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.
Highlights
Over the last two decades, a significant spread of dirofilariasis has been observed in eastern and central Europe
There were no differences in the average sum of potential Dirofilaria spp. transmission days between sampling sites that were positive for D. immitis (120.87 ± 7.76) or D. repens (121.54 ± 10.09)
All of them were screened for the presence of D. repens and D. immitis DNA (Table 1)
Summary
Over the last two decades, a significant spread of dirofilariasis has been observed in eastern and central Europe. Over the last two decades, a significant spread of human Dirofilaria spp. infections has been observed in eastern and central Europe, including an increase of human cases [10, 11]. Three autochthonous human cases of ocular dirofilariasis were reported from Tiraspol (2000), Chisinau (2007) and Bender (2009) in eastern and central Moldova [21, 22]. There are hardly any studies evaluating Dirofilaria spp. infections in the local canine populations and only one recent study reports the presence of D. immitis identified by morphology in 24% of examined dogs from central Moldova, indicating circulation of the parasite at least in this part of the country [24]
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