Host genetic diversity and body condition influence parasite resistance and clearance in a wild marine mammal population.

Host genetic variability can modulate infection resistance, although its role in infection clearance remains unclear. Hookworm disease (Uncinaria sp.) is the leading cause of pup mortality in several otariid species, although the parasite can be cleared through immune-mediated processes. We evaluated the association of host genetic diversity, body condition and immune response with hookworm resistance and/or clearance in the South American fur seal (Arctocephalus australis). Uninfected pups had higher heterozygosity than parasitized individuals, indicating a negative relationship between heterozygosity and the chances of infection. Likewise, pups that died of hookworm infection had lower heterozygosity than those that died of non-infectious causes. Interestingly, once infected, pups that survived hookworm infection had heterozygosities similar to pups that died of hookworm disease. However, pups that cleared the infection had a higher body mass and parasite-specific immunoglobulin G levels than those that did not recover or died of hookworm disease. Thus, although heterozygosity predicted resistance to and mortality from hookworm infections, it did not affect parasite clearance, which was facilitated by better body condition and adaptive immune responses. This demonstrates that host genetic variability and host-environment interactions influence disease dynamics, acting at different, well-defined stages of infection.

Molecular identification and genetic diversity of zoonotic hookworm infections in domestic dogs from northeastern, Thailand.

Hookworm infections remain a significant public health concern in tropical and subtropical regions, including Thailand. This study investigated the species and genetic diversity of hookworm infections in domestic dogs from northeastern Thailand. The molecular analysis focused on amplifying and sequencing specific regions of ribosomal RNA genes (ITS1-5.8S-ITS2 region) and the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene in hookworm larvae recovered from 21 domestic dog stool samples. Among 21 larvae (one larva per infected dog) analyzed, 14 had sequences identical to Ancylostoma caninum, and 7 showed sequences almost identical to Ancylostoma ceylanicum. Phylogenetic analysis of cox1 sequences placed A. caninum and A. ceylanicum in separate clades. The median-joining network of A. caninum cox1 sequences from Thailand showed high haplotype diversity and belonged to the same cluster as sequences from Australia while forming separate clusters from those of A. caninum samples from the USA. The available published A. ceylanicum cox1 sequences (n = 33), in combination with seven sequences in the present study, represented 15 haplotypes distributed among three clusters. Interestingly, A. ceylanicum sequences from dogs and humans shared the same haplotypes. These findings are crucial for recognizing the potential for zoonotic transmission, highlighting the necessity for targeted control measures, and increasing awareness among pet owners and healthcare professionals to mitigate the risk of hookworm transmission to humans.

Hookworm Anthelmintic Resistance: Novel Fecal Polymerase Chain Reaction Ancylostoma caninum Benzimidazole Resistance Marker Detection in a Dog.

A 4 yr old castrated male greyhound presented with a history of chronic (>3 wk) intermittent diarrhea. Initial fecal analysis identified infection with Ancylostoma caninum. Despite treatment with routine anthelmintics, the dog remained persistently A caninum positive for several months. A novel fecal gastrointestinal real-time polymerase chain reaction (qPCR) parasite panel detected A caninum and the genetic benzimidazole (BZ) F167Y resistance marker in multiple samplings over 48 hr. This finding, together with the dog's clinical signs (diarrhea) and lack of response to routine anthelmintics, prompted treatment with cyclooctadepsipeptide emodepside, a drug currently not registered for dogs in the United States. The dog's clinical signs resolved and post-treatment fecal qPCR testing was negative. However, 5 mo later, retesting with fecal qPCR detected A caninum and concurrent BZ resistance marker, as well as Giardia. A presumptive diagnosis of re-infection was made and the emodepside treatment was continued. The dog again reverted to undetected (A caninum and the 167 resistance marker) on reassessment fecal qPCR. This case report describes the use of a novel fecal qPCR panel for gastrointestinal parasites, persistent hookworm and BZ F167Y resistance marker detection in a dog, and highlights the importance of a stepwise approach to clinical management, treatment, and retesting.

Epidemiological and molecular updates on hookworm species in dogs from southern Italy.

