Case Studies of Severe Microfilaremia in Four Dogs Naturally Infected With Dirofilaria repens as the Primary Disease or a Disease Complicating Factor

Abstract

Subcutaneous dirofilariosis in dogs, caused by Dirofilaria repens, is an underdiagnosed disease, now recognized for its zoonotic potential, and growing distribution and prevalence across Europe and Asia. Our understanding of the pathogenicity in human and canine host remains unclear, but case reports suggest that microfilariae (Mf) as well as adult D. repens may directly cause internal organs damage or may be a factor complicating the course of other ailments. The purpose of the study was to report high Mf in dogs and to discuss potential relevance with co-morbidity. Our data from a modified Knott's test performed on 62 infected dogs indicate that the median Mf count in D. repens infections is 675 Mf/ml and we consider microfilaremia above 10,000 Mf/ml as high intensity. This collection of case reports discusses 4 cases of high intensity D. repens microfilaremia in companion dogs; one presenting pathology from a very high intensity of adult D. repens with post-treatment complications, and 3 dogs in which high microfilaremia was detected incidentally during the management of other primary illnesses. To our knowledge this report describes the highest D. repens microfilaremia ever detected in a dog, at 178,000 Mf/ml. The issue of high microfilaremic infections in dogs is poorly studied and there is growing need to identify the presentation and understand the mechanisms of associated pathogenesis in the host-parasite relationship.

Human and Animal Dirofilariasis in Southeast of France

“…On the contrary to this, D. repens infestation is often asymptomatic [ 53 ]. However, fatal outcomes of this diseases were observed in D. repens infestation, due to the massive release of the filarial endosymbiotic bacterium Wolbachia after microfilaricidal treatment [ 54 ]. Hence, in order to avoid fatal outcomes, these complications of antifilarial treatment have to be carefully considered while treating dirofilariasis [ 50 , 51 , 54 ].…”

Selection of New Diagnostic Markers for Dirofilaria Repens Infections With the Use of Phage Display Technology

“…A recent study shows that D. repens infection leads to anemia and a state of chronic stress response that likely affects antibodies' production 35 . It has also been reported that high micro laremia develops in dogs with immunode ciency-related conditions 36 . On the contrary, in dogs infected with Brugia pahangi, the IgG levels speci c for adult worm extract were highest in amicro laremic dogs 37 .…”

Cannabinoid oilwith gabapentin for the treatment of chronicneuropathic pain– case report

“…A blood smear revealed the presence of Dirofilaria repens microfilariae in the patient. In this dog, Dirofilaria repens infection was likely associated with underlying immunodeficiency, which may have predisposed susceptibility to parasitic infection (22).…”