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Spicule lengths of the ruminant stomach nematodes Haemonchus contortus, Haemonchus placei, and their hybrids
... Those changes have important implications for the development of new approaches for the diagnosis, treatment and control of parasitic diseases, and to study the taxonomy, population genetics, ecology and epidemiology of parasites (Gasser RB, 2006). Parasitic nematodes have been traditionally identified and distinguished on the basis on their morphology using features such as cuticular ridge patterns, sublateral hypodermic chords and morphometrics of the male bursa and spicules (Lichtenfels JR, 1988;Lichtenfels et al., 1994;Lichtenfels JR, 1994;Lichtenfels and Pilitt, 2000). However, these approaches are specialist and time consuming and often insufficient for specific identification. ...
... There are a few published reports of apparently pure H. contortus infections in cattle and H. placei infections in small ruminants . Further, H. contortus and H. placei co-infections have been reported in sheep, goats, cattle and buffalo Lichtenfels JR, 1988). The only genetic evidence for presence of H. placei and H. contorus hybrids in sheep in the field come from the identification of two worms from Brazil that were apparently heterozygous at the rDNA ITS-2 locus . ...
... Our study has revealed a striking difference in the prevalence of H. placei, and of coinfection with H. contortus, between small ruminants from southern India and Pakistan. In Lichtenfels JR, 1988). The only genetic evidence for hybridisation to date was the recovery of two worms from sheep in Brazil that were heterozygous for H. contortus and H. placei rDNA ITS-2 sequences . ...
... It sucks blood and causes significant production losses due to morbidity and mortality. Although the worm from both hosts share similar general morphology, differences in the characteristics of cuticular ridges (synlophe) of H. contortus recovered from the two animals has kindled much interest to look further into a more detailed morphology of the worm, more so when H. contortus is synmpatric in many regions of the world, especially where goats and sheep share the same pastures (Lichtenfels et al., 1986(Lichtenfels et al., , 1988(Lichtenfels et al., , 1994. In such conditions, a rapid tool for identification of individual worms is useful. ...
... According to Lichtenfels et al. (1994), the variations in ridges or synlophe is due to either the presence of short extra ridges in a location or cross overs where one ridge reversed positions with an adjacent ridge. Lichtenfels et al., (1988) showed that spicule lengths provided the quickest and easiest character used for separating most populations of H. contortus and H. placei. Gibbons (1979) showed that the relative positions of the spicule are quite variable among the species of the genus Haemonchus. ...
... Gibbons (1979) showed that the relative positions of the spicule are quite variable among the species of the genus Haemonchus. However, spicule lengths of H. contortus in the present study were generally longer than those reported for H. contortus in Australia (Lichtenfels et al., 1988) and North America (Lichtenfels et al., 1994). In this study, the proportions of the different vulvar morphs (linguiform, knobbed and smooth) remained almost constant irrespective of the host animals. ...
The large stomach worm, Haemonchus contortus is an important pathogen of goats (Capra hircus) and sheep (Ovis aries). This paper describes characteristics of surface cuticular ridges (synlophe) of H. contortus adults from the two hosts. There were more ridges in H. contortus from goats compared to that from sheep. Total body length, vulvar morphology, spicule length and cervical papillae had been considered as markers of physical adaptation and were studied and described.
... The spicules of male nematodes rank as perhaps their best-known defining features, critically important in the taxonomy of the phylum Nematoda and valuable in distinguishing between genera in the phylum (Crofton, 1966;Kaufmann, 1996), as well as in the identification of individual species (Lichtenfels et al., 1988(Lichtenfels et al., , 1994. Nematode spicules can be easily studied because when the worms are cleared by appropriate media such as lactic acid, in preparation for microscopical examination, their spicules remain distinct and visible against the translucent background tissues of the worms. ...
... and Myolaimus spp.), in those that do, spicules may vary between species in length and shape, and whether they are present as a pair or just as a single spicule. In species that have a pair of spicules, both may be of identical length and shape, and hence symmetrical, or radically different from one another in both respects (Högger and Bird, 1974;Lichtenfels et al., 1988;Smales et al., 2009) and may even be atypical and malformed in some individual worms (Andrews, 1970;Roy and Beveridge, 1997). Relatively few studies have explored the chemical composition of nematode spicules, but unlike the calcareous spicules of other invertebrate phyla (Kingsley, 1984), those of nematodes are thought not to be comprised of calcium as their structural element. ...
Nematode spicules play a vital role in the reproductive activity of species that possess them. Our primary objective was to compare the lengths of spicules of the laboratory mouse ( Mus musculus ) – maintained isolate H. bakeri – with those of H. polygyrus from naturally infected wood mice ( Apodemus sylvaticus ). On a more limited scale, we also included H. glareoli from bank voles ( Myodes glareolus ), a species reputed to possess longer spicules than either of the 2 former species. In total, we measured 1264 spicules ( H. bakeri , n = 614; H. polygyrus n = 582; and H. glareoli, n = 68). There was a highly significant difference between the spicule lengths of the Nottingham-maintained H. bakeri (mean = 0.518 mm) and H. polygyrus (0.598 mm) from 11 different localities across the British Isles. A comparison of the spicules of H. bakeri maintained in 4 different laboratories in 3 continents revealed a range in the mean values from 0.518 to 0.540 mm, while those of worms from Australian wild house mice were shorter (0.480 mm). Mean values for H. polygyrus from wood mice from the British Isles ranged from 0.564 to 0.635 mm, although isolates of this species from Norway had longer spicules (0.670 mm). In agreement with the literature, the spicules of H. glareoli were considerably longer (1.098 mm). Since spicules play a vital role in the reproduction of nematode species that possess them, the difference in spicule lengths between H. bakeri and H. polygyrus adds to the growing evidence that these 2 are quite distinct species and likely reproductively isolated.
