Identification of Leishmania spp. promastigotes in the intestines, ovaries and salivary glands of Rhipicephalus sanguineus actively infesting dogs

Authors: VIOL, MILENA - Sao Paulo State University (UNESP); Guerrero, Felicito; CESAR MIRANDA, BRUNO - Sao Paulo State University (UNESP); CONCEICAO COSTA, MONALLY - Sao Paulo State University (UNESP); HUDSON LOIOLA, SAULO - Sao Paulo State University (UNESP); DIAS DE MELO, GUILHERME - Sao Paulo State University (UNESP); HELENA DE SOUZA, APARECIDA - The Institute Adolfo Lutz; TAKAMI KANAMURA, CRISTINA - The Institute Adolfo Lutz; VALERIO GARCIA, MARCOS - Embrapa; ANDREOTTI, RENATO - Embrapa; MARCAL FELIX DE LIMA, VALERIA - Sao Paulo State University (UNESP); DENISE SARAIVA, KATIA - Sao Paulo State University (UNESP)

Submitted to: Parasitology Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/3/2016
Publication Date: 5/12/2016
Citation: Viol, M., Guerrero, F., Cesar Miranda, B., Conceicao Costa, M., Hudson Loiola, S., Dias De Melo, G., Helena De Souza, A., Takami Kanamura, C., Valerio Garcia, M., Andreotti, R., Marcal Felix De Lima, V., Denise Saraiva, K. 2016. Identification of Leishmania spp. promastigotes in the intestines, ovaries and salivary glands of Rhipicephalus sanguineus actively infesting dogs. Parasitology Research. 115:3479-3484.

Interpretive Summary: Sand flies are recognized as the major vector of canine visceral leishmaniasis. However, in some areas of Brazil where sand flies do not occur, this disease is found in humans and dogs. There has been speculation that ticks might play a role in transmission of this disease because the DNA of the pathogen that causes the disease, Leishmania spp., has been found in ticks. We dissected ticks that were feeding upon Leishmania-infected dogs from two cities of Brazil and tested the intestines, ovaries, and salivary glands for Leishmania. We used immunohistochemistry (IHC) to directly test for the Leishmania organisms and diagnostic real-time polymerase chain reaction (PCR) to test for Leishmania DNA. IHC results showed Leishmania spp. in 98%, 14%, and 8% of the intestines, ovaries, and salivary glands, respectively. Real-time PCR showed that 89%, 41% and 33% of the tick intestine, ovary, and salivary glands, respectively, were positive for Leishmania spp DNA. This was the first study that tested dissected tick organs for Leishmania and our results showed there is need for clarification of the role of ticks in the transmission of canine visceral leishmaniasis.

Technical Abstract: Sand flies are recognized as the major vector of canine visceral leishmaniasis. However, in some areas of Brazil where sand flies do not occur, this disease is found in humans and dogs. There has been speculation that ticks might play a role in transmission of canine visceral leishmaniasis and the DNA of Leishmania spp. has been reported in whole ticks. We investigated the presence of Leishmania spp. promastigotes in the intestines, ovaries, and salivary glands of Rhipicephalus sanguineus ticks collected from tick-infested dogs in two cities of Brazil. We used 66 dogs that tested positive and 33 that tested negative for Leishmania spp. according to direct cytological examination assays. Ten ticks were collected from each dog and dissected to collect the intestines, ovaries and salivary glands for immunohistochemistry (IHC) and diagnostic real-time polymerase chain reaction (PCR). IHC results showed Leishmania spp. in 98%, 14%, and 8% of the intestines, ovaries, and salivary glands, respectively. Real-time PCR showed that 89%, 41% and 33% of the tick intestine, ovary, and salivary glands, respectively, were positive for Leishmania spp. The verification of promastigotes of Leishmania spp. by two independent techniques in ticks collected from these urban region dogs showed there is need for clarification of the role of ticks in the transmission of canine visceral leishmaniasis in Brazil.