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Parasites & Vectors May 2023Few anthelminthics are currently available, manifesting the urgent need for new treatment options. In vitro profiling of current anthelminthics against larval and adult...
BACKGROUND
Few anthelminthics are currently available, manifesting the urgent need for new treatment options. In vitro profiling of current anthelminthics against larval and adult stage helminths displayed varying effects on closely related worm species and between life stages of the same species. Conversely, limited research has been performed on the egg stage of human hookworms, and the effects of investigational compounds on the egg stage are not routinely assessed.
METHODS
We profiled the development and hatching of Heligmosomoides polygyrus, Ancylostoma duodenale and Necator americanus eggs isolated from rodent faeces in liquid media with various nutrient levels, osmolar concentrations, and acidities in dependence on incubation temperature and light exposure. Incubation conditions were optimised to allow the study of drug effect on immature and embryonated eggs. We analysed concentration-effect relationships of commercially available anthelminthics over 72 h.
RESULTS
Rapid embryonation and hatching were observed at room temperature with and without light exposure without nutrient supplementation in a wide range of acidities. Hookworms hatched optimally at room temperature in PBS achieving > 75% hatching over 34 h. Developmental delays were seen when eggs were stored at 4 °C with no effect on viability. Similar delays were also seen with increased osmolar concentrations resulting in decreased viability. Benzimidazole anthelminthics effectively reduced the viability and prevented hatching of hookworm eggs, with albendazole and thiabendazole eliciting particularly potent effects at EC values below 1 µM. Macrolide anthelminthics as well as emodepside, oxantel pamoate, and pyrantel pamoate were inactive while monepantel, levamisole, and tribendimidine displayed varied potencies among the hookworm species.
CONCLUSION
The presented egg-hatching assay will complement ongoing anthelminthic drug discovery and allow a full characterisation of drug activity against all life stages. In the development and application of the egg-hatching assay, good accordance was observed between the three hookworm species evaluated. Marketed anthelminthics show differences of drug action compared to larval and adult stages highlighting the importance of profiling drug activity against all life stages.
Topics: Animals; Adult; Humans; Anthelmintics; Hookworm Infections; Ancylostomatoidea; Albendazole; Necator americanus; Ancylostoma; Larva
PubMed: 37143169
DOI: 10.1186/s13071-023-05771-8 -
The Canadian Veterinary Journal = La... Apr 2023The canine hookworm is one of the most prevalent parasitic nematodes in dogs worldwide and has the potential for zoonotic transmission to humans, including the... (Review)
Review
The canine hookworm is one of the most prevalent parasitic nematodes in dogs worldwide and has the potential for zoonotic transmission to humans, including the development of cutaneous larva migrans. Recent confirmation of anthelmintic resistance (AR) in to several anthelmintic classes, mainly in the USA, indicates the potential for this scenario in Canada. We consider various factors that may lead to resistant isolates in Canada, such as the widespread use of antiparasitic drugs without the assessment of efficacy; increased prevalence in various Canadian provinces; and the importation of dogs, mostly from the USA, with a history of persistent infection by . Our objective was to review factors that influence to develop AR and raise awareness regarding the need for a strategic plan to control this parasitic nematode through the appropriate use of anthelmintics.
Topics: Dogs; Animals; Humans; Ancylostoma; Ancylostomatoidea; Ancylostomiasis; Canada; Anthelmintics; Hookworm Infections; Dog Diseases
PubMed: 37008647
DOI: No ID Found -
International Journal For Parasitology.... Apr 2023Anthelmintic resistance to benzimidazole has been detected in the canine hookworm, Ancylostoma caninum. Benzimidazole resistance is believed to have developed originally...
BACKGROUND
Anthelmintic resistance to benzimidazole has been detected in the canine hookworm, Ancylostoma caninum. Benzimidazole resistance is believed to have developed originally in greyhounds, but has also been detected in non-greyhound pet dogs. The aim of this study was to validate a probe-based allele-specific real-time PCR tests for the F167Y polymorphism on the β-tubulin isotype-1 gene and to determine the geographic distribution.