BACKGROUND: The zoonotic hookworms Ancylostoma caninum and Uncinaria stenocephala are widespread soil-transmitted helminths in dogs in Europe. Given the veterinary and public health importance of hookworms in dogs and the recent changes in the molecular epidemiology of some species, there is a need to continuously monitor the epidemiological and molecular prevalence of these parasites also at the "local" level. The present study aimed to update the epidemiological scenario of hookworm infections in both owned and stray dogs in southern Italy and to discriminate between different hookworm species (A. caninum and U. stenocephala) through molecular analyses. For this purpose, a retrospective analysis was performed over 10 years (2011-2021), including a total of 7008 owned dogs and 5642 stray dogs referred to our laboratory for copromicroscopic examinations. Moreover, 72 faecal samples, from dogs naturally infected by hookworms, were used to discriminate between A. caninum and U. stenocephala using two PCR protocols. Prior to molecular analyses, a subsample of 40/72 positive faecal samples was used for morphometric investigations on hookworm eggs. RESULTS: The results of the ten-year retrospective analysis (2011-2021) showed an overall prevalence of hookworm infection of 9.16%, specifically 5.1% in owned dogs and 14.2% in stray dogs. Logistic regression showed a significant association between positivity to hookworms and the variable "puppies" both in stray (13.84%; OR = 2.4) and owned (7.07%; OR = 2.2) dogs. The results of molecular analyses showed that positivity was confirmed only in 21/72 samples, specifically, 6 samples using protocol A and 19 with protocol B. Sequencing revealed 15 samples positive to U. stenocephala and 6 to A. caninum. CONCLUSIONS: The findings of this study showed a high prevalence of hookworm infections in dogs in southern Italy, updating the epidemiological scenario of the last decade. Moreover, the results of the study revealed the first identification of hookworm species in dogs in Italy by molecular studies, highlighting that U. stenocephala is more prevalent than A. caninum.

Molecular variability of the Ancylostoma secreted Protein-2 (Aca-asp-2) gene from Ancylostoma caninum contributes to expand information on population genetic studies of hookworms.

Hookworm infection is a major public health problem in many regions of the world. Given the high levels of host morbidity and even mortality of the host caused by these infections, it is crucial to understand the genetic structure of hookworm populations. This understanding can provide insights into the ecology, transmission patterns, mechanisms of drug resistance, and the development of vaccines and immunotherapeutic strategies. Previously, we examined presumably neutral molecular markers, such as microsatellites and COI (Cytochrome C oxidase subunit 1) in Brazilian populations of Ancylostoma caninum. Here we analyze the molecular variability of a genomic fragment of the Aca-asp-2 (Ancylostoma secreted protein-2) gene from Ancylostoma caninum. This gene is a highly expressed and activated following the infection of the L3 larvae in the host. We obtained individuals of A. caninum from five different geographic locations in Brazil, sequenced and analyzed parts of the gene. The results revealed extensive polymorphism at this fragment, especially in the intronic region, indicating low selective pressure acting on these sequences. However, we also observed irregular distributions of nucleotides and polymorphisms in the coding region of this gene, resulting in the identification of 27 alleles. The data presented here contribute to expanding the understanding of population genetic studies of hookworms.

A case of severe hookworm infection. / 临床极重症钩虫感染1例.

With the improvement of sanitation, the infection rate of hookworm is greatly reduced and the severe infected case is rarely reported. Combined morphological and molecular biological examinations, a severe hookworm infection patient was diagnosed in Department of Laboratorial Examination, Quanzhou First Affiliated Hospital of Fujian Medical University. The morphological methods such as direct fecal smear microscopy, saturated brine flotation and hookworm larvae culture methods were used to identify the eggs and larvae from stool samples of the patient. There were a large number of hookworm eggs in patient's stool samples, and the average count was 60 840 per gram by modified Kato method, which belonged to severe hookworm infection. Meanwhile, to distinguish the hookworm species, the semi-nested RT-PCR assay was employed to detect hookworm internal transcribed spacer series from eggs in patient's stool samples, and the result showed that the hookworm species was confirmed to be Necator americanus.

