ИНВАЗИРОВАННОСТЬ КРОВОСОСУЩИХ КОМАРОВ ВОЗБУДИТЕЛЯМИ ДИРОФИЛЯРИОЗА В ГОРОДЕ ХАБАРОВСКЕ И ПРИГОРОДНОЙ ЗОНЕ

BackgroundDirofilariosis is an emerging vector-borne parasitic disease in Europe. Monitoring of wild and domestic carnivores demonstrated circulation of Dirofilaria spp. in Romania in the past. For the implementation of control measures, knowledge on the native mosquito community responsible for Dirofilaria spp. transmission is required.MethodsMosquito samples originated from a longitudinal study previously performed in the Danube Delta Biosphere Reserve. Mosquito pools were screened for Dirofilaria immitis and Dirofilaria repens. The samples comprised 240,572 female mosquito specimens collected every ten days between April and September in 2014 at four different trapping sites. In addition, blood samples of 36 randomly selected dogs were collected in 2016 in each of the four mosquito sampling sites. A duplex real-time assay was used to detect the presence of one or both Dirofilaria species for each sample. This assay targets the cytochrome c oxidase subunit 1 and the 16S rRNA gene fragments to differentiate both parasites.ResultsDirofilaria immitis and D. repens were detected in mosquito pools at all four trapping sites. In the 2118 mosquito pools tested, D. immitis was identified for eight and D. repens for six of the 14 screened mosquito taxa, with a higher prevalence of D. immitis (4.53% of analysed pools) compared to D. repens (1.09%). Dirofilaria spp. were also identified in dogs from the same sampling sites with a prevalence of 30.56%. For both Dirofilaria species, the highest estimated infection rates (EIRs) were found in Anopheles maculipennis (s.l.) (D. immitis: EIR = 0.206 per 100 specimens, D. repens: EIR = 0.066 per 100 specimens). In contrast, Coquillettidia richiardii and Anopheles hyrcanus as the most frequent taxa had infection rates which were significantly lower: Cq. richiardii (D. immitis: EIR = 0.021; D. repens: EIR = 0.004); An. hyrcanus (D. immitis: EIR = 0.028; D. repens: EIR = 0.006). The number of positive pools per calendar week was positively correlated with the number of screened pools per calendar week, suggesting constant Dirofilaria spp. transmission during the observation period.ConclusionsThis study further confirms significant circulation of Dirofilaria spp. in eastern Europe, with high parasite prevalence in domestic canids and mosquitoes. Therefore, systematic monitoring studies are required to better understand the environmental risk factors for Dirofilaria transmission, allowing the implementation of effective surveillance and control measures.

Blood samples of 252 male and female dogs, aged between 7 months and 12 years, different races, and usefulness (utilities), which came from lowland and demi-highland and highland districts of Serrae province, of Macedonia-Greece. The purpose of this survey was to find out the infected dogs with filarial parasites. Ninety six (38,1%) out of the examined dogs were found to be infected with one or more parasitic species. The 86 (34,13%) dogs were infected with Dirofilaria immitis, the 84 (33,33%) dogs were infected with Dirofilaria repens and the 10 (3,97%) dogs were infected with Dipetalonema reconditum. Single infection, with Dirofilaria immitis was observed in 9, with Dirofilaria repens in 7, whereas, no single infection with Dipetalonema reconditum were observed. Mixed infection with Dirofilaria immitis + Dirafilaria repens were observed in 66, with Dirofilaria immitis + Dipetalonema reconditum were observed in 2, with Dirofilaria repens + Dipetalonema reconditum in 2 and finely, in 10 the combination with Dirofilaria immitis + Dirofilaria repens + Dipetalonema reconditum. The microfilarial burden per ml of the infected dogs fluctuated between 85 and 7.375. There were no any significant difference between the different group of dogs according sex, age, usefulness, longhair or shorthair as well as lowland and semi-highland districts, on the percentage of infected or microfilarial population of each.

