20 research outputs found
Could Artificial Intelligence/Machine Learning and Inclusion of Diet-Gut Microbiome Interactions Improve Disease Risk Prediction? Case Study : Coronary Artery Disease
Get PDFFunding Information: This research was funded by the Latvian Council of Science within the project Gut microbiome composition and diversity among health and lifestyle induced dietary regimen, project No. lzp-2018/2-0266. Publisher Copyright: Copyright Ā© 2022 Vilne, Ķibilds, Siksna, Lazda, ValciÅa and KrÅ«miÅa.Coronary artery disease (CAD) is the most common cardiovascular disease (CVD) and the main leading cause of morbidity and mortality worldwide, posing a huge socio-economic burden to the society and health systems. Therefore, timely and precise identification of people at high risk of CAD is urgently required. Most current CAD risk prediction approaches are based on a small number of traditional risk factors (age, sex, diabetes, LDL and HDL cholesterol, smoking, systolic blood pressure) and are incompletely predictive across all patient groups, as CAD is a multi-factorial disease with complex etiology, considered to be driven by both genetic, as well as numerous environmental/lifestyle factors. Diet is one of the modifiable factors for improving lifestyle and disease prevention. However, the current rise in obesity, type 2 diabetes (T2D) and CVD/CAD indicates that the āone-size-fits-allā approach may not be efficient, due to significant variation in inter-individual responses. Recently, the gut microbiome has emerged as a potential and previously under-explored contributor to these variations. Hence, efficient integration of dietary and gut microbiome information alongside with genetic variations and clinical data holds a great promise to improve CAD risk prediction. Nevertheless, the highly complex nature of meals combined with the huge inter-individual variability of the gut microbiome poses several Big Data analytics challenges in modeling diet-gut microbiota interactions and integrating these within CAD risk prediction approaches for the development of personalized decision support systems (DSS). In this regard, the recent re-emergence of Artificial Intelligence (AI) / Machine Learning (ML) is opening intriguing perspectives, as these approaches are able to capture large and complex matrices of data, incorporating their interactions and identifying both linear and non-linear relationships. In this Mini-Review, we consider (1) the most used AI/ML approaches and their different use cases for CAD risk prediction (2) modeling of the content, choice and impact of dietary factors on CAD risk; (3) classification of individuals by their gut microbiome composition into CAD cases vs. controls and (4) modeling of the diet-gut microbiome interactions and their impact on CAD risk. Finally, we provide an outlook for putting it all together for improved CAD risk predictions.publishersversionPeer reviewe
Evaluation of Genetic Diversity and Virulence Potential of Legionella pneumophila Isolated from Water Supply Systems of Residential Buildings in Latvia