... Most commonly, the morphology of adult male Haemonchus worms based on spicule measurements (Lichtenfels et al., 1988;Lichtenfels et al., 1994) and a linear discriminant function (Jacquiet et al., 1997;Achi et al., 2003) are used for species identification. However, the measured values obtained may overlap as often occurs among the two main species, H. contortus and H. placei (Silva et al., 2015;Vongnady et al., 2020b), resulting in potential misidentification. ...
... However, the measured values obtained may overlap as often occurs among the two main species, H. contortus and H. placei (Silva et al., 2015;Vongnady et al., 2020b), resulting in potential misidentification. The cuticular ridge pattern or synlophe (Lichtenfels et al., 1994;Lichtenfels & Pilitt, 2000) is known as one of the most valuable morphological characters mainly used for identifying trichostrongylids to the species level in ruminants (Lichtenfels et al., 1988;Lichtenfels et al., 1994;Lichtenfels & Pilitt, 2000;. This character has been applied successfully for classifying Haemonchus spp. ...
Species of the blood sucking nematode Haemonchus are a main problem in the small ruminant industry worldwide. Haemonchus worms were taken from 68 infected native goats slaughtered in three provinces of Laos in June and July 2019. Cuticular ridge patterns were used for the first time to identify adult female Haemonchus spp. and their vulvar morphs were characterized. The results showed that the variations in vulvar morphology of female Haemonchus spp. presented a knobbed morph as the dominant morphotype and predominant linguiform B subtype was also detected. In total, 270 selected female worms from each vulvar morph type were examined based on their cuticular ridge patterns in cross sections at positions of the esophageal-intestinal junction (EI), the 4 mm region from the anterior end (4 mm), and the mid-body (MB). Only Haemonchus contortus was identified and most worms had constant numbers of ridges at EI, 4 mm, and MB, namely 30, 26, and 22 ridges, respectively, accounting for 99.26%, 97.41%, and 97.04%, respectively, of worms detected, while the lowest variation in the number of ridges was at region EI which is recommended as the single best position. Based on synlophe and ITS2 sequence analysis, it was assumed that H. contortus might dominate in the sample areas with the possible numbers of ridges of H. contortus females in the ranges 29-30, 25-27, and 21-23 for positions EI, 4 mm, and MB, respectively. The cuticular ridge pattern was a useful character for identifying female Haemonchus species in this study and could be utilized as an affordable alternative method for epidemiological studies and as part of parasite control management in native goats of Laos.
... The infection causes anaemia, occasional death of the animals, and is a major animal health problem. Although the worm from both hosts share similar general morphology, differences in the characteristics of cuticular ridges (synlophe) of the worms recovered from the two animals has kindled much interest in its detailed morphology, more so in regions where H. contortus is sympatric, especially where goats and sheep share the same pastures (Lichtenfels et al. 1986(Lichtenfels et al. , 1988(Lichtenfels et al. , 1994. In Malaysia, it had been reported that there were more cuticular ridges in H. contortus from goats compared to that of sheep, although the study was confined to Penang Island, Peninsular Malaysia (Rahman and Hamid 2007). ...
... In the present study, morphological differences in H. contortus worms were found in the total body lengths, cervical papillae lengths, spicules lengths and the number of synlophe. Spicule length was found to be a discriminant character to distinguish between most populations of H. contortus and H. placei (Lichtenfels et al. 1988). The spicule measurements in this study were in the same range as H. contortus in North America as described by Lichtenfels et al. (1994). ...
The large stomach worm, Haemonchus contortus is a highly pathogenic nematode parasite of sheep (Ovis aries) and goats (Capra hircus). It sucks blood and causes acute disease, anaemia and severe economic losses due to morbidity and mortality. This paper compares characteristics of surface cuticular ridges (synlophe) and morphometrics of total body length, cervical papillae, spicules, barbs, gubernaculum and vulvar flap morphology of H. contortus recovered in the two hosts from the States of Perak and Kelantan, Peninsular Malaysia. The morphological variation in H. contortus samples recovered from the two hosts in Kelantan was found to be higher than from Perak. A discriminant function, based on three measurements of the spicule, confirmed the identity of male worms in the two hosts as belonging to the same species H. contortus.
... Morphological traits of Haemonchus worm populations of cattle and sheep origin often differ. However, they do show some phenotypic traits that are similar, making measurements crucial for the classification of individual worms (6,8). Therefore, proper identification and understanding of the epidemiology of H. placei are crucial for implementing sustainable control measures and minimizing the economic impact of the disease in Africa (9). ...