A total of 38 species of mosquitoes of the Culicidae family of two subfamilies Anophelinae and Culicinae belonging to 6 genera, were identified on the territory of Kharkiv Region from 2009 to 2019. Dirofilaria larvae were found in 932 insects, which was 4.46 % of the surveyed mosquitoes. The prevalence of the infection of female mosquitoes by dirofilaria was 4.46 ± 0.24 %, while the mean intensity of dirofilariae was 5.4 ± 2.1. Infection of mosquitoes with dirofilariae is currently detected in 11 districts of Kharkiv Region and the city of Kharkiv. The infection rate of mosquitoes of the genus Aedes was 3.83 ± 0.63 %, of the genus Culex — 0.75 ± 0.34 %, of the genus Anopheles — 0.12 ± 0.39 %, whereas females of the genera Culiseta, Coquillettidia, and Uranotaenia were uninfected. It was found that in Kharkiv Region there were 2 types of canine dirofilariae — Dirofilaria immitis (Leidy, 1856) and Dirofilaria repens (Railliet & Henry, 1911), with a predominance of Dirofilaria repens. For the period from 2009 to 2019, we examined 378 blood samples from dogs (190 males and 188 females) aged from 8 months to 13 years with suspected dirofilariasis. According to the results of the studies, 140 samples were positive, the prevalence of infection by the larvae of Dirofilaria spp. in blood samples from dogs with suspected dirofilariasis was 37.03 ± 0.12 %, while infection with Dirofilaria immitis was 2.86 ± 0.45 %, and Dirofilaria repens — 97.35 ± 0.24 %. The number of positive samples from mongrel dogs was 42 (30 %). It was found that cats are more often amicrofilariaemic than dogs.

A duplex real-time polymerase chain reaction assay for the detection of and differentiation between Dirofilaria immitis and Dirofilaria repens in dogs and mosquitoes

Wuchereria bancrofti, Dirofilaria immitis, and Dirofilaria repens are filarial nematodes transmitted by mosquitoes belonging to Culex, Aedes, and Anopheles genera. Screening by vector dissection is a tiresome technique. We aimed to screen filarial parasites in their vectors by single and multiplex PCR and evaluate the usefulness of multiplex PCR as a rapid xenomonitoring and simultaneous differentiation tool, in area where 3 filarial parasites are coexisting. Female mosquitoes were collected from 7 localities in Assiut Governorate, were microscopically identified and divided into pools according to their species and collection site. Detection of W. bancrofti, D. immitis, and D. repens using single PCR was reached followed by multiplex PCR. Usefulness of multiplex PCR was evaluated by testing mosquito pools to know which genera and species are used by filarial parasites as a vector. An overall estimated rate of infection (ERI) in mosquitoes was 0.6%; the highest was Culex spp. (0.47%). W. bancrofti, D. immitis, and D. repens could be simultaneously and differentially detected in infected vectors by using multiplex PCR. Out of 100 mosquito pools, 8 were positive for W. bancrofti (ERI of 0.33%) and 3 pools each were positive for D. immitis and D. repens (ERI 0.12%). The technique showed 100% sensitivity and 98% specificity. El-Nikhila, El-Matiaa villages, and Sahel Seleem district in Assiut Governorate, Egypt are still endemic foci for filarial parasites. Multiplex PCR offers a reliable procedure for molecular xenomonitoring of filariasis within their respective vectors in endemic areas. Therefore, it is recommended for evaluation of mosquito infection after lymphatic filariasis eradication programs.

Dirofilaria immitis (Leidy, 1856) and Dirofilaria repens (Railliet & Henry, 1911) are mosquito-borne filarial nematodes that primarily affect dogs, causing heartworm disease and subcutaneous dirofilariosis. The canine heartworm is reported in different provinces in Turkey. However, studies about the transmitting mosquito species are limited. Hence, this study aimed to investigate potential vectors of D. immitis and D. repens in Aras Valley, Turkey. In total, 17,995 female mosquitoes were collected from eight villages during three mosquito seasons (2012-2014) in Aras Valley, located in north-eastern Turkey. A total of 1,054 DNA pools (527 abdomen and 527 head-thorax) were tested with Dirofilaria primers by multiplex-polymerase chain reaction (PCR). Aedes caspius was the most abundant species in collection sites with 90%; this was followed by Culex theileri Theobald, 1903 (Diptera: Culicidae) (7.31%), Anopheles maculipennis Meigen 1818 (Diptera: Culicidae) (1.28%), Culex pipiens Linnaeus, 1758 (Diptera: Culicidae) (0.43%), (Anopheles) hyrcanus (Pallas, 1771) (Diptera: Culicidae) (0.37%), Aedes vexans (Meigen, 1830) (Diptera: Culicidae) (0.25%), and Culiseta annulata Schrank, 1776 (Diptera:Culicidae) (0.02%). Dirofilaria immitis and D. repens were detected in mosquito pools from five villages. The total Dirofilaria spp. estimated infection rate was 1.33%. The highest estimated infection rate was found in Ae. vexans (6.66%) and the lowest was in Ae. caspius (1.26%). The results show that An. maculipennis sl, Ae. caspius, Ae. vexans, Cx. theileri and Cx. pipiens are potential vectors of D. immitis and D. repens with DNA in head-thorax pools; An. hyrcanus is also a likely vector, but Dirofilaria DNA was found only in abdomen pools for the study area. This study revealed new potential vector species for D. immitis. Mosquitoes with natural infections of D. repens were reported for the first time in Turkey.

