Identity of Microfilariae Circulating in Dogs from Western and South-Western Romania in the Last Decade

Microfilaremic infection in canine filariosis in Colombia: a challenge in morphological and molecular diagnostics

Canine filariosis is caused by filiform nematodes and affects several species of animals as well as humans. The disease produces a wide range of symptoms that can often be confused with other diseases, which increases the complexity of its diagnosis. The search for methodologies to facilitate its diagnosis is a challenge, and specific and differential identification of the parasite species causing the disease holds key to a successful diagnosis. In Colombia, there is a problem of underdiagnosis of filariosis in microfilaremic dogs infected by Dirofilaria immitis and Acanthocheilonema reconditum, and of microfilaremias not related to heartworm disease. The highest prevalences have been reported for D. immitis infections, although new cases of A. reconditum infections are beginning to appear. The aim of this study was to differentiate the microfilariae infections caused by D. immitis and A. reconditum by a morphological and molecular characterization of microfilariae so as to facilitate an accurate diagnosis of canine filariosis in the metropolitan area of Bucaramanga (Colombia). For this purpose, 400 blood samples with anticoagulants were collected from the dogs and analyzed with the help of a commercial immunochromatography kit for the detection of D. immitis circulating antigen. The Woo, Knott, and polymerase chain reaction (PCR) techniques were employed for determining the parasite count, morphological observation, and molecular identification of microfilariae present in the dogs respectively. The prevalence of microfilaremic dogs in Bucaramanga metropolitan area was 18.75% (75/400). The prevalence of dogs that tested positive for D. immitis in the antigen and in PCR tests was 1.25% (5/400) and 1% (4/400), respectively. Furthermore, the PCR test revealed that 17.75% of the microfilaremic dogs tested positive for A. reconditum (71/400) (first report in the metropolitan area of Bucaramanga), with one animal co-infected by both species, and 0% for D. repens (0/400). However, by morphological characterization, 4% of the microfilariae (3/75) corresponded to D. immitis, 20% (15/75) to D. repens, and 76% (57/75) to A. reconditum. The use of molecular diagnostic methods such as PCR aids in the specific identification of the parasite, thus making it a more accurate method than the morphological characterization of microfilariae. The identification of the parasites by PCR helps improve the veterinary diagnosis of canine filariosis in Colombia, which would lead to the establishment of an appropriate treatment protocol for each species of filaria and also to the generation of reliable data to be used at the clinical and epidemiological levels.

What Has Happened to Heartworm Disease in Europe in the Last 10 Years?

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.

Dirofilaria repens predominates in shelter dogs from South Romania

Canine filarioids are zoonotic vector-borne parasitic nematodes distributed mostly in the tropics and subtropics. The aim of this study was to determine the prevalence, distribution, etiology and genetic variation of canine filarioid infections by three different PCR techniques in four Southern Romanian counties. Blood samples of 300 shelter dogs were screened for infections with canine filarioids by real-time PCR. To determine filarioid species and coinfections, samples positive in the initial screening were further tested by conventional PCR and sequenced. Results indicated that 17% of the tested dogs were positive for at least one filarioid species. The prevalence of D. repens infection was 11.7%, significantly higher than that of D. immitis (4.7%) and A. reconditum (1.3%) (p ≤ 0.003). The high prevalence of canine filarioid infections represents a challenge to animal and human health in the South of Romania, and they should be constantly monitored.