Background
Haemonchosis is a major parasitic infestation in ruminant livestock, causing significant economic losses annually. The causative organisms are helminths of the genus Haemonchus spp. Detection of the causative agent is important for effective management and control of the disease. Molecular detection and characterization of parasites is a very dependable approach for parasite identification, especially where morphological characterization is unreliable.
Methods
To detect and characterize Haemonchus species in cases of haemonchosis at a Municipal abattoir in Ibadan, Nigeria; abomasal samples were collected from cattle at the abattoir. Polymerase chain reaction (PCR) was used to detect and amplify 320 bp internal transcribed spacer-2 (ITS-2) and 400 bp external transcribed spacer (ETS) genes of the adult worms in the samples. Multiple sequence alignment and phylogenetic tree reconstruction were carried out to further confirm the presence of the worms.
Results
PCR, multiple sequence alignment, and phylogenetic reconstruction confirmed the presence of H. placei in the abomasal samples and further confirmed the species as a distinct species of bovine worms at the abattoir. Multiple sequence alignment also revealed genetic sites that can be employed to distinguish H. placei from H. contortus and H. similis.
Conclusion
Molecular techniques; PCR and sequence analysis are very important and reliable in the diagnosis of parasitic diseases. This will help to formulate effective control measures for eradication of the parasite.
... Note that using the spicules might provide the easiest and quickest method for differentiating various species, for example, H. contortus and H. placei, identified by SEM (78,79). In this study, the spicules of male H. contortus showed fused barbed tips, whereas that of male H. placei exhibited split barbed tips, which are the same features described elsewhere (1 placei with a dome-shaped anal pore, whereas the average tail length in H. longistipes was 179 µm with an elongated transverse slit. ...
Goats can be infected by multiple groups of external and internal parasites. Haemonchus spp. are among abomasal parasites that can result in higher mortality and several considerable economic losses in goats. Early detection of parasites and better understanding of the major risk factors associated with infection are among the main strategies for controlling the infection. Considering this, information on hemonchosis in goats from Egypt, and the contribution of goats in the maintenance of the epidemiological foci of the disease is limited. This study investigated the prevalence of Haemonchus species among 240 abomasum samples collected during postmortem examination of goat carcasses from Assiut Governorate, Egypt. Moreover, the association of the major risk factors to describe the epidemiological pattern of the disease was explored. This study demonstrated that 16.66% of abomasa samples harbored Haemonchus species. Additionally, age, sex, and sampling season were the most significant risk factors associated with infection. Following the variable factors under study, goats aged 1 year or older were at higher risk, with an infection rate of 22.14% (31 of 140), than
those younger than 1 year (9%) [p = 0.008; odds ratio (OR) = 2.87; 95% confidence interval (CI), 1.30–6.35]. The infection rate was 25% (19 of 76) in males and 12.8% (21 of 164) in females [p = 0.024; odds ratio (OR) = 2.26; 95% confidence interval (CI), 1.13–4.53]. Moreover, the exposure to infection was higher in summer (22.22%) than
in winter (8.33%) (p = 0.007; odds ratio (OR) = 0.318; 95% confidence interval (CI), 0.139–0.725). More importantly, three species of the parasite—Haemonchus contortus, Haemonchus placei, and Haemonchus longistipes—were identified for the first time, and the confirmation of the identification and morphological characterization of the worms was performed using light microscopy and SEM. Collectively, this study reveals interesting epidemiological, morphological, and morphometric findings associated with the occurrence of hemonchosis among goats in Egypt. This study suggests further research for exploring the major circulating species of the parasite in Egypt, which is mandatory for controlling the disease
... Note that using the spicules might provide the easiest and quickest method for differentiating various species, for example, H. contortus and H. placei, identified by SEM (78,79). In this study, the spicules of male H. contortus showed fused barbed tips, whereas that of male H. placei exhibited split barbed tips, which are the same features described elsewhere (1 placei with a dome-shaped anal pore, whereas the average tail length in H. longistipes was 179 µm with an elongated transverse slit. ...
Goats can be infected by multiple groups of external and internal parasites. Haemonchus spp. are among abomasal parasites that can result in higher mortality and several considerable economic losses in goats. Early detection of parasites and better understanding of the major risk factors associated with infection are among the main strategies for controlling the infection. Considering this, information on hemonchosis in goats from Egypt, and the contribution of goats in the maintenance of the epidemiological foci of the disease is limited. This study investigated the prevalence of Haemonchus species among 240 abomasum samples collected during postmortem examination of goat carcasses from Assiut Governorate, Egypt. Moreover, the association of the major risk factors to describe the epidemiological pattern of the disease was explored. This study demonstrated that 16.66% of abomasa samples harbored Haemonchus species. Additionally, age, sex, and sampling season were the most significant risk factors associated with infection. Following the variable factors under study, goats aged 1 year or older were at higher risk, with an infection rate of 22.14% (31 of 140), than those younger than 1 year (9%) [p = 0.008; odds ratio (OR) = 2.87; 95% confidence interval (CI), 1.30–6.35]. The infection rate was 25% (19 of 76) in males and 12.8% (21 of 164) in females [p = 0.024; odds ratio (OR) = 2.26; 95% confidence interval (CI), 1.13–4.53]. Moreover, the exposure to infection was higher in summer (22.22%) than in winter (8.33%) (p = 0.007; odds ratio (OR) = 0.318; 95% confidence interval (CI), 0.139–0.725). More importantly, three species of the parasite—Haemonchus contortus, Haemonchus placei, and Haemonchus longistipes—were identified for the first time, and the confirmation of the identification and morphological characterization of the worms was performed using light microscopy and SEM. Collectively, this study reveals interesting epidemiological, morphological, and morphometric findings associated with the occurrence of hemonchosis among goats in Egypt. This study suggests further research for exploring the major circulating species of the parasite in Egypt, which is mandatory for controlling the disease.
