Leptospira spp. in Free-Ranging Capybaras ( Hydrochoerus hydrochaeris ) from Midwestern Brazil

Abstract

Background:

Leptospirosis is a contagious disease that affects domestic and wild animals as well as humans. It is caused by infection with some pathogenic species of the genus Leptospira. In Brazil, studies on leptospirosis in capybaras are scarce or nonexistent in some regions, such as the Federal District. The objective of this study was to analyze the presence of DNA of the agent and/or anti-Leptospira spp. antibodies in capybaras.

Materials and Methods:

Blood samples were collected from 56 free-living capybaras captured in two different sites in the study region. The samples were submitted to hematology and clinical chemistry tests. To identify Leptospira positive samples, a conventional PCR (cPCR) and analysis of anti-Leptospira spp. antibodies by microscopic agglutination test (MAT) were used.

Results:

No animal showed cPCR amplification of the Lip32 gene, but 41.1% (23/56) of the animals had anti-Leptospira spp. antibodies on MAT. The serovars present were icterohaemorrhagiae (82.61%), copenhageni (65.22%), grippotyphosa (4.35%), and hardjo (4.35%). In the laboratorial tests, differences (p < 0.05) were observed in the biochemical assays of alkaline phosphatase, creatinine, albumin, and globulin. Although these values differed significantly between groups, they all remained within reference range (excluding albumin), and thus there is not enough to infer that this alteration could be caused by Leptospira infection.

Conclusions:

cPCR using whole blood samples to evaluate Leptospira spp. infection of free-living capybaras was not an efficient tool. The presence of Leptospira seroreactive capybaras shows that the bacteria are circulating in the urban environment of the Federal District.

Introduction

The genus Leptospira belongs to the family Leptospiraceae and is divided into three groups: pathogenic, intermediate, and nonpathogenic (Philip et al., 2021). There are 66 Leptospira species, and based on the structural heterogeneity of surface-exposed lipopolysaccharides, >300 serovars are known (Casanovas-Massana et al., 2020; Guglielmini et al., 2020; Vincent et al., 2019). Bacteria of the genus Leptospira cause leptospirosis or Weil's disease (Fouts et al., 2016). Leptospirosis is recognized as an important public health problem due to the increasing incidence in both developing and developed countries, mainly in tropical climates (Diz and Conceição, 2021).

Almost all known species of mammals can carry and excrete Leptospira; however, mice and rats are the universal reservoirs of this bacterium (Gomes-Solecki et al., 2017). Capybaras are considered the largest living rodents in nature, belonging to the Caviidae family and the subfamily Hydrochoerinae (Cueto, 2013; Fontenele et al., 2019; Woods and Kilpatrick, 2005). They are extremely adaptable animals and can be found in various human-altered environments. Capybaras can reach high densities in these sites if predators are lacking and the environment has the ability to sustain them, being considered a pest on some occasions (Ferraz et al., 2007).

These rodents can often be found in large populations in urban areas, parks, and even in residential areas (Serra-Medeiros et al., 2021). In Brazil, capybaras have also been studied as reservoirs of Leptospira. The results of these studies showed seroprevalence rates ranging from 30% to 94%, highlighting the fact that seroreactive animals did not present clinical signs of the disease (Chiacchio et al., 2014; Gonçalves et al., 2020; Langoni et al., 2016; Silva et al., 2009).

In Brazil, especially in Brasilia (capital of Brazil), Federal District, the media has reported an increase of herds of capybaras close to residential and recreational urban areas (G1, 2017; Medeiros, 2018; Quadros et al., 2021). This fact raised the importance to evaluate the presence of the causative agent of leptospirosis in the capybaras from these areas of the Federal District. Thus, this study aimed to determine the prevalence of pathogenic Leptospira serovars that affect capybaras in the Federal District using serological and molecular methods and compare possible laboratorial changes between seropositive and seronegative animals.

Materials and Methods

Ethics committee

This project was approved by the Sistema of Authorization and Information in Biodiversity (SISBIO) under protocol No 43798-1 and by the ethics committee on animal use (CEUA) of the University of Brasília (UnB) under protocol No. 20/2019.

Study and sampling area

Fifty-six free-living capybaras were captured from two distant recreation sites in the Federal District: Group 1 and Group 2. Group 1 was composed of three herds of capybaras living in three small nearby lakes. This group was divided into Group 1A (15°50′48.34″S, 47°56′27.34″W)—21 animals, which were collected during the spring in the southern hemisphere, Group 1B (15°50′59.29″S, 47°55′57.70″W)—10 animals, and Group 1C (15°51′3.28″S, 47°56′18.18″W)—10 animals, these two groups being collected during the autumn of the southern hemisphere.

