Pasteurization of dairy products and education regarding fresh cheese must be pursued for eradication of brucellosis. A major risk factor for acquiring brucellosis is the existence of another infected family member. Therefore screening family members of an index case of brucellosis may lead to the detection of additional cases.

Occult hepatitis B virus (HBV) infection is characterized by presence of HBV infection with undetectable hepatitis B surface antigen (HBsAg). Occult HBV infection harbors potential risk of HBV transmission through hemodialysis (HD). The aim of this study was to assess the occult HBV infection in hemodialysis patients with isolated hepatitis B core antibody (anti-HBc). A total of 289 HD patients from five dialysis units in Tehran, Iran, were included in this study. Hepatitis B surface antigen (HBsAg), Hepatitis B surface antibody (anti-HBs), anti-HBc, Hepatitis C antibody (anti-HCV), alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were tested in all subjects. The presence of HBV-DNA was determined quantitatively in plasma samples of HD patients with isolated anti-HBc (HBsAg negative, anti-HBs negative and anti-HBc positive) by real-time PCR using the artus HBV RG PCR kit on the Rotor-Gene 3000 real-time thermal cycler. Of 289 patients enrolled in this study, 18 subjects (6.2%, 95% confidence interval (CI), 3.5%-8.9%) had isolated anti-HBc. HBV-DNA was detectable in 9 of 18 patients (50%, 95% CI, 27%-73%) who had isolated anti-HBc. Plasma HBV-DNA load was less than 50 IU/ml in all of these patients. Our study showed that detection of isolated anti-HBc could reflect unrecognized occult HBV infection in HD patients. The majority of these infections are associated with low viral loads.

Introduction: Anti-hepatitis B core antibody (Anti-HBc) alone is defined as the presence of anti-HBc in the absence of HBsAg and anti-HBs. The significance of this serological pattern as a predicting factor for occult hepatitis B virus (HBV) infection remains largely unknown. This study aimed to assess the significance of anti-HBc alone in predicting occult HBV infection in high-risk and low-risk individuals. Methodology: A total of 926 individuals were enrolled in this study, including 289 hemodialysis (HD) and 106 HIV-infected patients who were considered as a high-risk group and 531 blood donors who were considered as low-risk. HBsAg, anti-HBs, anti-HBc were tested in all subjects. The presence of HBV-DNA was determined quantitatively in patients with anti-HBc alone by real-time PCR. Results: Of the 395 high-risk patients, 40 cases (10.13%) had anti-HBc alone, while 11 subjects (2.07%) out of 531 blood donors had anti-HBc alone. HBV-DNA was detected in 12 out of 40 (30%) high-risk patients and none of the blood donors with anti-HBc alone. Conclusion: Our study showed that the serological pattern of anti-HBc alone could reflect occult HBV infection in high risk cases but did not presume occult HBV infection in low-risk individuals.

Our study showed that all the blood donors with isolated anti-HBc were negative for HBV-DNA, and occult HBV infection did not occur in the blood donors of this low prevalence region for HBV infection.

COVID-19 immunity in infected individuals may not be persistent. The specific response wanes in patients who have recovered from this infection. Nevertheless, it has not been fully understood whether true re-infection occurs or the viral reactivation. In this study, we investigated three COVID-19 patients who represented the symptoms after recovery. Chest CT scan was applied to assess the patients along with the viral samples from oropharyngeal/nasopharyngeal which were subjected to RT-PCR. The viral genome sequencing was applied where possible to distinguish possible re-infection or latent reactivation. Moreover, COVID-19specific antibodies available data were evaluated in each incidence. The second episode of SARS-CoV-2 infection was different among the investigated subjects who experienced an interval between positive PCR tests ranged between 63 and 156 days. The disease presentation was less or more severe in the second infection. All cases were found IgG positive in the re-infection phase. The sequencing of SARS-CoV-2 sample obtained from two cases revealed a D614G mutation of S gene from the second isolated sample strengthens the case for the re-infection. The possibility of re-infection and reactivation could have significant effect on clinical implications and also vaccination. Our data supports clear warning of SARS-CoV-2 continuous circulation potency among the populations in spite of herd immunity either with natural infection or vaccination. This issue is critical in term of the patients, clinical investigate, and viral transmission.