Spatial distribution of equine seroreagent to Leptospira spp. in Northeastern Brazil

Considering the importance of leptospirosis in both equine husbandry and public health, as well as the relevance of knowledge of current serogroup and the small number of studies addressing this disease in equines in Northeastern Brazil, the present study performed a serological survey of Leptospira spp. in a serum bank of 1,267 equines originating from 177 municipalities, located in four states in Northeastern Brazil: Ceará, Rio Grande do Norte, Paraíba and Pernambuco. The microscopic agglutination test (MAT) was used for diagnosis of leptospirosis using 24 serovars as antigens. The frequency of reagent equines was 29.7% (376/1,267), and 68.9% (122/177) of municipalities had at least one positive reaction. The serogroups reagent were Australis (37.2%), Icterohaemorrhagiae (29.3%), Tarassovi (9.6%), Sejroe (5.8%), Pomona (5.3%), Grippotyphosa (4.5%), Pyrogenes (2.4%), Bataviae (1.9%), Ballum and Hebdomadis (1.3%), Mini (0.5%), Celledoni, Shermani, and Javanica (0.3% each). There were significant statistical differences regarding sex and age, with a higher frequency in females (P= 0.014), and in animals ≥ 6 years (P=0.001). We concluded that seropositivity to Leptospira spp. is high in equines in Northeastern Brazil, with a predominance of serologic reactions to the Australis serogroup in the border areas between the states, and the Icterohaemorrhagiae serogroup in coastal areas or their vicinity. The high degree of seropositivity found points to the need to implement prophylactic strategies, both intraspecies infection prophylaxis and rodent control. We also recommended avoiding animal crowding and separating animals according to sex and age group during handling.