Group 2 was composed by 15 animals captured from a central area of Paranoá Lake (15°47′30″S, 47°47′49.43″W), which were collected during the winter in the southern hemisphere. Of these animals, 14 were males (2 cubs and 12 adults) and 42 were females (7 cubs and 35 adults). The classification of animals between young and adults was performed based on the estimated visualization of the capybaras' size according to Ojasti (1973). Blood was collected by venopuncture of the femoral or saphenous vein, in tubes of 4 mL containing anticoagulant (ethylenediaminetetraacetic acid [EDTA]) and in dry tubes of 8 mL to obtain serum.

Capture of animals

The animals were captured using restraining cages and food consisting of fruits and vegetables. After capture, the subjects were sedated intramuscularly, using a blowgun and anesthetic dart containing a combination of ketamine 1% (2.0 mg/kg) and xylazine 2% (0.5 mg/kg). After harvesting, a dose of yohimbine (0.1 mg/kg) was administered to reverse the action of xylazine and reduce the time from anesthetic recovery. Once anesthetized, blood collection and trichotomy marking were performed on the right flank. The animals were released only after complete recovery from sedation.

Hematological analysis

The EDTA blood samples were used for complete blood count. The number of erythrocytes (/μL) and leukocytes (/μL) was determined manually using a hemocytometer. The hemoglobin concentration (g/dL) was measured using spectrophotometry in a semiautomatic biochemical analyzer Bioplus 2000 (Bioplus, Barueri, Brazil). The mean cell volume (MCV) and mean cell hemoglobin concentration (MCHC) were obtained by standard calculation (Weiser, 2012).

Blood smears were made and stained with Diff-Quick (NewProv Panotic^®, Pinhais, Brazil) to perform the differential leukocytes count and to estimate the number of platelets. Platelets were estimated by visualization in the slide, where platelets present in 10 fields were counted. We used the correction factor x/10xy, in which x is the number of platelets found in the 10 fields and y the correction factor 20,000.

Total plasma proteins were determined with the aid of a refractometer. After performing all these procedures, whole blood was stored for further DNA extraction for molecular analysis.

One serum aliquot was used to determine the activity of the enzymes alanine aminotransferase (ALT), aspartate aminotransferase (AST), and alkaline phosphatase (ALP), and the enzyme quantification of urea, creatinine, total proteins, and albumin was done using the automatic analyzer Cobas C-111 (Roche Diagnostics, Basel, Switzerland). Globulins were calculated by subtracting albumin from total proteins.

DNA extraction

DNA extraction was performed with 200 μL of whole blood using the Illustra Blood Genomicprep Kit (GE Healthcare^®, Chicago, IL, USA) according to the manufacturer's guidelines. DNA samples were stored at −20°C until conventional PCR (cPCR) was performed.

Amplification protocols

All samples extracted from whole blood were subjected to a control cPCR for gene encoding the enzyme GAPDH (glyceraldehyde 3-phosphate dehydrogenase), to assess integrity and check for the presence of cPCR inhibitors. The sequences of the oligonucleotides used for this assay were GAPDH-F (5′ CCT TCA TTG ACC TCA ACT TCA T 3′) and GAPDH-R (5′ CCA AAG TTG TCA TGG ATG ACC 3′) according to Birkenheuer et al. (2003). The cPCR mixture was composed of 1 × buffer (Invitrogen^® Brasil Ltda, São Paulo, Brazil), 10 ng of DNA, 1.5 mM of MgCl₂ (Invitrogen Brasil Ltda), 0.2 mM of each deoxynucleotide (Invitrogen Brasil Ltda), 1 μL of each oligonucleotide at 10 pmol, and 1.25 U of Taq DNA polymerase (Invitrogen Brasil Ltda), for a final volume of 25 μL.

The amplification protocol was composed of an initial denaturation step of 95°C for 5 min, followed by 40 amplification cycles (94°C for 30 s, 52°C for 1 min, and 72°C for 1 min) and a final extension at 72°C for 5 min. To detect Leptospira spp., the oligonucleotides used in the cPCR were LIPL3245Fw (5′-AAG CAT TAC CGC TTG TG TG-3′) and LIPL32286Rv (5′- GAA CTC CCA TTT CAG CGA TT-3′) directed to the LipL32 gene, presenting an amplification product of 242 bp according to Cordeiro et al. (2017).