... In the present study, the recovered Haemonchus spp. specimens were identified as adult male and female H. contortus based on their morphological characteristics as suggested by Lichtenfels et al. 21 and Gibbons 18 . The adult female H. contortus were recognised mainly by their reddish colour and vulvar flap features. ...
A metagenomic approach was used to study the gut microbiome of Haemonchus contortus field strains and that of its predilection site, the abomasum of Dohne Merino sheep. The abomasum contents and H. contortus were collected from 10 naturally infected Dohne Merino sheep. The H. contortus specimens were classified and sexually differentiated using morphometric characters and was further confirmed through molecular identification. We investigated differences and similarities between the bacterial composition of the adult male and female H. contortus gut microbiomes, which were both dominated by bacteria from the Escherichia, Shigella, Vibrio and Halomonas genera. Major abundance variations were identified between the shared adult male and female H. contortus microbiomes. The results also revealed that Succiniclasticum, Rikenellaceae RC9 gut group and Candidatus Saccharimonas were the predominant genera in the Dohne Merino abomasum. This study provides insight into the highly diverse bacterial composition of the H. contortus gut microbiome and the Dohne Merino abomasum which needs to be studied further to explore the complex interactions of different gastrointestinal nematode microbiomes with the host.
... Over time, two camps have emerged; those wishing to define H. contortus and H. placei as distinct species and those considering them as morphs, races or isolates of a single, widespread species. Since comparative morphological criteria were recognized, supporting their classification as distinct species (Jacquiet et al., 1995(Jacquiet et al., , 1997Lichtenfels et al., 1986Lichtenfels et al., , 1988Lichtenfels et al., , 1994, studies of the epidemiology and population genetics of these organisms have become dependent on increasingly rapid and cost-effective protocols for accurate identification. Although there is a dearth of methods currently available that allow accurate differentiation of H. contortus from H. placei, those that are available are not routinely applied. ...
Diagnosis is often equated with identification or detection when discussing parasitic diseases. Unfortunately, these are not necessarily mutually exclusive activities; diseases and infections are generally diagnosed and organisms are identified. Diagnosis is commonly predicated upon some clinical signs; in an effort to determine the causative agent, identification of genera and species is subsequently performed. Both identification and diagnosis play critical roles in managing an infection, and involve the interplay of direct and indirect methods of detection, particularly in light of the complex and expanding problem of drug-resistance in parasites. Accurate and authoritative identification that is cost- and time-effective, based on structural and molecular attributes of specimens, provides a foundation for defining parasite diversity and changing patterns of geographical distribution, host association and emergence of disease. Most techniques developed thus far have been grounded in assumptions based on strict host associations between Haemonchus contortus and small ruminants, that is, sheep and goats, and between Haemonchus placei and bovids. Current research and increasing empirical evidence of natural infections in the field demonstrates that this assumption misrepresents the host associations for these species of Haemonchus. Furthermore, the capacity of H. contortus to utilize a considerably broad spectrum of ungulate hosts is reflected in our understanding of the role of anthropogenic forcing, the ‘breakdown’ of ecological isolation, global introduction and host switching as determinants of dis- tribution. Nuanced insights about distribution, host association and epidemiology have emerged over the past 30 years, coincidently with the development of increasingly robust means for parasite identification. In this review and for the sake of argument, we would like to delineate the diagnosis of haemonchosis from the identification of the specific pathogen. As a foundation for exploring host and parasite biology, we will examine the evolution of methods for distinguishing H. contortus from other com- mon gastrointestinal nematodes of agriculturally significant and free-ranging wild ru- minants using morphological, molecular and/or immunological methods for studies at the species and genus levels
... Не выявив существенных различий в развитии описанных выше личинок гемонхов и не установив достоверных видовых различий у половозрелых гемонхов, полученных от разных хозяев, ряд авторов [5,37,39,50,51] Кроме того, имеется ряд работ, посвященных изучению морфологических и ультраструктурных строений гемонхов мелкого и крупного рогатого скота [66,67,69,75,76,93,101,107,114,116,118,119,130,132,133,134,135,162,165,183,199]. D.A. Wharton [195] описаны ультраструктурные изменения инвазионных личинок H. contortus, связанных с их линькой. ...
