Anthelmintic resistance in goat herds-In vivo versus in vitro detection methods.

Anthelmintic resistance (AR) is a serious threat to animal health and has a major economic impact worldwide due to production and financial losses. The aim of this study was to determine the occurrence of AR on 30 goat farms in Slovakia during the pasturing seasons and to compare three widely used in vitro and in vivo methods for detecting AR in field conditions. A three-year survey was conducted during the pasturing seasons of 2014-2016. Goats on each farm were split into treated and control groups and were treated by recommended (5 mg/kg body weight) and double doses (10 mg/kg b.w.) of albendazole. Comparisons between percent reduction in a faecal egg count reduction test (FECRT) and an egg hatch test (EHT) and the presence of L3 larvae in a larval development test (LDT) using resistant concentrations of benzimidazole (BZ) were monitored after treatment. The FECRT indicated percent reductions of 69.2-86.2% for the single dose and of 36.3-45.4% for the double dose. The EHT indicated that all farms had BZ-resistant nematodes. Low (<15% hatching) and high (>15% hatching) levels of resistance were detected on 13 and 17 farms, respectively. The LDT failed to detect resistant larvae on seven farms but detected low and high levels of resistance on seven and 14 farms, respectively. The data indicate a moderate correlation between in vitro and in vivo tests for detecting BZ resistance among the 30 goat farms. The hatching detected by the EHT and the presence of L3 larvae by the LDT at resistant BZ concentrations provided reasonable identification of low levels of resistance in the parasite populations, but the use of a double dose for a treatment may underestimate the real occurrence of low levels of resistant parasites on goat farms.

Simultaneous infection by four feline lungworm species and implications for the diagnosis.

Besides Aelurostrongylus abstrusus, other parasites belonging to the superfamily Metastrongyloidea, namely Oslerus rostratus, Troglostrongylus brevior and to the family Trichuridae, i.e. Eucoleus aerophilus (syn. Capillaria aerophila), have also been reported as agents of respiratory infection in domestic cats. A case of simultaneous infection by four feline lungworm species in Sardinia is herein described. An adult female cat (Felis silvestris catus), road-killed in the southeast part of Sardinia (municipality of Villacidro, province of Cagliari), Italy, was referred to the Laboratory of Parasitology of the Veterinary Teaching Hospital in Sassari. At necropsy, the lungs were examined and dissected under a stereomicroscope for the presence of parasites, and first-stage larvae (L1) of broncho-pulmonary nematodes were searched for in a faecal sample using the Baermann method. Parasites collected in the lungs were morphologically identified as A. abstrusus, E. aerophilus, and O. rostratus. In addition to the above species, L1s of Troglostrongylus spp. were detected at coproscopy but no adult specimen was found in the lungs. The morphological identification was confirmed by the molecular amplification and sequencing of cox1 mitochondrial gene, 18S and ITS2 ribosomal DNA. This finding stands as the first simultaneous infection by four feline lungworm species in the same animal, and as the first report of O. rostratus and E. aerophilus in Sardinia.

Invasive species and their parasites: eastern cottontail rabbit Sylvilagus floridanus and Trichostrongylus affinis (Graybill, 1924) from Northwestern Italy.

The eastern cottontail Sylvilagus floridanus is a native American lagomorph. Within the genus Sylvilagus, the eastern cottontail is the species with the widest distribution. From 1950s, the species was introduced to several European countries. A rapid territorial expansion of the introduced eastern cottontails has been observed in many areas of Italy. The eastern cottontail has been demonstrated to play a main role as carrier of exotic parasites. To date, three nematode species, exotic in Italian ecosystems, have been reported from introduced S. floridanus. However, its parasite fauna biodiversity is richer in native populations of the American continent. The aim of this work was to further investigate the gastrointestinal parasites of S. floridanus, to evaluate the potential presence of other exotic species. During 2010, 101 hosts were examined, and three nematodes were collected from their digestive tract. Two parasite species (Obeliscoides cuniculi, Trichostrongylus calcaratus) were already reported in Italy; the isolation of Trichostrongylus affinis is instead the first report of this nematode in Italy and in Europe as a whole. This study wants to highlight the great risks related to the introduction of allochthonous species. The impact of the invasion by alien animal species may be particularly severe for public and animal health, due to the potential introduction of new pathogens. The good number of exotic parasites found in introduced eastern cottontails, together with the few sanitary surveys carried out, suggests that an epidemiological survey, with specimens from multiple localities on a wider geographic range, could lead to interesting findings on parasites of native and alien lagomorphs in Europe.

