Next Article in Journal
Parasites in Sewage: Legal Requirements and Diagnostic Tools
Previous Article in Journal
A Conserved Di-Lysine Motif in the E2 Transactivation Domain Regulates MmuPV1 Replication and Disease Progression
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Pathogens
Volume 14
Issue 1
10.3390/pathogens14010085
pathogens-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Prevalence of Leptospira spp. in Lithuanian Wild Boars (Sus scrofa)

by
Birutė Karvelienė
1,*,
Inga Stadalienė
1,
Jūratė Rudejevienė
1,
Evelina Burbaitė
1,2,
Dalia Juodžentė
1,
Marius Masiulis
1,
Jūratė Buitkuvienė
3,
Jurgita Šakalienė
3 and
Gintaras Zamokas
1
1
Dr. L. Kriaučeliūnas Small Animal Clinic, Faculty of Veterinary, Veterinary Academy, Lithuanian University of Health Sciences, 47181 Kaunas, Lithuania
2
Neurology and Neurosurgery Division, San Marco Veterinary Clinic, 35030 Veggiano, Italy
3
National Food and Veterinary Risk Assessment Institute, 08409 Vilnius, Lithuania
*
Author to whom correspondence should be addressed.
Pathogens 2025, 14(1), 85; https://doi.org/10.3390/pathogens14010085
Submission received: 19 December 2024 / Revised: 13 January 2025 / Accepted: 14 January 2025 / Published: 16 January 2025
(This article belongs to the Section Epidemiology of Infectious Diseases)
Browse Figure
Versions Notes

Abstract

:
Leptospira is a bacteria responsible for a widespread zoonosis that affects both humans and animals. Leptospirosis is a challenging pathology to diagnose and treat since its signs are unspecific and symptoms vary greatly. The disease seems to be highly prevalent in environments where reservoir animals such as rats and small mammals are common. Even though leptospirosis in humans in Lithuania is rare, it remains a disease of significance in Europe. Information on reservoir animals and prevalence of Leptospira in wild animals in Lithuania is lacking. The aim of this country-wide study was to evaluate the seroprevalence of Leptospira in wild boars in Lithuania. Hunted animals were collected from ten counties that represented the boar population of the country. The sera of 451 collected boars were evaluated for eight Leptospira serovars using the microscopic agglutination test. Seropositivity was observed in 102 (22.6%) boars. Overall, 194 positive reactions occurred. Boars older than 2 years were affected by more serovars and were more seropositive than younger boars (p < 0.05). The highest number of positive reactions was observed in Panevėžys (87.9%) and Vilnius (69.1%) counties. The results of this study might indicate that the wild boar is a reservoir animal of Leptospira and plays a role in its transmission in Lithuania.

1. Introduction

Leptospira was first described in 1907 and has been studied ever since [1]. Spirochetes are the causatives of a zoonotic leptospirosis disease in humans and infection in animals that manifests with a wide variety of clinical presentations [1,2,3,4]. In humans, leptospirosis has been recognized as an important cause of febrile disease, renal failure, and jaundice [5,6,7,8]. In dogs, all organ systems can be affected, from acute kidney injury to ophthalmologic, dermatologic, and reproductive tract involvement [4,9]. In farm animals, abortions and infertility cases are as common as reduced production of milk, resulting in economic losses [6,10,11]. Reservoir animals, such as rats, mice, opossums, bats, or even cattle, are usually asymptomatic, but play an important role in the transmission of Leptospira, shedding the bacteria in their urine [2,6,12,13]. Multiple risk factors have been established for contracting leptospirosis. The most significant one is being in close contact with reservoir animals, especially rats [1,13,14]. Equally as important is occupational hazard, as Leptospira thrives in certain locations such as humid soils and water bodies. Being a hunter, butcher, farmer, veterinarian or working in agriculture increases the risk of being in close contact to the causative of the disease [2,7,15,16]. A recent seroepidemiological study of hunters in Austria has concluded that as many as 10% of hunters [17] and 75% of hound dogs in Japan [18] were seropositive for Leptospira. A higher risk of infection was also observed in socioeconomically challenged areas [15,16,19]. It is speculated that communities affected by poverty are more likely to be in contact with rural areas that contain small mammals, rodents, and other Leptospira reservoir animals.
The prevalence of leptospirosis in humans varies greatly based on geographical location. The United States Centers for Disease Control and Prevention has estimated that a million cases of human leptospirosis occur worldwide yearly [20]. Its prevalence in Europe is considerably lower. The data of the European Centre for Disease Prevention and Control (ECDC) state that 1261 cases of leptospirosis were reported in Europe in 2023, 14 of which were fatal [21]. This disease is not common in Lithuania and the last case was recorded in 2021 [22,23]. However, information on Leptospira, its prevalence, possible reservoir animals, and risk factors in Lithuania is lacking. The aim of this study was to evaluate the prevalence of Leptospira antibodies in the population of wild boars (Sus scrofa) in Lithuania. We hypothesized that even though human leptospirosis is rare, boars could be reservoir animals.

2. Materials and Methods

This study was approved by the Ethics Committee of the Lithuanian University of Health Sciences with the license number 2024-BEC3-T-034, issued on the 2nd of December, 2024.

2.1. Sample Collection

This study was conducted during the wild boar hunting season of the year 2021 in the months from May to November in 10 different counties that represent the country as a whole. All animals were hunted in adherence to the national hunting law, with the purpose of controlling the population. None of the animals were specifically hunted for the conduction of this study. The collected blood samples were also used for national African swine fever disease control and assessment. Responsible veterinary doctors from the State Food and Veterinary Service collected blood samples from the hunted wild boars using sterile vacuum tubes free of anticoagulant. The samples were transported in ice-cooled containers to the National Food and Veterinary Risk Assessment Institute‘s Serology Unit, accompanied by documentation indicating the location, county code, gender, and age of each hunted wild boar. The samples were centrifuged, and the obtained separated sera were stored at −20 °C until further analysis. For each hunted wild boar, its age group was determined by evaluating the degree of tooth eruption and wear of the lower jaw teeth, as reported previously [24]. Three age groups were identified: juvenile (up to 12 months old), sub-adult (12–24 months old), and adult (over 24 months old).

