ZOONOTIC HELMINTHOSIS OF DOMESTIC AND WILD CARNIVORES IN THE EPIZOOTIOLOGIC TERRITORY OF SERBIA

In the last decade, as the result of climate changes, there have been considerable changes in the parasitofauna of domestic and wild carnivores. Th e prevalence of the existing parasitic species has varied signifi cantly, showing an increasing tendency, and some parasitic species not present before in this epizootiologic territory have been diagnosed as well. It is thought that the reason for such an epizootiological situation is increased presence of owners with their pet animals in the regions endemic for particular zoonotic helminthoses during summer holidays and touristic visits. Th is tendency has become especially conspicuous in the last several years characterized by warm winters and very hot summers due to global warming eff ects, with abundant atmospheric precipitation. Oral vaccination of foxes against rabies, regulated in Serbia by appropriate laws since 2010, has led to an increased number of foxes and rise of prevalence of the parasitic diseases 1* Corresponding author: pedja@vet.bg.ac.rs; prstepanovic@gmail.com Arhiv veterinarske medicine, Vol. 13, No. 1, 5 28, 2020 Ilić, T. ... et al.: Zoonotic helminthosis of domestic and wild carnivores...


INTRODUCTION
Th ere is a great number of zoonotic endoparasites infesting carnivorous animals which represent a risk for the health of pets or human public health, and the most important among them are the species from the genera Toxocara, Echinococcus, Taenia, Dirofi laria, Dipylidium caninum, Capillaria aerophila and Th elazia callipaeda (Overgaauw and van Knapen, 2013;Marino et al., 2018;ESCCAP, 2018).
Special risk factors associated with the infection of carnivores with endoparasites are free roaming, contacts with stray dogs or cats, feeding on carcasses of paratenic hosts, feeding on intermediate host animals, age-related susceptibility, animal hormonal status (gravidity/lactation), contacts with children or immunodefi cient individuals and travelling to the regions endemic for particular endoparasitoses (McNamara et al., 2018).
As the consequence of global warming and active migrations of owners with their pet animals into the countries of this region and Europe, there has been an increase in the prevalence of helminths with zoonotic potential in domestic and wild carnivores in the territory of Serbia in the last ten years. Many of the European countries have already been registered as endemic regions for certain zoonotic nematodoses (Wall and Morgan, 2009;ESCCAP, 2018). Such an epizootiologic situation, associated with the action of the above predilection factors, has caused increased occurrence of particular cardiorespiratory, subcutaneous, ocular and intestinal parasitoses, some of which have developed endemic characteristics in the territory of Serbia as well.
Routine treatment and prevention of endoparasitoses aff ecting carnivores depend on legislation in individual countries and information available to doctors of veterinary medicine, the most important of which are parasite epidemiology, education of pet owners and individual risk estimations. In accordance with the ESCCAP guidelines (2018), it is recommended that every protocol of planned dehelminthization should be implemented aft er the following: 1) completed clinical examination; 2) coprological examination aft er the request by the owner; and 3) coprological diagnosis within the preparation for vaccinal immunization, in accordance with the advice given by the doctor of veterinary medicine.