Comparison of real-time PCR and the Kato-Katz method for the diagnosis of soil-transmitted helminthiasis and assessment of cure in a randomized controlled trial.

BACKGROUND: Diagnosis of soil-transmitted helminths (STHs) in developing countries is commonly based on microscopic detection of eggs in stool samples, using the Kato-Katz (KK) method, which has a poor sensitivity for detecting light intensity infections. We compared the performance of the KK method and real-time PCR in the framework of a randomized trial, which evaluated four novel treatments against Trichuris trichiura and concomitant STH infections. RESULTS: Two stool samples obtained from 320 participants were examined at baseline and follow-up with quadruplicate KK and PCR analyses of one of the two samples using "bead-beating" for DNA extraction. At follow-up, 80 samples were negative according to both PCR and KK and 173 were positive with both methods for any of the STHs. Relative to PCR, the calculated sensitivity of KK at follow-up was 83.6%, 43.0% and 53.8% for T. trichiura, for hookworm and for Ascaris lumbricoides, respectively. The sensitivity of PCR compared with KK at this time point was 89.1% for T. trichiura, 72.7% for hookworm and 87.5% for A. lumbricoides. Cure rates (CRs) for T. trichiura and A. lumbricoides were slightly lower with the PCR method. For hookworm CRs with KK were mostly significantly lower, namely 36.7%, 91.1%, 72.2% and 77.8% for moxidectin, moxidectin in combination with tribendimidine, moxidectin in combination with albendazole and albendazole in combination with oxantel pamoate, respectively, whereas with PCR the CRs were 8.3%, 82.6%, 37.1% and 57.1%, respectively. CONCLUSIONS: In conclusion, a single real-time PCR is as sensitive as quadruplicate KK for T. trichiura and A. lumbricoides detection but more sensitive for hookworm, which has an influence on the estimated treatment efficacy. PCR method with DNA extraction using the "bead-beating protocol" should be further promoted in endemic areas and laboratories that can afford the needed equipment. The study is registered at ISRCTN (no. 20398469).

A two-step morphology-PCR strategy for the identification of nematode larvae recovered from muscles after artificial digestion at meat inspection.

To ensure that meat from livestock and game is safe for human consumption, European legislation lays down rules for mandatory testing. Helminth larvae are a category of zoonotic foodborne pathogens that can contaminate meat. Among helminths, the only zoonotic nematode regulated in Europe regarding meat inspection is Trichinella spp.. It is precisely during Trichinella testing that other potentially zoonotic larvae can be found. Due to current lack of tools, their identification is often very complicated. Nematode larvae other than Trichinella, recovered from artificial digestions of pig and wild boar muscles from France and Germany, were subjected to a newly developed two-step identification scheme, which includes both morphological examination and molecular assays. The first step is a general orientation towards a broad taxonomic group; the second step consists of targeted identification based on the results of first step. Different parasites were identified, some of which were not zoonotic such as Metastrongylus spp. and Angiostrongylus vasorum, but others are known to be zoonotic such as Toxocara cati, Ascaris suum, and Uncinaria stenocephala. The strategy is efficient for the identification of nematode larvae recovered from muscles but could also be applied for larvae from other sources.

Helminth infections of wild European gray wolves (Canis lupus Linnaeus, 1758) in Lower Saxony, Germany, and comparison to captive wolves.

