Comparison of different diagnostic tests in dogs uninfected and naturally infected with visceral leishmaniasis

Abstract

Abstract:Uninfected dogs (n = 10) and those naturally infected with leishmaniasis (n = 10) were subjected to several diagnostic tests, namely: hemoculture, polymerase chain reaction (PCR) of hemoculture, indirect immunofluorescence (RIFI), cytological examination of lymph node aspirate, culture of lymph node aspirate and PCR of lymph node aspirate. RIFI -followed by PCR of lymph node aspirate culture -presented more positive results in infected dogs than in uninfected ones. In infected animals, RIFI was more effective than PCR of lymph node aspirate culture. There was no statistical difference in positivity between RIFI and hemoculture; lymph node aspirate culture/cytological examination of lymph node aspirate and PCR of hemoculture; and between PCR of lymph node aspirate culture and PCR of hemoculture. All infected and uninfected animals had positive and negative results in at least one test. In conclusion, the association of several tests improves the efficacy of canine visceral leishmaniasis diagnosis.Key words: diagnosis, dogs, visceral leishmaniasis. Visceral leishmaniasis is a chronic infectious disease provoked by the protozoan Leishmania chagasi (in the Americas) and Leshmania infantum (in Europe and Mediterranean regions) that affects the reticuloendothelial system involving the spleen, liver, bone marrow and lymph nodes. Leishmaniasis is found throughout Brazil and has a great impact on public health (1-3). Short CommuniCationThe presence of a susceptible population, infected reservoirs and abundant vectors constitute the basic requirements for the development of the disease. The Brazilian Program for Visceral Leishmaniasis Surveillance and Control monitors the disease by treating human cases, controlling vectors and euthanizing seropositive infected dogs. Seropositive infected animals are considered to be a source of transmission regardless of the presence of clinical signs (2, 4).Theoretical studies based on mathematical models of transmission of Leishmania infantum infection to humans showed that euthanasia of dogs can be less effective than other control strategies such as the use of insecticides and vaccination (4). Therefore, in order to prevent the infection in dogs and consequently the vector-parasite transmission, and thus reduce the number of cases of human leishmaniasis, in 2003, a canine vaccine for visceral leishmaniasis -Leishmune® produced by Fort Dodge Health Animal Ltd. -came to be commercialized in Brazil (3,(5)(6)(7)(8).In animals immunized with this vaccine and subsequently challenged, both in field and experimental laboratory settings, the induced cellular immune response was demonstrated by flow cytometry, through measurement of CD4, CD8 and CD215,9 and by intradermoreaction (IDR) (6). A study carried out during two years demonstrated, by polymerase chain reaction (PCR) of blood and lymph nodes and intradermal reaction, that vaccination provided significant protection against leishmaniasis in 550 dogs from endemic and peri-endemic areas (6). The concomitant reduction of cases of l...

Canine leishmaniasis in an endemic region, Northeastern Brazil: a comparative study with four groups of animals

“…The positivity of animals observed here was higher than those obtained in epidemiological surveys carried out in other states, such as Bahia (Rodrigues et al 2020 ), Mato Grosso (Carvalho et al 2020 ), Minas Gerais (Castro-Júnior et al 2014 ), and São Paulo (Julião et al 2007 ). These results may be related to the diversity of biological samples and laboratory tests used in our study, which may allow an increase in the rates of sensitivity for the LC diagnosis (Sassaki et al 2011 ; Braz et al 2016 ).…”