Abstract
(1) Dirofilariosis is a vector-borne parasitic disease mainly in domestic and wild carnivores caused by Dirofilaria (Noctiella) repens, which is endemic in many countries of the Old World, and D. immitis, which has a worldwide distribution. In recent years, an increase in the number of human cases has been reported, suggesting that dirofilariosis is an emergent zoonosis. Here, we describe further cases (N = 8), observed in Central Italy during the years 2018–2019. (2) Molecular diagnosis was performed on: (i) live worms extracted from ocular conjunctiva, cheek, and calf muscle; (ii) histological sections of surgically removed nodules from parenchymal lung, coccyx, and breast. (3) Sequence analysis (650-bp) of the mitochondrial cytochrome oxidase subunit I gene (mtDNA cox1) showed a match of 100% with the sequences of D. repens previously deposited in GenBank. ELISA test to detect IgG against filarial antigens was performed on four patients’ sera and resulted positive in two patients who showed ocular and subcutaneous dirofilariosis, respectively. Microfilariae have been never detected in the peripheral blood of the patients. (4) The occurrence of N = 8 new cases of human D. repens-infections observed in a two-year period suggests an increased circulation of the parasite in Italy. Therefore, dirofilariosis should be included in differential diagnosis in patients presenting subcutaneous and/or pulmonary nodules. Molecular diagnosis of the etiological agents is fundamental. Specific serological diagnosis needs to be improved in future research work.
Highlights
IntroductionHumans are accidental dead-end hosts of Dirofilaria spp. as in most of the reported cases, the infective larvae perish before attaining worm maturity
Considering that only superficial infections can be detected, the actual number of infected subjects is likely to be higher than what is reported, suggesting that dirofilariosis is an underestimated, emergent zoonosis. Supporting this hypothesis, here we describe eight new cases of human dirofilariosis that have come to our attention in the last two years in different Hospitals of Central Italy
Repens, which shows a higher zoonHere, we to describe eight further cases of human dirofilariosis caused by D. repens otic potential in comparison overfurther two years inofCentral
Summary
Humans are accidental dead-end hosts of Dirofilaria spp. as in most of the reported cases, the infective larvae perish before attaining worm maturity. Few confirmed cases of D. immitis have been reported [3,4] The latter species is well known to be the causative agent of many cases of human dirofilariosis in North America [5] and in Japan, where D. repens is not endemic [6,7]. Cryptic species or intraspecific genetic variation might exist within the taxon D. repens In this regard, a fixed nucleotide variation detected in the sequences of the 18S-ITS1-5.8S region allowed to suggest the existence of a novel Dirofilaria species, i.e., D. hongkongensis, responsible for both human and canine infection in Hong Kong [7,8]. The comparison of complete mitochondrial genome obtained from D. repens from Europe and Dirofilaria sp
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