В монографии изложены результаты морфологических и молекулярно-генетических исследований и выяснены валидность двух видов гемонхов-Haemonchus contortus и Haemonchus placei паразитирующих у овец и крупного рогатого скота. При сравнении нуклеотидных последовательностей ITS2 участков гена рибосомальной ДНК между Н. contortus и H. placei обнаружено различие 2,6 %, что показывает их различия. Выяснены эколого-функциональные взаимоотношения рода Haemonchus в системе «паразит–хозяин». В сравнительном аспекте изучено аэробное и тканевое дыхание нематод Haemonchus contortus и Parabronema skrjabini и определена активность ферментов дыхательной цепи митохондрии. Проведен мониторинг эпизоотического процесса при гемонхозе животных и оптимизированы методы и принципы профилактики.
The monograph presents the results of morphological and molecular genetic studies and elucidates the validity of two species of haemonchus: Haemonchus contortus and Haemonchus placei parasitizing in sheep and cattle. When comparing the nucleotide sequences of ITS2 regions of the ribosomal DNA gene between H. contortus and H. placei, a difference of 2.6% was found, this shows their differences. The ecological and functional relationships of the genus Haemonchus in the “parasite – host” system have been determined. In a comparative aspect, the aerobic and tissue respiration of the nematodes Haemonchus contortus and Parabronema skrjabini was studied and the activity of mitochondrial respiratory chain enzymes was determined. The epizootic process was monitored during animal haemonchosis and the methods and principles of prevention were optimized.
... Over time, two camps have emerged; those wishing to define H. contortus and H. placei as distinct species and those considering them as morphs, races or isolates of a single, widespread species. Since comparative morphological criteria were recognized, supporting their classification as distinct species (Jacquiet et al., 1995(Jacquiet et al., , 1997Lichtenfels et al., 1986Lichtenfels et al., , 1988Lichtenfels et al., , 1994, studies of the epidemiology and population genetics of these organisms have become dependent on increasingly rapid and cost-effective protocols for accurate identification. Although there is a dearth of methods currently available that allow accurate differentiation of H. contortus from H. placei, those that are available are not routinely applied. ...
Diagnosis is often equated with identification or detection when discussing parasitic diseases. Unfortunately, these are not necessarily mutually exclusive activities; diseases and infections are generally diagnosed and organisms are identified. Diagnosis is commonly predicated upon some clinical signs; in an effort to determine the causative agent, identification of genera and species is subsequently performed. Both identification and diagnosis play critical roles in managing an infection, and involve the interplay of direct and indirect methods of detection, particularly in light of the complex and expanding problem of drug-resistance in parasites. Accurate and authoritative identification that is cost- and time-effective, based on structural and molecular attributes of specimens, provides a foundation for defining parasite diversity and changing patterns of geographical distribution, host association and emergence of disease. Most techniques developed thus far have been grounded in assumptions based on strict host associations between Haemonchus contortus and small ruminants, that is, sheep and goats, and between Haemonchus placei and bovids. Current research and increasing empirical evidence of natural infections in the field demonstrates that this assumption misrepresents the host associations for these species of Haemonchus. Furthermore, the capacity of H. contortus to utilize a considerably broad spectrum of ungulate hosts is reflected in our understanding of the role of anthropogenic forcing, the ‘breakdown’ of ecological isolation, global introduction and host switching as determinants of distribution. Nuanced insights about distribution, host association and epidemiology have emerged over the past 30 years, coincidently with the development of increasingly robust means for parasite identification. In this review and for the sake of argument, we would like to delineate the diagnosis of haemonchosis from the identification of the specific pathogen. As a foundation for exploring host and parasite biology, we will examine the evolution of methods for distinguishing H. contortus from other common gastrointestinal nematodes of agriculturally significant and free-ranging wild ruminants using morphological, molecular and/or immunological methods for studies at the species and genus levels.
... A total of 180 Haemonchus spp. from sheep, goat and camel isolates were cleared in phenol-alchohol and examined for spicule length and right/left spicule barber length in male worms (8,9). In order to check for statistic analyse, t-student test and SPSS 18 software were adopted. ...
Haemonchosis has a negative effect on the farming industry throughout the world, especially in the tropic and sub-tropic countries. The present study was carried out to differentiate Haemonchus species from its main hosts in Iran, including sheep, goat and camel.
The identification took place based on the morphometrics of the spicules and molecular characters. Two hundred seventy adult male nematodes were collected from the abomasums of different ruminants (90 samples from each animal) at the slaughterhouses from different localities in Iran. Samples were morphologically identified according to the spicules' morphometric measurements. In the section on molecular study, 10 samples of each Haemonchus isolates were genetically examined. A simple PCR-restriction fragment length polymorphism (PCR-RFLP) assay of the second internal transcribed spacer of ribosomal DNA (ITS2-rDNA) were described to confirm the PCR results.
PCR-RFLP profile obtained from the restriction enzyme HPa1 in H. contortus and H. longistipes indicated 1 (278 bp) and 2 (113 and 135 bp) different fragments, respectively. The morphological parameters clearly distinguish H. contortus from H. longistipes. Moreover, regarding the ITS2-rDNA, sequences of 295 bp and 314 bp were obtained from H. contortus and H. longistipes, respectively.