2.2. Laboratory Testing

Leptospirosis was detected using the microscopic agglutination test (MAT) with live leptospiral cultures to detect antibodies against specific serogroups. The standard methodology used for this study adhered to the guidelines as proposed by the OIE (World Organization for Animal Health) Manual of Standards for Diagnostic Tests and Vaccines, Chapter 3.1.12. Leptospirosis, Serological tests [25]. The antigens used for serogroup 8 detection were as follows: Leptospira Bratislava (strain Jez Bratislava); L. Canicola (strain Hond Utrecht IV); L. Saxcoebing (strain Mus 24); L. Copenhageni (strain M-20); L. Grippotyphosa (strain Andaman); L. Pomona (strain Pomona); L. Sejroe (strain M 84); and L. Tarassovi (strain Perepelicin). The MAT was conducted using microplates with duplicate dilutions of 1:50 and 1:100. However, only the results from the 1:100 dilution were considered to be significant and further analyzed. The reaction was assessed using a dark-field microscopy to evaluate the degree of agglutination. A four-plus scale was used. A positive reaction was defined as a 2+ agglutination (50%) in the 1:100 dilution.

2.3. Statistical Analysis

The data were recorded and analyzed with Microsoft Office Excel (for Microsoft 365 MSO, Version 2412). Additional statistical data analysis was performed using the IBM SPSS Statistics® software package (Statistical Package for Social Sciences 29 for Windows, version 29). Boar groups are described using the number (n) of boars within a certain group, and seropositive percentage (%) (i.e., seropositivity by month is described by the number of seropositive boars/number of boars hunted that month). Relationships between boar age groups, sex, and county were evaluated using the Chi-square (χ2) test. A Confidence Interval (CI) of 95% was used in the statistical analysis. Differences were considered statistically significant when p < 0.05.

3. Results

In total, sera samples from 451 boars were collected and examined. Male boars were more common (342/451; 75.9%) than females (109/451; 24.2%) in our study. The toungest boars (up to 12 months of age) were the least common (30/451; 6.7%). About half of the boars (233/451; 51.7%) were 12–24-month-olds and the remainder (188/451; 41.7%) were older than 24 months. Boars were hunted in 10 counties: Vilnius (55; 12.2%), Kaunas (60; 13.3%), Klaipėda (42; 9.3%), Šiauliai (56; 12.4%), Panevėžys (33; 7.3%), Marijampolė (15; 3.3%), Telšiai (56; 12.4%), Tauragė (41; 9.1%), Alytus (37; 8.2%), and Utena (56; 12.4%). Hunting took place in the months from May to November. In May, 118 (26.2%) boars were hunted and enrolled in the study; in June, 191 (42.4%); July, 97 (21.5%), September, 11 (2.4%); October, 31 (6.9%); November, 3 (0.7%). None of the boar samples were examined in August, as it is a month with significant hunting restrictions in Lithuania. Almost two-thirds (68.5%) of the boars were hunted in May and June.
Within the study, boar seropositivity and the number of positive reactions were described as different entities. Overall seropositivity was observed in 102 (22.6%) boars, but 194 positive reactions were observed. Of the seropositive boars, 65 (63.7%) were positive for one serovar and 37 (36.3%) were positive for multiple pathogens. Of boars that were seropositive for multiple serovars, 12 (32.4%) tested positive for two serovars, 13 (35.1%) for three serovars, 5 (13.5%) for four serovars, 1 (2.7%) for five serovars, 3 (8.1%) for six serovars, 2 (5.4%) for seven serovars, and 1 (2.7%) for eight serovars. Seropositivity for serovars (sv.) was as follows: Copenhageni 44 (9.8%), Bratislava 42 (9.3%), Canicola 37 (8.2%), Sejroe 21 (4.7%), Tarassovi 15 (3.3%), Pomona 13 (2.9%), Grippotyphosa 12 (2.7%), Saxkoebing 10 (2.2%).
No statistical difference was observed between sexes: males were positive in 72/342 cases (21.1%) and females were positive in 30/109 cases (27.5%) (p > 0.05). Within age groups, seropositivity was lowest in boars up to 12 months old (5/30; 16.7%). Boars from 12 to 24 months old were slightly more seropositive (41/233; 17.6%). Boars older than 24 months were the most seropositive (56/188; 29.8%). This finding was statistically significant (p < 0.05). Seropositivity for the serovars Saxkoebing, Canicola, and Bratislava was significantly more common in older boars (p < 0.05). In terms of the number of positive reactions, the youngest boars had 10 positive reactions (5.2%), the middle age group had 73 positive reactions (37.6%), and boars older than 2 years had 111 positive reactions (57.2%). Out of all the positive reactions, 57.2% belonged to boars older than 24 months. Boars older than 2 years were statistically significantly affected by more serovars and more seropositive than younger boars (p < 0.05). The results are summarized in Table 1.
Seropositivity varied statistically significantly in different months and peaked in September (p < 0.05). Seropositivity by month was as follows: May, 14/118 (11.9%); June, 24/191 (12.6%); July, 42/97 (43.3%); September, 6/11 (54.5%); October, 16/31 (51.6%); November, 0/3 (0%).
Boar seropositivity within the counties was as follows: Vilnius, 18/55 (32.7%); Kaunas, 15/60 (25.0%); Klaipėda, 7/42 (16.7%); Šiauliai, 17/56 (30.4%); Panevėžys, 8/33 (24.2%); Marijampolė, 2/15 (13.3%); Telšiai, 9/56 (16.1%); Tauragė, 7/41 (17.1%); Alytu, 6/37 (16.2%); Utena, 13/56 (23.2%). No significant associations between distribution for serovars and county were observed. The number of positive reactions for different serovars in the counties is summarized in Figure 1 and Table 2. The highest numbers of positive reactions were observed in Panevėžys (87.9%) and Vilnius (69.1%) counties. The fewest numbers of positive reactions were found in Marijampolė (13.3%) and Telšiai (17.9%) counties.

