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The genus Gyrodactylus von Nordmann, 1832 represents one of the most diverse and widespread taxa within Monogenea, with approximately 500 species described worldwide. Thirty-three species of Gyrodactylus have been recorded in Mexico, and in the last two decades, at least 26 new species have been described mainly from freshwater fish families such as poeciliids, goodeids, profundulids, characids, and cichlids. In this study, we describe two new species of Gyrodactylus infecting freshwater cyprinids based on morphological and molecular characteristics. Gyrodactylus ticuchi n. sp. and Gyrodactylus tobala n. sp. were recovered from Notropis moralesi de Buen and N. imeldae Cortés, respectively, captured in five localities from the State of Oaxaca, Mexico. The new species differ slightly from their congeners in the morphology of the haptoral hard parts and the male copulatory organ. Sequences of the Internal Transcribed Spacers rDNA (ITS1-5.8S-ITS2), cytochrome oxidase subunit I (cox1), and the D2 + D3 domains of the large subunit (28S rDNA) were obtained from multiple specimens and analyzed using Maximum Likelihood (ML) and Bayesian Inference (BI). Phylogenetic hypotheses using ITS rDNA, cox1, and 28S rDNA genes recovered two new species of Gyrodactylus from N. moralesi and N. imeldae; we briefly discuss their phylogenetic relationship with other congeners. These gyrodactylids represent the first species described in species of Notropis from southern Mexico, the cyprinids exhibiting the southernmost distribution in the New World.

In the present work, a morphological and biometrical study of whipworms Trichuris Roederer, 1761 (Nematoda: Trichuridae) parasitizing Colobus guereza kikuyensis has been carried out. Biometrical and statistical data showed that the mean values of individual variables between Trichuris suis and Trichuris sp. from C. g. kikuyensis differed significantly (P < 0.001) when Student's t test was performed: seven male variables (width of esophageal region of body, maximum width of posterior region of body, width in the place of junction of esophagus and the intestine, length of bacillary stripes, length of spicule, length of ejaculatory duct, and distance between posterior part of testis and tail end of body) and three female variables (width of posterior region of body, length of bacillary stripes, and distance of tail end of body and posterior fold of seminal receptacle). The combination of these characters permitted the discrimination of T. suis with respect to Trichuris sp. from C. g. kikuyensis, suggesting a new species of Trichuris. Furthermore, males of Trichuris sp. from C. g. kikuyensis showed a typical subterminal pericloacal papillae associated to a cluster of small papillae that were absent in males of T. suis, while females of Trichuris from Colobus appeared with a vulval region elevated/over-mounted showing a crater-like appearance. The everted vagina showed typical triangular sharp spines by optical microscopy and SEM. Thus, the existence of a new species of Trichuris parasitizing C. g. kikuyensis has been proposed.

Traditional medicines have been used to treat malaria for thousands of years and are the source of artemisinin and quinine derivatives. With the increasing levels of drug resistance, the high cost of artemisisnin-based combination therapies, and fake antimalarials drugs, traditional medicine have become an important and sustainable source of malaria treatment. For the benefit of those who use traditional medicine to treat malaria, there is an urgent need to study the efficacy and toxicity of herbal remedies. Hintonia latiflora stem bark infusions are use in Mexican traditional medicine to treat malaria, diabetes, and gastrointestinal diseases. Its efficacy in the treatment of complicated malaria and its ability to generate DNA damage to the host is not fully evaluated. In our search for antimalarial natural products, in the present study, we tested the efficacy of H. latiflora stem bark methanolic extract (HlMeOHe) in CD1 male mice infected with lethal Plasmodium yoelii yoelii and its in vivo cytotoxicity and genotoxicity. To assess the antimalarial activity, the extract was evaluated in a 4-day test scheme in oral doses of 1,200, 600, and 300 mg/kg prior acute toxicity test; oral chloroquine (15 mg/kg) was used as positive control. The ability of 1,200 mg/kg of HlMeOHe to induce cytotoxicity and DNA damage in the peripheral blood of mice was assessed using a fluorochrome-mediated viability test and the micronucleus (MN) assay; N-ethyl-N-nitrosourea (ENU) was used as a positive control. HlMeOHe median acute toxicity (LD₅₀) was 2,783.71 mg/kg and LD10 was 1,293.76 mg/kg (taken as the highest work dose). Plasmodium yoelii yoelii-infected mice in the untreated control group died between 6 and 7 days post-infection (PI) with parasitemia over 70%. Even though mice treated with 600 and 300 mg/kg showed a chemosuppression percentage of total parasitemia of 99.23 and 23.66, respectively, animals in both groups died 6 to 7 days PI with parasitemia over 45%. A 4-day dosage of 1,200 mg/kg of the extract showed, in the P. yoelii yoelii-infected mice, a 100% chemosuppression of total parasitemia on 5 days PI and a 23 days survival time with a mean parasitemia of 23.6% at the date of death. Only mice treated with chloroquine survived until the end of the experiment. Cell viability was not affected. The average number of micronuclei in the treated mice increased significantly (P < 0.05) to 4.8 MN when compared with the untreated control group (0.9 MN). The results obtained in this study showed that the infection outcome of P. yoelii yoelii-infected mice is affected by HlMeOHe. Although a concentration of 1,200 mg/kg of HlMeOHe is suitable to use in the treatment of malaria fever, slowed down the parasite replication, retarded the patency time, and increased the infected P. yoelii yoelii mice survival time, its chemical composition should be studied in detail in order to reduce its genotoxic potential.