The cPCR was composed of 1 × buffer (Invitrogen Brasil Ltda), 1 μL of the sample (DNA) at 10 ng/μL, 1.5 mM of MgCl₂ (Invitrogen Brasil Ltda), 0.2 mM of each deoxynucleotide triphosphate (dATP, DCTP, dGTP, dTTP) (Invitrogen Brasil Ltda), 0.5 μL of each oligonucleotide at 10 pmol, and 1.0 U of Taq DNA (Recombinant^® Taq DNA Polymerase, Invitrogen), for a final volume of 25 μL. The amplification protocol was composed of an initial denaturation step of 94°C for 3 min, followed by 35 amplification cycles (94°C for 45 s, 52°C for 45 s, and 72°C for 45 s) and final extension at 72°C for 5 min.

All samples were tested in duplicate in the same thermocycler (BioRad C100 Thermal Cycler; Bio-Rad Laboratories, Inc., Berkeley, USA). Water (H₂O milQ) was used as a negative control and the Guard-Vac LCI/GP vaccine (Zoetis, Inc., Parsippany-Troy Hills, NJ, USA) was used as a positive control.

Electrophoresis in agarose gel

cPCR products were subjected to electrophoresis in 2% agarose gel (Invitrogen™). After electrophoresis, the gels were stained in ethidium bromide (Vetec Sigma-Aldrich^®, St Louis, MO, USA) 0.3 μg/mL for ∼30 min. The results were visualized through an ultraviolet light transilluminator (UVP^®) and positive samples were considered to present products whose sizes corresponded to ∼242 bp compared with molecular weight marker 100 bp (EasyGen^®).

Serological diagnosis

The serological test for the detection of anti-Leptospira spp. antibodies was performed at the serology laboratory of the Department of Preventive Veterinary Medicine and Animal Reproduction—FCAV/UNESP Jaboticabal/SP. A microscopic agglutination test was used for Leptospira serological diagnosis (Cole et al., 1973). The diagnosis was performed using a collection of living antigens that includes 24 serological variants (sv) of pathogenic leptospires (australis, bratislava, autumnalis, butembo, castellonis, batavie, canicola, whitcombi, cynopteri, grippotyphosa, hebdomadis, copenhageni, icterohaemorrhagiae, javanica, panama, pomona, pyrogenes, hardjo, wolffi, shermani, tarassovi, and sentot) and two of saprophyte leptospires (andamana and patoc).

Screening was performed at 1:100 dilution; when there was agglutination, the sera were titrated in a geometric series of two ratio dilutions. The titer was given as the reciprocal of the greatest dilution in which there was agglutination (Santa Rosa, 1970). The sera that presented 50% or more agglutination from the dilution of 1:100 were considered seroreactive (Hässle et al., 2019).

Statistical analysis

The normality of data distribution was evaluated by the Shapiro-Wilk test. The Student's t-test for unpaired samples was conducted to compare the means of quantitative variables between the seroreactive and nonseroreactive animals of the parameters with normal distribution, and the Mann–Whitney test for the parameters with non-normal distribution. These variables were presented in the form of mean and standard deviation. All statistical analyses already described were performed using the GraphPad prism 6 statistical program (GraphPad Software, San Diego, USA) for Windows, and the significance level was established at 5%.

The proportion of seroreactive animals was calculated, total and in the categories of the factors analyzed, with their respective confidence interval (CI), by Wilson method, using the “binom” package of software R. In the comparison between the frequencies of seroreactive according to the factors analyzed, chi-squared test was used, calculated through the software Epi Info 7.2.2.6. In situations where a significant association (p < 0.05) was observed between the factor categories and the frequency of seroreactive, simple logistic regression analysis was performed using the Epi Info software.

To investigate the influence of confounding variable, the adjusted Mantel–Haenszel odds ratio (OR) was used, stratifying the frequency according to the capture sites of the animals. The homogeneity of the ORs was evaluated by the Breslow–Day test. Since the sample is small, resulting in cells with 0 value, mainly in the tables per stratum, value 1 was added to each cell, so that the Epi Info software could perform the calculations (Thrusfield and Christley, 2018).

