Prevalence of infectious diseases, immunity to vaccine-preventable diseases and chronic medical conditions among Ukrainian refugees in Germany - A cross sectional study from the German Network University Medicine (NUM).

BACKGROUND: Vulnerability to infectious diseases in refugees is dependent on country of origin, flight routes, and conditions. Information on specific medical needs of different groups of refugees is lacking. We assessed the prevalence of infectious diseases, immunity to vaccine-preventable diseases, and chronic medical conditions in children, adolescents, and adult refugees from Ukraine who arrived in Germany in 2022. METHODS: Using different media, we recruited Ukrainian refugees at 13 sites between 9-12/2022. An antigen test for acute respiratory syndrome coronavirus type 2 (SARS-CoV-2) infection, serologies for a range of vaccine-preventable diseases, as well as interferon gamma release assays (IGRAs) for tuberculosis (TB), and SARS-CoV-2 were performed. We assessed personal and family history of chronic medical conditions, infectious diseases, vaccination status, and conditions during migration. RESULTS: Overall, 1793 refugees (1401 adults and 392 children/adolescents) were included. Most participants were females (n = 1307; 72·3%) and from Eastern or Southern Ukraine. TB IGRA was positive in 13% (n = 184) of the adults and in 2% (n = 7) of the children. Serology-based immunological response was insufficient in approximately 21% (360/1793) of the participants for measles, 32% (572/1793) for diphtheria, and 74% (1289/1793) for hepatitis B. CONCLUSIONS: We show evidence of low serological response to vaccine-preventable infections and increased LTBI prevalence in Ukrainian refugees. These findings should be integrated into guidelines for screening and treatment of infectious diseases in migrants and refugees in Germany and Europe. Furthermore, low immunity for vaccine-preventable diseases in Ukrainians independent of their refugee status, calls for tailor-made communication efforts.

Two cases of airport-associated falciparum malaria in Frankfurt am Main, Germany, October 2019.

Two cases of presumably airport-acquired falciparum malaria were diagnosed in Frankfurt in October 2019. They were associated with occupation at the airport, and Plasmodium falciparum parasites from their blood showed genetically identical microsatellite and allele patterns. Both had severe malaria. It took more than a week before the diagnosis was made. If symptoms are indicative and there is a plausible exposure, malaria should be considered even if patients have not travelled to an endemic area.

Streptococcal Pyrogenic Exotoxin A-Stimulated Monocytes Mediate Regulatory T-Cell Accumulation through PD-L1 and Kynurenine.

Bacterial superantigens (SAgs) are exotoxins that promote a fulminant activation of the immune system. The subsequent intense release of inflammatory cytokines often results in hypotension, shock, and organ failure with high mortality rates. In the current paradigm, the direct and simultaneous binding of SAgs with T-cell receptor (TCR)-bearing Vß regions and conserved structures on major histocompatibility complex class II (MHC class II) on antigen-presenting cells (APCs) induces the activation of both cell types. However, by crosslinking MHC class II molecules, APCs can be activated by SAgs independently of T lymphocytes. Recently, we showed that streptococcal pyrogenic exotoxin A (SPEA) of Streptococcus pyogenes stimulates an immunogenic APC phenotype with upregulated costimulatory molecules and inflammatory cytokines. Additionally, we revealed that SPEA triggers immunosuppressive programs in monocytes that facilitate the accumulation of regulatory T cells (Tregs) in in vitro monocyte/CD4+ T-cell cocultures. Immunosuppressive factors include anti-inflammatory interleukin 10 (IL-10), co-inhibitory surface molecule programmed cell death 1 ligand 1 (PD-L1), and the inhibitory indoleamine 2,3-dioxygenase (IDO)/kynurenine effector system. In the present study, we investigated the underlying mechanism of SPEA-stimulated monocyte-mediated accumulation of Tregs. Blood-derived monocytes from healthy donors were stimulated with SPEA for 48 h (SPEA-monocytes). For the evaluation of SPEA-monocyte-mediated modulation of CD4+ T lymphocytes, SPEA was removed from the culture through extensive washing of cells before adding allogeneic CD3/CD28-activated T cells. Results: In coculture with allogeneic CD4+ T cells, SPEA-monocytes mediate apoptosis of CD4+Foxp3- lymphocytes and accumulation of CD4+Foxp3+ Tregs. PD-L1 and kynurenine are critically involved in the mediated cell death because blocking both factors diminished apoptosis and decreased the proportion of the CD25+/Foxp3+ Treg subpopulation significantly. Upregulation of PD-L1 and kynurenine as well as SPEA-monocyte-mediated effects on T cells depend on inflammatory IL-1ß. Our study shows that monocytes activated by SPEA mediate apoptosis of CD4+Foxp3- T effector cells through PD-L1 and kynurenine. CD4+Foxp3+ T cells are resistant to apoptosis and accumulate in SPEA-monocyte/CD4+ T-cell coculture.

IL-1ß As Mediator of Resolution That Reprograms Human Peripheral Monocytes toward a Suppressive Phenotype.

During infection pathogen-associated molecular patterns activate immune cells to initiate a cascade of reactions leading to inflammation and the activation of the adaptive immune response culminating in the elimination of foreign pathogens. However, shortly after activation of the host defense machinery, a return to homeostasis is preferred to prevent inflammation-induced tissue damage. This switch from the initial immunogenic to the subsequent tolerogenic phase after clearance of the infection can be mediated through highly plastic peripheral monocytes. Our studies reveal that an early encounter with toll-like receptor 7/8-ligand R848 mediates a strong pro-inflammatory monocytic phenotype that primes its own reprogramming toward an immunosuppressive one. Previously, we showed that these R848-treated antigen-presenting cells (APCs) fail to activate allogeneic T cells and induce regulatory T cells (Tregs) through signal transducer and activator of transcription 3 (STAT3)-dependent PD-L1. Here, we further demonstrate that R848-treated APCs suppress CD3/CD28-mediated and dendritic cell-mediated T cell activation and that adenosine and indoleamine 2,3-dioxygenase/kynurenin pathways are involved in tolerance induction. Reprogramming of monocytes after R848 stimulation requires the pro-inflammatory cytokine IL-1ß and a boosted IL-6 release. The subsequent autocrine prolonged activation of STAT3 induces direct upregulation of tolerogenic factors which finally downregulate proliferation of activated T cells and mediate Tregs. Thereby our study suggests that inflammatory cytokines, such as IL-1ß and IL-6, should be considered as mediators of resolution of inflammation.