Prevalence of Leptospira serogroups in buffaloes from the Brazilian Amazon

Abstract

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.

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

“…The other study by employing three serovars (Copenhageni, Icterohaemorrhagiae, and Lai) representing the Icterohaemorrhagiae serogroup and two serovars (Kaup and Tarassovi) representing Tarassovi serogroup in MAT with endpoint titration of cattle serum samples from different geographical locations of India revealed that there was 1-2-fold titer variation on the reactivity of different homologous serovars within specific serogroup (unpublished data). A similar observation was also earlier reported from other endemic countries[34].…”

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

“…Despite in the literature there are no reports of evaluate the effectiveness of the ranking technique in a controlled way, when the infectious serogroup is known (experimental inoculation), this technique were used in MAT serology for random herds of cattle, buffaloes, sheep, horses and other species (5)(6)(7)(8).…”

“…First, it is worth noting that the ranking technique, when used, does not negate any sample that was reactive for at least one antigen of the MAT panel, regardless of the titer found, and if there was a tie between antigens from different serogroups, the sample remains positive for leptospirosis and can be considered for calculating the general prevalence of the disease within a herd; however, it is not possible to predict the most likely infecting serogroup for this sample, so it is disregarded only to stipulate the serogroups prevalent in a herd (5)(6)(7)(8).…”

“…Nevertheless, in this study, the serology of the animals was performed 30 days after inoculation, when the disease was in the chronic phase (13), and cross reactions were also found. This situation is frequently observed in epidemiological studies, wherein random sampling, it is not possible to establish which phase of the disease the animal is in (5)(6)(7)(8).…”

“…A general scheme for how the ranking technique can be used in MAT for a herd is shown in Figure 1. This technique can be very useful for epidemiological studies, as it seems to reduce paradoxical reactions, being used both for herds (5)(6)(7)(8) and for humans (9); however, the ability of this technique to identify the presumptive infecting serogroup, namely, the most likely, has not been examined. Thus, the aim of this study was to evaluate the usefulness of the ranking technique for predicting the most likely infecting serogroup with the MAT carried out with serum from experimentally infected hamsters.…”