Systematics of gastrointestinal nematodes of domestic ruminants: advances between 1992 and 1995 and proposals for future research

The Systematics of trichostrongyloid nematodes of ruminants provides a foundation for diagnostics and responds to the need to identify eggs in feces, free-living larvae from pastures or fecal cultures and larval or adult nematodes collected from hosts. These needs are associated with diagnostic problems or research projects. Difficulties in identifying all developmental stages of trichostrongyloid nematodes of domestic ruminants still severely limit the effective diagnosis and control of these parasites. Phylogentetic hypotheses as the basis for predictive classifications have been developed only for the subfamilies of the Trichostrongylidae. This report briefly describes recent progress in the development of improved tools for identification, phylogenetic analyses and predictive classifications. It also describes future research needed on the identification and classification of trichostronglyoid nematode parasites of domestic ruminants. Nematodes included are species of the superfamily Trichostrongloidea known to be important pathogens of domestic ruminants. The information summarized is presented by nematode developmental stage and by taxonomic groups. Eggs: While eggs of some trichostrongyloid nematode parasites of ruminants can be readily identified to their genus (Nematodirus), and some to species (e.g. Nematodirus battus), most of the important pathogens (including the Ostertagiinae and Haemonchinae) cannot be identified morphologically even to family level. However, DNA technology has been developed for determining not only the presence of specific pathogens in eggs from fecal samples, but also for estimating the percentage of the total eggs that each pathogens comprises. This new method will make possible a rapid determination of which individual animals in a herd should be treated. Larvae: The most commonly used method for identifying infective larvae is time-consuming (several weeks), unreliable for estimating intensities of individual species as components of mixed populations and requires highly-trained specialists. Available identification keys for larvae are not well illustrated and need to be augmented. Adults: Recent advances in the identifications of adult trichostronglyoids and their systematics are organized by taxonomic group. General included are Ostertagia, Haemonchus, Cooperia, Trichostrongylus and Nematodirus. Recently, the first phylogenetic analysis of the Trichostrongylidae family established monophyly for the family. A similar analysis of the Molineidae is needed. Ostertagia: Several studies of polymorphism summarized the phenomenon and listed 19 polymorphic species of Osteragiinae supported of DNA differences within and among polymorphic species of Ostertagiinae supported earlier hypotheses that the species pairs represent polymorphic species. A phylogenetic analysis of the Ostertagiinae and generic concepts are needed. Haemonchus: A key to three species of Haemonchus provides, for the first time, morphological characteristics for the microscopical identifucation to species of individual adult nematodes of either sex. The Food and Drug Administration is now requiring that results of drug trials included identification of Haemonchus to species. Cooperia: Studies using random amplified polymorphic DNA methods showed a high degree of variation within and among C. oncophora/ C. surnabada. but supported a polymorphic relationship for the species pair. A phylogenetic analysis of the Cooperiinae is needed. Trichostronglys: Restriction Fragment Lenght Polymorphisms (RFLPs) of genomic DNA polymorphism. However, other studies demonstrated expected species-level differences between T. colubriformis and T. vitrinus using Random Amplified Polymorphic DNA (RAPD) methods. Sequences of the second Internal Transcribed Spacer Region (ITS-2) ribosomal repeat showed sequence differences of 1.3-7.6% among five well-defined species of Trichostrongylus. This provides a standard for species-level differences within the Trichostrogylidae. Nematodirus: This origin of N. battus in the British Isles is still a mystery. Recently, DNA studies have provided evidence that populations on both coasts of the United States originated from Canada. A phylogenetic study of Nematodirus is in progress. Modern systematic methods have not yet been applied to the development of classifications for all subfamilies and most genera of the Trichostrongyloidea. Additional factors complicating these problems are a lack of knowledge of the parasites of wild bovids and cervids, the international transport of wild and domestic hosts and environmental changes that may alter the parasite fauna in a modern farm

Systematics of gastrointestinal nematodes of domestic ruminants: advances between 1992 and 1995 and proposals for future research