4. Discussion

Leptospira is an organism responsible for a zoonosis dangerous to both animals and humans. Species such as mice, rats, boars, deer, and other mammals are thought to be reservoir animals that continue to spread the pathogen by shedding bacteria in their urine [5,26,27,28]. In Lithuania, the wild boar population is carefully monitored, as African swine fever is a disease of increasing importance [29]. It is estimated that 20–30 thousand boars are hunted yearly to limit their spread into rural areas, where they are capable of transmitting various pathogens and becoming a potential health hazard to both humans and other animals.
Multiple studies have already been performed worldwide to evaluate seroprevalence of Leptospira in boars and the data is variable [30,31,32,33,34,35,36,37,38,39,40,41,42,43]. The main findings of boar Leptospira seroprevalence in different countries are summarized in Table 3. In Portugal, the seroprevalence seems to be the highest (65.4%) [37]. In Slovenia, it reached 45.5% [41]; in Croatia it ranged from 26 to 31.9% [31,35]; in Brazil, 20.5% [33]; in France, 18.4% [38]; in Germany, 17.7% [34]; in the Czech Republic, 16.9% [36]; in Spain, 14.6% [43]; in Italy it varied 6–15.3% [30,32,42]; in Poland, 10.4% [39]; and in Sweden, 3.1% [40]. In our study, it was established to be 22.6%. In the context of the current data in the European continent, the Leptospira seroprevalence in the boars of Lithuania is considered high.
In this study, boar sera were tested for eight chosen Leptospira serovars. However, new serovars that can potentially affect people and animals are emerging. For instance, when Leptospira wolffii was first detected in a dog, it was determined that it was a predominant species affecting 93% of tested dogs in Iran [44]. To minimize the risk of dogs becoming a host animal and shedding bacteria in a household environment, preventative measures have been taken. In Europe and North America, vaccines have been used for almost half a century and dog seroprevalence is successfully decreasing [4,45]. However, vaccination does not prevent disease completely and protocols are not uniform around the globe. Vaccines can contain from one to four different serovars, depending on the geographic location [4,46]. It was found, however, that even immunized animals can be infected if prevention is not properly conducted [47]. Vaccinated dogs, therefore, may be susceptible to novel serovars not found in the vaccines. Constant efforts are being made to establish which serovars are the most relevant clinically and if collected evidence is sufficient to include certain Leptospira serovars in the vaccines [4,45,48]. Consequently, understanding the distribution of serovars within different countries is of incredible importance.
To date, in Lithuania, several epidemiological studies have been performed to detect Leptospira (in small rodents, swine, horses, and cattle) and to establish possible reservoir animals [49,50,51,52]. Only 4.4% of small rodents, such as mice and voles had Leptospiral DNA, and L. Kirschneri was isolated from them [49]. Swine were mostly seropositive for serovars Bratislava and Pomona [50]. Prevalence in horses was 18.6%, and they were mostly affected by serovars Canicola and Copenhageni [51]. Cattle were most seropositive for serovar Grippotyphosa and total seroprevalence for Leptospira was 7% [52]. Our study results indicate that boars in Lithuania are mostly affected by serovars Copenhageni and Bratislava. Based on the current literature and our findings, it is speculated that serovars Copenhageni, Bratislava, and Canicola are common serovars among reservoir animals in Lithuania [50,51].
The boar seroprevalence between sexes did not differ. However, in accordance with recent literature [35,36,37,42], the oldest boars (older than 24 months) were the most affected in this study. Boars older than 2 years were statistically significantly affected by more serovars and were more seropositive than younger boars. This could be explained by several factors. Older individuals have a longer cumulative exposure time to Leptospira and the chances, therefore, are higher for older boars to have had multiple subclinical infections with different serovars. Boars that had a humoral response to Leptospira have the antibodies for specific serovars in their sera.
Leptospira detection by polymerase chain reaction (PCR) is known for its specificity and sensitivity, but it does not allow for the identification of the serovar [6,53]. To date, several studies have been performed using boar kidneys, livers, and reproduction organs [30,31,54,55,56]. It was established that in Croatia, 8.4% of boar kidneys had Leptospira DNA [31]; in Japan, 15.2% of boar kidneys were positive [55], while in Italy the percentage varied 11.2–12.6% for kidneys and was 30.3% for reproductive organs [30,54,56], demonstrating yet another Leptospira transmission method. In swine, artificial insemination is demonstrated to be an important risk factor for Leptospira contraction [47]. Additionally, in boars, subclinical genital leptospirosis was detected and isolated in testicles, epididymes, uteri, placentas, and fetuses [56,57]. This newly recognized spreading mechanism should be further investigated as it could explain why older, sexually mature boars tend to have a significantly higher prevalence of infection [35,36,37,42].
Panevėžys is located in northeast Lithuania, and it was the county with the highest percentage of Leptospira antibody-positive boars (87.9%), as well as horses [51]. Possible explanations include different climatic and socioeconomic reasons. As described by Taminskas et al., 2011 [58], Panevėžys county is located in a highly humid climate: soils there are less permeable to water and the Nevėžis river sub-basin area has the second largest expanse of wet forests (wet woodlands make up 21.5% of the territory). Abundant rivers, lakes, and wetlands create ideal conditions for leptospires to thrive in water and soil as well as for the boars to inhabit. In our study, Marijampolė county had the fewest seropositive boars (13.3%). This location has significantly fewer wetlands and wet woodlands than Panevėžys [58].
We acknowledge that our study has several limitations. MAT is a test that has a limited specificity and sensitivity. It requires careful attention and inspection to avoid false positive or false negative results [2,4,6,7,28]. However, the most important limitation of our study is that we only tested boar sera for eight serovars. It is possible, therefore, that other serovars were distributed within the boar population as well, but we failed to identify them.

5. Conclusions

One hundred and two (22.6%) boars had Leptospira antibodies in their sera. The hunted animals were mostly positive for serovars Copenhageni (9.8%), Bratislava (9.3%), and Canicola (8.2%). Boars over 24 months old had higher serological prevalence and were affected by a higher number of serovars than younger boars. The highest number of positive reactions was observed in Panevėžys (87.9%), which is known for its highly humid soil, and is rich in wet woodlands. The results of our study might indicate that boars are reservoir animals of Leptospira and contribute to its transmission in Lithuania.