Dirofilariasis is an infection caused by parasites of the Dirofilaria genus, which are natural parasites of dogs and cats. Humans are accidental hosts who become infected by the bite of an infected mosquito. The most common vectors are female mosquitoes from Aedes, Anopheles, Culex genera. There are more than 40 described species of Dirofilaria, but human infection is most commonly caused by two species: Dirofilaria repens and Dirofilaria immitis. Human infections are most commonly manifested as subcutaneous/ocular Dirofilariasis (Dirofilaria repens) and pulmonary Dirofilariasis (Dirofilaria immitis). We presented a case of subcutaneous dirofilariasis of the right knee in a 52-year-old patient that manifested as a subcutaneous nodule. He described spending a lot of recreational time near the river Sava. Five years ago, he noticed swelling of his right leg. Two years ago, a subcutaneous nodule appeared in the front part of the knee. Excision in local anesthesia was performed. During the operative procedure, a moving filarial worm was found. The worm was identified as Dirofilaria spp. at the Croatian Institute of Public Health Zagreb.

Dirofilariasis is a vector-borne disease caused by parasitic nematodes of the genus Dirofilaria spp., considered an emerging concern in both veterinary and human medicine. Climate changes and human activities, such as pet travel, contribute to the spread of diseases to new non-endemic regions. Poland is dominated by subcutaneous dirofilariasis caused by D. repens infections. Cardiopulmonary dirofilariasis, also known as a heartworm disease is much more rare with only single autochthonous cases reported so far. Also, imported infections are observed sporadically in dogs traveling to endemic countries. In this study, we report the first case of a dog in Poland, never having traveled abroad, co-infected with Dirofilaria repens and Dirofilaria immitis. A 14-year-old mixed breed, an intact male dog with fever, lightly pale mucosal membranes, moderate abdominal pain, and a mild cough was presented in a veterinary clinic in Warsaw, Poland. The examination of the blood sample collected for complete morphology and biochemistry revealed the presence of live microfilariae. Presence of the DNA of both microfilariae species was detected using Real-Time PCR with species-specific primers. Since the remaining diagnostic methods like Knott's test, antigen test or echocardiography did not reveal the presence of D. immitis, we discussed the impact of microfilariae periodicity and low worm burden infections on the limited efficiency of these techniques. We strongly recommend using a mixed diagnostic approach for the most sensitive and specific diagnosis since the ideal diagnostic method does not exist, and several factors may contribute to misdiagnosis. Furthermore, we considered factors that contribute to the uncontrolled spread of dirofilariasis such as climate changes, introduction of new species of mosquitoes competent for the transmission of the disease, and wildlife animals as an important reservoir of this parasitosis. Given that Poland shares borders with countries classified as endemic and pre-endemic for D. immitis, such as Slovakia and Ukraine, it is reasonable to anticipate a rise in autochthonous heartworm infections and shifts in the epidemiological pattern of dirofilariasis in the coming years.

As a result of global warming, the change in the biological cycle of vectors and the increase in intercontinental travels, we are now facing an increase in the number of cases of vector-borne diseases. Among these, heartworm disease has escalated in recent years in Romania, with cases increasing in many parts of our country. Our study was carried out in the South-Eastern part of Romania, with the aim of establishing the prevalence of heartworm disease in dogs, with the identification of the two species Dirofilaria immitis and Dirofilaria repens. Blood samples were collected during the period May - July 2022 and January - July 2023, from 220 dogs with and without an owner from Tulcea county, from places such as Tulcea, Murighiol, Somova, Mineri, Niculițel. The blood samples were tested through the Knott method, which is considered as the reference method in the diagnosis of dirofilariosis in dogs. The results show a prevalence of Dirofilaria spp. infection of 11.36% in dogs. Of the 220 samples examined by the Knott test, 25 were positive for circulating microfilariae, of which 21 showed infestations with Dirofilaria immitis and 4 with co-infection with Dirofilaria immitis and Dirofilaria repens. The study underlines the importance of introducing monitoring and control programs for heartworm disease in dogs in Romania.

BackgroundDirofilaria immitis and Dirofilaria repens are the main causative agents of heartworm disease and subcutaneous dirofilariasis in domestic and wild canids, respectively. Both pathogens have zoonotic potential and are transmitted by mosquitoes. The present study aimed to determine the transmission period, prevalence and diversity of Dirofilaria spp. vectors from endemic areas of Corsica (France).MethodsA monthly point data model based on average temperature recorded by four meteorological stations during 2017 was used to calculate the Dirofilaria transmission period. From June to September 2017, female mosquitoes (n = 1802) were captured using Biogents® Sentinel 2 traps lured with carbon dioxide and BG-Lure™ or octanol. Mosquitoes were identified to species level, pooled accordingly, and screened using multiplex real-time qPCR to detect D. immitis and D. repens.ResultsThe monthly point data model showed the possible transmission of Dirofilaria spp. from the third week in May to the last week in October in the studied area. Mosquitoes were identified as Ochlerotatus caspius (n = 1432), Aedes albopictus (n = 199), Culex pipiens sensu lato (n = 165) and Aedes vexans (n = 6) and were grouped into 109 pools (from 1 to 27 specimens, mean 11.4 ± 0.7), of which 16 scored positive for Dirofilaria spp. (i.e., n = 13; estimated infection rate [EIR] = 1.1% for D. immitis and n = 3; EIR = 0.2% for D. repens). Specifically, 6 (i.e., EIR = 3.8%) of 15 pools of Ae. albopictus were positive for D. immitis, 2 of 14 of Cx. pipiens s.l. were positive for D. immitis and D. repens, respectively, and 8 of 77 pools of Oc. caspius were positive for D. immitis (i.e., n = 6; EIR = 0.4%) and D. repens (i.e., 2; EIR = 0.1%). The highest mosquito infection rate was recorded in July (EIR = 2.5%), then in June (EIR = 1.3%) and September (EIR = 0.6%).ConclusionsThe data suggest that both Dirofilaria species are endemic and occur possibly in sympatry in the studied area in Corsica, highlighting the need to implement preventive chemoprophylaxis and vector control strategies to reduce the risk of these filarioids in dog and human populations.Graphical

BackgroundDespite long-term research on dirofilariosis in Slovakia, little attention has thus far been paid to Dirofilaria vectors. The particular aim of the present study was molecular screening for filarioid parasites in two different habitats of Bratislava, the capital city of Slovakia. In addition, the effect of urbanisation on mosquito species abundance and composition, associated with the risk of mosquito-borne infections, was studied and discussed.MethodsMosquitoes were identified by morphological features, and molecular methods were also used for determination of selected individuals belonging to cryptic species from the Anopheles maculipennis and Culex pipiens complexes. The presence of filarioid DNA (Dirofilaria repens, Dirofilaria immitis and Setaria spp.) was detected using standard PCR approaches and sequencing.ResultsA total of 6957 female mosquitoes were collected for the study. Overall, the most abundant mosquito species was Aedes vexans, closely followed by unidentified members of the Cx. pipiens complex and the less numerous but still plentiful Ochlerotatus sticticus species. Further investigation of mosquito material revealed 4.26% relative prevalence of Dirofilaria spp., whereby both species, D. repens and D. immitis, were identified. The majority of positive mosquito pools had their origin in a floodplain area on the outskirts of the city, with a relative prevalence of 5.32%; only two mosquito pools (1.26%) were shown to be positive in the residential zone of Bratislava. Setaria spp. DNA was not detected in mosquitoes within this study.ConclusionsThe study presented herein represents initial research focused on molecular mosquito screening for filarioid parasites in urban and urban-fringe habitats of Bratislava, Slovakia. Molecular analyses within the Cx. pipiens complex identified two biotypes: Cx. pipiens biotype pipiens and Cx. pipiens biotype molestus. To our knowledge, Dirofilaria spp. were detected for the first time in Slovakia in mosquitoes other than Ae. vexans, i.e. D. repens in Anopheles messeae and unidentified members of An. maculipennis and Cx. pipiens complexes, and D. immitis in Coquillettidia richiardii and Cx. pipiens biotype pipiens. Both dirofilarial species were found in Och. sticticus. The suitable conditions for the vectors’ biology would represent the main risk factor for dirofilariosis transmission.

BackgroundDirofilaria immitis and Dirofilaria repens are transmitted by bloodsucking culicid mosquitoes belonging to Culex, Aedes, Ochlerotatus, Anopheles and Mansonia genera.The detection of filarioids in mosquitoes for assessing distribution of vectors and/or of pathogens in a given area (also known as “xenomonitoring”), when based on individual dissection of wild-caught female mosquitoes is time consuming and hardly applicable in large epidemiological surveys.Our study aimed to evaluate the recently developed duplex real-time PCR for screening large number of culicids and to assess their positivity for D. immitis and D. repens in an area where both species are endemic.MethodsA duplex real-time PCR was used to detect and differentiate D. immitis and D. repens in mosquitoes collected in six provinces of the Veneto region using 43 carbon dioxide-baited traps under the frame of an entomological surveillance program to monitor the vectors of West Nile disease. From early May till October 2010, unfed female mosquitoes (n = 40,892) were captured in 20 selected sites.ResultsMosquitoes identified as Culex pipiens, Ochlerotatus caspius, Aedes vexans and Culex modestus were grouped into 995 pools according to species, day and site of collection (from minimum of 1 to maximum of 57). Out of 955 pools, 23 (2.41 %) scored positive for Dirofilaria spp. of which, 21 (2.2 %) for D. immitis and two (0.21 %) for D. repens. An overall Estimated Rate of Infection (ERI) of 0.06 % was recorded, being higher in Och. caspius and Ae. vexans (i.e., 0.18 % and 0.14 %, respectively). At least one mosquito pool was positive for Dirofilaria spp. in each province with the highest ERI recorded in Vicenza and Padova provinces (i.e., 0.42% and 0.16 %, respectively). Mosquitoes collected in all provinces were positive for D. immitis whereas, only two (i.e., Padova and Rovigo) provinces scored positive for D. repens. All mosquito species, except for Cx. modestus, were positive for D. immitis, whereas D. repens was only found in Cx. pipiens.ConclusionsThe results suggest that both Dirofilaria species are endemic and may occur in sympatry in the examined area. The molecular approach herein used represents a powerful tool for surveillance programs of D. immitis and D. repens in the culicid vectors towards a better understanding of the epidemiology of the infections they cause and their seasonal transmission patterns.

A recent increase in the occurrence of Dirofilaria repens and Dirofilaria immitis has been reported from the eastern neighbouring countries of Austria (Slovakia, Hungary). In order to obtain data from Austria--especially from the areas bordering these countries--blood samples of dogs from Gänserndorf (northeastern Austria, bordering Slovakia) and Neusiedl (eastern Austria, bordering Hungary) were examined for the presence of Dirofilaria spp.-DNA by quantitative real-time PCR (qPCR). For D. repens one (out of eight) and six (out of ninety) positive dogs were found, respectively. D. immitis-DNA was not detected. Most of the positive dogs had previously been abroad in known Dirofilaria endemic areas. Two dogs, however, had never been abroad and presumably became infected in Austria. To investigate an autochthonous focus, 1366 mosquitoes from the eastern part of Austria were also examined by qPCR. Although positive mosquitoes could not be found, an emerging endemic occurrence of D. repens in Austria due to positive dogs seems possible.

BackgroundAs a result of globalization and climate change, Dirofilaria immitis and Dirofilaria repens, the causative agents of dirofilariosis in Europe, continue to spread from endemic areas in the Mediterranean to northern and northeastern regions of Europe where autochthonous cases of dirofilarial infections have increasingly been observed in dogs and humans. Whilst D. repens was recently reported from mosquitoes in putatively non-endemic areas, D. immitis has never been demonstrated in mosquitoes from Europe outside the Mediterranean.MethodsFrom 2011 to 2013, mosquitoes collected within the framework of a German national mosquito monitoring programme were screened for filarial nematodes using a newly designed filarioid-specific real-time PCR assay. Positive samples were further processed by conventional PCR amplification of the cytochrome c oxidase subunit I (COI) gene, amplicons were sequenced and sequences blasted against GenBank.ResultsApproximately 17,000 female mosquitoes were subjected to filarial screening. Out of 955 pools examined, nine tested positive for filariae. Two of the COI sequences indicated D. immitis, one D. repens and four Setaria tundra. Two sequences could not be assigned to a known species due to a lack of similar GenBank entries. Whilst D. immitis and the unknown parasites were detected in Culex pipiens/torrentium, D. repens was found in a single Anopheles daciae and all S. tundra were demonstrated in Aedes vexans. All positive mosquitoes were collected between mid-June and early September.ConclusionThe finding of dirofilariae in German mosquitoes implies the possibility of a local natural transmission cycle. While the routes of introduction to Germany and the origin of the filariae cannot be determined retrospectively, potential culicid vectors and reservoir hosts must prospectively be identified and awareness among physicians, veterinarians and public health personnel be created. The health impact of S. tundra on the indigenous cervid fauna needs further investigation.

Dirofilariasis is a dangerous transmissible disease of carnivores and humans caused by two species of parasitic nematodes - Dirofilaria repens Railliet et Henry and D. immitis Leidy. The intermediate hosts of Dirofilariae are blood-sucking mosquitoes. Both species are typical of the mild climate of southern Europe, but in recent decades the parasites have spread to the north and northeast due to the global climate change. They have been registered in Western Siberia since 1989, and diro-filariasis cases in both animals and humans cause concern. To assess prospects for the spread of dirofilariasis and develop strategies to combat this disease, one has to determine the main mosquito vectors. Malaria mosquitos are the significant dirofilaria vectors in Europe, but there is a shortage of information on potential dirofilariasis vectors in Siberia. This paper is meant to estimate how extensive the invasion of different species of the malaria mosquitos D. repens and D. immitis is in the territory of Tomsk Region due to the global climate change. 64 samples of mosquitos from 36 localities of Tomsk Region were taken during the summer seasons of 2018 to 2020. Mosquitos were caught in stables, dissected to determine invasion via light microscopy. The species of malaria mosquitos and dirofilariae were identified through an ITS2 PCR-RFLP analysis (Artemov et al., 2021) and COI site-specific PCR (Rishniw et al., 1998), respectively. In total, the authors analyzed 7,591 female malaria mosquitos and 233 female non-malaria mosquitos, where 159 and 1 of them were infected with dirofilariae, respectively. They registered invasion in 44 samples from 21 localities, including the northernmost one - Strezhevoy town (60°44N, see Figure 1). Dirofilariasis is a common helminthiasis in Tomsk Region. The average invasion extensiveness is 2.1+0.2% in the region. In the natural populations of malaria mosquitos on the right bank of the River Ob, the invasion extensiveness is 3.7 times higher vs. the left bank of the Ob, despite the high transport accessibility of this bank (see Figure 2). Invasion extensiveness decreases from the south to the north, but the local conditions might disrupt this trend (see Table 3). Three species of malaria mosquitos - Anopheles daciae, An. messeae and An. beklemishevi (but not An. claviger) - are dirofilariasis vectors in Tomsk Region (see Table 1). South of 57° N, only D. repens and one mixed invasion case were found in An. daciae being the dominant species in this area. However, all the three species mainly invaded with D. repens were detected as vectors north of 57° N. One case of An. messeae invasion with the nematode D. immitis and mixed invasions of An. daciae and An. beklemishevi were found in Kolpashevo agglomeration. All the invasions with D. immitis (including mixed ones) were observed on the right bank of the Ob (see Table 2). The extensiveness of An. messeae and An. daciae invasion were significantly higher vs. An. beklemishevi, despite its domination north of 57° N. The northernmost location where an infective female of An. beklemishevi invaded with D. repens was found is Bolshaya Griva village at 59° N. Approximately 6.5% of the infected mosquitos had superinvasion - re-invasion with dirofilariae (see Figure 3). Thus, malaria mosquitos play a significant role in the circulation and, probably, the spread of dirofilariasis in Tomsk Region. Conclusion: 1. Dirofilariae are widespread within Tomsk Region. The northernmost border of the Dirofilaria repens spread is 60° 44' and that of D. immitis - 58° 32' N. The northernmost border of the D. repens transmission is 59° N. 2. The contribution made by malaria mosquitos to the spread of dirofilariasis in Tomsk Region is as high as that of other blood-sucking mosquitos. 3. Anopheles daciae, An. messeae and An. beklemishevi are the vectors of Dirofilaria repens and D. immitis. Anopheles beklemishevi get infected less often than the two remaining species. 4. The invasion extensiveness of malaria mosquitos is higher on the right bank of the River Ob. 5. Mixed invasions and superinvasions of malaria mosquitos with dirofilariae are frequent phenomena for Tomsk Region. The article contains 4 Figures, 3 Tables, 55 References. The Authors declare no conflict of interest.