title: Xenodiagnosis on dogs with visceral leishmaniasis: Canine and sand fly aspects related to the parasite transmission.
abstract: One of the main limitations for the effective control of canine leishmaniasis in endemic areas is the difficulty in identifying infectious dogs. The objective of this study was to determine factors, related to dogs and to parasite detection in sand flies, which are associated with the positive xenodiagnosis of Leishmania infantum using the vector Lutzomyia longipalpis. The xenodiagnosis was performed in 50 owned dogs residing in endemic areas, which were divided into three different groups: G1-26 dogs proved to be infected and classified by severity of VL clinical signs on physical examination; G2-15 dogs proved to be infected and classified by severity of clinical signs and intensity of laboratory abnormalities; G3-nine dogs that were seropositive for anti-Leishmania IgG in ELISA tests. Parasite search in the sand flies after having fed on dogs in the xenodiagnosis was performed by both methodologies, PCR and dissection followed by microscopy. In G1, 58% (15/26) of dogs were able to transmit Leishmania to the vector, when parasite detection in sand flies were performed by PCR technique, 5 days after blood meal, whereas in G2, 53% (8/15) transmitted the parasite to the vector, however, confirmation was performed by direct observation of parasite through optical miscroscopy held 10 days after blood meal. Rate of infectiousness of dogs to sand flies was positively associated to severity of disease (p=0.042 and p=0.040), regardless the method used for clinical classification or for parasite detection in sand flies after xenodiagnosis. In G1 30% (3/10) of dogs with subclinical infection were infectious to the vector, while 80% (12/16) of dogs with clinical disease were also infectious. Even more, 17% (1/6) of dogs that had moderate disease were infectious to the sand flies, while 78% (7/9) of dogs with severe disease were infectious in G2. Still in G2, the proportion of sand flies infected (grade of infectiousness) was significantly lower (p=0.0098) when they fed on dogs with moderate disease (1%) in comparison with dogs with severe disease (38%). The dogs from G3 presented a rate of infectiousness of 11% (1/9), demonstrating that the indirect ELISA is not a good indicator of infectiousness and, therefore, should not be used as a confirmatory test for the euthanasia of dogs, as it is currently done in Brazil.
authors.affiliation: Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil; Multidisciplinary Center of Barra, Federal University of Bahia West (UFOB), Barra, Bahia, Brazil. Electronic address: jairomev@gmail.com.
authors.forename: Jairo Torres
authors.initials: JT
authors.lastname: Magalhães-Junior
authors.affiliation: Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil.
authors.forename: Tiago Feitosa
authors.initials: TF
authors.lastname: Mota
authors.affiliation: Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil.
authors.forename: Gabriela
authors.initials: G
authors.lastname: Porfirio-Passos
authors.affiliation: Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil; Department of Anatomy, Pathology and Veterinary Clinics, School of Veterinary Medicine and Zootechny (Departamento de Anatomia, Patologia e Clínicas Veterinárias, Escola de Medicina Veterinária e Zootecnia), Federal University of Bahia (UFBA), Salvador, Bahia, Brazil.
authors.forename: Daniela Farias
authors.initials: DF
authors.lastname: Larangeira
authors.affiliation: Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil; Department of Preventive Veterinary Medicine and Animal Production, School of Veterinary Medicine and Zootechny, UFBA, Brazil.
authors.forename: Carlos Roberto
authors.initials: CR
authors.lastname: Franke
authors.affiliation: Laboratory of Veterinary Infectious Diseases, Hospital of Veterinary Medicine (Laboratório de Infectologia Veterinária, Hospital de Medicina Veterinária), Federal University of Bahia (Universidade Federal da Bahia-UFBA), Avenida Adhemar de Barros, 500, Ondina, ZIP: 40170-110 Salvador, Bahia, Brazil; Department of Anatomy, Pathology and Veterinary Clinics, School of Veterinary Medicine and Zootechny (Departamento de Anatomia, Patologia e Clínicas Veterinárias, Escola de Medicina Veterinária e Zootecnia), Federal University of Bahia (UFBA), Salvador, Bahia, Brazil. Electronic address: barrouin@ufba.br.
authors.forename: Stella Maria
authors.initials: SM
authors.lastname: Barrouin-Melo
mesh_terms: D000818:Animals; D004198:Disease Susceptibility; D004283:Dog Diseases / Q000175:diagnosis / Q000469:parasitology*; D004285:Dogs; D004797:Enzyme-Linked Immunosorbent Assay / Q000662:veterinary; D007303:Insect Vectors / Q000502:physiology; D018314:Leishmania infantum / Q000502:physiology; D007898:Leishmaniasis, Visceral / Q000175:diagnosis / Q000469:parasitology / Q000635:transmission / Q000662:veterinary*; D011576:Psychodidae / Q000469:parasitology*
keywords: Canine leishmaniasis; Infectiousness; Infectivity; Phlebotomine; Xenodiagnosis