Get PDFLegionella is an opportunistic pathogen with a biphasic life cycle that occasionally infects humans. The aim of the study was to assess the distribution of virulence genes and genetic diversity among L. pneumophila isolated from water supply systems of residential buildings in Latvia. In total, 492 water samples from 200 residential buildings were collected. Identification of Legionella spp. was performed according to ISO 11731, and 58 isolates were subjected to whole-genome sequencing. At least one Legionella-positive sample was found in 112 out of 200 apartment buildings (56.0%). The study revealed extensive sequence-type diversity, where 58 L. pneumophila isolates fell into 36 different sequence types. A total of 420 virulence genes were identified, of which 260 genes were found in all sequenced L. pneumophila isolates. The virulence genes enhC, htpB, omp28, and mip were detected in all isolates, suggesting that adhesion, attachment, and entry into host cells are enabled for all isolates. The relative frequency of virulence genes among L. pneumophila isolates was high. The high prevalence, extensive genetic diversity, and the wide range of virulence genes indicated that the virulence potential of environmental Legionella is high, and proper risk management is of key importance to public health.Peer reviewe
Retrospective study of genetic diversity of Acinetobacter baumannii -resistant strains isolated from patients in Riga East University Hospital in Latvia
Get PDFAffiliations are different in Web of Science database and original journal publication. Here are given affiliations from original publication in Proceedings of the Latvian Academy of Sciences, Section B: Natural Exact and Applied Sciences.publishersversionPeer reviewe
Coāoccurrence of freeāliving amoeba and legionella in drinking water supply systems
Get PDFFunding Information: Funding: This study was funded by National Research Programme No. 7, Agricultural Resources for Sustainable Production of Qualitative and Healthy Foods in Latvia project No. 5 āResistance of microorganisms and other biological and chemical risks: research procedure development and application in the food chain.ā Publisher Copyright: Ā© 2019 by the authors. Licensee MDPI, Basel, Switzerland.Background and Objectives: Legionella is one of the most important water-related pathogens. Inside the water supply systems and the biofilms, Legionella interact with other bacteria and free-living amoeba (FLA). Several amoebas may serve as hosts for bacteria in aquatic systems. This study aimed to investigate the co-occurrence of Legionella spp. and FLA in drinking water supply systems. Materials and Methods: A total of 268 water samples were collected from apartment buildings, hotels, and public buildings. Detection of Legionella spp. was performed in accordance with ISO 11731:2017 standard. Three different polymerase chain reaction (PCR) protocols were used to identify FLA. Results: Occurrence of Legionella varied from an average of 12.5% in cold water samples with the most frequent occurrence observed in hot water, in areas receiving untreated groundwater, where 54.0% of the samples were Legionella positive. The occurrence of FLA was significantly higher. On average, 77.2% of samples contained at least one genus of FLA and, depending on the type of sample, the occurrence of FLA could reach 95%. In the samples collected during the study, Legionella was always isolated along with FLA, no samples containing Legionella in the absence of FLA were observed. Conclusions: The data obtained in our study can help to focus on the extensive distribution, close interaction, and long-term persistence of Legionella and FLA. Lack of Legionella risk management plans and control procedures may promote further spread of Legionella in water supply systems. In addition, the high incidence of Legionella-related FLA suggests that traditional monitoring methods may not be sufficient for Legionella control.Peer reviewe