This study aimed to investigate the endoparasite fauna of wild European gray wolves, which are currently recolonizing Germany. In total, 69 fecal samples of wild wolves were collected in Lower Saxony, Germany, from 2013 to 2015, analyzed by the sedimentation-flotation and McMaster techniques and compared to previous results on captive European Gray wolves living in zoological gardens in Germany. In addition to coproscopy, taeniid-positive samples from wild as well as captive wolves were differentiated by amplification and sequencing of small subunit ribosomal RNA (SSU rRNA) and NADH dehydrogenase 1 (nad1) gene fragments. Missing Taenia krabbei SSU rRNA reference sequences were generated from two T. krabbei specimens. Overall, 60.87% (42/69) of wild wolve samples were microscopically positive for at least one of seven egg types. Capillaria/Eucoleus spp. showed the highest frequency (31.88% [22/69]), followed by Taeniidae (21.74% [15/69]), Ancylostomatidae (20.29% [14/69]), Alaria alata (15.94% [11/69]), Toxocara canis (13.04% [9/69]), and Toxascaris leonina and Trichuris vulpis (each 5.80% [4/69]). Amplification of SSU rRNA was successful for 7/15 Taeniidae-positive samples from wild and 20/39 samples from captive wolves, revealing T. hydatigena in two and 14 samples, respectively. Taenia krabbei was detected in two further samples of wild and three samples of captive wolves, while for the remaining samples, no differentiation between T. serialis/T. krabbei was possible. Echinococcus spp. were not detected. Sequence comparisons revealed that the SSU rRNA gene fragment was not suitable to differentiate between T. serialis and T. krabbei. Therefore, the use of this fragment alone cannot be recommended for species identification in future studies.

Molecular identification of zoonotic hookworms in dogs from four counties of Kenya.

All canine hookworms are known to be zoonotic, causing infections ranging from transient skin irritations to prolonged 'creeping eruptions', eosinophilic enteritis and even patent intestinal infections. There is little information on canine hookworm species and their public health significance in sub-Saharan Africa. This study determined the prevalence and species of hookworms in dogs from different climatic zones of Kenya. Dog faecal samples were collected from the environment, and hookworm eggs were isolated by zinc chloride flotation and subjected to DNA extraction. Polymerase chain reaction (PCR) assays targeting the internal transcribed spacer (ITS) 1 and 2, 5.8S and 28S ribosomal RNA of Ancylostoma spp. and Uncinaria stenocephala were performed, and hookworm species were identified by PCR-restriction fragment length polymorphism (RFLP) or DNA sequencing. Hookworm eggs were detected by microscopy in 490/1621 (30.23%, 95% CI 28.01-32.54) faecal samples. Estimates of faecal prevalence were high in counties receiving higher rainfall (Narok 46.80%, Meru 44.88%) and low in those with a more arid climate (Isiolo 19.73%, Turkana 11.83%). In a subset of 70 faecal samples, Ancylostoma caninum (n = 59) was the most common species, followed by A. braziliense (n = 10) and A. cf. duodenale (n = 1). This study reports for the first time the detection of A. cf. duodenale in dog faeces and zoonotic hookworm species in Kenyan dogs. These findings emphasize the need for control measures such as enforcing laws for restraining stray dogs, regular deworming of dogs, and public health awareness programmes aimed at informing communities on outdoor use of footwear.

Molecular identification of zoonotic hookworm species in dog faeces from Tanzania.

The presence and distribution of various species of canine hookworms in Africa are poorly known. The main objective of this study, therefore, was to identify the hookworm species present in canine faecal samples from Morogoro, Tanzania, using molecular techniques. Faecal samples from 160 local dogs were collected and hookworm positive samples processed to recover larvae for further molecular characterization. DNA was extracted from pools of larvae from individual samples (n = 66), which were analysed subsequently using two different molecular approaches, polymerase chain reaction-linked restriction fragment length polymorphism (PCR-RFLP) and species-specific PCR coupled with Sanger sequencing. The PCR-RFLP technique detected only the presence of the ubiquitous Ancylostoma caninum in the 66 samples. However, by species-specific PCR coupled with Sanger sequencing we identified ten samples with A. braziliense, two with Uncinaria stenocephala and five with A. ceylanicum. Thus, all four known species of canine hookworms were identified in Morogoro, Tanzania. To our knowledge this is the first report of the detection of the presence of U. stenocephala and A. ceylanicum in Africa using molecular techniques. In addition to their veterinary importance, canine hookworms have zoonotic potential and are of public health concern.

Molecular identification of hookworm isolates from stray dogs, humans and selected wildlife from South Africa.