METHODS
Allele-specific real-time PCR tests were established and validated to detect the codon 167 polymorphism in the Ancylostoma caninum β-tubulin isotype-1gene. Additionally, real-time PCR tests were validated for Ancylostoma spp. and Uncinaria stenocephala. Two nucleic acid extraction protocols were validated including mechanical disruption of parasite structures in stool. The frequency of the F167Y single nucleotide polymorphism (SNP) was determined in hookworm confirmed stool samples. Samples with the resistant 167Y genotype were confirmed by β-tubulin gene sequencing and allele frequencies were determined.
RESULTS
The Ancylostoma spp. and A. caninum F167Y allele-specific real-time PCR tests were highly sensitive and specific when tested against synthetic DNA, spiked samples, and characterized parasites. Using an optimized total nucleic acid extraction protocol, 54 of 511 (10.6%) were found to contain the benzimidazole resistance allele. All 55 samples containing hookworms with the resistance mutation were confirmed by β-tubulin gene sequencing. The majority of resistant hookworms (44 resistant, 183 tested; 24.4%) originated from Florida, five from California (103 tested, 4.9%), three from Idaho (40 tested, 7.5%), two from Nevada (22 tested, 9.1%), and one sample from Hawaii (13 tested, 7.7%). Resistant genotypes were found in 14 different dog breeds including eight in Greyhounds. Allele-frequency determination revealed resistance allele frequencies between 1 and 100% with 58% above 50%.
CONCLUSIONS
This data strongly supports recent findings of benzimidazole resistant canine hookworms present throughout the general US pet dog population.
Topics: Dogs; Animals; Ancylostoma; Parasites; Tubulin; Drug Resistance; Anthelmintics; Benzimidazoles; Hookworm Infections; Ancylostomatoidea; Polymorphism, Single Nucleotide; Real-Time Polymerase Chain Reaction
PubMed: 36958067
DOI: 10.1016/j.ijpddr.2023.01.001 -
Parasitology May 2023Soil-transmitted nematodes (STNs) place a tremendous burden on health and economics worldwide with an estimate of at least 1.5 billion people, or 24% of the population,...
Soil-transmitted nematodes (STNs) place a tremendous burden on health and economics worldwide with an estimate of at least 1.5 billion people, or 24% of the population, being infected with at least 1 STN globally. Children and pregnant women carry the heavier pathological burden, and disease caused by the blood-feeding worm in the intestine can result in anaemia and delays in physical and intellectual development. These parasites are capable of infecting and reproducing in various host species, but what determines host specificity remains unanswered. Identifying the molecular determinants of host specificity would provide a crucial breakthrough towards understanding the biology of parasitism and could provide attractive targets for intervention. To investigate specificity mechanisms, members of the hookworm genus provide a powerful system as they range from strict specialists to generalists. Using transcriptomics, differentially expressed genes (DEGs) in permissive (hamster) and non-permissive (mouse) hosts at different early time points during infection with were examined. Analysis of the data has identified unique immune responses in mice, as well as potential permissive signals in hamsters. Specifically, immune pathways associated with resistance to infection are upregulated in the non-permissive host, providing a possible protection mechanism that is absent in the permissive host. Furthermore, unique signatures of host specificity that may inform the parasite that it has invaded a permissive host were identified. These data provide novel insight into the tissue-specific gene expression differences between permissive and non-permissive hosts in response to hookworm infection.
Topics: Pregnancy; Cricetinae; Female; Animals; Humans; Mice; Ancylostoma; Ancylostomiasis; Host Specificity; Transcriptome; Hookworm Infections; Intestines
PubMed: 36883013
DOI: 10.1017/S0031182023000227 -
PLoS Pathogens Mar 2023Ancylostoma caninum is an important zoonotic gastrointestinal nematode of dogs worldwide and a close relative of human hookworms. We recently reported that racing...
