SUMMARY: Dirofilariasis represents a zoonotic mosaic, which includes two main filarial species (Dirofilaria immitisandD. repens) that have adapted to canine, feline, and human hosts with distinct biological and clinical implications. At the same time, bothD. immitisandD. repensare themselves hosts to symbiotic bacteria of the genusWolbachia, the study of which has resulted in a profound shift in the understanding of filarial biology, the mechanisms of the pathologies that they produce in their hosts, and issues related to dirofilariasis treatment. Moreover, because dirofilariasis is a vector-borne transmitted disease, their distribution and infection rates have undergone significant modifications influenced by global climate change. Despite advances in our knowledge ofD. immitisandD. repensand the pathologies that they inflict on different hosts, there are still many unknown aspects of dirofilariasis. This review is focused on human and animal dirofilariasis, including the basic morphology, biology, protein composition, and metabolism ofDirofilariaspecies; the climate and human behavioral factors that influence distribution dynamics; the disease pathology; the host-parasite relationship; the mechanisms involved in parasite survival; the immune response and pathogenesis; and the clinical management of human and animal infections.

The main objective of the present study was to evaluate the prevalence of canine obesity and obesity –related metabolic dysfunction (ORMD) in the obesogenic area in Spain. The prevalence of overweight/obesity among owners of obese pets was also evaluated. In the sample population studied (93 client-owned dogs), 40.9% of dogs presented obesity (body condition score (BCS), 7-9/9), 40.9% of dogs presented hypertension, 20.4% of dogs presented fasting hypertriglyceridemia, 20.4% fasting hypercholestrolemia, and 5.4% of dogs presented fasting hyperglycemia. The overall prevalence of ORMD was of 22.6%. Seventy eight percent of overweight/obese owners had overweight/obese dogs (P<0.001) including all dogs diagnosed with ORMD. In conclusion, in the studied obesogenic region of Spain the prevalence of canine obesity and ORMD were shown to be elevated and related to the presence of overweight/obesity in owners. All dogs with ORMD were owned by overweight/obese persons. These results provide new inputs for future studies highlighting the relationship between owner and pet obesity and indicating the need of further efforts to control and reduce obesity prevalence in both.

Heartworm disease caused by Dirofilaria immitis is a vector-borne disease that affects canids and felids, both domestic and wild, throughout the world. It is a chronic disease which causes vascular damage in pulmonary arteries, and in advanced stages, the presence of pulmonary hypertension and right-sided congestive heart failure can be evidenced. Moreover, pulmonary thromboembolism is caused by the death of the worms, which can be lethal for the infected animal. Furthermore, it is the causative agent of human pulmonary dirofilariosis, being a zoonotic disease. The aim of this review was to update the current epidemiological situation of heartworm in Europe in dogs, cats, wild animals, and vectors insects, and to analyse the factors that may have contributed to the continuous spread of the disease in the last decade (2012–2021). In Europe, the disease has extended to eastern countries, being currently endemic in countries where previously only isolated or imported cases were reported. Furthermore, its prevalence has continued to increase in southern countries, traditionally endemic. This distribution trends and changes are influenced by several factors which are discussed in this review, such as the climate changes, presence of vectors in new areas, the appearance of new competent vector species in the continent, increased movement of pets that travelled to or originated from endemic countries, the urbanisation of rural areas leading to the formation of so-called “heat islands”, or the creation of extensive areas of irrigated crops. The continuous expansion of D. immitis must be monitored, and measures adapted to the situation of each country must be carried out for adequate control.