CARDIOPULMONARY AND SUBCUTANEOUS DIROFILARIOSIS
Th e fi rst research of dirofi lariosis in dogs in the territory of former Yugoslavia took place at the end of the last century. Up to then, there were sporadic reports in the literature about the fi ndings of Dirofi laria immitis species in the heart of dogs (Dimitrijević, 1999), mostly as incidental autopsy observations (Milosavljević and Kulišić, 1989;Blitva-Mihajlović et al., 1995). Aft er that, some autochthonous cases of cardiopulmonary dirofi lariosis in dogs in Serbia were diagnosed (Kulišić and Milosavljević, 1994;Dimitrijević et al., 2007). Th e study by Tasić et al. (2008) in the territory of Vojvodina confi rmed that this region was the northernmost border for cardiopulmonary dirofi lariosis in dogs in the Balkans and one of European regions with the highest prevalence of subcutaneous dirofi lariosis in dogs. Th e authors diagnosed Dirofi laria repens in 49.2% of dogs, D. immitis in 7.2%, and Acanthocheilonema reconditum in 2.1% of dogs. Tasić et al. (2012) reported about the occurrence of fi lariosis in dogs in the territory of Pančevo and Veliko Gradište municipalities, where cardiopulmonary dirofi lariosis was found in 12.3%, and subcutaneous dirofi lariosis in 42.6% of dogs. Th e fi rst cases of D. immitis in dogs in the territory Arhiv veterinarske medicine, Vol. 13, No. 1, 5 -28, 2020 Ilić, T. … et al.: Zoonotic helminthosis of domestic and wild carnivores… of Novi Sad were detected by Savić-Jevđenić et al. (2004). Th e prevalence of dirofi lariosis in dogs in Vojvodina was examined by Savić et al. (2012) and they established the seroprevalence of D. immitis of 18% in police dogs, and in the same region in the period 2009-2013, the presence of microfi laria of D. immitis was detected in 27.6% of dogs (Savić et al., 2014). Stepanović et al. (2015) reported about their fi nding of D. immitis in 68% of police dogs in the Belgrade municipality, which had been declared endemic for this nematodosis several years before (Jovanović, 2012). D. immitis infection was established in 24.2% of non-owned dogs in the Belgrade municipality (Gajić, 2016). Krstić et al. (2016) established the presence of D. immitis in 12.7% of tested animals without clinical symptoms. Out of the total number of positive animals, 44% were dogs from dog shelters and 60% were pets.
Th e prevalence of adult forms of D. immitis in wild carnivores in Serbia was monitored by Penezić et al. (2014). In the period 2009-2013 they diagnosed this fi laria in 7.32% of golden jackals, in 1.55% of foxes, in 1.43% of wolves and 7.69% of wild cats. Cardiopulmonary dirofi lariosis was demonstrated on autopsy in 13.33% of foxes (Gavrilović et al., 2014) and in one wolf (Gavrilović et al., 2015) from the South Banat District.
Microfi laremia established in the above host animals indicated that they represented an infection source for mosquitoes. High prevalence percentages of D. immitis of 18.52% in jackals from Romania (Ionică et al., 2016), 9.6% in those from Bulgaria (Kirkova et al., 2011) and 7.4% in animals from Hungary (Tolnai et al., 2014) suggest that this species of wild carnivores has an important role in the maintenance of infection. According to some authors (Otranto and Deplazes, 2019) it is necessary to elucidate the epidemiological role of foxes as well, especially bearing in mind the report on 32.3% of foxes positive to D. immitis in some of the irrigated regions in Spain (Gortázar et al., 1998).
Th e fi rst study of Dirofi laria spp. in disease vectors in Serbia was performed by Kurucz et al. (2016). In the period May-August, by way of molecular analysis of grouped samples from 13 municipalities in Vojvodina, 11 species of mosquitoes were identifi ed, and in 60% of samples the presence of Dirofi laria spp. was found. Dirofi laria immitis was diagnosed in 80% of positive grouped samples of Culex pipiens, Coquillettidia richiardii and Ochlerotatus caspius species, while D. repens was diagnosed in 20% of positive samples of Aedes vexans, Cx. pipiens and Oc. sticticus species, without any D. immitis and D. repens coinfections.
Several factors have infl uenced the accelerated spread of Dirofi laria spp. into European countries in which these nematodes have not been reported before. Increased duration of warm periods due to climatic change is one of the main factors of impact on the development, activity and seasonal survival of mosquitoes, as well as the development of larval forms of dirofi larios in disease vectors (Farkas et al., 2020). Th e introduction of the "Pet Travel Scheme" in 2000 has contributed to the spread of dirofi lariosis, facilitating the movement of infected, microfi laremic dogs from endemic regions to other parts of Europe (Genchi et al., 2011).