Author Contributions

Conceptualization, B.K., I.S., J.R. and G.Z.; methodology, M.M., J.B. and J.Š.; formal analysis, I.S., E.B. and D.J.; investigation, M.M., J.B. and J.Š.; data curation, J.B., J.Š. and I.S.; writing—original draft preparation, E.B. and D.J.; writing—review and editing, E.B., B.K., I.S., J.R. and G.Z.; visualization, B.K.; supervision, B.K. and G.Z. All authors have read and agreed to the published version of the manuscript.

Funding

This research received no external funding.

Institutional Review Board Statement

Not applicable.

Informed Consent Statement

Not applicable.

Data Availability Statement

Partial data is available upon request.

Conflicts of Interest

The authors declare no conflicts of interest.

References

  1. Adler, B. History of leptospirosis and Leptospira. In Leptospira and Leptospirosis. Current Topics in Microbiology and Immunology; Springer: Berlin/Heidelberg, Germany, 2015; Volume 387, pp. 1–9. [Google Scholar] [CrossRef]
  2. Bharti, A.R.; Nally, J.E.; Ricaldi, J.N.; Matthias, M.A.; Diaz, M.M.; Lovett, M.A.; Levett, P.N.; Gilman, R.H.; Willig, M.R.; Gotuzzo, E.; et al. Leptospirosis: A zoonotic disease of global importance. Lancet Infect. Dis. 2003, 3, 757–771. [Google Scholar] [CrossRef] [PubMed]
  3. Lau, C.L.; Townell, N.; Stephenson, E.; Berg, D.v.D.; Craig, S.B. Leptospirosis: An important zoonosis acquired through work, play and travel. Aust. J. Gen. Pract. 2018, 47, 105–110. [Google Scholar] [CrossRef]
  4. Sykes, J.E.; Francey, T.; Schuller, S.; Stoddard, R.A.; Cowgill, L.D.; Moore, G.E. Updated ACVIM consensus statement on lepto-spirosis in dogs. J. Vet. Intern. Med. 2023, 37, 1966–1982. [Google Scholar] [CrossRef]
  5. Allan, K.J.; Biggs, H.M.; Halliday, J.E.B.; Kazwala, R.R.; Maro, V.P.; Cleaveland, S.; Crump, J.A. Epidemiology of Leptospirosis in Africa: A Systematic Review of a Neglected Zoonosis and a Paradigm for ‘One Health’ in Africa. PLoS Neglected Trop. Dis. 2015, 9, e0003899. [Google Scholar] [CrossRef]
  6. Ellis, W.A. Animal Leptospirosis. Curr. Top. Microbiol. Immunol. 2015, 387, 99–137. [Google Scholar] [CrossRef]
  7. Haake, D.A.; Levett, P.N. Leptospirosis in Humans. Curr. Top. Microbiol. Immunol. 2015, 387, 65–97. [Google Scholar] [CrossRef] [PubMed]
  8. Jansen, A.; Nöckler, K.; Schönberg, A.; Luge, E.; Ehlert, D.; Schneider, T. Wild boars as possible source of hemorrhagic leptospirosis in Berlin, Germany. Eur. J. Clin. Microbiol. Infect. Dis. 2006, 25, 544–546. [Google Scholar] [CrossRef]
  9. Adin, C.A.; Cowgill, L.D. Treatment and outcome of dogs with leptospirosis: 36 cases (1990–1998). J. Am. Vet.-Med. Assoc. 2000, 216, 371–375. [Google Scholar] [CrossRef] [PubMed]
  10. Diaz, E.A.; Luna, L.; Burgos-Mayorga, A.; Donoso, G.; Guzman, D.A.; Baquero, M.I.; Pearson, T.; Barragan, V.A. First detection of Leptospira santarosai in the reproductive track of a boar: A potential threat to swine production and public health. PLoS ONE 2022, 17, e0274362. [Google Scholar] [CrossRef]
  11. Brihuega, B.; Grune Loffler, S.; Samartino, L.E.; Romero, G.; Auteri, C.; Martinez, M. First isolation of Leptospira borgpetersenii from fetuses of Wild boars (Sus scrofa). Electron. J. Biol. 2017, 13, 63–66. [Google Scholar]
  12. Barragan, V.; Chiriboga, J.; Miller, E.; Olivas, S.; Birdsell, D.; Hepp, C.; Hornstra, H.; Schupp, J.M.; Morales, M.; Gonzalez, M.; et al. High Leptospira Diversity in Animals and Humans Complicates the Search for Common Reservoirs of Human Disease in Rural Ecuador. PLoS Neglected Trop. Dis. 2016, 10, e0004990. [Google Scholar] [CrossRef] [PubMed]
  13. Koizumi, N.; Muto, M.; Tanikawa, T.; Mizutani, H.; Sohmura, Y.; Hayashi, E.; Akao, N.; Hoshino, M.; Kawabata, H.; Watanabe, H. Human leptospirosis cases and the prevalence of rats harbouring Leptospira interrogans in urban areas of Tokyo, Japan. J. Med. Microbiol. 2009, 58, 1227–1230. [Google Scholar] [CrossRef] [PubMed]
  14. Thaipadungpanit, J.; Wuthiekanun, V.; Chierakul, W.; Smythe, L.D.; Petkanchanapong, W.; Limpaiboon, R.; Apiwatanaporn, A.; Slack, A.T.; Suputtamongkol, Y.; White, N.J.; et al. A Dominant Clone of Leptospira interrogans Associated with an Outbreak of Human Leptospirosis in Thailand. PLoS Neglected Trop. Dis. 2007, 1, e56. [Google Scholar] [CrossRef]
  15. Dupouey, J.; Faucher, B.; Edouard, S.; Richet, H.; Kodjo, A.; Drancourt, M.; Davoust, B. Human leptospirosis: An emerging risk in Europe? Comp. Immunol. Microbiol. Infect. Dis. 2013, 37, 77–83. [Google Scholar] [CrossRef]
  16. Wasiński, B.; Dutkiewicz, J. Leptospirosis–current risk factors connected with human activity and the environment. Ann. Agric. Environ. Med. 2013, 20, 239–244. [Google Scholar]
  17. Deutz, A.; Fuchs, K.; Schuller, W.; Nowotny, N.; Auer, H.; Aspöck, H.; Stünzner, D.; Kerbl, U.; Klement, C.; Köfer, J. Seroepidemi-ological studies of zoonotic infections in hunters in southeastern Austria—Prevalences, risk factors, and preventive methods. Berl. Munch. Tierarztl. Wochenschr. 2003, 116, 306–311. [Google Scholar]
