Correlations between peripheral parasite load and common clinical and laboratory alterations in dogs with visceral leishmaniasis

Abstract

(2016) Correlations between peripheral parasite load and common clinical and laboratory alterations in dogs with visceral leishmaniasis. Preventive Veterinary Medicine, 132 . pp. 83-87. Permanent WRAP URL:http://wrap.warwick.ac.uk/82952 Copyright and reuse:The Warwick Research Archive Portal (WRAP) makes this work by researchers of the University of Warwick available open access under the following conditions. Copyright © and all moral rights to the version of the paper presented here belong to the individual author(s) and/or other copyright owners. To the extent reasonable and practicable the material made available in WRAP has been checked for eligibility before being made available.Copies of full items can be used for personal research or study, educational, or not-for-profit purposes without prior permission or charge. Provided that the authors, title and full bibliographic details are credited, a hyperlink and/or URL is given for the original metadata page and the content is not changed in any way. Intensity of peripheral parasite infection has an important role in the transmission of 25Leishmania spp. from one host to another. As parasite load quantification is still an expensive 26 procedure to be used routinely in epidemiological surveillance, the use of surrogate predictors may be 27 an important asset in the identification of dogs with high transmitting ability. The present study 28 examined whether common clinical and laboratory alterations can serve as predictors of peripheral 29 parasitism in dogs naturally infected with Leishmania spp. Thirty-seven dogs were examined in order 30 to establish correlations between parasite load (PL) in multiple peripheral tissues and common clinical 31 and laboratory findings in canine visceral leishmaniasis (CVL). Quantitative polymerase chain reaction 32 was employed to determine PL in conjunctival swabs, ear skin, peripheral blood and buffy coat. 33Additionally, a series of hematological, biochemical and oxidative stress markers were quantified. 34Correlations between net peripheral infection and severity of clinical alterations and variation in 35 laboratory parameters were assessed through a new analytical approach, namely Compressed Parasite 36Load Data (CPLD), which uses dimension reduction techniques from multivariate statistics to 37 summarize PL across tissues into a single variable. The analysis revealed that elevation in PL is 38 positively correlated with severity of clinical sings commonly observed in CVL, such as skin lesions, 39 ophthalmic alterations, onycogriphosis, popliteal lymphadenomegaly and low body mass. Furthermore, 40 increase in PL was found to be followed by intensification of non-regenerative anemia, neutrophilia, 41 eosinopenia, hepatic injury and oxidative imbalance. These results suggest that routinely used clinical 42 and laboratory exams can be predictive of intensity of peripheral parasite infection, which has an 43 important implication in the identification of dogs with high transmitting ability. 44 45

Improving the reference standard for the diagnosis of canine visceral leishmaniasis: a challenge for current and future tests

“…More recently, molecular techniques have allowed the detection of infection in animals that are seronegative. 14 , 17 This more sensitive form of detecting asymptomatic infection can contribute to better understanding of the dynamics of transmission and the lack of efficacy in the measures for CVL control that are currently based on the application of serological tests. That is a relevant point because these dogs, although asymptomatic, may act as competent reservoirs.…”

“… 11 , 12 , 13 Symptomatic animals also present a higher parasite load, allowing its detection in peripheral blood and tissues through molecular diagnosis methods. 14 …”

Biomarkers Associated With Leishmania infantum Exposure, Infection, and Disease in Dogs

“…Neutrophilia is also common in dogs with CanL (Ciaramella et al, 1997 ; Koutinas et al, 1999 ; Reis et al, 2006a ; Paltrinieri et al, 2010 ; Nicolato et al, 2013 ; Meléndez-Lazo et al, 2018 ), and may be due to the inflammatory response resulting from the presence of parasites in multiple organs (Torrecilha et al, 2016 ). Leishmania infantum infection causes oxidative stress [i.e., a disruption in the normal balance between the production of reactive oxygen species (ROS) and antioxidant defenses] of canine neutrophils.…”

“…Leishmania infantum infection causes oxidative stress [i.e., a disruption in the normal balance between the production of reactive oxygen species (ROS) and antioxidant defenses] of canine neutrophils. The release of ROS from phagocytes present in inflammatory sites, leads to the consumption of antioxidant compounds (Torrecilha et al, 2016 ), representing a mechanism use by the parasite to evade the immune system. In fact, dogs presenting clinical signs have reduced antioxidant levels and increased levels of oxidants with enhanced lipid peroxidation (Heidarpour et al, 2012 ; Almeida et al, 2017 ).…”

Mathematical Modelling Using Predictive Biomarkers for the Outcome of Canine Leishmaniasis upon Chemotherapy

“…Dogs are susceptible to the development of high parasitic loads, playing a key role in the transmission cycle of L. infantum via phlebotomine sand flies in endemic areas [5,6]. Higher parasite loads in dogs are related to more severe clinical disease [7] and higher infectiousness to sand flies [5]. As full-blown disease is associated with active infection [8], efficacy of CanL treatment should be primarily centered in its capability of reducing L. infantum load.…”