A molecular phylogenetic hypothesis is presented for the genus Trichuris based on sequence data from the mitochondrial cytochrome c oxidase 1 (cox1) and ribosomal 18S genes. The taxa consisted of different described species and several host-associated isolates (undescribed taxa) of Trichuris collected from hosts from Spain. Sequence data from mitochondrial cox1 (partial gene) and nuclear 18S near-complete gene were analyzed by maximum likelihood and Bayesian inference methods, as separate and combined datasets, to evaluate phylogenetic relationships among taxa. Phylogenetic results based on 18S ribosomal DNA (rDNA) were robust for relationships among species; cox1 sequences delimited species and revealed phylogeographic variation, but most relationships among Trichuris species were poorly resolved by mitochondrial sequences. The phylogenetic hypotheses for both genes strongly supported monophyly of Trichuris, and distinct genetic lineages corresponding to described species or nematodes associated with certain hosts were recognized based on cox1 sequences. Phylogenetic reconstructions based on concatenated sequences of the two loci, cox1 (mitochondrial DNA (mtDNA)) and 18S rDNA, were congruent with the overall topology inferred from 18S and previously published results based on internal transcribed spacer sequences. Our results demonstrate that the 18S rDNA and cox1 mtDNA genes provide resolution at different levels, but together resolve relationships among geographic populations and species in the genus Trichuris.

Canine demodicosis is a severe and highly prevalent dermatologic disease in dogs. Pet dogs can be affected by three recognized Demodex species that can produce clinical effects. In this paper, three morphological types of Demodex mites have been isolated from Spanish dogs. A complete morphobiometrical study of each one has been carried out. Morphological and biometrical studies revealed three closely related populations with some distinctive characteristics and could be identified as Demodex canis, Demodex injai, and Demodex sp. "cornei." Furthermore, one population of D. canis from China, different populations of Demodex folliculorum from human skin (Spain and China), D. folliculorum from human eyelashes (Spain), and Demodex brevis from human skin (China) were considered to find out the level of variation between different species and geographical origin. The aim of the present study is to assess the usefulness of mitochondrial DNA molecular markers in establishing phylogenetic relationships and resolve taxonomic questions in Demodex mites. Molecular studies based on the amplification and sequencing of the 16S rDNA and cytochrome oxidase I mitochondrial genes did not show clear differences between the three morphotypes considered. Furthermore, phylogenetic relationships in Demodex mites were analyzed. The resulting phylogenetic trees show that Demodex species from dogs were gathered together, and populations of D. folliculorum from humans appear together in a different branch; however, D. brevis from humans seemed to be more distant. Our results show that cytochrome oxidase I region is a useful tool to solve different taxonomic questions at the species and population level and to infer phylogenetic relationships in Demodex species. However, 16S mitochondrial rDNA seems a good marker for comparisons at an interspecies level, but not at a population level in this group of mites. Furthermore, from genetic distance and divergence data, we would suggest that D. canis, D. injai, and Demodex sp. cornei are polymorphisms of the same species.

A morphobiometrical and molecular study of two populations of Demodex folliculorum from humans isolated from different habitats, skin and eyelashes follicles, were carried out. Morphological and biometrical studies revealed two closely related populations with any distinctive characteristics. For molecular study, a 436-bp region of the 16S rDNA gene and a 453-bp region of the cytochrome oxidase I (COI) gene from individual mites of each population considered were sequenced. Intraindividual and interindividual sequence variation was studied in both populations. Our data show that 16S rDNA is not a useful marker to discriminate between populations; however, COI gene sequences can help to identify the two populations considered, which are morphologically very close and difficult to separate by classic methods. These results are in agreement with the morphological and biometrical differences detected between D. folliculorum from eyelashes and human skin. This study appeals for the revision of the taxonomic status of the D. folliculorum populations, as well as for the species included within genus Demodex.