The genotypic results are in agreement with the phenotypic findings of both species.
... The ability of H. contortus and H. placei to hybridise in experimental crosses and the presence of co-infections raises the possibility of interspecies hybridisation between these two species in the field. An early study reported six individual worms recovered from sheep in Georgia, United States of America, with spicule measurements that were intermediate between H. placei and H. contortus, leading to the suggestion of hybridisation (Lichtenfels et al., 1986;Lichtenfels, 1988). The only genetic evidence for hybridisation to date was the recovery of two worms from sheep in Brazil that were heterozygous for H. contortus and H. placei rDNA ITS-2 sequences (Brasil et al., 2012). ...
The most comprehensive genetic proof of F1 hybrids between two parasitic nematode species of humans or animals in the field.•Definitive demonstration is presented that hybridization occurs between Haemonchus contortus and H. placei in the field.•New genetic markers were used to identify H. contortus, H. placei and hybrid worms.•Co-infection of H. contortus and H. placei is common in small ruminants from Pakistan.•Only H. contortus is found in small ruminants from southern India.
... Some authors (Gibbons, 1979;Taylor et al., 2007) synonymized these two parasites, but currently, there is strong evidence that Hc and Hp are different species. Lichtenfels (Lichtenfels et al., 1986;1988) described morphological differences between appointed species, and Hoberg et al. (2004) revealed relationships among thirteen species of Haemonchus (Hc and Hp included) through phylogenetic analysis of twenty-five morphological characters. The cytological (Bremner, 1955) and especially molecular biological characters (Zarlenga et al., 1994;Stevenson et al., 1995;Blouin et al., 1997;Brasil et al., 2012) also confirmed that Hc and Hp are two different species. ...
A combined approach in the determination of Haemonchus nematodes from sheep was applied in this trial. Using selected morphological characters 90.2 % females and 84.2 % males of Haemonchus contortus and 9.8 % females and 15.8 % males of Haemonchus placei were identified. Although cluster analysis based on morphological identification clearly separated two Haemonchus species, H. contortus was exclusively detected in all specimens using restriction cleavage of the ITS-2 region with FspBI endonuclease as well as through the sequencing analysis. Because sheep from both farms have never had contact with other ruminants, and the farmers apply only closed flock turnover, we assume that only H. contortus mono-infection occurred on both farms. This opinion is also supported by molecular data. The most striking result of our study was the finding which indicates that the discriminant function is not able to accurately identify Haemonchus males at the species level.
... Specimens of Cooperia punctata, C. spatulata and C. oncophora were identified on the basis of spicule morphology and characteristics of the synlophe described by Lichtenfels (1977). Specimens of H. contortus and H. placei were identified on the basis of spicule length (Lichtenfels et al., 1988a) and morphology, and characteristics of the synlophe (Lichtenfels et al., 1994). Specimens of Nematodirus helvetianus were identified on the basis of characteristics of the spicules and synlophe (Lichtenfels and Pilitt, 1983). ...
Resistance to modern anthelmintics by ruminant nematode parasites is an increasing problem throughout the world. To date the problem has largely been reported in parasites of small ruminants, but there are increasing reports of such resistance in nematodes recovered from cattle. Until now there have been no published reports of drug resistant parasites from cattle in North America. In 2002 a producer in the upper Midwest who backgrounds young cattle acquired from the southeastern US experienced lower than expected weight gain as well as apparent parasitic gastroenteritis in his cattle during the fall. Fecal sample results supported the suspicion that decreased productivity and diarrhea were the result of GI nematode parasitism. The operation used intensive grazing management and practiced strategically timed deworming for >17 year. In 2003, all animals were dewormed the first week of May with Ivomec Plus, then with Dectomax Injectable on 4 June and 17 July. On 31 July, 10 randomly taken fecal samples showed EPG values from 0 to 55. To assess whether the apparent decreased drug efficacy was the result of drug resistance in the nematode population, on 18 August approximately 150 heads, previously strategic timed dewormed, of 9-11 month old cattle from one pasture were selected for study. The calves were randomly assigned to 1 of 6 treatment groups: untreated (U), ivermectin injectable (I), moxidectin pour-on (M), doramectin injectable (D), eprinomectin pour-on (E), albendazole oral (A). Cattle were weighed prior to treatment and the drug was dosed according to label directions. Seven days later, 3 calves from each group were slaughtered for worm recovery. Fecal samples taken from the remaining animals at 14 days after treatment showed that the reduction of mean fecal EPG value for each group was: U-46%, I-52%, M-72%, D-61%, E-8%, and A-68%. Worm recovery from the slaughter calves showed that all groups harbored significant numbers of Haemonchus placei and H. contortus. In addition, all avermectin-treated groups contained significant numbers of Cooperia punctata, and smaller numbers of C. oncophora and C. spatulata. These results imply that the pastures studied contain substantial numbers of H. contortus resistant to both avermectins and benzimidazoles, and H. placei and Cooperia sp. resistant to all the commonly used avermectin anthelmintics. This is the first report of anthelmintic resistance in American cattle parasites.