Microbiological Quality of Ready-To-Eat Products and Potential Risks for Consumers in Latvia
Get PDFPublisher Copyright: Ā© 2016 by ElÄ«na Ciekure.Ready-to-eat (RTE) foods are challenging for food business operators as they need to remain qualitative and safe for consumers. However, consumers tend to choose them more and more often because of fast and easy handling. The highest risk from RTE foods is microbiological contamination, particularly for vulnerable groups like children, elderly, and pregnant women. The aim of the research was to assess the microbiological quality of RTE meat and fish products to highlight possible risks for consumers. A total of 15 984 analyses performed on RTE meat and fish products were included in this study. It was found that RTE meat and fish product samples representative of the market in Latvia in the period 2012-2015 had high microbiological quality and only in rare cases was contamination with hygiene indicatororganisms (coliforms and Escherichia coli) and pathogens (Salmonella spp., Listeria monocytogenes, Staphylococcus aureus, and sulphite-reducing clostridia) detected. However, it is important to pay attention to customer habits of cooking and preparing RTE foods as well-thermal processing for products intended to be used cooked, use before expiration date and adequate storage rules for products, as these have important regarding microbiological risks for health.publishersversionPeer reviewe
Prevalence, Genetic Diversity, and Virulence Potential of Legionella spp. Summary of the Doctoral Thesis
No full textPromocijas darbs izstrÄdÄts PÄrtikas droŔības, dzÄ«vnieku veselÄ«bas un vides zinÄtniskajÄ institÅ«tÄ āBIORā, LatvijÄ. AizstÄvÄÅ”ana: medicÄ«nas bÄzes zinÄtÅu, tai skaitÄ farmÄcijas promocijas padomes atklÄtÄ sÄdÄ 2023. gada 28. decembrÄ« plkst. 15.00 HipokrÄta auditorijÄ, Dzirciema ielÄ 16, un attÄlinÄti, tieÅ”saistes platformÄ Zoom.Legionella spp. ir viens no nozÄ«mÄ«gÄkajiem ar Å«deni saistÄ«tajiem patogÄniem, kas var izraisÄ«t gan novÄrÅ”amus uzliesmojumus, gan sporÄdiskus gadÄ«jumus. LeÄ£ionellu izplatÄ«Å”anÄs notiek ar baktÄrijas saturoÅ”iem Å«dens aerosoliem. Aerosolu veidÄ baktÄrijas var izplatÄ«ties vairÄku kilometru attÄlumÄ no primÄrÄ infekcijas avota, vienlaikus saglabÄjot dzÄ«votspÄju. LeÄ£ioneloze ir novÄrÅ”ama slimÄ«ba un atipiskas pneimonijas forma, ko izraisa Legionella pneumophila un radniecÄ«gÄs baktÄrijas. SlimÄ«bas klÄ«niskÄs izpausmes variÄ no vieglas, paÅ”limitÄjoÅ”as gripai lÄ«dzÄ«gas slimÄ«bas (Pontiakas drudzis) lÄ«dz potenciÄli letÄlai pneimonijai (leÄ£ionÄru slimÄ«ba). PÄtÄ«juma mÄrÄ·is bija izpÄtÄ«t Legionella spp. izplatÄ«bas tendences, Ä£enÄtisko daudzveidÄ«bu un virulences potenciÄlu leÄ£ionelozes diagnostikai un profilaksei LatvijÄ. MateriÄli un metodes. Lai noteiktu L. pneumophila seroprevalenci vispÄrÄjÄ veselÄ populÄcijÄ un identificÄtu asociÄtos riska faktorus, tika paÅemti 2007 asins paraugi no veseliem asins donoriem. Lai novÄrtÄtu Legionella