The Systematics of trichostrongyloid nematodes of ruminants provides a foundation for diagnostics and responds to the need to identify eggs in feces, free-living larvae from pastures or fecal cultures and larval or adult nematodes collected from hosts. These needs are associated with diagnostic problems or research projects. Difficulties in identifying all developmental stages of trichostrongyloid nematodes of domestic ruminants still severely limit the effective diagnosis and control of these parasites. Phylogentetic hypotheses as the basis for predictive classifications have been developed only for the subfamilies of the Trichostrongylidae. This report briefly describes recent progress in the development of improved tools for identification, phylogenetic analyses and predictive classifications. It also describes future research needed on the identification and classification of trichostronglyoid nematode parasites of domestic ruminants. Nematodes included are species of the superfamily Trichostrongloidea known to be important pathogens of domestic ruminants. The information summarized is presented by nematode developmental stage and by taxonomic groups. Eggs: While eggs of some trichostrongyloid nematode parasites of ruminants can be readily identified to their genus (Nematodirus), and some to species (e.g. Nematodirus battus), most of the important pathogens (including the Ostertagiinae and Haemonchinae) cannot be identified morphologically even to family level. However, DNA technology has been developed for determining not only the presence of specific pathogens in eggs from fecal samples, but also for estimating the percentage of the total eggs that each pathogens comprises. This new method will make possible a rapid determination of which individual animals in a herd should be treated. Larvae: The most commonly used method for identifying infective larvae is time-consuming (several weeks), unreliable for estimating intensities of individual species as components of mixed populations and requires highly-trained specialists. Available identification keys for larvae are not well illustrated and need to be augmented. Adults: Recent advances in the identifications of adult trichostronglyoids and their systematics are organized by taxonomic group. General included are Ostertagia, Haemonchus, Cooperia, Trichostrongylus and Nematodirus. Recently, the first phylogenetic analysis of the Trichostrongylidae family established monophyly for the family. A similar analysis of the Molineidae is needed. Ostertagia: Several studies of polymorphism summarized the phenomenon and listed 19 polymorphic species of Osteragiinae supported of DNA differences within and among polymorphic species of Ostertagiinae supported earlier hypotheses that the species pairs represent polymorphic species. A phylogenetic analysis of the Ostertagiinae and generic concepts are needed. Haemonchus: A key to three species of Haemonchus provides, for the first time, morphological characteristics for the microscopical identifucation to species of individual adult nematodes of either sex. The Food and Drug Administration is now requiring that results of drug trials included identification of Haemonchus to species. Cooperia: Studies using random amplified polymorphic DNA methods showed a high degree of variation within and among C. oncophora/ C. surnabada. but supported a polymorphic relationship for the species pair. A phylogenetic analysis of the Cooperiinae is needed. Trichostronglys: Restriction Fragment Lenght Polymorphisms (RFLPs) of genomic DNA polymorphism. However, other studies demonstrated expected species-level differences between T. colubriformis and T. vitrinus using Random Amplified Polymorphic DNA (RAPD) methods. Sequences of the second Internal Transcribed Spacer Region (ITS-2) ribosomal repeat showed sequence differences of 1.3-7.6% among five well-defined species of Trichostrongylus. This provides a standard for species-level differences within the Trichostrogylidae. Nematodirus: This origin of N. battus in the British Isles is still a mystery. Recently, DNA studies have provided evidence that populations on both coasts of the United States originated from Canada. A phylogenetic study of Nematodirus is in progress. Modern systematic methods have not yet been applied to the development of classifications for all subfamilies and most genera of the Trichostrongyloidea. Additional factors complicating these problems are a lack of knowledge of the parasites of wild bovids and cervids, the international transport of wild and domestic hosts and environmental changes that may alter the parasite fauna in a modern farm

Correção de dados sobre a Coleção Helmintológica do Instituto Pasteur de São Paulo Rectification of data on the Helminthological Collection of the Pasteur Institute

A presente nota se destina a corrigir informações anteriores a respeito da condição da Coleção Helmintológica do Instituto Pasteur, que é, de fato, uma coleção institucional e que foi designada, erroneamente, como um acervo particular incorporado à Coleção Helmintológica do Instituto Oswaldo Cruz. Também, dados bibliográficos e históricos são retificados.<br>This note is to correct previous information about the status of the Helminthological Collection of the Pasteur Institute, that is, in fact, an institutional collection, and that appeared erroneously as a private survey incorporated to the Helminthological Collection of the Oswaldo Cruz Institute. Also, bibliographical and historical data are rectified

A PCR-ELISA for the identification of cyathostomin fourth-stage larvae from clinical cases of larval cyathostominosis

We report the use of six oligoprobes designed from intergenic spacer region sequences to identify fourth-stage larvae (L4) of the tribe Cyathostominae. Oligoprobes were designed for identification of the following species: Cylicocyclus ashworthi, Cylicocyclus nassatus, Cylicocyclus insigne, Cyathostomum catinatum, Cylicostephanus goldi, and Cylicostephanus longibursatus. A seventh probe was designed as a positive control to identify all these members of the Cyathostominae. The intergenic spacer region was amplified by PCR using conserved primers. Initially, three oligoprobes were used in Southern blot analysis. To facilitate high-throughput identification, these and a further four oligoprobes were developed for use in a PCR–ELISA. All probes were validated for their ability to detect cyathostomin PCR products in the PCR–ELISA, using DNA from morphologically identified adult parasites. Initially, 712 L4 were isolated from the diarrhoeic faeces from horses (n = 17) with clinical larval cyathostominosis. PCR products from 522 of these L4 were subjected to analysis, with 413 L4 being identified as one of the aforementioned species. With reference to individual species analysis, 28.5% of the 522 L4 were identified as C. longibursatus, 25.7% as C. nassatus, 15.9% as C. ashworthi, 7.3% as C. goldi and 1.7% as C. catinatum. No L4 were identified as being C. insigne species. When L4 within faeces from individual horses were compared, no sample was found to comprise parasites of one species. The least number of species identified in a single sample was two. This study suggests that clinical larval cyathostominosis is predominantly caused by mixed-species infections