Since the prevalence of dirofi lariosis in dogs in hyperendemic regions (northern parts of Serbia) exceeds 60% (Tasić et al., 2008)  A striking buccal mucosa edema along the lateral edge of the right maxilla was observed in this patient, followed by leukocytosis. Surgical extirpation was performed, and subsequent histopathological, parasitological, and molecular analysis of the specimen revealed the presence of the D. repens nematode. Of the 13 such cases reported so far worldwide, this is the fi rst case analyzed by molecular methods.

RESPIRATORY CAPILLARIOSIS
Considering the available epizootiological data on the distribution of Capillaria aerophila species in domestic and wild carnivores in Europe, it is certain that global warming has an important impact on the distribution of this parasite Th ere is a close association between the population of foxes and populations of dogs and cats. It is assumed that the process of urbanization and extension of urban belts into the natural habitats of foxes can lead to the opportunities for closer contacts between street dogs and cats, and foxes (Ilić et al., 2017a). Th e population of foxes thus represents a permanent source of infection for dogs and cats in suburbia, which is especially important for the epidemiology of respiratory capillariosis.
It is supposed that one of the reservoirs of this zoonosis in Serbia are foxes from the territory of Vojvodina, which is additionally confi rmed by a case of pulmonary capillariosis diagnosed in an individual from Bačka Palanka Circulation of the nematode across diff erent animal species and its recent appearance in Europe is in accordance with the common genetic haplotype of T. callipaeda present in all examined wild and domestic animals (Otranto and Deplazes, 2019). Considering the fact that wild carnivores have a very broad movement area, 10 to 30 km for foxes (Doncaster and Macdonald, 1991) and even up to 800 km for wolves (Mech, 1970) Since T. callipaeda has got zoonotic potential and presents a risk for human health, it is necessary that veterinarians, doctors and ophthalmologists should include this nematodosis with ocular manifestations into their diff erential diagnostic considerations. Such a clinical approach is especially important in regions where ocular thelaziosis has assumed endemic character, such as in Serbia.

INTESTINAL ZOONOTIC HELMINTHOSES
Regarding geographical distribution and clinical relevance, Toxocara canis, Ancylostomatidae and Trichuris vulpis are the most prevalent intestinal helminths aff ecting dogs, the importance of which is oft en unacknowledged by doctors of veterinary medicine, medical doctors and general public . Depending on the intensity of dog infection, we should not overlook some cestodes (D. caninum and Taenia spp.), as well as trematodes (Alaria alata) and protozoans (Giardia intestinalis, Amoeba spp., and In the period from September 2017 to June 2018, in a study of endoparasitoses in street dogs aged one year and over from six dog shelters in the Republic of Serbia, the highest prevalence of endoparasitic infections was found in the Shelter for street dogs and cats in Požarevac (69.54%). In dogs below one year of age, most prevalent were toxocarosis (42.85%) and ancylostomatidosis (26.53%) in the Shelter for abandoned dogs in Zemun, while toxocarosis was most prevalent (35.14%) in the Shelter for abandoned dogs in Subotica (Nišavić, 2019).