spp. izplatÄ«bu Å«densapgÄdes sistÄmÄs, tika paÅemti 1467 Å«dens paraugi dažÄda tipa ÄkÄs. Ä¢enÄtiskÄs daudzveidÄ«bas izpÄtei izvÄlÄti 137 Legionella pneumophila izolÄti, un 58 izolÄtiem tika veikta virulences gÄnu noteikÅ”ana. Visiem asins paraugiem veikta imÅ«nfermentatÄ«vÄ reakcija, lai noteiktu IgG antivielas pret L. pneumophila SG 1-6. LeÄ£ionellu noteikÅ”ana Å«denÄ« un bioplÄvÄs veikta ar standartizÄtu metodi. BrÄ«vi dzÄ«vojoÅ”ie vienŔūÅi noteikti morfoloÄ£iski un ar trÄ«s dažÄdiem PĶR protokoliem. AtdzÄ«vinÄtiem L. pneumophila izolÄtiem veikta pilna genoma sekvencÄÅ”ana ar Illumina MiSeq. SekvencÄ bÄzÄtÄ tipÄÅ”ana veikta atbilstoÅ”i ESCMID izstrÄdÄtajai shÄmai. cgMLST tipÄÅ”ana veikta, izmantojot iepriekÅ” aprakstÄ«tu protokolu. Virulences gÄnu noteikÅ”anai izmantota virulences faktoru datu bÄze. RezultÄti. L. pneumophila SG 1-6 seroprevalence asins donoriem bija 4,8 %, un 0,2 % donoru bija seropozitÄ«vi pret L. pneumophila SG1. Seroprevalence bija augstÄka sievietÄm (5,9 %) nekÄ vÄ«rieÅ”iem (3,3 %) un reÄ£ionos ar lielÄku iedzÄ«votÄju skaitu, sÄkot no 3,5 % lauku reÄ£ionos lÄ«dz 6,8 % galvaspilsÄtÄ RÄ«gÄ. Legionella spp. prevalence Å«densapgÄdes sistÄmÄs variÄja no vidÄji 25 % aukstÄ Å«dens paraugos lÄ«dz 35 % karstÄ Å«dens paraugos. DominÄjoÅ”Ä L. pneumophila serogrupa (SG) bija SG 3, kas tika identificÄta 208 no 482 gadÄ«jumiem (43,2 %). Vismaz viena brÄ«vi dzÄ«vojoÅ”a amÄbu Ä£ints konstatÄta 77,2 % paraugu. VidÄjÄ karstÄ Å«dens temperatÅ«ra bija 47,8 Ā± 0,7 Ā°C. TemperatÅ«ras mÄrÄ«jumi parÄdÄ«ja, ka tikai 249 no 1275 karstÄ Å«dens paraugiem temperatÅ«ra pÄrsniedza 55 Ā°C. PÄtÄ«jumÄ iekļautie 137 L. pneumophila celmi sadalÄs 46 sekvenÄu tipos, turklÄt 10 sekvenÄu tipi ir jauni, iepriekÅ” pasaulÄ nereÄ£istrÄti. Izmantojot cgMLST tipÄÅ”anu, iegÅ«ti 116 genotipi. KopumÄ 58 dzÄ«vojamo mÄju izolÄtiem tika identificÄti 420 virulences gÄni, no kuriem 260 gÄni tika atrasti visos sekvencÄtajos L. pneumophila izolÄtos. Visos izolÄtos tika atklÄti virulences gÄni enhC, htpB, omp28 un mip, kas liecina, ka visiem izolÄtiem ir iespÄjota adhÄzija, piesaiste un iekļūŔana saimniekŔūnÄ. Virulences gÄnu relatÄ«vais biežums starp L. pneumophila izolÄtiem bija augsts. SecinÄjumi. DaudzdzÄ«vokļu mÄju iedzÄ«votÄji ir pakļauti lielÄkam leÄ£ionelozes riskam nekÄ privÄtmÄjÄs dzÄ«vojoÅ”ie (OR = 2,23; p = 0,011); augstÄkais seropozitivitÄtes risks bija to Äku iedzÄ«votÄjiem, kas centralizÄti saÅÄma karsto Å«deni (OR = 3,16; p = 0,001); augstÄ Legionella spp. prevalence Å«densapgÄdes sistÄmÄs ir saistÄ«ta ar zemo karstÄ Å«dens temperatÅ«ru (vid. 47,8 Ā± 0,7 Ā°C) un augsto brÄ«vi dzÄ«vojoÅ”o amÄbu klÄtbÅ«tni (84,2 %); L. pneumophila vides izolÄtiem bija liela SBT un cgMLST sekvenÄu tipu daudzveidÄ«ba, un tika novÄrotas reÄ£ionÄlÄs klonÄlÄs ekspansijas pazÄ«mes ar mÅ«su reÄ£ionam raksturÄ«go dominÄjoÅ”o sekvenÄu tipu grupu ST-338, ST-366 un ST-1104. Virulences gÄnu relatÄ«vais biežums liecina, ka L. pneumophila izolÄtiem piemÄ«t augsts virulences potenciÄls un plaÅ”a virulences faktoru klÄtbÅ«tne
Prevalence and Genetic Diversity of Legionella spp. in Hotel Water-Supply Systems in Latvia
