Objective: The severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2) and the resulting COVID-19 pandemic pose significant challenges in terms of diagnosis and recurrent infections. Literature data suggest that age, gender and BMI factors are associated with immune response. The first aim of the study was to analyze the change in antibody titer at 15-day intervals until 60 days post symptom onset (PSO) The second aim was to analyze relationship between antibody titer and symptom grade, gender, age, BMI, therapeutic drugs, vitamin supplements, and herbal therapies. Materials and methods: Blood samples were collected from 43 patients (5 mild, 21 moderate, 17 severe diseases), 18 women (41.9 %), and 25 men (58.1 %), on 15, 30, 45, and 60 days PSO after COVID-19 infection. The serum antibody titers were determined by measuring the COVID-19 IgG antibodies by ELISA. Associations between the duration of symptoms, demographic and clinical parameters, medications and vitamins used, and herbal therapies were evaluated by interviewing the participants. Results: Within the first 15 days of illness, 81.4% of the patients were positive. From day 45 PSO, seropositivity was 89.5%. The anti-SARS-CoV-2 antibody titers were statistically higher in men than women at all-time (p<0.01). Antibody titer was higher in older participants compared to younger participants (p<0.02). Plaquenil or Favipiravir use did not effect antibody response (p>0.05). Men had higher fever (p=0.006), shortness of breath (p=0.004), and chest pain (p=0.03) than women. Conclusion: We found powerful antibody response by sixty days PSO, as well as higher antibody response and severity of symptoms in men gender. Data also showed that SARS-CoV-2 antibodies are higher in individuals with older age, whereas BMI, coexisting chronic disease, and drug used had no effect on antibody titers.

Aims: The differential diagnosis of Fever of Unknown Origin (FUO) is still a major clinical challenge despite the advances in diagnostic procedures. In this multicenter study, we aimed to reveal FUO etiology and factors influencing the final diagnosis of FUO in Turkey. Methods: A total of 214 patients with FUO between the years 2015-2019 from 13 tertiary training and research hospitals were retrospectively evaluated. Results: The etiologic distribution of FUO was infections (44.9%), malignancies (15.42%), autoimmune/inflammatory (11.68%) diseases, miscellaneous diseases (8.41%) and undiagnosed cases (19.62%). Brucellosis (10.25%), extrapulmonary tuberculosis (6.54%) and infective endocarditis (6.54%) were the most frequent three infective causes. Solid malignancies (7.1%) and lymphoma (5.6%), adult-onset still’s disease (6.07%) and thyroiditis (5.14%) were other frequent diseases. The etiologic spectrum did not differ in elderly (p<0.05). Infections were less frequent in Western (34.62%) compared to Eastern regions of Turkey (60.71%) (p< 0.001, OR: 0.31, 95% Cl: 0.19 to 0.60). The ratio of undiagnosed etiology was significantly higher in elderly (p: 0.046, OR: 2.34, 95% Cl: 1.00 to 5.48) and significantly lower in Western Turkey (p: 0.004, OR: 3.07, 95% Cl: 1.39 to 6.71). Conclusion: Brucellosis, extrapulmonary tuberculosis and infective endocarditis remain to be the most frequent infective causes of FUO in Turkey. Solid tumors and lymphomas, AOSD and thyroiditis are the other common diseases. The etiologic spectrum did not differ in elderly, on the other hand, infections were more common in Eastern Turkey. A considerable amount of etiology remained undiagnosed despite the state-of-the-art technology in healthcare services.

Objective: Increasing evidences suggest that oxidative stress is closely related to the pathogenesis of hepatitis C virus (HCV) infection. The purpose of this study was to examine the dynamic thiol/disulfide homeostasis (DTDH) and total oxidant/antioxidant status in patients with HCV infection. Methods: Levels of serum total thiol (TT), native thiol (NT), disulfide (DS), total oxidant status (TOS), total antioxidant status (TAS), and oxidative stress index (OSI; TOS/TAS ratio) as oxidative stress markers were determined in 162 individuals, including 74 patients with HCV infection and 88 non-HCV controls. Results: The NT, TT levels and NT/TT ratio were significantly lower and DS level, DS/NT and DS/TT ratios were significantly higher in HCV group compared to the control group. The TOS and OSI values were significantly higher and the TAS level was significantly lower in the HCV group than in the control group. No significant correlations were found between oxidative stress markers and albumin, alanine aminotransferase, aspartate aminotransferase and bilirubin levels in patients with HCV infection. A negative correlation was found only between OSI and albumin. Conclusion: These results indicate that patients with HCV infection are vulnerable to oxidative stress and have disturbed status of oxidant and antioxidant.