Are vector-borne pathogen co-infections complicating the clinical presentation in dogs?

Abstract

BackgroundInfection by two or more canine vector-borne disease (CVBD)-causing pathogens is common in subtropical and tropical regions where vectors are plentiful. Co-infections may potentiate disease pathogenesis, thereby altering clinical manifestations typically associated with singular infections. These factors complicate diagnosis, treatment and can adversely influence prognosis if the practitioner fails to suspect, document, and treat each concurrent infection. The spectrum of pathogens co-infecting dogs may change over time in a given practice location due to the rapid expansion of arthropods and their associated vectored agents, and international transit among pets and wild animals. This applies, for example, to Dirofilaria immitis and Leishmania infantum, the distributions of which have expanded from northern to southern Italy, and vice versa, respectively. Indeed, mixed infections by D. immitis and L. infantum have only been reported once in Italy, probably due to the fact that competent vectors for these infections do not usually occur in the same geographical areas. Thus, information that would help practitioners to identify clinical presentations in dogs co-infected by D. immitis and L. infantum and other CVBD-causing pathogens is scant.FindingsThis manuscript describes the clinical history and physical examination of findings for 7 CVBD co-infected dogs that were examined because of a spectrum of clinical signs. Five dogs were co-infected with L. infantum and Ehrlichia canis, one dog with L. infantum, E. canis and D. immitis and the remaining dog with L. infantum and D. immitis.ConclusionsThe clinical signs and haematological abnormalities associated with the diagnostic evaluation and treatment of these dogs is discussed. Also, the usefulness of bone marrow specimens for the molecular diagnosis of CVBDs and for the enhanced monitoring of treatment response is emphasized.

Evaluation of blood and bone marrow in selected canine vector-borne diseases

“…Since the above-mentioned pathogens are transmitted by arthropod vectors, they are commonly referred to as canine vector-borne diseases (CVBDs); CVBDs are widely distributed and highly prevalent throughout much of the world, including the southern Mediterranean region [6]. Furthermore, multiple canine vector-borne pathogens can simultaneously infect the same host, thereby causing co-infections, which may exacerbate disease severity and alter clinical and pathological scenarios associated with single infections, thus complicating diagnosis, treatment and prognosis in co-infected dogs [7]. The presence of vectorborne pathogens in the BM may induce substantial alterations in erythrocyte, granulocyte, monocyte, lymphocyte and thrombocyte numbers and/or function.…”

It shouldn’t happen to a dog … or a veterinarian: clinical paradigms for canine vector-borne diseases

“…There are several reasons for this; the clinical signs associated with vector-borne diseases in dogs are frequently non-specific, and co-infections -another hallmark of CVBDs -may alter the clinical picture typically associated with a single pathogen [45,46] While the development of in-house diagnostic kits has been a welcome addition to the diagnostic armoury, these are generally available for only the most common CVBDs, and a significant diagnostic challenge remains for pathogens that are less commonly associated with dogs, yet are frequently zoonotic (Table 3). Not only is detection of these organisms currently restricted to relatively few research laboratories worldwide, stealth organisms also require advanced diagnostic methodologies and complex protocols for successful identification [47].…”

Oxidative status and lipid profile in mono- and co-infection with canine monocytic ehrlichiosis

“…Although dogs may be infected with a single pathogen, multiple vector-borne diseases can occur sequentially or simultaneously when dogs are exposed to vectors infected with different organisms (4). Co-infections with vector-borne diseases are reported to cause more severe pathological effects than mono-infections (9,14). However, a large proportion of studies in dogs have been carried out by evaluating vector-borne diseases separately.…”

“…Some vectors, especially ticks, can act as vectors for more than one infectious agent, causing co-infections (3). Co-infection with canine vector-borne diseases appears to be common in endemic regions and potentially complicates the diagnosis and management of cases (9,14). The risk of acquiring vector-borne co-infections may depend on the prevalence of multi-infected vectors.…”

“…Dogs are reservoir hosts for a wide spectrum of vector-borne pathogens (9,28). Although dogs may be infected with a single pathogen, multiple vector-borne diseases can occur sequentially or simultaneously when dogs are exposed to vectors infected with different organisms (4).…”