TDK conference 2008

The significance of vector-borne parasitic diseases worldwide increases and in connection with that, also infection caused by Dirofilaria repens emerges more frequently in Hungarian dog population. This filarioid nematode lives in the subcutaneous tissue of carnivores, and similarly to Dirofilaria immitis, produces first stage larvae (microfilariae) that are released into the bloodstream of the host.

Data show that 14 % of the dogs living in Hungary are infected with this parasite. The presence of D. repens is mostly revealed only by coincidence, and in most cases veterinarians do not assign much importance to the fact of the infection, because the parasite was formerly thought to be apathogenic. But then subsequent surveys have proven that D. repens should be preferably described as “potentially pathogen”, which gives a justification of further examinations on this nematode. The magnitude of the disease is increased also by two other factors: the fact that D. repens is a zoonotic worm and the importance of the ability to differentiate between D. repens and D. immitis.

There are barely few publications about the clinical signs of subcutaneous dirofilariosis. Moreover most of these studies describe only individual cases.

My survey set forth to examine the clinical laboratory findings of dogs infected with D. repens, so as to get a more precise view of the pathological alterations induced by the parasite. In addition the practical features of two diagnostical methods, those of the modified Knott’s method and the species specific PCR were investigated. Between October 2007 and August 2008, 550 blood samples were examined by modified Knott’s method and 75 of these by PCR technique. The prevalence of infection caused by D. repens was determined to be 13,6 % for the investigated dog population. The comparative examination of the hematological and serum biochemical profiles of the dogs revealed leukocytosis, eosinophilia, higher liver enzyme values, higher urea value and thrombocytopenia in the infected group compared to those not infected.

About the diagnostic methods it can be stated that nevertheless the PCR has a very high specificity, its sensitivity is not as high as of the modified Knott’s method. In accordance to these the most reliable diagnosis can be achieved by the combination of the two techniques.