Prevalence of Leptospira serogroups in buffaloes from the Brazilian Amazon

Molecular epidemiology of Leptospira spp. serogroup Sejroe associated with chronic bovine leptospirosis

Pathogenic bacteria Leptospira spp. are commonly associated with bovine leptospirosis, characterized chiefly by chronic and subclinical reproductive disorders. Strains from the Sejroe serogroup play a significant role in these chronic genital infections known as Bovine Genital Leptospirosis (BGL), which notably impact cattle health. This study aims to deepen our understanding of BGL by investigating the genetic diversity, geographical distribution, and specific anatomical sites of infection of the causative agents. Initially, uterine fragments and cervicovaginal mucus were collected from 47 cows and subjected to PCR targeting the lipL32 gene. Positive samples in lipL32-PCR (9 samples) underwent genotyping based on the secY gene. Subsequently, sequences were aligned with GenBank entries (108 sequences) and analyzed in silico. All nine sequences from this study were identified as L. interrogans with an identity >99 % to serogroup Sejroe reference strains (Norma and L53). In the broader analysis, the most prevalent species observed was L. borgpetersenii, followed by L. interrogans and L. santarosai. The haplotype network of L. interrogans revealed that haplogroups B and C exclusively included L. interrogans strains of genital origin, while haplogroup A encompassed strains from renal sources as well. These findings underscore the significance of the L. borgpetersenii genotype Hardjobovis and L. interrogans genotype Hardjoprajitno as the predominant circulating strains and highlight the existence of distinct haplogroups of pathogenic leptospires originating from genital sources. We advocate for the use of secY as an effective genetic marker for Leptospira spp. and stress the necessity for additional research prioritizing the genital tract. The outcomes of this study contribute to the development of improved control measures for chronic cattle diseases and provide valuable guidance for future investigations.

Prevalence and risk factors of bovine leptospirosis in the Ecuadorian Amazon

Background and Aim

Leptospirosis is an infectious zoonotic disease that significantly affects animal health, particularly the reproduction of ruminants. However, some aspects of epidemiology and clinical characteristics have not been clarified. This study aimed to estimate the prevalence and identify risk factors of leptospirosis in female bovines at reproductive age in the Ecuadorian Amazon rainforest.

Materials and Methods

A total of 213 bovines were studied in the Amazon province of Zamora Chinchipe, in which a microscopic agglutination test was used to diagnose a panel of eight serovars of Leptospira borgpetersenii (Sejroe) and Leptospira interrogans, Australis, Bataviae, Canicola, Tarassovi, Icterohaemorrhagiae, Wolffi, and Hardjo. An epidemiological survey was conducted to identify risk factors by animal and herd and clinical symptoms associated with Leptospira spp. infection; and blood samples were collected to determine the differences between seropositive and seronegative animals regarding hematocrit, hemoglobin (Hb), mean corpuscular Hb concentration, total red blood cell count, total platelet count, leukocytes, total proteins, creatinine, and ureic nitrogen.

Results

The prevalence of bovine leptospirosis was 12.21% (26/213), with positive reactions in the Australis, Sejroe, Bataviae, Canicola, and Tarassovi serovars. No variables were considered risk factors, nor clinical signs associated with the infection, nor were there differences in the hematological parameters between the seropositive and seronegative animals.

Conclusion

These findings indicate the persistence of Leptospira on cattle farms in the Ecuadorian Amazon and highlight the interaction between domestic and wild species. It is crucial to implement control measures and improvements in management practices under the One Health approach to reduce accidental infections from contact with wildlife; the awareness of farmers is essential for effective prevention.

Detection of Pathogenic Leptospira in Captive Chelonians (Kinosternon scorpioides-Linnaeus, 1766) in the Brazilian Amazon

Leptospirosis is a zoonosis of great importance for One Health. In this context, the Amazonian biome may harbor numerous hosts for Leptospira spp. that contribute to the maintenance of the pathogen in the environment. Some reptiles, such as chelonians, have been little studied in terms of their involvement with leptospires. The objective of this study was to detect Leptospira spp. DNA in Kinosternon scorpioides turtles kept in captivity in a region of the Brazilian Amazon. A total of 147 samples of blood (n = 40), cloacal fluid (n = 27), cloacal lavage (n = 40), and stomach (n = 40) were collected from 40 chelonians. After DNA extraction, the samples were subjected to amplification of a 331 base pair product of the 16S rRNA gene using the Lep1 and Lep2 primers. PCR products were Sanger sequenced, assembled, and subjected to online blast search and phylogenetic analysis. Of the animals tested, 40% (16/40, 95% confidence interval [CI]: 25-55) had at least one or two samples positive for Leptospira spp. Considering the total number of samples collected, 12.93% (19/147) were positive, being blood clots (27.5%; 11/40), followed by cloacal washings (10%; 4/40), cloacal fluid (11.11%; 3/27) and gastric washings (2.5%; 1/40). Of these, 11 samples were sequenced and showed 99% to 100% identity with Leptospira interrogans sequences, which was confirmed by phylogenetic analysis. This is the first study to detect pathogenic Leptospira DNA in chelonians in a region of the Brazilian Amazon. It has been concluded that K. scorpioides turtles in captivity have been exposed to pathogenic Leptospira.