Molecular evidence of widespread benzimidazole drug resistance in Ancylostoma caninum from domestic dogs throughout the USA and discovery of a novel β-tubulin benzimidazole resistance mutation.
Ancylostoma caninum is an important zoonotic gastrointestinal nematode of dogs worldwide and a close relative of human hookworms. We recently reported that racing greyhound dogs in the USA are infected with A. caninum that are commonly resistant to multiple anthelmintics. Benzimidazole resistance in A. caninum in greyhounds was associated with a high frequency of the canonical F167Y(TTC>TAC) isotype-1 β-tubulin mutation. In this work, we show that benzimidazole resistance is remarkably widespread in A. caninum from domestic dogs across the USA. First, we identified and showed the functional significance of a novel benzimidazole isotype-1 β-tubulin resistance mutation, Q134H(CAA>CAT). Several benzimidazole resistant A. caninum isolates from greyhounds with a low frequency of the F167Y(TTC>TAC) mutation had a high frequency of a Q134H(CAA>CAT) mutation not previously reported from any eukaryotic pathogen in the field. Structural modeling predicted that the Q134 residue is directly involved in benzimidazole drug binding and that the 134H substitution would significantly reduce binding affinity. Introduction of the Q134H substitution into the C. elegans β-tubulin gene ben-1, by CRISPR-Cas9 editing, conferred similar levels of resistance as a ben-1 null allele. Deep amplicon sequencing on A. caninum eggs from 685 hookworm positive pet dog fecal samples revealed that both mutations were widespread across the USA, with prevalences of 49.7% (overall mean frequency 54.0%) and 31.1% (overall mean frequency 16.4%) for F167Y(TTC>TAC) and Q134H(CAA>CAT), respectively. Canonical codon 198 and 200 benzimidazole resistance mutations were absent. The F167Y(TTC>TAC) mutation had a significantly higher prevalence and frequency in Western USA than in other regions, which we hypothesize is due to differences in refugia. This work has important implications for companion animal parasite control and the potential emergence of drug resistance in human hookworms.
Topics: Animals; Dogs; Ancylostoma; Ancylostomatoidea; Anthelmintics; Benzimidazoles; Caenorhabditis elegans; Drug Resistance; Mutation; Tubulin
PubMed: 36862759
DOI: 10.1371/journal.ppat.1011146 -
BioMed Research International 2023Soil-transmitted helminths (STHs) are parasitic worms that are widely distributed in the tropical and subtropical regions. In Ethiopia, one of the tropical countries,...
High Prevalence of Hookworm Species and Associated Factors among Soil-Transmitted Helminth-Infected Household Contacts in Burie Zuria District, Northwest Ethiopia: A Community-Based Cross-Sectional Study.
BACKGROUND
Soil-transmitted helminths (STHs) are parasitic worms that are widely distributed in the tropical and subtropical regions. In Ethiopia, one of the tropical countries, STH infections are high and cause a huge burden. Several STH species show a pattern of household clustering with regard to prevalence and intensity. However, there is a scarcity of data on the status of STH infection among family contacts of STH-infected individuals in Ethiopia in general and in the study area in particular.
OBJECTIVE
This study is aimed at assessing the prevalence of soil-transmitted helminths and associated factors among STH-infected household contacts in Burie Zuria district, northwest Ethiopia.
METHOD
A community-based cross-sectional study was conducted among 422 study participants from March to May 2021. Study participants were traced to their residences by following STH-infected patients. A convenient sampling technique was used to recruit the study participants. The stool samples were processed using duplicate Kato-Katz thick smears and a modified Ritchie's technique. The data were entered and analyzed using the Statistical Package for Social Sciences, version 26 of the software package. A value <0.05 was considered a statistically significant association.
RESULTS
The overall prevalence of STHs was 36.5% (95% CI: 31.7%-41.5%). Two STHs, namely hookworm species (33.2%, 140/422) at (95% CI: 28.9%-37.8%) and (4.3%, 18/422) at (95% CI: 2.7%-6.6%), were identified, with a double infection of 2.6% (4/154) at (95% CI: 1.0%-6.5%). Almost the majority (96.9%) of hookworm species and all infections were categorized under a light intensity of infection. Family size >5 (AOR = 1.74; 95% CI: 1.15-2.60; = 0.008) and lack of latrine facility (AOR = 1.86; 95% CI: 1.17-2.90; = 0.02) were significantly associated with STH infections.
