Detection of Leishmania infantum by PCR, serology and cellular immune response in a cohort study of Brazilian dogs

Abstract

The sensitivity and specificity of PCR, serology (ELISA) and lymphoproliferative response to Leishmania antigen for the detection of Leishmania infantum infection were evaluated in a cohort of 126 dogs exposed to natural infection in Brazil. For PCR, Leishmania DNA from bone-marrow was amplified with both minicircle and ribosomal primers. The infection status and time of infection of each dog were estimated from longitudinal data. The sensitivity of PCR in parasite-positive samples was 98 %. However, the overall sensitivity of PCR in post-infection samples, from dogs with confirmed infection, was only 68 %. The sensitivity of PCR varied during the course of infection, being highest (78-88 %) 0-135 days postinfection and declining to around 50 % after 300 days. The sensitivity of PCR also varied between dogs, and was highest in sick dogs. The sensitivity of serology was similar in parasite-positive (84 %), PCR-positive (86 %) and post-infection (88 %) samples. The sensitivity of serology varied during the course of infection, being lowest at the time of infection and high (93-100 %) thereafter. Problems in determining the specificity of serology are discussed. The sensitivity and specificity of cellular responsiveness were low. These data suggest that PCR is most useful in detecting active or symptomatic infection, and that serology can be a more sensitive technique for the detection of all infected dogs.

Serological, parasitological and molecular tests for canine visceral leishmaniosis diagnosis in a longitudinal study

“…Regarding the ELISA test, the lower sensitivity (43.6%) and specificity (86.3%) observed in our study, in comparison with others (QUINNELL et al, 1997(QUINNELL et al, , 2001REITHINGER et al, 2002;ALMEIDA et al, 2005;ROSÁRIO et al, 2005), may have been because we included all the samples collected over the entire period and not just single samplings. Methodological differences, such as the antigen and reagents used, are likely to have contributed to this difference as well.…”

“…At the beginning, parasitological examinations and PCR are more sensitive; with the evolution of the infection, symptomatic dogs present an increase in serum antibody levels and parasite load (QUINNELL et al, 2001(QUINNELL et al, , 2003. In our study, despite the effect of the sample size, this effect was observed, with greater positivity according to parasitological examinations and PCR in the first nine months, which subsequently decreased.…”

“…These studies involved different designs with different diagnostic techniques (QUINNELL et al, 2001(QUINNELL et al, , 2003(QUINNELL et al, , 2013FRANÇA-SILVA et al, 2005;OLIVA et al, 2006;CARSON et al, 2009;GRIMALDI et al, 2012a;COURA-VITAL et al, 2013), and this makes comparisons with the data presented here more difficult.…”

“…At the beginning of the infection, before seroconversion or the onset of clinical signs, parasitological examinations and PCR are more sensitive; however, with disease progression, the variation among individuals and their ability to control the disease leads to higher seroconversion and parasitemia, and the detection of positive dogs tends to be best performed by serological and parasitological examinations (QUINNELL et al, 2001;OLIVA et al, 2006).…”

A serological study of exposure to arthropod-borne pathogens in dogs from northeastern Spain

“…Unsurprisingly, statistically significant differences were found between seroprevalences in clinically healthy (15%) and sick dogs (49.3%) further supporting the importance of Li infection as a cause of clinical disease in dogs in the Mediterranean basin. It is well known that the detection of Li antibodies correlates with clinical disease in dogs with leishmaniasis [30,37]. Furthermore, higher seroprevalences were found in dogs from Tarragona (51.7%) and Barcelona (65%) perhaps due to the fact that there were higher proportions of sick dogs compared to Mallorca in the samples obtained in these cities.…”