Tick-borne encephalitis (TBE), caused by the TBE virus (TBEV), is a life-threatening disease with clinical symptoms ranging from non-specific to severe inflammation of the central nervous system. Despite TBE is a notifiable disease in Serbia since 2004, there is no active TBE surveillance program for the serologic or molecular screening of TBEV infection in humans in the country. This prospective cohort study aimed to assess the TBEV exposure among tick-infested individuals in Serbia during the year 2020. A total of 113 individuals exposed to tick bites were recruited for the study and screened for anti-TBEV antibodies using a commercial indirect fluorescent antibody test (IFA) test. Blood samples from 50 healthy donors not exposed to tick bites were included as a control group. Most of the enrolled patients reported infestations with one tick, being I. ricinus the most frequent tick found in the participants. The TBEV seroprevalence was higher (13.27%, 15 total 113) in tick-infested individuals than in healthy donors (4%, 2 total 50), although the difference was not significant. Notably, male individuals exposed to tick bites showed five times higher relative risk (RR) of being TBEV-seropositive than healthy donors of the same gender (RR= 5.1, CI = 1.6–19; p = 0.007). None of the seropositive individuals developed clinical manifestations of TBE, but the first clinical-stage of Lyme borreliosis (i.e., erythema migrans) was detected in seven of them. Potential TBEV foci were identified in rural areas, mostly in proximity or within the Fruška Gora mountain. We conclude that the Serbian population is at high risk of TBEV exposure. Further epidemiological studies should focus on potential TBEV foci identified in this study. The implementation of active surveillance for TBEV might contribute to evaluating the potential negative impact of TBE in Serbia.

Passive immunotherapy with convalescent COVID-19 plasma (CCP) is used as a therapeutic procedure in many countries, including Serbia. In this study, we analyzed the association between demographic factors, COVID-19 severity and the reactivity of anti-SARS-CoV-2 antibodies (Abs) in Serbian CCP donors. Individuals (n = 468) recovered from confirmed SARS-CoV-2 infection, and who were willing to donate their plasma for passive immunization of COVID-19 patients were enrolled in the study. Plasma samples were tested for the presence of IgG reactive to SARS-CoV-2 spike glycoprotein (S1) and nucleocapsid antigens. Individuals were characterized according to age, gender, comorbidities, COVID-19 severity, ABO blood type and RhD factor. Total of 420 candidates (420/468; 89.74%) reached the levels of anti-SARS-CoV-2 IgG that qualified them for inclusion in CCP donation program. Further statistical analysis showed that male individuals (p = 0.034), older age groups (p < 0.001), existence of hypertension (p = 0.008), and severe COVID-19 (p = 0.000) are linked with higher levels of anti-SARS-CoV-2 Abs. These findings will guide the selection of CCP donors in Serbia. Further studies need to be conducted to assess the neutralization potency and clinical efficiency of CCP collected from Serbian donors with high anti-SARS-CoV-2 IgG reactivity.

Lyme borreliosis (LB) and tick-borne encephalitis (TBE) are important tick-borne diseases in Europe. This study aimed to investigate the seroreactivity against Borrelia burgdorferi and TBE virus (TBEV) in tick-infested individuals in North Macedonia and Serbia. Serum samples were collected from tick-infested individuals and from healthy individuals in the same regions. Samples were tested for anti-Borrelia IgG reactivity and TBEV-neutralizing antibodies. Results showed higher seroreactivity against Borrelia antigens in patients and healthy donors from Novi Sad compared to those from the Skopje region. However, there was no statistically significant difference between tick-infested patients and healthy donors within each region. No TBEV-neutralizing antibodies were detected in participants from Novi Sad or in the control groups, except for one person from North Macedonia who had a moderate TBEV-neutralizing reaction. The study highlights the need for improved surveillance and diagnostic capabilities for LB and TBE in these regions. It also suggests the potential existence of TBEV foci in North Macedonia. The findings provide a complementary understanding of the LB and TBE epidemiology in the studied regions; however, further research is needed to investigate the presence and distribution of Borrelia spp. and TBEV in ticks to assess the significance of detected seroreactivity.

Background/Aim. Pregnancy-induced red blood cell (RBC) alloimmunization is important not only because of the possible negative effects on subsequent pregnancy outcomes, in case the fetus carries the antigen, but also because of the optimal transfusion management in cases of obstetric haemorrhage. Timely detection of RBC antibodies is part of a testing, prevention and treatment strategy aimed at achieving better outcomes for alloimmunized mothers with an affected fetus. The aim was to determine the frequency and specificity of alloantibodies among pregnant women from the South Backa District, with special attention to the incidence of anti-D alloantibody. Methods. A retrospective study was conducted from January 1, 2010 to December 31, 2019 in the Blood Transfusion Institute of Vojvodina. Screening and antibody identification were performed by an indirect antiglobulin test in gel-microcards (ID-Card Liss/Coombs) with two test RBC (ID-DiaCell I-II screening cells, Bio-Rad, Cressier, Switzerland), on an automated system (IH-500, Bio-Rad). Results. Among 25694 tested pregnant women 1.38% were actively immunized, while 1.12% antibodies was identified in the current pregnancy. Among 3622 (14.09%) RhD-negative women 1.77% with anti-D produced during the ongoing pregnancy were found. Distribution of antibody specificity was: anti-D 23.34%, anti-M 11.85%, anti-E 9.41%, anti-K 9.41%, anti-C 5.92%, anti-Fyb 5.92%, anti-c 3.13%, anti-S 3.13%, anti-Lea 3.13%, anti-Leb 3.13%, anti-Cw 1.75%, anti-Jka 1.40%, anti-P 1.05%, anti-Lub 0.70%, anti-Fya 0.35%, autoantibody of undetermined specificity 0.70%, and irregular antibodies of undetermined specificity 15.68%. Conclusion. Immune globulin prophylaxis has led to a significant reduction in the frequency of D alloimmunization among pregnant women in the South Backa District over the last ten years, but the incidence of anti-D is still significantly higher than in published data for developed countries. We also identified the other, less commonly present, clinically significant antibodies. There is a need to introduce uniform recommendations for immunohematological testing in pregnancy on the territory of the Republic of Serbia, in accordance with modern requirements.

Background/Aim. Plateletpheresis is a medical procedure used for the collection of donor platelets with multiple benefits for patients who will receive apheresis platelets. The procedure takes one hour and is well tolerated by donors. Nevertheless, adverse events may occur during and after the plateletpheresis procedure. The aim was to present one centre experiences in order to determine the incidence and type of adverse events associated with donor plateletpheresis. Methods. A retrospective analysis of adverse events associated with donor plateletpheresis was conducted in the Blood Transfusion Institute of Vojvodina over the period from January 1, 2010 through December 31, 2019. Results. Out of 2073 platelet donors 94.84% were multiple blood donors, predominantly male (98.55%). Adverse events were identified during 180 (8.68%) platelet donations with no statistical significance in occurrence in the first time (10.28%) and repeat donors (8.59%). Mild local reactions related to venous access (42.22%) were the most common adverse events. Generalized symptoms exhibited 16.67% of donors, 26.11% exhibited symptoms related to apheresis - citrate reactions and 15% exhibited those related to other complications. During plateletpheresis occurred 95.55% adverse events and 4.45% after. Conclusion. Donor plateletpheresis is a generally safe procedure, well tolerated by donors. Understanding risk factors for possible occurrence of adverse events provide support for adoption of measures to prevent them.