Results

No animal showed cPCR amplification for the LipL32 gene common to pathogenic species of Leptospira spp. Table 1 gives the serology results, in which it can be observed that 41.1% (23) of the animals were seroreactive and 58.9% (33) were nonseroreactive. There was no difference (p > 0.05) in frequency between Leptospira seroreactive males (28.57%) and females (45.24%). Considering age group, 48.94% of adult animals were seroreactive, whereas among cubs none were seroreactive to Leptospira (Table 1).

Table 1.

Frequency and Confidence Interval of Capybaras Seroreactive to Leptospira According to Gender, Age, and Capture Sites, Brasilia, Brazil, 2019

Factor	Category	Examined	Positives	Frequency% (95% CI)	p
Gender	Male	14	4	28.57 (11.72–54.65)	0.433
Gender	Female	42	19	45.24 (31.22–60.05)	0.433
Age group	Adult	47	23	48.94 (35.28–62.76)	0.01818
Age group	Cub	9	0	0.00 (0.00–29.92)	0.01818
Capture sites	Group 1	41	13	31.71 (19.56–46.98)	0.04054
Capture sites	Group 2	15	10	66.67 (41.71–84.82)	0.04054
Total	—	56	23	41.07 (29.17–54.12)	—

CI, confidence interval.

The general raw OR, 5.2885 (Table 2) with a CI of 1.0639–26.2877, and the p-value (0.0296) suggest a significant association between age group and frequency of seroreactive animals. Table 1 shows that a higher proportion of seroreactive animals was detected in capybaras captured in Group 2 (66.67%) than in Group 1 (31.71%). These proportions were statistically different (p < 0.05), although there is some overlap in the CIs. Among the 24 serological variants evaluated, the animals presented titers for only 4 (16.7%) variants. Some animals presented titers for >1 serological variant (Table 3).

Table 2.

Analysis of the Association Between Age Group (Adults/Cub) and Frequency of Capybaras Seroreactive to Leptospira in the Joint Data and in the Data Stratified by Capture Site

Group	OR	95% CI	p
All (OR raw)	5.2885	1.0639–26.2877	0.0296
Capture site 1	7.0	0.8023–61.0729	0.0523
Capture site 2	1.8333	0.0964–34.851	0.6914
All—OR adjusted MH	4.8538	0.9105–25.8748	0.1113

p: MH χ² test; Breslow–Day test for ORs homogeneity: p = 0.4726.

CI, confidence interval; OR, odds ratio.

Table 3.

Most Likely Serological Variants and Titers Detected in Leptospira Seroreactive Capybaras Divided by Capture Sites (Groups 1 and 2) in Microscopic Agglutination Test

			Serological variant
Group	Age	Sex	hardjo	icterohaemorrhagiae	copenhageni	grippotyphosa
1A	Adult	Male	—	200	400	—
1A	Adult	Female	—	100	—	—
1A	Adult	Female	—	200	200
1A	Adult	Female	—	100	—	—
1A	Adult	Female	—	100	200	—
1A	Adult	Female	100	—	—	—
1A	Adult	Male	—	—	—	100
1B	Adult	Male	—	100	—	—
1B	Adult	Female	—	100	200	—
1B	Adult	Male	—	100	200	—
1C	Adult	Female	—	100	200	—
1C	Adult	Female	—	200	200	—
1C	Adult	Female	—	100	100	—
2	Adult	Female	—	—	400	—
2	Adult	Female	—	100	200	—
2	Adult	Female	—	400	1600	—
2	Adult	Female	—	100	—	—
2	Adult	Female	—	200	200	—
2	Adult	Female	—	100	—	—
2	Adult	Female	—	200	1600	—
2	Adult	Female	—	100	—	—
2	Adult	Female	—	—	400	—
2	Adult	Female	—	400	800	—

1A, 1B, and 1C were animals from nearby lakes, assembled in one big group (Group 1).

Tables 4 and 5 show the results of hematology and biochemical assays between seroreactive and nonseroreactive capybaras. A statistical difference (p < 0.05), between seroreactive and nonseroreactive capybaras, was observed in the biochemical assays of ALP, creatinine, albumin, and globulin.

Table 4.