Morphological identification of parasitic nematode infective larvae of small ruminants and cattle: a practical lab guide.

In 2004, a new concept was introduced for simplifying identification of larvae of the common nematodes of cattle, sheep and goats that comprises estimates of the lengths of the sheath tail extensions of infective third-stage larvae (L3) of each genus and/or species to that of Trichostrongylus spp., instead of having to be dependent only on measurements in micrometre. For example, if the mean length of the sheath tail extension (the extension of the sheath caudad, beyond the caudal tip of the larva) of Trichostrongylus colubriformis and Trichostrongylus axei is assumed to be 'X', then that of Haemonchus contortus is 2.0-2.7 'X' - a difference that is not difficult to estimate. An additional new approach suggested now, particularly for L3 of species and/or genera difficult to differentiate (such as Chabertia ovina and Oesophagostomum columbianum), is to estimate the proportion of the larval sheath tail extension comprising a terminal thin, whip-like filament. For the experienced person, it is seldom necessary to measure more than one or two sheath tail extensions of L3 in a mixed culture, because the identity of most of the remaining L3 can thereafter be estimated in relation to those measured, without having to take further measurements. The aim of this article was to present the novel approach in the form of a working guide for routine use in the laboratory. To facilitate identification, figures and a separate organogram for each of small ruminants and cattle have been added to illustrate the distinguishing features of the common L3.

Additional morphometrical data on some Heligmonellidae (Nematoda: Trichostrongylina) parasitic in Neotropical rodents (Cricetidae).

Some additional morphological and metrical data are provided, particularly on the synlophe of the following species: Hassalstrongylus dessetae Pinto, 1978, Stilestrongylus eta (Travassos, 1937), Stilestrongylus manni Denké & Murúa, 1977 and Stilestrongylus valdivianus Durette-Desset & Murúa, 1979, based on type and voucher material deposited in Brazilian and French collections. Heligmonoides crassidorsualis Franco, 1967 is considered as a Nippostrongylinae incertae sedis: its synlophe not being known it is impossible to report the species to a given genus. However, it is unlikely that the species belong to the genus Heligmonoides Baylis, 1928, present only in commensal Murinae from the Old World. Heligmonoides mirzai Smales, 2009, is also regarded, temporarily, as a Nippostrongylinae incertae sedis.

Observations of the sheath extension of the third stage, infective larvae of Trichostrongylus rugatus.

The length of the sheath extension of third stage (L(3)), infective larvae of Trichostrongylus rugatus is reported. The total length and length of the sheath extension of L(3) recovered from the faeces of sheep originating from two localities in South Australia were measured. The total length of larvae was 615-722 microm and the length of the sheath extension was 46-56 microm (mean 51.5). The larvae of T. rugatus comprised up to 72% of the larvae recovered. Worm free sheep were infected with larvae from the two localities and L(3) were recovered following culture of faeces from these experimentally infected animals. L(3) measured 640-746 microm in total length with a sheath extension of 46-56 microm (mean 51.4). Adult nematodes recovered from gastro-intestinal tracts were identified as T. rugatus. The length of the sheath extension used in conjunction with the total length is a characteristic that enables confident differentiation of infective larvae of T. rugatus from other Trichostrongylus species infecting sheep in southern Australia and Haemonchus contortus.

Morphological identification of nematode larvae of small ruminants and cattle simplified.

A simplified system has been developed to facilitate identification of nematode larvae of the common nematodes of cattle, sheep and goats. Firstly, in addition to the characteristics conventionally used for identification (such as the shape of the cranial extremity and numbers of intestinal cells), the lengths of the infective sheath tails of infective larvae of each genus/species are related to that of Trichostrongylus spp. instead of using measurements for differentiation. For instance, if the mean length of the sheath tail (the distance the sheath extends caudad beyond the caudal tip of the larva) of Trichostrongylus spp. is assumed to be "X", then that of Haemonchus contortus is 2-2.7"X", and that of Oesophagostomum spp. from sheep is 4-7"X", etc. Secondly, by estimating the proportion of the sheath tail of a larva comprised of a terminal thin whip-like filament, identification is aided, particularly in those L3 of species that resemble one another closely, such as Chabertia ovina and Oesophagostomum venulosum or Oesophagostomum columbianum. After some practice with the system it is usually necessary to measure only one or two sheath tails of L3 in a mixed population, whereupon the identity of most of the remaining L3 can be estimated in relation to those measured, without a need for further measurements. The keys were found to facilitate differential larval identification and are particularly useful for training.