  18. Koizumi, N.; Muto, M.; Yamamoto, S.; Baba, Y.; Kudo, M.; Tamae, Y.; Shimomura, K.; Takatori, I.; Iwakiri, A.; Ishikawa, K.; et al. Investigation of Reservoir Animals of Leptospira in the Northern Part of Miyazaki Prefecture. Jpn. J. Infect. Dis. 2008, 61, 465–468. [Google Scholar] [CrossRef]
  19. Bradley, E.A.; Lockaby, G. Leptospirosis and the Environment: A Review and Future Directions. Pathogens 2023, 12, 1167. [Google Scholar] [CrossRef]
  20. Center for Disease Control and Prevention. Clinical Overview of Leptospirosis. Available online: https://www.cdc.gov/leptospirosis/hcp/clinical-overview/index.html (accessed on 5 October 2024).
  21. European Centre for Disease Prevention and Control. Surveillance Atlas of Infectious Diseases. Available online: https://www.ecdc.europa.eu/en/surveillance-atlas-infectious-diseases (accessed on 12 November 2024).
  22. National Public Health Center Under the Ministry of Health of Lithuania. Statistics: Incidence of Communicable Diseases in Lithuania. Available online: https://nvsc.lrv.lt/lt/uzkreciamuju-ligu-valdymas/statistika-apie-uzkreciamasias-ligas/ (accessed on 7 December 2024).
  23. European Centre for Disease Prevention and Control. Leptospirosis—Annual Epidemiological Report for 2022. Available online: https://www.ecdc.europa.eu/en/publications-data/leptospirosis-annual-epidemiological-report-2022 (accessed on 17 November 2024).
  24. Sáez-Royuela, C.; Gomariz, R.P.; Tellería, J.L. Age determination of European wild boar. Wildl. Soc. Bull. 1989, 17, 326–329. [Google Scholar]
  25. World Organisation for Animal Health (WOAH). Manual of Diagnostic Tests and Vaccines for Terrestrial Animals (Chapter 3.1.12: Leptospirosis). Available online: https://www.woah.org/en/what-we-do/standards/codes-and-manuals/terrestrial-manual-online-access/ (accessed on 5 April 2024).
  26. Wójcik-Fatla, A.; Zając, V.; Sroka, J.; Piskorski, M.; Cisak, E.; Sawczyn, A.; Dutkiewicz, J. A small scale survey of Leptospira in mammals from eastern Poland. Ann. Agric. Environ. Med. 2013, 20, 705–707. [Google Scholar]
  27. Žákovská, A.; Treml, F.; Nejezchlebová, H.; Nepeřený, J.; Budíková, M.; Bártová, E. Leptospira interrogans Sensu Lato in Wild Small Mammals in Three Moravian Localities of the Czech Republic. Pathogens 2022, 11, 888. [Google Scholar] [CrossRef] [PubMed]
  28. Urbanskas, E.; Karvelienė, B.; Radzijevskaja, J. Leptospirosis: Classification, epidemiology, and methods of detection. A review. Biologija 2022, 68, 129–136. [Google Scholar] [CrossRef]
  29. Pautienius, A.; Grigas, J.; Pileviciene, S.; Zagrabskaite, R.; Buitkuviene, J.; Pridotkas, G.; Stankevicius, R.; Streimikyte, Z.; Salomskas, A.; Zienius, D.; et al. Prevalence and spatiotemporal distribution of African swine fever in Lithuania, 2014–2017. Virol. J. 2018, 15, 177. [Google Scholar] [CrossRef]
  30. Cilia, G.; Bertelloni, F.; Angelini, M.; Cerri, D.; Fratini, F. Leptospira survey in wild boar (Sus scrofa) hunted in Tuscany, Central Italy. Pathogens 2020, 9, 377. [Google Scholar] [CrossRef]
  31. Cvetnic, Z.; Margaletic, J.; Toncic, J.; Tturk, N.; Milas, Z.; Spicic, S.; Lojkic, M.; Terzic, S.; Jemersic, L.; Humski, A.; et al. Serological survey and isolation of leptospires from small rodents and wild boars in the Republic of Croatia. Vet. Med. 2003, 48, 321. [Google Scholar] [CrossRef]
  32. Ebani, V.V.; Cerri, D.; Poli, A.; Andreani, E. Prevalence of Leptospira and Brucella antibodies in wild boars (Sus scrofa) in Tus-cany, Italy. J. Wildl. Dis. 2003, 39, 718–722. [Google Scholar] [CrossRef] [PubMed]
  33. Fornazari, F.; Camossi, L.; Silva, R.; Guazzelli, A.; Ribeiro, M.; Chiacchio, S.; Langoni, H. Leptospiral antibodies in wild boars (Sus scrofa) bred in Brazil. J. Venom. Anim. Toxins Incl. Trop. Dis. 2011, 17, 94–97. [Google Scholar] [CrossRef]
  34. Jansen, A.; Luge, E.; Guerra, B.; Wittschen, P.; Gruber, A.D.; Loddenkemper, C.; Schneider, T.; Lierz, M.; Ehlert, D.; Appel, B.; et al. Leptospirosis in Urban Wild Boars, Berlin, Germany. Emerg. Infect. Dis. 2007, 13, 739–742. [Google Scholar] [CrossRef]
  35. Slavica, A.; Cvetnić, Ž.; Konjević, D.; Janicki, Z.; Severin, K.; Dežđek, D.; Starešina, V.; Sindičić, M.; Antić, J. Detection of Leptospira spp. serovars in wild boars (Sus scrofa) from continental Croatia. Vet. Arhiv. 2010, 80, 247–257. [Google Scholar]
  36. Treml, F.; Pikula, J.; Holešovská, Z. Prevalence of antibodies against leptospires in the wild boar (Sus scrofa L., 1758). Vet.-Med. 2003, 48, 66–70. [Google Scholar] [CrossRef]
  37. Vale-Gonçalves, H.M.; Cabral, J.A.; Faria, M.C.; Nunes-Pereira, M.; Faria, A.S.; Veloso, O.; Vieira, M.L.; Paiva-Cardoso, N. Prevalence of Leptospira antibodies in wild boars (Sus scrofa) from Northern Portugal: Risk factor analysis. Epidemiol. Infect. 2014, 143, 2126–2130. [Google Scholar] [CrossRef]
  38. Roquelo, C.; Kodjo, A.; Marié, J.-L.; Davoust, B. Serological and molecular survey of Leptospira spp. infections in wild boars and red foxes from Southeastern France. Vet.-World 2021, 14, 825–828. [Google Scholar] [CrossRef]