Mean Hematological Parameters and Standard Deviations of the Leptospira Seroreactive and Nonseroreactive Capybaras

Hematological parameters	Seroreactive (n = 23/56)	Nonseroreactive (n = 33/56)
Hematological parameters	Average and SD	Average and SD
RBC ( × 10⁶/μL)	2.819 ± 0.5006	2.978 ± 0.5991
WBC ( × 10³/μL)	7291 ± 2230	7027 ± 2291
Segmented ( × 10³/μL)	3253 ± 1319	3336 ± 1762
Lymphocytes( × 10³/μL)	1883 ± 813.9	1816 ± 939.2
Monocytes( × 10³/μL)	927.2 ± 606.6	791.7 ± 379.0
Eosinophils ( × 10³/μL)	1078 ± 611.4	1046 ± 596.9
Basophils ( × 10³/μL)	3.696 ± 17.72	17.94 ± 46.57
Platelets (μL)	202,000 ± 63,900	202,281 ± 55,326
Hemoglobin (g/dL)	12.14 ± 3.398	11.56 ± 2.039
PCV (%)	37.39 ± 2.589	38.73 ± 3.907
MCV (fL)	133.4 ± 32.14	132.4 ± 30.48
MCHC (%)	32.47 ± 8.757	29.98 ± 4.986

MCHC, mean cell hemoglobin concentration; MCV, mean cell volume; PCV, packed cell volume; RBCs, red blood cells; SD, standard deviation; WBCs, white blood cells.

Table 5.

Mean Biochemical Parameters and Standard Deviations of the Leptospira Seroreactive and Nonseroreactive Capybaras

Biochemical analysis	Seroreactive (n = 23/56)	Nonseroreactive (n = 33/56)	p
Biochemical analysis	Average and SD	Average and SD	p
ALT (UI/L)	49.39 ± 25.50	59.24 ± 22.30	0.1311^■
AST (UI/L)	42.78 ± 25.30	43.12 ± 21.21	0.4790^▲
ALP (UI/L)	127.3 ± 109.1	154.5 ± 93.50	0.0325^▲
Creatinine (mg/dL)	1.574 ± 0.2220	1.247 ± 0.2501	<0.0001^■
Urea (mg/dL)	28.26 ± 10.27	34.25 ± 12.08	0.0592^■
TP (g/dL)	5.926 ± 0.7448	6.109 ± 0.6925	0.3498^■
Albumin (g/dL)	2.422 ± 0.5624	2.967 ± 0.6513	0.0020^■
Globulin (g/dL)	3.504 ± 0.6034	3.142 ± 0.6577	0.0409^■

■

Unpaired t-test; ^▲Mann–Whitney test.

ALT, alanine aminotransferase; AST, aspartate aminotransferase; ALP, alkaline phosphatase; TP, total protein.

Discussion

In this study, all blood samples tested for LipL32 gene were negative. Leptospira circulate in the bloodstream (leptospiremia) for up to 7 days, and after which they become nonexistent in the bloodstream and act on tissues (Adler and Moctezuma, 2010). The absence of Leptospira DNA on blood samples may suggest that the animals were captured after the leptospiremic phase or they were not even infected.

Because urine collection was prevented by the anatomy of the urinary system of capybaras, only whole blood samples were used to perform PCR, which may have been the cause of nonamplification in the samples. The use of tissue samples, such as renal or hepatic tissues, would produce better results with PCR when evaluating animals in the chronic phase, or those that do not present clinical signs due to physiological adaptations.

The study region has two well-marked climatic periods: a well-defined period of rain, between October and April, and of drought, between May and September (INMET, 2019). In general, in humans and companion animals, there is an increase in leptospirosis infection in the rainy season, due to direct exposure to situations resulting from the accumulation of water (Pereira et al., 2014).

In the animals of this study, we did not observe this particularity, since there was seropositivity in the rainy season, and in the dry season, this may have occurred due to the behavioral issue of the studied species, where capybaras have permanent bodies of water as their natural habitat, that is, river banks. rivers and lakes, flooded areas, and close to dams (Mones and Ojasti, 1986), and these sources of water and humidity are extremely important for the epidemiology of the disease.

Previous studies of Leptospira seroreactive capybaras in Brazil showed wide variation, ranging from 20% to 90% (Albuquerque et al., 2017; Chiacchio et al., 2014; Gonçalves et al., 2020; Ito et al., 1998; Langoni et al., 2016; Silva et al., 2009). In this study, 41.1% of seropositivity was found in the studied population, which would be within the range found in Brazil. These variations on seroreactive animals seem to be related to the region studied, weather, and environmental conditions. However, these variations may also be due to a lack of consistency between laboratories.