CONCLUSION
A high prevalence of hookworms was found in the study area, where the majority of the study participants were adults. This finding may provide a basis for revising the school-based deworming programs that exclude the adult population. Public health interventions like accessing latrines, health education, and deworming programs should be regularly implemented for all age groups in the areas.
Topics: Animals; Ancylostomatoidea; Cross-Sectional Studies; Soil; Prevalence; Ethiopia; Risk Factors; Helminths; Helminthiasis; Feces
PubMed: 36647545
DOI: 10.1155/2023/6553913 -
Scientific Reports Jan 2023Accurate diagnosis by precise identification of causative agents is essential for the effectiveness of any control interventions. Despite high zoonotic potential,...
Accurate diagnosis by precise identification of causative agents is essential for the effectiveness of any control interventions. Despite high zoonotic potential, available literature on hookworms in Bangladesh is still scarce and nonspecific. The objective of this study was to determine the occurrence of hookworms in public locations across northeastern Bangladesh (Sylhet metropolitan area) using integrated parasitological and molecular assays. A total of 130 samples (80 soil and 50 environmental canine feces) were collected and examined using modified flotation technique and formalin-ether sedimentation methods. Modified plate culture was used to isolate larvae. The identification was made based on morphometric features and confirmed by amplifying the ITS region of the nuclear rDNA. Overall, 66.2% (86/130) of examined samples were positive for hookworms infection. Characteristic eggs (61-68 × 29-37 μm) and/or larvae of hookworms were observed in 73.8% (59/80) soils and 54.0% (27/50) environmental fecal samples. Rhabditiform larvae (0.48-0.54 × 0.04-0.07 mm) were observed in cultured samples. Genetic analysis of rDNA sequences revealed the presence of Ancylostoma caninum and Ancylostoma ceylanicum. In this study, hookworms' contamination of the public environment was substantial. To the best of our knowledge, this is the first molecular proof of A. caninum and A. ceylanicum observed in urban public environment in Bangladesh.
Topics: Animals; Dogs; Ancylostomatoidea; Bangladesh; Hookworm Infections; Ancylostoma; Feces; DNA, Ribosomal; Soil; Larva; Dog Diseases
PubMed: 36599848
DOI: 10.1038/s41598-022-26813-8 -
PloS One 2022Intestinal parasitic infections (IPIs) remain a public-health problem worldwide, including in countries of the Lower Mekong subregion. Increases in human migration from...
Prevalence of intestinal parasitic infections and genetic differentiation of Strongyloides stercoralis among migrant workers from Myanmar, Lao PDR and Cambodia in northeastern Thailand.
Intestinal parasitic infections (IPIs) remain a public-health problem worldwide, including in countries of the Lower Mekong subregion. Increases in human migration from neighboring countries might cause reemerging parasitic infections, leading to spread of parasites in the landscape. Here, we conducted a cross-sectional study to identify the prevalence of IPIs in migrant workers from Myanmar, Lao PDR, and Cambodia who were dwelling in Nakhon Ratchasima Province, northeastern Thailand. The identification of Strongyloides species and genetic differentiation of worms from migrant workers with different countries of origin was also assessed. Fresh stool samples were collected from 338 migrant workers and examined for evidence of IPIs using agar plate culture (APC) and the formalin-ethyl acetate concentration technique (FECT). Among those nine samples positive for nematodes by APC, the Strongyloides or hookworm species present was confirmed using the polymerase chain reaction (PCR) followed by DNA sequencing. This revealed eight cases of Strongyloides stercoralis infection and one of Necator americanus. Fifty-one out of 338 individuals (15.09%) were positive for IPIs using FECT and APC. Eggs of Opisthorchis-like flukes were the most common parasite (11.83% of samples), followed by S. stercoralis (2.37%), Entamoeba coli (1.50%), hookworm (0.89%), Taenia sp. (0.60%) and Hymenolepis nana (0.30%). The genetic differentiation of S. stercoralis recovered from migrant workers with different countries of origin was analyzed. Specimens of S. stercoralis isolated from workers from Lao PDR, Cambodia and Myanmar were genetically similar to those sequenced from Thailand. However, there were population-genetic differences between S. stercoralis from these Southeast Asian countries and other regions of the world. This study demonstrated that IPIs were prevalent in migrant workers in the northeastern region of Thailand. Our findings provided molecular confirmation of the presence of S. stercoralis and explored the genetic differentiation of S. stercoralis from those infected migrant workers. An effective anti-parasitic drug should be provided for migrant workers and its administration enforced.