  39. Żmudzki, J.; Jabłoński, A.; Nowak, A.; Zębek, S.; Arent, Z.; Bocian, L.; Pejsak, Z. First overall report of Leptospira infections in wild boars in Poland. Acta Vet.-Scand. 2015, 58, 3. [Google Scholar] [CrossRef]
  40. Boqvist, S.; Bergström, K.; Magnusson, U. Prevalence of Antibody to Six Leptospira Servovars in Swedish Wild Boars. J. Wildl. Dis. 2012, 48, 492–496. [Google Scholar] [CrossRef] [PubMed]
  41. Vengust, G.; Lindtner-Knific, R.; Zele, D.; Bidovec, A. Leptospira antibodies in wild boars (Sus scrofa) in Slovenia. Eur. J. Wildl. Res. 2008, 54, 749–752. [Google Scholar] [CrossRef]
  42. Chiari, M.; Figarolli, B.M.; Tagliabue, S.; Alborali, G.L.; Bertoletti, M.; Papetti, A.; D’Incau, M.; Zanoni, M.; Boniotti, M.B. Sero-prevalence and risk factors of leptospirosis in wild boars (Sus scrofa) in northern Italy. Hystrix It. J. Mamm. 2016, 27, 145–149. [Google Scholar] [CrossRef] [PubMed]
  43. Espí, A.; Prieto, J.M.; Alzaga, V. Leptospiral antibodies in Iberian red deer (Cervus elaphus hispanicus), fallow deer (Dama dama) and European wild boar (Sus scrofa) in Asturias, Northern Spain. Vet.-J. 2010, 183, 226–227. [Google Scholar] [CrossRef] [PubMed]
  44. Zakeri, S.; Khorami, N.; Ganji, Z.F.; Sepahian, N.; Malmasi, A.-A.; Gouya, M.M.; Djadid, N.D. Leptospira wolffii, a potential new pathogenic Leptospira species detected in human, sheep and dog. Infect. Genet. Evol. 2010, 10, 273–277. [Google Scholar] [CrossRef]
  45. Ellis, W.A. Control of canine leptospirosis in Europe: Time for a change? Vet.-Rec. 2010, 167, 602–605. [Google Scholar] [CrossRef]
  46. Esteves, S.B.; Santos, C.M.; Salgado, F.F.; Gonçales, A.P.; Guilloux, A.G.A.; Martins, C.M.; Hagiwara, M.K.; Miotto, B.A. Efficacy of commercially available vaccines against canine leptospirosis: A systematic review and meta-analysis. Vaccine 2022, 40, 1722–1740. [Google Scholar] [CrossRef] [PubMed]
  47. Valença, R.M.; Mota, R.A.; Castro, V.; Anderlini, G.A.; Pinheiro Júnior, J.W.; Brandespim, D.F.; Valença, S.R.; Guerra, M.M. Prevalence and risk factors associated with Leptospira spp. infection in technified swine farms in the state of Alagoas, Brazil risk factors associated with Leptospira spp. in swine farms. Transbound. Emerg. Dis. 2013, 60, 79–86. [Google Scholar] [CrossRef] [PubMed]
  48. Ko, A.I.; Goarant, C.; Picardeau, M. Leptospira: The dawn of the molecular genetics era for an emerging zoonotic pathogen. Nat. Rev. Microbiol. 2009, 7, 736–747. [Google Scholar] [CrossRef] [PubMed]
  49. Jeske, K.; Schulz, J.; Tekemen, D.; Balčiauskas, L.; Balčiauskienė, L.; Hiltbrunner, M.; Drewes, S.; Mayer-Scholl, A.; Heckel, G.; Ulrich, R.G. Cocirculation of Leptospira spp. and multiple orthohantaviruses in rodents, Lithuania, Northern Europe. Transbound. Emerg. Dis. 2022, 69, E3196–E3201. [Google Scholar] [CrossRef]
  50. Stankevičienė, M.; Juknius, T.; Steponavičienė, A.; Buitkuvienė, J. The prevalence of leptospirosis in Lithuanian swine farms. Vet. Med. Zoot. 2013, 63, 85. [Google Scholar]
  51. Stankevičienė, M.; Buitkuvienė, J.; Bartaševičiūtė, N.; Adomkienė, R. Seroepizootic survey of leptospirosis in horses. Vet. Med. Zoot. 2016, 74, 96. [Google Scholar]
  52. Šiugždinienė, R.; Ružauskas, M.; Virgailis, M.; Buitkuvienė, J. The prevalence of Leptospira serovars among cattle in Lithuania. Vet. Med. Zoot. 2007, 37, 86–90. [Google Scholar]
  53. Karpagam, K.B.; Ganesh, B. Leptospirosis: A neglected tropical zoonotic infection of public health importance—An updated review. Eur. J. Clin. Microbiol. Infect. Dis. 2020, 39, 835–846. [Google Scholar] [CrossRef]
  54. Cilia, G.; Bertelloni, F.; Mignone, W.; Spina, S.; Berio, E.; Razzuoli, E.; Vencia, W.; Franco, V.; Cecchi, F.; Bogi, S.; et al. Molecular detection of Leptospira spp. in wild boar (Sus scrofa) hunted in Liguria region (Italy). Comp. Immunol. Microbiol. Infect. Dis. 2019, 68, 101410. [Google Scholar] [CrossRef] [PubMed]
  55. Koizumi, N.; Muto, M.; Yamada, A.; Watanabe, H. Prevalence of Leptospira spp. in the Kidneys of Wild Boars and Deer in Japan. J. Vet.-Med. Sci. 2009, 71, 797–799. [Google Scholar] [CrossRef] [PubMed]
  56. Cilia, G.; Bertelloni, F.; Piredda, I.; Ponti, M.N.; Turchi, B.; Cantile, C.; Parisi, F.; Pinzauti, P.; Armani, A.; Palmas, B.; et al. Presence of pathogenic Leptospira spp. in the reproductive system and fetuses of wild boars (Sus scrofa) in Italy. PLoS Neglected Trop. Dis. 2020, 14, e0008982. [Google Scholar] [CrossRef]
  57. Cilia, G.; Bertelloni, F.; Cerri, D.; Fratini, F. Leptospira fainei Detected in Testicles and Epididymis of Wild Boar (Sus scrofa). Biology 2021, 10, 193. [Google Scholar] [CrossRef] [PubMed]
  58. Taminskas, J.; Pileckas, M.; Šimanauskienė, R.; Linkevičienė, R. Lietuvos šlapynės: Klasifikacija ir sklaida. Baltica 2011, 24, 151–162. [Google Scholar]
Pathogens 14 00085 g001
Figure 1. Percentage of seropositive reactions (%) in 10 Lithuanian counties.
Figure 1. Percentage of seropositive reactions (%) in 10 Lithuanian counties.
Pathogens 14 00085 g001