Monitoring endoparasitic fauna of foxes and jackals from eight diff erent localities in Serbia in the period 2010-2014, Ilić et al. (2016b) have diagnosed as the most prevalent helminths A. alata (49.41% in foxes and 30.00% in jackals), T. canis (49.41% in foxes and 23.33% in jackals), ancylostomatids (40.69% in foxes and 33.33% in jackals) and T. vulpis (55.23% in foxes and 11.66% in jackals). Ristić et al. (2020a) have studied the prevalence of zoonotic intestinal parasites in dogs from the public parks in the city of Niš and assessed the health risks they presented for people in public places and children's playgrounds. Endoparasitoses were diagnosed with overall prevalence of 58-70%. Depending on the season of the study, four most common endoparasites were T. canis (36.66-38%), ancylostomatids (24.66-32%), T. vulpis (20-28%) and A. alata (28%). Certainly worth mentioning was the fact that these helminths were identifi ed in soil/sand samples taken from these public parks in Niš. In soil samples, a high and medium degree of contamination with T. canis ascaridid was found (14-22%), as well as a low and medium degreeof contamination with ancylostomatids (4-12%), medium degree of contamination with T. vulpis species (4-6%), and medium and high degree of contamination with A. alata trematode (2%). In sand samples, diff erent degrees of contamination with helminths T. canis (26%), ancylostomatids (8%), T. vulpis (4%) and A. аlata (16%) (Ristić et al., 2020b) were established. Based on the results of this parasitological screening, the authors concluded that a large number of street dogs circulated in public parks in Niš, which presented the reservoir of numerous parasitic zoonoses for owned dogs and people (particularly for preschool and school children).
Th e literature data suggest that T. canis is overall the most prevalent helminth in dogs, the prevalence of which varies between European countries from 7.5% (Riggio et al., 2013)  In recent years, there has been a growing interest for the infection with A. alata trematode, which is very prevalent in Europe, has a potential zoonotic importance since it causes larval alariosis, and is diagnosed in a number of countries nearby Serbia, such as Croatia, Romania and Bulgaria (Lalošević et al., 2014).
A high intensity infection with this trematode has been reported to occur in intermediate hosts (wild pigs) living in the areas with high prevalence of alariosis in defi nitive hosts (domestic and wild carnivores). In addition to rodents, reptiles and amphibians (Esite et al., 2012), humans as well can be incidental paratenic hosts if they consume insuffi ciently thermally processed frog legs, pork (Wójcik et al., 2002;Möhl et al., 2009) or wild goose meat (Kramer et al., 1996) infected with A. alata mesocercarias.
In recent years, larval alariosis has been reported in other European countries as well. Th e fi rst fi nding in the meat of wild pigs in Bulgaria was reported by Portier et al. (2014), when the overall prevalence of 0.6% was established. Th e study of the vitality of mesocercarias in products made from infected wild pig meat, prepared in a traditional fashion in Germany, has shown than only fresh products contain living mesocercarias and could be the source of infection for humans (González-Fuentes et al., 2014).
In addition to trichinellosis, wild pig meat can be the source of infection with trematode mesocercarias, so that any preparation of thermally unprocessed products (e.g., sausages) cannot be recommended. Safe for human nutrition is only well cooked wild pig meat. Bearing in mind this information, it is necessary to adjust accordingly the legislation on food safety for human consumption in Serbia (Lalošević et al., 2014).
In view of human population, zoonotic parasites from the feces of carnivores can threaten mostly dog owners or dog breeders who disregard the necessity to perform dehelminthization of their litters, children who do not wash their hands aft er their contacts with animals, or those with geophagic practices, agricultural workers and greengrocers (especially in semirural and rural areas where dogs freely defecate in the vicinity of vegetables).
In people in Serbia, the cases of a familial epidemic of cryptosporidiosis have been coprologically diagnosed in three immunocompetent patients (Gvozdenović et al., 2012) and there is also the case of 4.5-year-old girl in whom toxocarosis has been detected serologically (Mijatović et al., 2015).

CONCLUSION
In order to prevent and control zoonotic helminthoses of domestic and wild carnivores it is essential that their occurrence, infection spread and maintenance should be continually monitored in foxes, dogs and humans; that the problem of abandoned dogs should be eff ectively resolved in most urban environments; that the measures to control vector populations should be undertaken; that all goods, commodities, services and traffi c in international trade should be monitored; that all persons who travel with their pets to the regions endemic for these diseases or who return from these to Serbia should be monitored; that continued education of pet owners is organized; and that synchronized collaboration of appropriate services of veterinary medicine and human medicine is in place.