Prevalence of anti-leptospiral antibodies and frequency distribution of Leptospira serovars in small ruminants in enzootic South Peninsular India

Background and Aim:

For understanding the epidemiology of leptospirosis, the confined abundance of several species of pathogenic leptospires and knowledge on the serovar(s) prevalent in the reservoir and carrier hosts may be a useful indicator of transmission to incidental/accidental hosts in a geographical niche. The present study was carried out to ascertain the frequency distribution of Leptospira serovars and the prevalence of anti-leptospiral antibodies in small ruminants (sheep and goats) in the epidemiological units (villages) in the coastal districts of enzootic regions in South Peninsular India.

Materials and Methods:

A total of 1167 serum samples (sheep n=299 and goats n=868) from apparently healthy animals, randomly collected from various epidemiological units were tested in microscopic agglutination test (MAT) using 18 reference Leptospira serovars antigens.

Results:

The overall seroprevalence of 40% (at 95% confidence intervals [CI]: 36.82-42.43) in small ruminants (44% [95% CI: 40.49-52.26] in sheep and 38% [95% CI: 34.96-41.41] in goats) was observed with the predominance of Icterohaemorrhagiae, Javanica, Australis, Hurstbridge, and Pyrogenes serogroup anti-leptospiral antibodies in the studied region. The Chi-squared test revealed that the presence of anti-leptospiral antibodies is significantly not independent (associated) across the administrative division (Chi-square=105.80, p<0.05) as well as for sheep (Chi-square=34.67, p<0.01) and goats (Chi-square=68.78, p<0.01). Among seropositive samples (n=462 reactors), the MAT was positive for more than one serovar in 73% of sheep (95/131) and 53% of goats (177/331), representing an overall 59% cross-reactive prevalence in small ruminants. The determined frequency distribution (varied among small ruminants) of the employed serovars representing major reactive serogroup was Icterohaemorrhagiae (29.87), Javanica (20.78), Australis (20.35), Hurstbridge (16.23), Pyrogenes (15.8), Djasmin (15.58), Bataviae (15.37), Autumnalis (14.5), Canicola (14.5), Hebdomadis (14.07), Shermani (13.64), Panama (13.42), Sejroe (12.77), etc.

Conclusion:

This study indicates alarmingly high seroprevalence of leptospirosis in small ruminants with existing endemicity in the studied region in South Peninsular India. Further, these prevalent serovars in the administrative division may be of use in the reference panels of antigens in the MAT in both humans and animal disease diagnostic laboratories for effective and timely diagnosis of leptospirosis and to combat the challenges in public health.

Leptospira infection among human-close-contact animals in different geographical areas in Vietnam

Leptospirosis is a neglected disease in Vietnam. Only a few studies have evaluated the status of Leptospira infection in both humans and animals. To our knowledge, this is the first serological survey of Leptospira in both domestic and wild animals, which may act as reservoirs of this agent. This study aimed to evaluate the seroprevalence of Leptospira in animals that are in close contact with humans in different geographical areas in Vietnam. Sera were collected from 1205 individual animals of six species, including buffaloes, cattle, cats, dogs, swine, and rats. The microscopic agglutination test (MAT) against 25 serovars of Leptospira spp. has been employed to detect serovars of Leptospira among the studied population. Overall, 44.2% of buffaloes, 24.9% of cattle, 10.2% of swine, 32.9% of dogs, 12.2% of cats, and 16% of rats were seropositive. A total of 17 different serovars were detected, of which serovars Hebdomadis and Canicola circulated in all the studied animal species. Variability of the predominant serovars circulating in animal species and in different geographical areas of Vietnam has been noted. We conclude that this study showed a high prevalence of Leptospira circulating in animals that are in close contact with humans, raising an alert of the important sources of pathogenic leptospires transmission to humans in Vietnam. These findings prove an imperative need for effective measures for disease prevention.

