title: Seroprevalence and seroincidence of Leptospira infection in dogs during a one-year period in an endemic urban area in Southern Brazil.
abstract: BACKGROUND
  Leptospirosis is a zoonosis that affects both humans and animals. Dogs may serve as sentinels and indicators of environmental contamination as well as potential carriers for Leptospira. This study aimed to evaluate the seroprevalence and seroincidence of leptospirosis infection in dogs in an urban low-income community in southern Brazil where human leptospirosis is endemic.
  
  
  METHODS
  A prospective cohort study was designed that consisted of sampling at recruitment and four consecutive trimestral follow-up sampling trials. All households in the area were visited, and those that owned dogs were invited to participate in the study. The seroprevalence (MAT titers ≥100) of Leptospira infection in dogs was calculated for each visit, the seroincidence (seroconversion or four-fold increase in serogroup-specific MAT titer) density rate was calculated for each follow-up, and a global seroincidence density rate was calculated for the overall period.
  
  
  RESULTS
  A total of 378 dogs and 902.7 dog-trimesters were recruited and followed, respectively. The seroprevalence of infection ranged from 9.3% (95% CI; 6.7 - 12.6) to 19% (14.1 - 25.2), the seroincidence density rate of infection ranged from 6% (3.3 - 10.6) to 15.3% (10.8 - 21.2), and the global seroincidence density rate of infection was 11% (9.1 - 13.2) per dog-trimester. Canicola and Icterohaemorraghiae were the most frequent incident serogroups observed in all follow-ups.
  
  
  CONCLUSIONS
  Follow-ups with mean trimester intervals were incapable of detecting any increase in seroprevalence due to seroincident cases of canine leptospirosis, suggesting that antibody titers may fall within three months. Further studies on incident infections, disease burden or risk factors for incident Leptospira cases should take into account the detectable lifespan of the antibody.
authors: Departamento de Medicina Veterinária, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors: Vivien Midori
authors: VM
authors: Morikawa
authors: Departamento de Medicina Veterinária, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors: Daniele
authors: D
authors: Bier
authors: Departamento de Medicina Veterinária, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors: Maysa
authors: M
authors: Pellizzaro
authors: Departamento de Microbiologia e Imunologia, Instituto de Biociências de Botucatu, Universidade Estadual Paulista, Botucatu, SP, Brazil.
authors: Leila Sabrina
authors: LS
authors: Ullmann
authors: Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, BA, Brazil.
authors: Igor Adolfo Dexheimer
authors: IA
authors: Paploski
authors: Instituto de Saúde Coletiva, Universidade Federal da Bahia, Salvador, BA, Brazil.
authors: Mariana
authors: M
authors: Kikuti
authors: Departamento de Higiene e Saúde Pública, Faculdade de Medicina Veterinária e Zootecnia, Universidade Estadual Paulista, Botucatu, SP, Brazil.
authors: Hélio
authors: H
authors: Langoni
authors: Departamento de Medicina Veterinária, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors: Alexander Welker
authors: AW
authors: Biondo
authors: Departamento de Medicina Veterinária, Universidade Federal do Paraná, Curitiba, PR, Brazil.
authors: Marcelo Beltrão
authors: MB
authors: Molento
mesh_terms: D000372:Agglutination Tests / Q000662:veterinary; D000818:Animals; D000907:Antibodies, Bacterial / Q000097:blood; D001938:Brazil / Q000453:epidemiology; D004283:Dog Diseases / Q000453:epidemiology* / Q000382:microbiology; D004285:Dogs; D005260:Female; D006801:Humans; D015994:Incidence; D007919:Leptospira / Q000145:classification* / Q000276:immunology; D007922:Leptospirosis / Q000453:epidemiology / Q000382:microbiology / Q000662:veterinary*; D008297:Male; D011446:Prospective Studies; D016036:Seroepidemiologic Studies
chemical_list: D000907:Antibodies, Bacterial