There is a paucity of information on hookworm species in humans, domestic animals and wildlife in southern Africa. Our study aimed to identify hookworm species from stray dogs, humans, and selected wildlife from South Africa. A total of 356 faecal samples were screened for the presence of hookworm-like eggs and subsequently coproculture from the positive samples was carried out to obtain larvae. Hookworm-like eggs were detected in 23.03% (82/356) of samples. Of these samples, 78/296 were from dogs, 3/50 from humans and 1/10 from wildlife. DNA was then isolated from the larvae of 55 positive samples, which were subjected to polymerase chain reaction (PCR), polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) and sequencing of the nuclear ribosomal internal transcribed spacer (ITS1) and 5.8S rRNA region. Presence of Ancylostoma caninum, A. braziliense and A. ceylanicum-like species was recorded in stray dogs and A. caninum was recorded in wildlife and humans, using PCR-RFLP. Although PCR-RFLP results pointed to the presence of A. ceylanicum, we did not get a sequence that matched with A. ceylanicum from GenBank. This may have been due to the low proportion of A. ceylanicum larvae in our samples. Twenty-two of the 27 positive amplicons from stray dogs matched with A. caninum, three with A. braziliense and two had mixed infections of A. braziliense and A. caninum. Sequences from a lion and three humans matched with A. caninum. This is the first confirmation of a patent A. caninum infection in humans as evidenced by the presence of eggs in faeces, with the subsequent larvae from coproculture being identified as A. caninum.

Molecular differentiation of three canine and feline hookworms in South China through HRM analysis.

To investigate the prevalence of canine and feline hookworms in South China, and to assess the risk of zoonotic hookworms to humans, one pair of primers (HRM-F/HRM-R) was designed to establish a high-resolution melting (HRM) method based on internal transcribed spacer 1 (ITS-1) rDNA for the detection of Ancylostoma ceylanicum, A. caninum and A. tubaeforme infection. The results showed that the HRM for the three hookworms produced different melting-curve profiles, where melting temperature (Tm) values were 84.50°C for A. ceylanicum, 82.25°C for A. caninum and 81.73°C for A. tubaeforme, respectively. The reproducibility of intra- and inter-assay melting curves was almost perfect. The lowest concentration detected was about 5.69 ×10-4 g/µl. The HRM detection results from 18 canine and feline hookworm samples were in complete accordance with their sequencing results. The HRM method was more sensitive than the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) technique in the detection of 98 clinical samples. It is concluded that the HRM method can differentiate between A. ceylanicum, A. caninum, A. tubaeforme and their mixed infections, which may provide important technical support for the zoonotic risk assessment and molecular epidemiological survey of canine and feline hookworms.

Gastrointestinal helminths of gray wolves (Canis lupus lupus) from Sweden.

As the Scandinavian wolf population is limited in size, it is only rarely subject to systematic studies on its disease biology, especially gastrointestinal parasites. Therefore, this study aims to describe the prevalence of gastrointestinal helminths of gray wolves hunted on a limited license as a part of a wildlife management program. Helminths of 20 wolves were examined post mortem by macroscopy and coprology. Intestinal worms of five species were recovered from 18 wolves (90%): Uncinaria stenocephala (90%), Taenia spp. (45%), Alaria alata (25%), and Mesocestoides spp. (5%). Of the taeniid specimens typed by multiplex PCR and sequencing of the cox1 gene, 25% belonged to Taenia hydatigena and 25% to Taenia krabbei. The overall species diversity was low compared to findings from wolves of the northern hemisphere. Fecal eggs of Eucoleus boehmi were detected in 12 wolves (60%). Fecal metastrongylid larvae were found in seven individuals (39%), but PCR analyses specific for Angiostrongylus vasorum were negative. The wolves were in good body condition suggesting that the parasite infestation had no negative impact on the general health of the examined wolves. Although some of the recovered parasite species have zoonotic or veterinary impact, it is not likely that the spare wolf population pose substantial threat to human or veterinary health.

Morphometrical and molecular evidence suggests cryptic diversity among hookworms (Nematoda: Uncinaria) that parasitize pinnipeds from the south-eastern Pacific coasts.

