Abstract
Onchocercidae nematodes are heteroxenous parasites with worldwide distribution, and some of the species associated to animals may present zoonotic potential. Climatic changes and anthropic influences on the environment may result in vectors’ proliferation, facilitating the spillover to humans and/or non-typical animal hosts. The Iguaçu National Park (PARNA Iguaçu), one of the most important Brazilian natural remanescents of Atlantic rainforest, is strongly affected by human activities such as tourism and agriculture. The complexity of this area is especially characterized by the close nexus between the rich wildlife, humans, and domestic animals, especially domestic dogs. Based on this, this research aimed to diagnose the Onchocercidae nematodes in wild carnivores and domestic dogs in the PARNA Iguaçu and the surrounding areas. For this, we collected 162 samples of seven species of wild carnivores and 225 samples of domestic dogs. The presence of microfilariae in the blood samples was diagnosed by the modified Knott’s test and molecular screening, and the specific identification was based on sequencing of the myoHC and hsp70 genes. Microfilariae were detected only in ring-tailed coatis, in which we found five species: Mansonella sp. 1, Mansonela sp. 2, Onchocercidade gen. sp. 1, Onchocercidade gen. sp. 2, and Dirofilaria immitis. The morphological analysis supported the molecular findings. The domestic dogs were parasitized by Acanthocheilonema reconditum, representing a new locality record for this species. Phylogenetic analysis showed high genetic similarity among the four undetermined species and Mansonella spp., Brugia spp., and Wuchereria bancrofti. The presence of D. immitis in ring-tailed coatis may be result of spillover from dogs, even though the parasite was not diagnosed in the sampled dogs. The presence of several undetermined Onchocercidae species indicates the necessity of continuous investigations on wild and domestic animals from Neotropical area, especially considering the growing anthropic influence on forest remnants.
Highlights
The Onchocercidae nematodes are represented by 88 genera and constitute an important group of vector-borne spirurids with wordwide distribution [1,2]
Filarids are vector-borne Onchocercidae nematodes widely distributed around the world, related to several hosts, both wild and domestic, in different Biomes, including humanrelated species
Epidemiology and molecular genetic diversity studies of these filarial parasites are of great importance for three main reasons: zoonotic potential of many known species of filarids; the lack of data about the species inhabiting neotropical regions and the current worldwide deforestation and consequent habitat loss scenario, which favors the emergence or re-emergence of diseases resulting from the infection of domestic animals and humans by parasites that used to have as reservoirs only wild animals
Summary
The Onchocercidae nematodes are represented by 88 genera and constitute an important group of vector-borne spirurids with wordwide distribution [1,2]. The adult forms of filarids can be found in blood or lymphatic vessels, heart, lungs, body cavities, articulations, and subcutaneous tissues, while their larvae, named microfilariae, are located mainly in blood or subcutaneous tissues. The severity of the disease caused by these nematodes is related to the parasite species, the location of the adult form and to the lesions caused by the microfilariae in the tissues. The World Health Organization included three diseases caused by Onchocercidae nematodes, namely river blindness, lymphatic filariosis, and dracunculiosis, are included in the Tropical Neglected Diseases list [4]. The most studied filariosis are those that affect humans, as the Bancroftian filariosis, caused by Wuchereria brancofti; the river blindness, caused by Onchocerca volvulus, the African and Asian lymphatic filarioses, caused by Brugia timori, Brugia pahangi, Brugia malayi, and Loa loa [5]; and mansonellosis caused by Mansonella streptocerca in Africa, Mansonella perstans in African and American continents, and Mansonella ozzardi, commonly found in Latin America and endemic in the Brazilian Amazonia [6–9]
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