Morphogenesis and distribution of Trichostrongylus retortaeformis in the intestine of the rabbit.

The morphogenesis and the distribution along the digestive tract of Trichostrongylus retortaeformis(Zeder, 1800) (Nematoda) were studied in detail in one of its natural hosts, Oryctolagus cuniculus. Worm-free rabbits were each infected with T. retortaeformis larvae and were killed at 12 h post-infection (HPI) and on each day from 1 to 15 days post-infection (DPI). The distribution of worm populations along the small intestine was assessed. At the different dates of infection, more than 80% of the population was recovered from the first third of the intestine with more than 50% occurring in the first 30 cm. For each date, morphological descriptions of the different stages of the life cycle were also provided. In addition, adult worms collected from naturally infected rabbits from France were redescribed.

Distinguishing morphological features of the third larval stage of ovine Trichostrongylus spp.

In this paper we describe a procedure that enables the identification of species of infective third stage (L(3)) Trichostrongylus larvae. Lambs were infected with putatively monospecific infections of three species of Trichostrongylus commonly found in New Zealand (T. axei, T. colubriformis and T. vitrinus) and Teladorsagia (Ostertagia) circumcincta. After recovering L(3) from faecal cultures, the lambs were slaughtered and adult male worms recovered and examined for spicule morphology to verify identification. L(3) were examined for morphological features and measurement of their length. Further L(3) were exsheathed and examined under high power optics to observe posterior morphological features (tubercles). The posterior of T. colubriformis has a three-tubercle structure whereas T. vitrinus has a single tubercle and T. axei none. However, the tails of T. circumcincta also lack tubercles and thus T. axei cannot be readily distinguished from them on this feature. The range of lengths of L(3) of Trichostrongylus spp. (600-858 microm) and T. circumcincta (700-914 microm) were found to overlap considerably. The shape of the anterior end of these two species differs and this in combination with length provides an indication of the proportion of T. axei and T. circumcincta in a culture. A combination of tubercle number, with overall length and anterior morphology of L(3), can be used to differentiate nematode populations of T. axei, T. colubriformis, T. vitrinus and T. circumcincta.

Trichostrongylus auriculatus n. sp. (Nematoda: Trichostrongylidae) from the steenbok, Raphicerus campestris (Thunberg, 1811).

During a pilot survey of the parasites of some artiodactylids in the Kalahari Gemsbok National Park a new species of Trichostrongylus Looss, 1905 was recovered from the small intestine of a steenbok, Raphicerus campestris (Thunberg, 1811), a gemsbok, Oryx gazella (Linnaeus, 1758), and a red hartebeest, Alcelaphus buselaphus (Pallas, 1766). The male spicules were 0,120-0,148 mm long and an ear-shaped protuberance was present on the shaft of the left spicule. The presence of only a single protuberance is characteristic of the species.

Trichostrongylus angistris n. sp. from the red duiker Cephalophus natalensis A. Smith, 1834 and a redescription of Trichostrongylus minor Mönnig, 1932.

Trichostrongylus angistris n. sp. was found in the abomasa of 13 red duiker Cephalophus natalensis A. Smith, 1834, culled in the Charter's Creek Nature Reserve, Natal. The species is closely related to Trichostrongylus minor Mönnig, 1932 and can be differentiated from it by the shorter dorsal ray and the different shape of the gubernaculum and spicules. The shoes of the spicules of T. minor are set at an angle to the long axis, while those of T. angistris are curved. Upon re-examination, the Trichostrongylus spp., tentatively identified as Trichostrongylus capricola Ransom, 1907 and Trichostrongylus vitrinus Looss, 1905, proved to be T. angistris. In this paper, T. angistris is compared with T. capricola and T. vitrinus and T. minor is redescribed.