Circulation of Dirofilaria repens and Dirofilaria immitis in Moldova

Abstract

BackgroundOver the last two decades, a significant spread of dirofilariasis has been observed in eastern and central Europe. However, data on the circulation of Dirofilaria spp. in Moldova were absent although direct neighbor states reported high incidence rates of human dirofilariasis.MethodsDaily mean temperature data were used to calculate Dirofilaria spp. development units, which were used to estimate the potential for complete extrinsic development in the mosquitoes (= sum of potential Dirofilaria spp. transmission days). In addition, 4,481 adult female mosquitoes were collected from 25 trapping sites. From 2010 to 2015, sampling was conducted with Centers for Disease Control miniature light traps, indoor resting mosquito collections as well as human landing catches in urban, rural and natural areas. Mosquitoes were analyzed for the presence of D. repens and D. immitis DNA using a duplex real-time PCR assay targeting nucleotide differences within the cytochrome c oxidase subunit 1 (D. repens) and 16S rRNA gene fragment (D. immitis).ResultsThe average of the yearly sum of potential Dirofilaria spp. transmission days between 2010 and 2015 ranged from 90 to 140 days with an increasing gradient from the North to the South of Moldova. Positive mosquito pools for D. repens were found countrywide at 13 of the 25 trapping sites and in 17 of the 22 screened mosquito taxa (26.51% of all 347 tested pools), while D. immitis was detected only at 4 of the trapping sites (Center and South) in 4 different mosquito species (8.65% of all 347 tested pools). Highest infection rates (EIR) per 100 specimens for both Dirofilaria species were found in An. maculipennis (s.l.) (D. repens: EIR = 4.91; D. immitis: EIR = 2.01), whereas the most frequent mosquito taxon Cx. pipiens (s.l.)/torrentium had significantly lower infections rates (D. repens: EIR = 0.88; D. immitis: EIR = 0.47).ConclusionsThe temperature conditions in Moldova are suitable for transmission of Dirofilaria spp. within the entire country, which is supported by a wide distribution of Dirofilaria spp.-positive mosquitoes with high infection rates. The low number of reported human cases most likely does not reflect the current epidemiological situation of dirofilariasis in Moldova.Electronic supplementary materialThe online version of this article (doi:10.1186/s13071-016-1916-4) contains supplementary material, which is available to authorized users.

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

“…This observation supports the assumption that a broad spectrum of mosquito taxa is potentially involved in the transmission cycles of Dirofilaria spp. in Europe with more than 20 species found infected so far [ 7 , 18 , 26 , 33 – 48 ].…”

“…All mosquito species positive for Dirofilaria spp. DNA in the DDBR were classified as suspected vectors in at least one European xenomonitoring study [ 7 , 26 , 33 – 48 ], including Ae. vexans determined as potential vector in Romania before [ 18 ].…”

“…DNA of mosquito pools and single dog samples were extracted with a KingFisher™ Flex Magnetic Particle Processor using MagMAX™ Pathogen ribonucleic acid/DNA Kit (both Thermo Fisher Scientific, Waltham, MA, USA). The samples were screened with the previously described duplex real-time PCR assay to detect D. repens and D. immitis [ 7 , 26 ]. This assay targets the mitochondrial cytochrome c oxidase subunit 1 and the nuclear 16S rRNA gene fragment to differentiate both parasites.…”

Little pigeons can carry great messages: potential distribution and ecology of Uranotaenia (Pseudoficalbia) unguiculata Edwards, 1913 (Diptera: Culicidae), a lesser-known mosquito species from the Western Palaearctic

“…Together with the recent detection of canine parasitic nematodes Dirofilaria repens in pools of Ur. unguiculata from Moldova [ 101 ], this strongly suggests much broader host range for this mosquito species and its possible relevance to the circulation of zoonotic pathogens in Europe.…”

Screening of mosquitoes for filarioid helminths in urban areas in south western Poland—common patterns in European Setaria tundra xenomonitoring studies

“…(Czajka et al 2012; Latrofa et al 2012; Bocková et al 2013; Czajka et al 2014; Kronefeld et al 2014; Silbermayr et al 2014; Rudolf et al 2014; Zittra et al 2015; Kemenesi et al 2015; Șuleșco et al 2016a, b; Kurucz et al 2016; Masny et al 2016; Ionică et al 2017). The range of conclusions drawn from molecular xenomonitoring depends on the ability to adequately sample the vector population, accurately determine the infection status in the vector, and link infections in the vector population to infections in the human or animal populations.…”