... Interbreeding experiments (Le Jambre, 1979) have demonstrated that they are distinct species. Roberts et al. (1954), Lichtenfels et al. (1988 found that cattle and sheep Haemonchus spp. were different in the mean length of the spicules and the position of the barbs on these spicules. ...
Haemonchus placei in cattle has never been completely described, possibly due to great morphological similarity with small ruminants Haemonchus contortus. It is newly described on one isolate from Argentina. It has clear distinct morphological features from sheep and goats Haemonchus contortus and presents only two female morphotypes (linguiform and knobbed) instead of three recorded in H. contortus. A key is proposed to identify females. Female as well as male Haemonchus placei from New World (Argentina, Mexico, USA) are morphologically different from those of Old World (Africa: Burkina-Faso, Mauritania and Ivory Coast) or Australia, possibly due to local evolution since their introduction several centuries ago from Africa or India. We propose to differentiate three sub-species, H. placei placei in Australia, H. placei africanus in western Africa and H. placei argentinensis in the New World.
В статье изучены фрагменты внутреннего транскрибирующегося спейсера (ITS-2) рибосомальной ДНК Teladorsagia circumcincta и T. davtiani, предположительно являющихся разными морфологическими формами одного вида. Установлены различия по ITS-2 T.circumcincta и T. davtiani на уровне 0,8 %. Различия ITS-2 у разных экземпляров T. circumcincta полностью отсутствовали. Относительно высокий процент различий ITS-2 T. circumcincta и T. davtiani при полном сходстве этого участка ДНК у разных экземпляров одной морфологической формы не позволяет отнести T.circumcincta и T. davtiani к одному виду.
Were obtained of partial sequences of the second internal transcribed spacer (ITS-2) rDNA for
Teladorsagia circumcincta and T. davtiani which are supposedly constitute two morphologically
distinct variants of a single species. The 0,8 % level of difference between the ITS-2 sequences
of T. circumcincta and T. davtiani was reported, whereas the sequences derived from worms of
the same morph were completely identical. Obtained data prevent an attribution of
T.circumcincta and T. davtiani to the same species.
Haemonchus contortus is a highly pathogenic nematode parasite of sheep and goats. This work was conducted to investigate the population and host variations of the parasitic nematode H. contortus of sheep and goats from Malaysia and Yemen. Eight morphological characters were investigated, namely the total body length, cervical papillae, right spicule, left spicule, right barb, left barb, gubernaculum and cuticular ridge (synlophe) pattern. Statistical analysis showed the presence of morphological variation between populations of H. contortus from Malaysia and Yemen, with minor variation in the synlophe pattern of these isolates. Isolates from each country were grouped together in the scatterplots with no host isolation. Body, cervical papillae and spicule lengths were the most important characters that distinguished between populations of the two countries. This variation between Malaysia and Yemen may be attributed to geographical isolation and the possible presence of a different isolate of this worm in each country.
The immune response of calves against excretory secretory (ES) products of adult Haemonchus placei was studied. The ES products of adult H. placei comprise at least ten polypeptides with molecular weights ranging from 10 to over 100 kDa. A primary infection of calves with H. placei did not result in a marked elevation of IgG serum antibodies reactive to ES antigens as demonstrated by ELISA. Immunoblotting experiments revealed that sera of primary infected calves recognised a 50 kDa antigen in most cases. An increase in the level of serum IgG antibodies was observed after trickle infections. The secondary immune response coincided with the recognition of a group of three ES antigens of around 50–55 kDa and one protein with a molecular weight of 24 kDa.
Monepantel is the first molecule from the amino-acetonitrile derivatives to be developed for controlling gastro-intestinal nematodes in sheep. Two studies were undertaken to examine the drug's efficacy against inhibited fourth-stage larvae of Haemonchus contortus and Teladorsagia spp. in sheep when administered as an oral solution at 2.5mg/kg bodyweight. In study 1, efficacy was 99.7% against H. contortus (p<0.0001) and in study 2, 99.8% against Teladorsagia spp. (p<0.0001). This population consisted of 93% T. circumcincta and 7% T. trifurcata. In conclusion, monepantel is a highly effective treatment against inhibited fourth-stage larvae of H. contortus and Teladorsagia spp. and the studies reported here provide the first published evidence of efficacy of this new anthelmintic against these parasites.
We previously documented the appearance of cattle nematode parasites resistant to avermectins, milbemycin, and a benzimidazole at the end of a grazing season in a backgrounding operation in the upper Midwestern US. To further characterize the pattern of drug resistance, we extended the study to (1) monitor the animals over the course of the grazing season; (2) increase the number of animals slaughtered at the end of the season to minimize the effect of potential outlying observations; (3) increase the time interval between treatment and slaughter to ensure sufficient time for drug action; (4) utilize repeated fecal sampling in the fecal egg reduction test to minimize procedural variation; (5) increase the number of drugs tested. The results of the present study were in agreement with those of the previous study and demonstrated that during the course of the grazing season the pastures harbored significant numbers of parasites that were refractory to avermectins, milbemycin, and a benzimidazole at the label recommended doses. As seen previously, Haemonchus contortus resistant to all these anthelmintics were present over the course of the study period. In contrast, Cooperia sp., mainly punctata, and Haemonchus placei were resistant only to the macrocyclic lactones. There was no apparent resistance against the older anthelmintic levamisole, which had not been used for >20 years in the operation. However, animals treated with this drug continued to harbor small but measurable numbers of Ostertagia ostertagi.