Isolation of an atypical Leptospira strain assigned to the Sejroe serogroup from a water buffalo in Brazil

The isolation of leptospires from buffaloes worldwide is still limited to a few strains. Thus, the aim of this study was to describe the first Leptospira isolate from buffalo urine, assigned to the Sejroe serogroup, which does not belong to the Wolffi subgroup, traditionally isolated in Brazil. A total of 244 urine samples of water buffaloes (Bubalus bubalis) raised in the Brazilian Amazon were subjected to bacteriological culturing and polymerase chain reaction (PCR) for the detection of leptospires. The obtained isolate was characterized by serogrouping using polyclonal antibodies, partial DNA sequencing, Hardjo-Bovis-specific PCR, multiple-locus variable-number tandem repeat analysis (MLVA/VNTR) and experimental infection in hamsters. PCR was performed on the urine samples; 11/244 were positive (4.5 %) for Leptospira, and only one isolate was recovered (0.4 %). Regarding characterization, the isolate was assigned to the Sejroe serogroup with high titers (12,800) for the Saxkoebing and Sejroe serovar antisera. The isolate was negative for Hardjo-Bovis-specific PCR, and the species Leptospira borgpetersenii was identified by DNA sequencing. The MLVA results showed that the VNTR profile of the isolate was 1-2-5, compatible with that of serovars Sejroe/Istrica. In the experimental infection in hamsters, the animals did not develop clinical signs, and no macroscopic lesions were observed on the organs at necropsy; however, the strain was detected in the kidneys, uterus, and testicles of the animals. The isolate described herein highlights infection by Sejroe strains that may be overlooked in buffaloes and that may be different from those normally isolated and used in serological studies.

Leptospira interrogans serogroup Pomona strains isolated from river buffaloes

At present, little is known regarding the prevalence of buffalo leptospirosis worldwide, especially with respect to which Leptospira strains may infect this animal species. Furthermore, most investigations into this disease in buffaloes have only been performed with serological studies. In Brazil, particularly in the Amazon, buffalo production is growing and is just as important as cattle production, although few studies have been performed on buffalo compared to cattle. Thus, the aim of this study was to isolate and characterise Leptospira strains from river buffaloes raised in the Brazilian Amazon region. We collected 109 kidney samples from slaughtered buffaloes raised in the Amazon Delta region of Brazil. The samples were analysed by bacteriological culture for the isolation of leptospires, and the obtained isolates were serologically and molecularly characterised by microscopic agglutination test (MAT), DNA sequencing and multiple locus variable-number tandem repeat analysis (MLVA). Five isolates were obtained, and in serogrouping analyses, these isolates were only reactive for the Pomona serogroup, with an observed titre of 25,600. The DNA sequencing results revealed that all the isolates belonged to the species Leptospira interrogans, and the MLVA results showed that the VNTR loci 4, 7 and 10 profile of all the isolates was 4-1-10. In this study, we observed that Pomona serogroup strains circulate in buffaloes in the Amazon, showing that in Brazil, buffaloes can be affected by Leptospira strains other than the Sejroe group, which are adapted to cattle.

Usefulness of the Ranking Technique in the Microscopic Agglutination Test (MAT) to Predict the Most Likely Infecting Serogroup of Leptospira

The microscopic agglutination test (MAT) used for the serological diagnosis of leptospirosis, as a robust and inexpensive method, is still the reality in many laboratories worldwide. Both the performance and the interpretation of the MAT vary from region to region, making standardization difficult. The prediction of the probable infecting serogroup using this test is indispensable for elucidating the epidemiology of the disease; however, in veterinary medicine, many studies consider any reaction detected with a titer of 100, which may ultimately overestimate some serogroups. Thus, the aim of this study was to evaluate the usefulness of the ranking technique for predicting the probable infecting serogroup identified by the MAT, eliminating cross reactions with other serogroups. Leptospira strains (12 samples) were inoculated in hamsters, and after 30 days, serology was performed by the MAT for these animals to confirm the infecting serogroup. Using the ranking technique, the probable infectious serogroup found with the MAT was the same as that in which the strains of inoculated leptospires belonged; additionally, the technique can be applied in epidemiological studies involving herds.

Prevalence of Leptospira serogroups in buffaloes from the Brazilian Amazon

Although Brazil has one of the largest buffalo populations in the Americas, buffalo leptospirosis is still poorly explored when compared to that in bovines; thus, the aim of this research was to carry out a large serological study for leptospirosis in this species in the Brazilian Amazon. For this, we collected 1,405 serum samples from buffaloes raised in the Amazon delta region, which is considered a major area of buffalo production in Brazil. The test used was a microscopic agglutination test (MAT) adopting 34 Leptospira antigens, some of which have never been tested for buffaloes in Brazil, including autochthonous strains; in total, 20 serogroups were evaluated. From the total of 1,405 serum samples, 894 (63.6%) reacted in the MAT to at least one of the 20 serogroups, and 511 (36.4%) did not react. The serogroups Sejroe, Autumnalis and Pomona were the most prevalent, with titres ranging from 100 to 12,800, and the autochthonous strains used were not significant in relation to the reference serovars. Leptospirosis in buffaloes seems to have a serological profile similar to leptospirosis in cattle, mainly due to the prevalence of the Sejroe serogroup; however, the results of this study suggested that in the Brazilian Amazon, Leptospira strains that are serologically distinct from the autochthonous strains isolated in the southeastern region of Brazil may be circulating in these animals. Other serovars could also be inserted into the panel of antigens used in MAT for serological studies on buffaloes.