBV non-endemic countries to prevent transmission of non-A and non-B hepatitis. That test remains in use for preventing of potential transmission of HBV from hepatitis B surface antigen(HBs Ag)-negative blood donors, even though anti-hepatitis C virus testshave been introduced. Studies of anti-HBc-positive donors have revealed an HBV DNA positivity rate of 0%-15%. As of 2012, 30 countries have implemented HBV NAT. The prevalence of OBI in blood donors was estimated to be 8.55 per 1 million donations, according to a 2008 international survey. OBI is transmissible by blood transfusion. The clinical outcome of occult HBV transmission primarily depends on recipient immune status and the number of HBV DNA copies present in the blood products. The presence of donor anti-HBs reduces the risk of HBV infection by approximately five-fold. The risk of HBV transmission may be lower in endemic areas than in non-endemic areas, because most recipients have already been exposed to HBV. Blood safety for HBV, including OBI, has substantially improved, but the possibility for OBI transmission remains.