Moguranema nipponicum was obtained from the Japanese larger shrew mole, Urotrichus talpoides and two species of the Japanese moles, Mogera wogura and M. kobeae, and redescribed. U. talpoides and M. kobeae are new hosts of this nematode. Principal component analysis was performed to study the intraspecific variations of the worms. The first and second principal components depended upon the size and shape of the worms, respectively and the former correlated to the body size of host.
Debates continue over the extent to which the parasitic trichostrongylids Haemonchus placei and Haemonchus contortus hybridise in nature, and whether they deserve species status. Mitochondrial ND4 gene sequences from individuals of each putative species collected from populations around the United States indicate that the two species are highly differentiated at the mtDNA level. Furthermore, there was no evidence of introgressive hybridisation occurring in wild populations. (C) 1997 Australian Society for Parasitology. Published by Elsevier Science Ltd.
In the course of a revision of Haemonchus Cobb, 1898 (Nematoda), commonly referred to as large stomach worms, significant new morphological information was discovered that allows the recognition of 2 species believed for more than 50 yr to be synonymous. Both species, Haemonchus mitchelli Le Roux, 1929, from the eland Taurotragus oryx and other African ruminants and H. okapiae van den Berghe, 1937, from the okapi Okapia johnstoni, have a synlophe of 42 ridges, but the synlophe of H. mitchelli is longer than that of H. okapiae. The distal tip of the left spicule of H. mitchelli bears a barb that is about twice as long as the short barb and half as long as the long barb on the right spicule. In contrast, the barb on the left spicule of H. okapiae is similar in size to the short barb and about 25% as long as the long barb of the right spicule. The dorsal ray of H. mitchelli is bifurcated distally for 25-39% (32%) of its length and its stem is expanded proximally, but the dorsal ray of H. okapiae is bifurcated 37-50% (42%) and its stem is of uniform thickness.
Three Haemonchus species (Haemonchus contortus, Haemonchus placei and Haemonchus similis) live in sympatry in the savanna of North Côte d'Ivoire. Four domestic ruminant hosts (zebu-cattle, taurine-cattle, sheep and goats) share the same pastures throughout the year. Our post-mortem data imply that a Haemonchus spp. circulation exists among the different hosts species in the savanna of North Côte d'Ivoire. Under field conditions, mixed congeneric infections were the rule except in sheep where mono-specific H. contortus infections were the most frequent. The associations H.contortus+H.placei and H.placei+H.similis were dominant in goats and in cattle, respectively. In the populations examined, triple infections occurred in 11.5% of zebu-cattle and 29% of the taurine-cattle. Considering the intensities of infections, H. contortus was the main Haemonchus species of sheep and goats whereas H. similis was very rare in these host species. About 10% of the worms recovered in goats belong to the H. placei species. In cattle, H. contortus was very rare. H. placei was the dominant species in zebu-cattle (58.7% of the identified worms) and in taurine-cattle (73.9%) nevertheless, the proportion of H. similis was higher in zebu-cattle (38.6%) than in taurine-cattle (21.3%). Only few hybrids between H. placei and H. similis were found. The importance of such Haemonchus spp. circulation is discussed.
Phylogenetic analysis of 25 morphological characters among the 12 species of Haemonchus resulted in 1 most parsimonious tree (60 steps; consistency index = 0.67, retention index = 0.80). Monophyly for Haemonchus was diagnosed by 3 unequivocal synapomorphies, including the asymmetric origin of the dorsal ray, relative size of the ventral rays, and the presence of a barb on each spicule tip. Species of Haemonchus have complex histories with respect to host and geographic associations: (1) origins in Africa with basal diversification in antelopes (H. krugeri, H. lawrencei, H. dinniki, H. horaki), (2) independent events of colonization for those species in Caprini and Bovinae (H. contortus, H. placei, H. bedfordi, H. similis), (3) colonization and development of core host associations within Camelidae (H. longistipes) and among Antilopinae, Tragelaphini, and Giraffidae (H. mitchelli, H. okapiae, H. vegliai), and (4) geographically widespread species that are represented only by those that have been translocated with domestic stock. The North American fauna is characterized by 3 introduced and exotic species, H. placei, H. contortus, H. similis, which emphasizes the importance of continued documentation of faunal diversity in the context of predictive foundations derived from phylogenetic studies. Satellite associations for species of Haemonchus, particularly among Cervidae and Camelidae in the Neotropics and Cervidae, Antilocapridae, and possibly wild Caprinae in the Nearctic, have been a consequence of introductions and exchange of parasites at historical interfaces for managed and natural ecosystems. Such distributions are emblematic of the overriding significance of anthropogenic factors as determinants of the global distributions for pathogenic parasites in domestic and wild ruminants.
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