In this study, sampling site was the only factor associated with frequency of Leptospira seroreactive animals. The statistical difference (p < 0.05) between age of seroreactive and non-seroactive animals was due to the confidence interval of the OR. This is confirmed when observing the adjusted Mantel-Haenszel OR, whose confidence interval includes the value 1 and whose p-value is above 0.05. The Breslow-Day test shows that the ORs are homogeneous (p > 0.05), indicating the validity of the use of Mantel-Haenszel's adjusted OR. Based on these, there is no real significant association between age (adult and cub) of seroreactive and non-seroactive capybaras. There was no statistical difference with respect to gender.

Table 1 shows that a higher proportion of seroreactive animals was detected in capybaras captured in Group 2 (66.67%) than in Group 1 (31.71%). A possible explanation for this result would be related to the site where Group 2 lived. Capybaras of Group 2 were captured in a public lake, with a large area that is cohabited by many other species, whereas the animals of Group 1 were captured near to smaller lakes where mainly capybaras lived. Therefore, the chances of other species contaminating the area where capybaras live are greater in the area of Group 2 than in Group 1.

Out of the 24 serological variants evaluated, the animals presented titers against 4 serovars: hardjo, icterohaemorrhagiae, copenhageni, and grippotyphosa, and in 13 (56.52%) animals the variants icterohaemorrhagiae and copenhageni presented concurrent titers (Table 4). It is important to notice that most capybaras presented titer against human-pathogenic serovars (icterohaemorrhagiae 82.61% and copenhageni 65.22%). The copenhageni variant presented the highest titers, with two (8.69%) animals presenting titers of 1:1600 and one (4.35%) animal presenting 1:800.

Generally single samples with high titers increase the suspicion of leptospirosis, although they are not definitive. In Brazil, serovars icterohaemorrhagiae and copenhageni are often related to the most severe leptospirosis cases in humans (Brazil—Technical Information, 2018). Rattus norvergicus, Mus musculus, and other rodents’ species serve as reservoirs for various pathogenic serovars, mainly copenhageni and icterohaemorrhagiae (Desvars-Larrive et al., 2020). These serovars identified in the sampled capybaras suggest they may serve as possible reservoirs of these serovars, being responsible for transmission to other animals, and for contamination of the environment.

Future studies should be done to confirm it. An important fact is that the animals seropositive to the grippotyphosa and hardjo serovars had contact with ruminants, shared food, and walked in the same area. This may justify how these animals became infected, since the hardjo serovar has been evidenced in cattle herds around the world with variable aspects of pathogenicity. In many countries, it has been recognized as a significant cause of failures and alterations in the reproductive parameters of cattle herds (Guedes et al., 2019). Serovar grippotyphosa is generally associated with goats and canids (Sessions and Greene, 2004).

Hematological and biochemical parameters of capybaras are scarce in the literature, and usually present a small number of samples, which may compromise the interpretation of the results. Therefore, laboratory results were compared among the groups sampled in this study. When seroreactive and nonseroreactive animals were compared, a statistically significant difference (p < 0.05) was observed in the biochemical analyses of ALP, creatinine, albumin, and globulins. These data corroborate the changes described in the literature for mammals affected by Leptospira spp., in which the primary lesion is vasculitis, ischemia located in the organs, resulting in renal tubular injury, necrosis, and hepatocellular damage (Adler and Moctezuma, 2010; Fraga et al., 2014; Sato and Coburn, 2017).

However, according to Santos (2011), only albumin concentration was below the reference range for the species. This hypoalbuminemia may be caused by Leptospira infection, or any other inflammatory condition. Hypoalbuminemia may also be attributed to gastrointestinal disease, and intestinal parasitism (Allison, 2012). Considering the sampled capybaras are free living animals and did not show any apparent clinical signs of the disease, the exact cause of hypoalbuminemia deserves a future investigation.

Conclusion

This study showed a high frequency of anti-Leptospira spp. antibodies detected in free-living capybaras of Federal District, Brazil. The capybaras had no clinical signs, but they had some laboratory changes that may be caused by the infection and deserves further investigation. The presence of Leptospira seroreactive animals shows that the bacterium is circulating in the urban environment of the Federal District and should be considered, since it can compromise public health.

Footnotes

Acknowledgment

The authors thank the Brasília Zoological Foundation for giving the space for the collection of samples.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

The authors thank National Council for Scientific and Technological Development (CNPq) and Federal Agency for the Support and Improvement of Higher Education (CAPES - Finance code 001) for their undergraduate and graduate scholarships grants, and the Decanate of Research and Innovation/University of BrasÚlia for financial assistance.

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