No full textLegionella is one of the most important waterborne pathogens that can lead to both outbreaks and sporadic cases. The majority of travel-associated Legionnaires’ disease (TALD) cases are contracted during hotel stays. The aim of this study was to evaluate the prevalence and genetic diversity of Legionella spp. in hotel water supply systems in Latvia. In total, 834 hot water samples were collected from the water systems of 80 hotels in Latvia. At least one Legionella spp. positive sample was detected in 47 out of 80 hotels (58.8%). Overall, 235 out of 834 samples (28.2%) were Legionella spp. positive. The average hot water temperature in Latvian hotels was 49.8 °C. The most predominant L. pneumophila serogroup (SG) was SG3 which was found in 113 (49.8%) positive samples from 27 hotels. For 79 sequenced L. pneumophila isolates, 21 different sequence types (ST) were obtained, including 3 new types—ST2582, ST2579, and ST2580. High Legionella contamination and high genetic diversity were found in the hotel water supply systems in Latvia, which, together with the insufficient hot water temperature, may indicate that the lack of regulation and control measures may promote the proliferation of Legionella
Prevalence, Genetic Diversity, and Virulence Potential of Legionella spp. Doctoral Thesis
No full textPromocijas darbs izstrÄdÄts PÄrtikas droŔības, dzÄ«vnieku veselÄ«bas un vides zinÄtniskajÄ institÅ«tÄ āBIORā, LatvijÄ. AizstÄvÄÅ”ana: medicÄ«nas bÄzes zinÄtÅu, tai skaitÄ farmÄcijas promocijas padomes atklÄtÄ sÄdÄ 2023. gada 28. decembrÄ« plkst. 15.00 HipokrÄta auditorijÄ, Dzirciema ielÄ 16, un attÄlinÄti, tieÅ”saistes platformÄ Zoom.Legionella spp. ir viens no nozÄ«mÄ«gÄkajiem ar Å«deni saistÄ«tajiem patogÄniem, kas var izraisÄ«t gan novÄrÅ”amus uzliesmojumus, gan sporÄdiskus gadÄ«jumus. LeÄ£ionellu izplatÄ«Å”anÄs notiek ar baktÄrijas saturoÅ”iem Å«dens aerosoliem. Aerosolu veidÄ baktÄrijas var izplatÄ«ties vairÄku kilometru attÄlumÄ no primÄrÄ infekcijas avota, vienlaikus saglabÄjot dzÄ«votspÄju. LeÄ£ioneloze ir novÄrÅ”ama slimÄ«ba un atipiskas pneimonijas forma, ko izraisa Legionella pneumophila un radniecÄ«gÄs baktÄrijas. SlimÄ«bas klÄ«niskÄs izpausmes variÄ no vieglas, paÅ”limitÄjoÅ”as gripai lÄ«dzÄ«gas slimÄ«bas (Pontiakas drudzis) lÄ«dz potenciÄli letÄlai pneimonijai (leÄ£ionÄru slimÄ«ba). PÄtÄ«juma mÄrÄ·is bija izpÄtÄ«t Legionella spp. izplatÄ«bas tendences, Ä£enÄtisko daudzveidÄ«bu un virulences potenciÄlu leÄ£ionelozes diagnostikai un profilaksei LatvijÄ. MateriÄli un metodes. Lai noteiktu L. pneumophila seroprevalenci vispÄrÄjÄ veselÄ populÄcijÄ un identificÄtu asociÄtos riska faktorus, tika paÅemti 2007 asins paraugi no veseliem asins donoriem. Lai novÄrtÄtu Legionella spp. izplatÄ«bu Å«densapgÄdes sistÄmÄs, tika paÅemti 1467 Å«dens paraugi dažÄda tipa ÄkÄs. Ä¢enÄtiskÄs daudzveidÄ«bas izpÄtei izvÄlÄti 137 Legionella pneumophila izolÄti, un 58 izolÄtiem tika veikta virulences gÄnu noteikÅ”ana. Visiem asins paraugiem veikta imÅ«nfermentatÄ«vÄ reakcija, lai noteiktu IgG antivielas pret L. pneumophila SG 1-6. LeÄ£ionellu noteikÅ”ana Å«denÄ« un bioplÄvÄs veikta ar standartizÄtu metodi. BrÄ«vi dzÄ«vojoÅ”ie vienŔūÅi noteikti morfoloÄ£iski un ar trÄ«s dažÄdiem PĶR protokoliem. AtdzÄ«vinÄtiem L. pneumophila izolÄtiem veikta pilna genoma sekvencÄÅ”ana ar Illumina MiSeq. SekvencÄ bÄzÄtÄ tipÄÅ”ana veikta atbilstoÅ”i ESCMID izstrÄdÄtajai shÄmai. cgMLST tipÄÅ”ana veikta, izmantojot iepriekÅ” aprakstÄ«tu protokolu. Virulences gÄnu noteikÅ”anai izmantota virulences faktoru datu bÄze. RezultÄti. L. pneumophila SG 1-6 seroprevalence asins