Asymptomatic dogs are highly competent to transmit Leishmania (Leishmania) infantum chagasi to the natural vector

Autor(es)

Laurenti, Marcia Dalastra ^[1] ; Rossi, Claudio Nazaretian ^[2] ; Ribeiro da Matta, Vania Lucia ^[1] ; Tomokane, Thaise Yumie ^[1] ; Pereira Corbett, Carlos Eduardo ^[1] ; Costa Secundino, Nagila Francinete ^[3] ; Paulocci Pimenta, Paulo Filemon ^[3] ; Marcondes, Mary ^[4]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Sch Med, Lab Pathol Infect Dis, Sao Paulo - Brazil

^[2] Univ Sao Paulo, Sch Vet Med, Dept Clin, Sao Paulo - Brazil

^[3] Fiocruz MS, Ctr Pesquisas Rene Rachou, Lab Med Entomol, Belo Horizonte, MG - Brazil

^[4] Sao Paulo State Univ, Coll Vet Med, Dept Clin Surg & Anim Reprod, Aracatuba, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: Veterinary Parasitology; v. 196, n. 3-4, p. 296-300, SEP 23 2013.
• Citações Web of Science: 62

Resumo

We evaluated the ability of dogs naturally infected with Leishmania (Leishmania) infantum chagasi to transfer the parasite to the vector and the factors associated with transmission. Thirty-eight infected dogs were confirmed to be infected by direct observation of Leishmania in lymph node smears. Dogs were grouped according to external clinical signs and laboratory data into symptomatic (n = 24) and asymptomatic (n = 14) animals. All dogs were sedated and submitted to xenodiagnosis with F1-laboratory-reared Lutzomyia longipalpis. After blood digestion, sand flies were dissected and examined for the presence of promastigotes. Following canine euthanasia, fragments of skin, lymph nodes, and spleen were collected and processed using immunohistochemistry to evaluate tissue parasitism. Specific antibodies were detected using an enzyme-linked immunosorbent assay. Antibody levels were found to be higher in symptomatic dogs compared to asymptomatic dogs (p = 0.0396). Both groups presented amastigotes in lymph nodes, while skin parasitism was observed in only 583% of symptomatic and in 35.7% of asymptomatic dogs. Parasites were visualized in the spleens of 66.7% and 71.4% of symptomatic and asymptomatic dogs, respectively. Parasite load varied from mild to intense, and was not significantly different between groups. All asymptomatic dogs except for one (93%) were competent to transmit Leishmania to the vector, including eight (61.5%) without skin parasitism. Sixteen symptomatic animals (67%) infected sand flies; six (37.5%) showed no amastigotes in the skin. Skin parasitism was not crucial for the ability to infect Lutzomyia longipalpis but the presence of Leishmania in lymph nodes was significantly related to a positive xenodiagnosis. Additionally, a higher proportion of infected vectors that fed on asymptomatic dogs was observed (p = 0.0494). Clinical severity was inversely correlated with the infection rate of sand flies (p = 0.027) and was directly correlated with antibody levels (p = 0.0379). Age and gender did not influence the transmissibility. Our data show that asymptomatic dogs are highly infective and competent for establishing sand fly infection, indicating their role in maintaining L. (L.) infantum chagasi cycle as well as their involvement in VL spreading in endemic areas. (C) 2013 Elsevier B.V. All rights reserved. (AU)

• Processo FAPESP: 04/07965-2 - Avaliacao da imunidade humoral e celular em caes naturalmente infectados com leishmania (l.) chagasi e sua correlacao com a transmissibilidade para o vetor.
• Beneficiário: Marcia Dalastra Laurenti
• Modalidade de apoio: Auxílio à Pesquisa - Regular