Association between canine leishmaniosis and Ehrlichia canis co-infection: a prospective case-control study

Charalampos Attipa,Chris Helps,Kostas Papasouliotis,Laia Solano-Gallego,Scott Carver,David Morris,Séverine Tasker,Francesca Soutter

doi:10.1186/s13071-018-2717-8

Abstract

BackgroundIn the Mediterranean basin, Leishmania infantum is a major cause of disease in dogs, which are frequently co-infected with other vector-borne pathogens (VBP). However, the associations between dogs with clinical leishmaniosis (ClinL) and VBP co-infections have not been studied. We assessed the risk of VBP infections in dogs with ClinL and healthy controls.MethodsWe conducted a prospective case-control study of dogs with ClinL (positive qPCR and ELISA antibody for L. infantum on peripheral blood) and clinically healthy, ideally breed-, sex- and age-matched, control dogs (negative qPCR and ELISA antibody for L. infantum on peripheral blood) from Paphos, Cyprus. We obtained demographic data and all dogs underwent PCR on EDTA-blood extracted DNA for haemoplasma species, Ehrlichia/Anaplasma spp., Babesia spp., and Hepatozoon spp., with DNA sequencing to identify infecting species. We used logistic regression analysis and structural equation modelling (SEM) to evaluate the risk of VBP infections between ClinL cases and controls.ResultsFrom the 50 enrolled dogs with ClinL, DNA was detected in 24 (48%) for Hepatozoon spp., 14 (28%) for Mycoplasma haemocanis, 6 (12%) for Ehrlichia canis and 2 (4%) for Anaplasma platys. In the 92 enrolled control dogs, DNA was detected in 41 (45%) for Hepatozoon spp., 18 (20%) for M. haemocanis, 1 (1%) for E. canis and 3 (3%) for A. platys. No Babesia spp. or “Candidatus Mycoplasma haematoparvum” DNA was detected in any dog. No statistical differences were found between the ClinL and controls regarding age, sex, breed, lifestyle and use of ectoparasitic prevention. A significant association between ClinL and E. canis infection (OR = 12.4, 95% CI: 1.5–106.0, P = 0.022) was found compared to controls by multivariate logistic regression. This association was confirmed using SEM, which further identified that younger dogs were more likely to be infected with each of Hepatozoon spp. and M. haemocanis, and dogs with Hepatozoon spp. were more likely to be co-infected with M. haemocanis.ConclusionsDogs with ClinL are at a higher risk of co-infection with E. canis than clinically healthy dogs. We recommend that dogs diagnosed with ClinL should be tested for E. canis co-infection using PCR.

Highlights

In the Mediterranean basin, Leishmania infantum is a major cause of disease in dogs, which are frequently co-infected with other vector-borne pathogens (VBP)
Study design and populations Through a case-control study design, we evaluated if dogs with clinical leishmaniosis (ClinL) are at a greater risk than healthy controls for VBP infections including Babesia spp., “Candidatus Mycoplasma haematoparvum” (CMhp), Ehrlichia/Anaplasma spp., Hepatozoon spp., and M. haemocanis
Eligible cases included dogs naturally infected with ClinL which were diagnosed based on the presence of clinical signs associated with L. infantum infection, and enrolled in the final statistical analysis if they were positive on both quantitative PCR on peripheral blood and serum antibodies for L. infantum

Summary

Introduction

In the Mediterranean basin, Leishmania infantum is a major cause of disease in dogs, which are frequently co-infected with other vector-borne pathogens (VBP). Dogs with clinical leishmaniosis (ClinL) are often concurrently infected with multiple pathogens, which are often vector-borne, such as Ehrlichia canis, the causative agent for canine monocytic ehrlichiosis, Anaplasma platys, Babesia vogeli and Hepatozoon canis, resulting in an unpredictable incubation period, atypical clinical outcome and poorer prognosis, compared with dogs infected with L. infantum alone [7, 8]. These vector-borne pathogens (VBP) are transmitted by different vectors to dogs, such as Rhipicephalus sanguineus (for A. platys, E. canis and H. canis), Ixodes ricinus (for Anaplasma phagocytophilum), Ixodes spp. ticks (for Borrelia burgdorferi) and mosquitoes (for Dirofilaria immitis) [9]. While it has been suggested that leishmaniosis is a predisposing factor for infection with other pathogens in dogs, this has not been investigated to date [8, 10]

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