donoriem bija 4,8 %, un 0,2 % donoru bija seropozitÄ«vi pret L. pneumophila SG1. Seroprevalence bija augstÄka sievietÄm (5,9 %) nekÄ vÄ«rieÅ”iem (3,3 %) un reÄ£ionos ar lielÄku iedzÄ«votÄju skaitu, sÄkot no 3,5 % lauku reÄ£ionos lÄ«dz 6,8 % galvaspilsÄtÄ RÄ«gÄ. Legionella spp. prevalence Å«densapgÄdes sistÄmÄs variÄja no vidÄji 25 % aukstÄ Å«dens paraugos lÄ«dz 35 % karstÄ Å«dens paraugos. DominÄjoÅ”Ä L. pneumophila serogrupa (SG) bija SG 3, kas tika identificÄta 208 no 482 gadÄ«jumiem (43,2 %). Vismaz viena brÄ«vi dzÄ«vojoÅ”a amÄbu Ä£ints konstatÄta 77,2 % paraugu. VidÄjÄ karstÄ Å«dens temperatÅ«ra bija 47,8 Ā± 0,7 Ā°C. TemperatÅ«ras mÄrÄ«jumi parÄdÄ«ja, ka tikai 249 no 1275 karstÄ Å«dens paraugiem temperatÅ«ra pÄrsniedza 55 Ā°C. PÄtÄ«jumÄ iekļautie 137 L. pneumophila celmi sadalÄs 46 sekvenÄu tipos, turklÄt 10 sekvenÄu tipi ir jauni, iepriekÅ” pasaulÄ nereÄ£istrÄti. Izmantojot cgMLST tipÄÅ”anu, iegÅ«ti 116 genotipi. KopumÄ 58 dzÄ«vojamo mÄju izolÄtiem tika identificÄti 420 virulences gÄni, no kuriem 260 gÄni tika atrasti visos sekvencÄtajos L. pneumophila izolÄtos. Visos izolÄtos tika atklÄti virulences gÄni enhC, htpB, omp28 un mip, kas liecina, ka visiem izolÄtiem ir iespÄjota adhÄzija, piesaiste un iekļūŔana saimniekŔūnÄ. Virulences gÄnu relatÄ«vais biežums starp L. pneumophila izolÄtiem bija augsts. SecinÄjumi. DaudzdzÄ«vokļu mÄju iedzÄ«votÄji ir pakļauti lielÄkam leÄ£ionelozes riskam nekÄ privÄtmÄjÄs dzÄ«vojoÅ”ie (OR = 2,23; p = 0,011); augstÄkais seropozitivitÄtes risks bija to Äku iedzÄ«votÄjiem, kas centralizÄti saÅÄma karsto Å«deni (OR = 3,16; p = 0,001); augstÄ Legionella spp. prevalence Å«densapgÄdes sistÄmÄs ir saistÄ«ta ar zemo karstÄ Å«dens temperatÅ«ru (vid. 47,8 Ā± 0,7 Ā°C) un augsto brÄ«vi dzÄ«vojoÅ”o amÄbu klÄtbÅ«tni (84,2 %); L. pneumophila vides izolÄtiem bija liela SBT un cgMLST sekvenÄu tipu daudzveidÄ«ba, un tika novÄrotas reÄ£ionÄlÄs klonÄlÄs ekspansijas pazÄ«mes ar mÅ«su reÄ£ionam raksturÄ«go dominÄjoÅ”o sekvenÄu tipu grupu ST-338, ST-366 un ST-1104. Virulences gÄnu relatÄ«vais biežums liecina, ka L. pneumophila izolÄtiem piemÄ«t augsts virulences potenciÄls un plaÅ”a virulences faktoru klÄtbÅ«tne
Legionella spp. izplatÄ«ba, Ä£enÄtiskÄ daudzveidÄ«ba un virulences potenciÄls. Promocijas darba kopsavilkums
No full textThe Doctoral Thesis was developed at the Institute of Food Safety, Animal Health and Environment āBIORā, Latvia. Defence: at the public session of the Promotion Council in Basic Medicine on 28 December 2023 at 15.00, in the Hippocrates Lecture Theatre, 16 Dzirciema Street, RÄ«ga StradiÅÅ” University and remotely via online platform Zoom.Legionella spp. is one of the most important water-borne pathogens that can cause both outbreaks and sporadic cases. Legionella is spread by water aerosols containing the bacteria. In the form of aerosols, bacteria can spread several kilometres from the primary source of infection while remaining viable. Legionellosis is a preventable disease and a form of atypical pneumonia caused by Legionella pneumophila and related bacteria. Clinical manifestations of the disease range from a mild, self-limiting flu-like illness (Pontiac fever) to potentially fatal pneumonia (Legionnaires' disease). The aim of the study was to investigate Legionella spp. distribution trends, genetic diversity and virulence potential for diagnosis and prevention of legionellosis in Latvia. Materials and methods. To assess the seroprevalence of L. pneumophila in the general healthy population and to identify associated risk factors, 2007 blood samples were collected from healthy blood donors. To evaluate Legionella spp. distribution in water supply systems, 1467water samples were taken in different types of buildings. 