A phylogeographic study was carried out of Trichuris muris, nematode parasitizing Murinae rodents from the Muridae family, isolated from four different hosts and from different geographical regions of Europe by amplification and sequencing of the ITS1-5.8S-ITS2 fragment of the ribosomal DNA. T. muris was found in the Apodemus sylvaticus, Apodemus flavicollis, Mus domesticus, and Rattus rattus rodents. The molecular results confirm the presence of DNA polymorphisms among T. muris isolates from Europe. The present study shows two clear-cut geographical and genetic lineages: one of them is widespread from northern Spain (Catalonia) to Denmark (Western European region), while the second is widespread in the Eastern European region (Croatia, Rumania, and Turkey). These two genotypes can be easily distinguished by a PCR-RFLP analysis of this sequence with the ApalI restriction enzyme. Moreover, networks and phylogenetic reconstructions also reveal that T. muris from various Murinae rodents did not differentiate according to the host species that they parasitize. Furthermore, T. muris isolated from The Canary Islands revealed a typical haplotype (H6) only present in The Canary Islands and not in continental Europe. It is suggested that one haplotype from La Gomera Island is the ancestor of T. muris in the Canary Islands.

The partial mitochondrial cytochrome c-oxidase subunit 1 gene (cox 1) and partial mitochondrial 16S ribosomal DNA of Trichuris skrjabini (Baskakov 1924) isolated from Capra hircus have been amplified and sequenced. The analyses of multiple sequence alignments of mitochondrial 16S rDNA and cox 1 of T. skrjabini revealed high homology with those of Trichinella species. For the first time, the mitochondrial DNA gene sequences of one species of trichurid nematode have been cited.

The complete internal transcribed spacer 1 (ITS1), 5.8S rDNA, and ITS2 region of the ribosomal DNA and a 390-bp region of the 16S rDNA gene from five taxa belonging to Rhinonyssus (Rhinonyssus vanellus, Rhinonyssus tringae, Rhinonyssus neglectus, Rhinonyssus echinipes from Kentish plover, and Rhinonyssus echinipes from grey plover) were sequenced to examine the level of sequence variation and the taxonomic levels to show utility in phylogeny estimation. Our data show that these molecular markers can help to discriminate between species and populations included in the Rhinonyssus coniventris complex (R. tringae, R. neglectus, R. echinipes), which are morphologically very close and difficult to separate by classic methods. A comparative study with sequences from other rhinonyssid mites previously published was also carried out. The resulting phylogenetic tree inferred from ITS1-5.8S-ITS2 region sequences obtained in this paper, together with those from other 11 taxa of rhinonyssid, shows slight differences from the current taxonomy of the Rhinonyssidae. This study appeals for the revision of the taxonomic status of the R. coniventris complex, as well as for the species included within it.

Trichuris suis was isolated from the cecum of two different hosts (Sus scrofa domestica -- swine and Sus scrofa scrofa -- wild boar) and Trichuris vulpis from dogs in Sevilla, Spain. Genomic DNA was isolated and internal transcribed spacers (ITS)1-5.8S-ITS2 segment from the ribosomal DNA (rDNA) was amplified and sequenced using polymerase chain reaction techniques. The sequence of T. suis from both hosts was 1,396 bp in length while that of T. vulpis was 1,044 bp. ITS1 of both populations isolated of T. suis was 661 nucleotides in length, while the ITS2 was 534 nucleotides in length. Furthermore, the ITS1 of T. vulpis was 410 nucleotides in length, while the ITS2 was 433 nucleotides in length. One hundred fifty-four nucleotides were observed along the 5.8S gene of T. suis and T. vulpis. Intraindividual and intraspecific variations were detected in the rDNA of both species. The presence of microsatellites was observed in all the individuals assayed. Sequence analysis of the ITSs and the 5.8S gene has demonstrated no sequence differences between T. suis isolated from both hosts (S. scrofa domestica -- swine and S. scrofa scrofa -- wild boar). Nevertheless, clear differences were detected between the ITS1 and ITS2 of T. suis and T. vulpis. Furthermore, a comparative molecular analysis between both species and the previously published ITS1-5.8S-ITS2 sequence data of Trichuris ovis, Trichuris leporis, Trichuris muris, Trichuris arvicolae, and Trichuris skrjabini was carried out. A common homology zone was detected in the ITS1 sequence of all species of trichurids.