Table 1. Seropositivity to different Leptospira serovars in three age groups. (Pom—Pomona; Gryp—Grypothyphosa; Sax—Saxkoebing; Sej—Sejroe; Can—Canicola; Brat—Bratislava; Copen—Copenhageni; Tar—Tarassovi). Results are displayed as n (%, Confidence Interval of 95% (CI)).
Table 1. Seropositivity to different Leptospira serovars in three age groups. (Pom—Pomona; Gryp—Grypothyphosa; Sax—Saxkoebing; Sej—Sejroe; Can—Canicola; Brat—Bratislava; Copen—Copenhageni; Tar—Tarassovi). Results are displayed as n (%, Confidence Interval of 95% (CI)).
Age of BoarsNumber of Positive Reactions, n (%, CI)
PomGrypSax *SejCan *Brat *CopenTarTotal
Younger than 12 months2 (1.0%,
0.1–3.7)		0 (0%, 0–1.9)0 (0%, 0–1.9)1 (0.6%
0.01–2.8)		2 (1.0%,
0.1–3.7)		2 (1.0%, 0.1–3.7)1 (0.6%,
0.01–2.8)		2 (1.0%,
0.1–3.7)		10 (5.2%, 2.5–9.3)
12 to 24 months4 (2.1%,
0.6–5.2)		4 (2.1%, 0.6–5.2)2 (1.0%,
0.1–3.7)		11 (5.7%, 2.9–9.9)12 (6.2%, 3.2–10.6)14 (7.2%, 4.0–11.8)22 (11.3%, 7.3–16.7)4 (2.1%, 0.6–5.2)73 (37.6%, 30.8–44.9)
Older than 24 months7 (3.6%,
1.5–7.3)		8 (4.1%, 1.8–8.0)8 (4.1%, 1.8–8.0)9 (4.6%, 2.1–8.6)23 (11.9%, 7.7–17.3)26 (13.4%, 9.0–19.0)21 (10.8%, 6.8–16.1)9 (4.6%, 2.1–8.6)111 (57.2%, 49.9–64.3)
Total13 (6.7%, 3.6–11.2)12 (6.2%, 3.2–10.6)10 (5.2%, 2.5–9.3)21 (10.8%, 6.8–16.1)37 (19.1%, 13.8–25.3)42 (21.6%, 16.1–28.1)44 (22.7%, 17.0–29.2)15 (7.7%, 4.4–12.4)194 (100%)
* Difference between age groups is statistically significant (p < 0.05).
Table 2. Number of positive reactions to different Leptospira serovars in 10 different counties. (Pom—Pomona; Gryp—Grypothyphosa; Sax—Saxkoebing; Sej—Sejroe; Can—Canicola; Brat—Bratislava; Copen—Copenhageni; Tar—Tarassovi). Results are displayed as n (%, Confidence Interval of 95% (CI)).
Table 2. Number of positive reactions to different Leptospira serovars in 10 different counties. (Pom—Pomona; Gryp—Grypothyphosa; Sax—Saxkoebing; Sej—Sejroe; Can—Canicola; Brat—Bratislava; Copen—Copenhageni; Tar—Tarassovi). Results are displayed as n (%, Confidence Interval of 95% (CI)).
Number of Positive Reactions, n (%, CI)
CountyPomGrypSaxSejCanBratCopenTarTotal
Vilnius3 (5.5%, 1.1–15.1)1 (1.8%, 0.1–9.7)1 (1.8%, 0.1–9.7)4 (7.4%, 2–17.6)8 (14.5%, 6.5–26.7)7 (12.7%, 5.3–24.5)11 (20.0%, 10.4–33.0)3 (5.5%, 1.1–15.1)38/55 (69.1%, 55.2–80.9)
Kaunas3 (5.0%, 1.0–13.9)3 (5.0%, 1.0–13.9)4 (6.7%, 1.9–16.2)3 (5.0%, 1.0–13.9)6 (10.0%, 3.8–20.5)6 (10.0%, 3.8–20.5)6 (10.0%,
3.8–20.5)		3 (5.0%, 1.0–13.9)34/60 (56.7%, 43.2–69.4)
Klaipėda2 (4.8%, 0.6–16.2)0 (0%,
0–8.4)		1 (2.4%, 0.06–12.6)3 (7.1%, 1.5–19.5)0 (0%, 0–8.4)3 (7.1%, 1.5–19.5)1 (2.4%,
0.06–12.6)		1 (2.4%,
0.06–12.6)		11/42 (26.2%, 13.9–42.0)
Šiauliai3 (5.4%, 1.1–14.9)2 (3.6%, 0.4–12.3)1 (1.8%, 0.04–9.6)3 (5.4%, 1.1–14.9)4 (7.1%, (2.0–17.3)8 (14.3%, 6.38–26.22)5 (8.9%,
3.0–19.6)		2 (3.6%, 0.4–12.3)28/56 (50.0%, 36.3–63.7)
Panevėžys2 (6.1%,
0.7–20.2)		3 (9.1%, 1.9–24.3)1 (3.0%,
0.08–15.8)		4 (12.1%, 3.4–28.2)5 (15.2%, 5.1–31.9)5 (15.2%,
5.1–31.9)		4 (12.1%,
3.4–28.2)		5 (15.2%, 5.1–31.9)29/33
(87.9%, 71.8–96.6)
Marijampolė0 (0%,
0–21.8)		0 (0%,
0–21.8)		0 (0%,
0–21.8)		0 (0%,
0–21.8)		1 (6.7%, 0.2–32.0)0 (0%,
0–21.8)		1 (6.7%,
0.2–32.0)		0 (0%,
0–21.8)		2/15 (13.3%, 1.7–40.5)
Telšiai0 (0%,
0–6.4)		1 (1.8%,
0.04–9.6)		0 (0%,
0–6.4)		1 (1.8%,
0.04–9.6)		5 (8.9%,
3.0–19.6)		2 (3.6%,
0.4–12.3)		0 (0%, 0–6.4)1 (1.8%,
0.04–9.6)		10/56 (17.9%, 8.9–30.4)
Tauragė0 (0%,
0–8.6)		1 (2.5%,
0.06–1.9)		0 (0%,
0–8.6)		2 (4.9%,
0.6–16.5)		4 (9.8%,
2.7–23.1)		4 (9.8%,
2.7–23.1)		5 (12.2%,
4.1–26.2)		0 (0%, 0–8.6)16/41 (39.0%, 24.2–55.5)
Alytus0 (0%,
0–9.5)		1 (2.7%, 0.07–14.2)1 (2.7%, 0.07–14.2)1 (2.7%, 0.07–14.2)2 (5.4%,
0.7–18.2)		3 (8.1%,
1.7–21.9)		1 (2.7%,
0.07–14.2)		0 (0%,
0–9.5)		9/37 (24.3%, 11.8–41.2)
Utena0 (0%,
0–6.4)		0 (0%,
0–6.4)		1 (1.8%,
0.04–9.6)		0 (0%,
0–6.4)		2 (3.6%, 0.4–12.3)4 (7.1%,
2.0–17.2)		10 (17.9%,
8.9–30.4)		0 (0%, 0–6.4)17/56 (30.4%, 18.8–44.1)
Table 3. Seropositivity to Leptospira in 12 different countries, adapted from references indicated within square brackets [30,31,32,33,34,35,36,37,38,39,40,41,42,43].
Table 3. Seropositivity to Leptospira in 12 different countries, adapted from references indicated within square brackets [30,31,32,33,34,35,36,37,38,39,40,41,42,43].
StudyCountryNumber of SeraPositive Samples% of Positive SamplesMost Common Serovar
Vale-Gonçalves, 2015 [37]Portugal1016665.4Tarassovi
Vengust G, 2008 [41]Slovenia43720045.5Tarassovi
Cvetnic Z, 2003 [31]Croatia1544026Pomona
Slavica A, 2010 [35]Croatia35111231.9Australis
Fornazari F, 2011 [33]Brazil3086320.5Hardjo
Roquelo C, 2021 [38]France3586618.4Australis
Jansen A, 2007 [34]Germany1412517.7Pomona
Treml F, 2003 [36]Czech
Republic		3075216.9Grippothyphosa
Espí A, 2010 [43]Spain1712514.6Pomona
Cilia G, 2020 [30]Italy2873913.6Australis
Chiari M, 2016 [42]Italy210132115.3Bratislava
Ebani VV, 2003 [32]Italy562346Bratislava
Żmudzki J, 2015 [39]Poland362137710.4Hardjo
Boqvist S, 2012 [40]Sweden386123.1Bratislava
Current studyLithuania45110222.6Copenhageni
Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content.