137 L. pneumophila isolates were selected for the study of genetic diversity and virulence genes were determined for 58 isolates. Immunoenzymatic reaction was performed for all blood samples to detect IgG antibodies against L. pneumophila SG 1-6. Determination of Legionella spp. in water and biofilm samples was performed according to a standardized method. Free-living protozoa were determined morphologically and by three different PCR protocols. Whole genome sequencing of L. pneumophila isolates was performed with Illumina MiSeq. Sequence-based typing was performed according to the scheme developed by ESCMID. cgMLST typing was performed using the previously described protocol. The database of virulence factors was used to determine virulence determinants. Results. The seroprevalence of L. pneumophila SG 1-6 in blood donors was 4.8 % and 0.2 % of donors were seropositive for L. pneumophila SG1. Seroprevalence was higher in women (5.9 %) than men (3.3 %), and in regions with a larger population, ranging from 3.5 % in rural regions to 6.8 % in the capital Riga. Legionella spp. prevalence in water supply systems varied from an average of 25 % in cold water samples to 35 % in hot water samples. The predominant L. pneumophila serogroup (SG) was SG 3, which was identified in 208 of 482 cases (43.2 %). At least one free-living amoeba genus was detected in at least 77.2 % of the samples. The average hot water temperature was 47.8 Ā± 0.7 Ā°C. Temperature measurements showed that only 249 out of 1275 hot water samples exceeded 55 Ā°C. Overall, 137 L. pneumophila strains included in the study represented 46 sequence types, including new 10 sequence types, previously unrecorded in the world. Using cgMLST typing 116 genotypes were obtained. 420 virulence genes were identified of which 260 genes were found in all sequenced L. pneumophila isolates. Virulence factors encoding enhC, htpB, omp28 and mip genes were detected in all isolates, suggesting that adhesion, attachment and entry into the host cell are enabled for all isolates. Relative frequency of virulence genes among L. pneumophila isolates was high. Conclusions. Residents of apartment buildings are exposed to a higher risk of legionellosis than those living in private houses (OR = 2.23; p = 0.011). The highest risk of seropositivity was for residents of buildings with centralized hot water supply (OR = 3.16; p = 0.001). High Legionella spp. prevalence in water supply systems is related to low hot water temperature (average 47.8 Ā± 0.7 Ā°C) and high presence of free-living amoebae (84.2 %). Environmental isolates of L. pneumophila exhibited a high diversity of SBT and cgMLST sequence types and showed signs of regional clonal expansion, with ST-338, ST-366 and ST-1104 as the predominant sequence type group characteristic of our region. The relative frequency of virulence genes suggests that L. pneumophila isolates have a high virulence potential and the presence of a wide range of virulence factors