Hookworms of the genus Uncinaria parasitize pinniped pups in various locations worldwide. Four species have been described, two of which parasitize pinniped pups in the southern hemisphere: Uncinaria hamiltoni parasitizes Otaria flavescens and Arctocephalus australis from the South American coast, and Uncinaria sanguinis parasitizes Neophoca cinerea from the Australian coast. However, their geographical ranges and host specificity are unknown. Uncinaria spp. are morphologically similar, but molecular analyses have allowed the recognition of new species in the genus Uncinaria. We used nuclear genetic markers (internal transcribed spacer (ITS) and large subunit (LSU) rDNA) and a mitochondrial genetic marker (cytochrome c oxidase subunit I (COI)) to evaluate the phylogenetic relationships of Uncinaria spp. parasitizing A. australis and O. flavescens from South American coasts (Atlantic and Pacific coasts). We compared our sequences with published Uncinaria sequences. A Generalized Mixed Yule Coalescent (GMYC) analysis was also used to delimit species, and principal component analysis was used to compare morphometry among Uncinaria specimens. Parasites were sampled from A. australis from Peru (12°S), southern Chile (42°S), and the Uruguayan coast, and from O. flavescens from northern Chile (24°S) and the Uruguayan coast. Morphometric differences were observed between Uncinaria specimens from both South American coasts and between Uncinaria specimens from A. australis in Peru and southern Chile. Phylogenetic and GMYC analyses suggest that south-eastern Pacific otariid species harbour U. hamiltoni and an undescribed putative species of Uncinaria. However, more samples from A. australis and O. flavescens are necessary to understand the phylogenetic patterns of Uncinaria spp. across the South Pacific.

Prevalence of Soil-Transmitted Helminths and Molecular Clarification of Hookworm Species in Ethnic Ede Primary Schoolchildren in Dak Lak Province, Southern Vietnam.

To know the infection status of helminths in primary schoolchildren of southern parts of Vietnam, we performed an epidemiological study in Krong Pac district, Dak Lak Province, Vietnam. A total of 1,206 stool specimens were collected from ethnic Ede schoolchildren in 4 primary schools in 2015 and examined by the Kato-Katz technique. In addition, stool cultures were done by the Harada-Mori method to obtain hookworm larvae and then to clarify the species of hookworms infected. The results showed that the helminth infection rate was 25.0%, including 2.0% Ascaris lumbricoides, 0.33% Trichuris trichiura, and 22.8% hookworm infections. The average intensity of infection was 102.0 eggs per gram of feces (EPG) for Ascaris, 36.0 EPG for Trichuris, and 218.0 EPG for hookworms. ITS1 gene sequences of the hookworm larvae were identical with those of Necator americanus (100% homology) reported in GenBank. It has been confirmed in this study that the hookworm, N. americanus, is a dominant helminth species infected in primary schoolchildren of a southern part of Vietnam. Public health attention is needed for control of hookworm infections among schoolchildren in surveyed areas of Vietnam.

Molecular identification of hookworms in stray and shelter dogs from Guangzhou city, China using ITS sequences.

Canine hookworm infections are endemic worldwide, with zoonotic transmission representing a potentially significant public health concern. This study aimed to investigate hookworm infection and identify the prevalent species from stray and shelter dogs in Guangzhou city, southern China by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) based on internal transcribed spacer (ITS) sequences. From March 2011 to July 2012, fresh faecal samples from a total of 254 dogs were obtained from five locations, namely Conghua, Baiyun, Liwan, Haizhu and Panyu, in Guangzhou. These samples were screened for the presence of hookworm eggs using light microscopy, with an overall prevalence of 29.53% being recorded. The highest prevalence of 45.28% was found in suburban dogs from Conghua compared with lower values recorded in urban dogs in Haizhu (21.43%), Baiyun (18.97%), Panyu (18.18%) and Liwan (15%). The prevalence in stray dogs was significantly higher than that in shelter dogs. PCR-RFLP analysis showed that 57.33% were detected as single hookworm infections with Ancyclostoma caninum, and 22.67% as A. ceylanicum, while 20% were mixed infections. This suggests that high prevalences of both hookworm species in stray and shelter dogs in China pose a potential risk of transmission from pet dogs to humans.