Share and Cite

MDPI and ACS Style

Karvelienė, B.; Stadalienė, I.; Rudejevienė, J.; Burbaitė, E.; Juodžentė, D.; Masiulis, M.; Buitkuvienė, J.; Šakalienė, J.; Zamokas, G. Prevalence of Leptospira spp. in Lithuanian Wild Boars (Sus scrofa). Pathogens 2025, 14, 85. https://doi.org/10.3390/pathogens14010085

AMA Style

Karvelienė B, Stadalienė I, Rudejevienė J, Burbaitė E, Juodžentė D, Masiulis M, Buitkuvienė J, Šakalienė J, Zamokas G. Prevalence of Leptospira spp. in Lithuanian Wild Boars (Sus scrofa). Pathogens. 2025; 14(1):85. https://doi.org/10.3390/pathogens14010085

Chicago/Turabian Style

Karvelienė, Birutė, Inga Stadalienė, Jūratė Rudejevienė, Evelina Burbaitė, Dalia Juodžentė, Marius Masiulis, Jūratė Buitkuvienė, Jurgita Šakalienė, and Gintaras Zamokas. 2025. "Prevalence of Leptospira spp. in Lithuanian Wild Boars (Sus scrofa)" Pathogens 14, no. 1: 85. https://doi.org/10.3390/pathogens14010085

APA Style

Karvelienė, B., Stadalienė, I., Rudejevienė, J., Burbaitė, E., Juodžentė, D., Masiulis, M., Buitkuvienė, J., Šakalienė, J., & Zamokas, G. (2025). Prevalence of Leptospira spp. in Lithuanian Wild Boars (Sus scrofa). Pathogens, 14(1), 85. https://doi.org/10.3390/pathogens14010085

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop