Circulation of Dirofilaria immitis and Dirofilaria repens in the Danube Delta Biosphere Reserve, Romania

Abstract

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.

The First Case of Elbow Bursitis Caused by Dirofilaria repens in Humans

“…Until recently, it was believed that in humans, only individual adult nematodes occurred, so no further development is observed. However, the occurrence of this nematode in the larval form—microfilariae—in the peripheral blood of humans, and in subcutaneous nodule aspirates, has also been described, which might indicate the complete development of this parasite in a human body [10, 11, 21].…”

“…The occurrence of microfilaremia in humans has also been described [10]. Dirofilaria immitis is larger than Dirofilaria repens , causes so-called pulmonary dirofilariasis, and causes human infection less frequent than Dirofilaria repens [3, 4, 11]. According to our knowledge, the presented case is the world’s first documented description of elbow bursitis caused by Dirofilaria repens in humans.…”

Epididymal Dirofilariasis in a Child: First Case Report from Bulgaria

“…The geographical distribution of human dirofilariasis coincides with that of the infected dogs. Not long ago, it was endemic mostly for the Mediterranean region and the eastern parts of the European continent, but now its geographic endemicity in Europe has increased [10]. There are also cases of people living outside endemic areas who were diagnosed with the disease after travelling to such places.…”

Infectious Alertness in Removal Benign Neoplasms in the Maxillofacial Area

“…Дирофиляриоз человека -паразитарное заболевание, трансмиссивный гельминтоз, вызванный паразитированием нематод рода Dirofilaria, чаще всего D. repens и D. immitis, которое протекает с преимущественным поражением кожи (63%), конъюнктивы (50%), слизистых оболочек, подкожной клетчатки, реже -внутренних органов, из которых наиболее часто поражаются легкие [1,2,3]. В организме человека самки Dirofilaria способны достигать половой зрелости, но не могут размножаться микрофилярии, поэтому человек не может являться распространителем данного заболевания [4,5].…”

“…Возбудитель в виде личинки проникает в организм человека чаще через укусы инфицированного комара рода Aedes, Anopheles, Culex [1,5]. Не исключено, что переносчиками могут выступать также блохи, вши, клещи [6,7].…”