Uncinaria sanguinis sp. n. (Nematoda: Ancylostomatidae) from the endangered Australian sea lion, Neophoca cinerea (Carnivora: Otariidae).

This study investigates the identity of hookworms parasitising the Australian sea lion, Neophoca cinerea (Péron), from three colonies in South Australia, Australia. The Australian sea lion is at risk of extinction because its population is small and genetically fragmented. Using morphological and molecular techniques, we describe a single novel species, Uncinaria sanguinis sp. n. (Nematoda: Ancylostomatidae). The new species is most similar to hookworms also parasitic in otariid hosts, Uncinaria lucasi Stiles, 1901 and Uncinaria hamiltoni Baylis, 1933. Comparative morphometrics offered limited utility for distinguishing between species within this genus whilst morphological features and differences in nuclear ribosomal DNA sequences delineated U. sanguinis sp. n. from named congeners. Male specimens of U. sanguinis sp. n. differ from U. lucasi and U. hamiltoni by relatively shorter anterolateral and externodorsal rays, respectively, and from other congeners by the relative lengths and angulations of bursal rays, and in the shape of the spicules. Female specimens of U. sanguinis sp. n. are differentiated from Uncinaria spp. parasitic in terrestrial mammals by differences in vulval anatomy and the larger size of their eggs, although are morphologically indistinguishable from U. lucasi and U. hamiltoni. Molecular techniques clearly delimited U. sanguinis sp. n. as a distinct novel species. Obtaining baseline data on the parasites of wildlife hosts is important for the investigation of disease and the effective implementation and monitoring of conservation management.

Nationwide USA re-analysis of amplicon metabarcoding targeting ß-tubulin isoform-1 reveals absence of benzimidazole resistant SNPs in Ancylostoma braziliense, Ancylostoma tubaeforme and Uncinaria stenocephala.

Nationwide sampling by Venkatesan and colleagues (2023) described the resistance status of the canine hookworm, Ancylostoma caninum, to benzimidazoles across the USA via ß-tubulin isotype-1 amplicon metabarcoding. In this study, we aimed to use the existing public amplicon metabarcoding data and mine it for the presence of ß-tubulin isotype-1 sequences that belong to hookworm species other than A. caninum. Through bioinformatics analysis we assigned species to A. caninum, Ancylostoma braziliense, Ancylostoma tubaeforme and Uncinaria stenocephala. All non-A. caninum sequences contained only the benzimidazole susceptible residues of ß-tubulin isotype-1. Using two ß-tubulin isotype-1 metabarcoding sequence data (assay targeting 134 and 167 codons, and assay targeting 198 and 200 codons), 2.0% (6/307) and 2.9% (9/310) individual samples had hookworms other than A. caninum (A. braziliense n = 5, A. tubaeforme n = 4 and U. stenocephala n = 2), respectively. We identified one sample containing A. braziliense in each of the Northeastern region and Midwestern region, and in three samples from the Southern region. Presence of A. tubaeforme in dog faeces is considered as pseudoparasitism. There were no statistically significant regional differences for the distribution of each species, for either of the two assays independently or combined (χ2 tests, P > 0.05). Our work demonstrates the utility of the amplicon metabarcoding for the identification of species through antemortem assays, thus resolving the dilemma of assigning hookworm species based on either post-mortem or egg sizes for the identification of hookworms.

Hookworm genomics: dusk or dawn?

Hookworms are parasites, closely related to the model nematode Caenorhabditis elegans, that are a major economic and health burden worldwide. Primarily three hookworm species (Necator americanus, Ancylostoma duodenale, and Ancylostoma ceylanicum) infect humans. Another 100 hookworm species from 19 genera infect primates, ruminants, and carnivores. Genetic data exist for only seven of these species. Genome sequences are available from only four of these species in two genera, leaving 96 others (particularly those parasitizing wildlife) without any genomic data. The most recent hookworm genomes were published 5 years ago, leaving the field in a dusk. However, assembling genomes from single hookworms may bring a new dawn. Here we summarize advances, challenges, and opportunities for studying these neglected but important parasitic nematodes.