Topics: Humans; Animals; Strongyloides stercoralis; Thailand; Cambodia; Prevalence; Laos; Myanmar; Cross-Sectional Studies; Transients and Migrants; Intestinal Diseases, Parasitic; Strongyloidiasis; Hookworm Infections; Parasites; Ancylostomatoidea; Feces
PubMed: 36584196
DOI: 10.1371/journal.pone.0279754 -
Journal of the American Veterinary... Dec 2022To evaluate the efficacy of the 3 major classes of anthelmintics used for the treatment of hookworms in dogs in the US and an extralabel treatment with an FDA-approved...
OBJECTIVE
To evaluate the efficacy of the 3 major classes of anthelmintics used for the treatment of hookworms in dogs in the US and an extralabel treatment with an FDA-approved product for use in cats in a Labrador kennel with a history of persistent hookworm infections.
ANIMALS
22 dogs housed in a single kennel comprised of the following breeds: 19 Labrador Retrievers, 1 English Cocker Spaniel, 1 Chesapeake Bay Retriever, and 1 Boykin Spaniel.
PROCEDURES
We performed a fecal egg count (FEC) reduction test using 22 dogs that were allocated randomly to 1 of 5 treatment groups: pyrantel pamoate (Pyrantel pamoate suspension), fenbendazole (Safe-Guard suspension 10%), milbemycin oxime (Interceptor), moxidectin plus imidacloprid (Advantage Multi), and emodepside plus praziquantel (Profender topical solution for cats). FEC was performed on samples collected on days 0 and 11.
RESULTS
FEC reductions for the milbemycin oxime, moxidectin plus imidacloprid, and emodepside plus praziquantel groups were 43.9%, 57.4%, and 100%, respectively. The FEC increased following treatment for the pyrantel and fenbendazole groups.
CLINICAL RELEVANCE
These data demonstrate that the Ancylostoma caninum infecting the dogs in this kennel are highly resistant to all major anthelmintic classes approved for use in dogs in the US but are susceptible to emodepside. This was the first report of multiple anthelmintic drug-resistant A caninum in a dog kennel that does not involve Greyhounds.
Topics: Animals; Dogs; Ancylostoma; Ancylostomatoidea; Anthelmintics; Cat Diseases; Dog Diseases; Drug Resistance; Feces; Fenbendazole; Georgia; Macrolides; Parasite Egg Count; Praziquantel; Pyrantel Pamoate
PubMed: 36520649
DOI: 10.2460/javma.22.08.0377 -
The American Journal of Tropical... Feb 2023Polymerase chain reaction (PCR) is increasingly used in the diagnosis of soil-transmitted helminth infections. Despite this, few studies have evaluated the impact of...
Polymerase chain reaction (PCR) is increasingly used in the diagnosis of soil-transmitted helminth infections. Despite this, few studies have evaluated the impact of different fecal fixatives on the outcome of fecal helminth qPCR analysis, and none have evaluated the effect of commercial parasitology fixatives commonly used in diagnostic laboratories. We fixed dog feces containing Ancylostoma spp. hookworm eggs in zinc polyvinyl alcohol (Zn-PVA) and Total-Fix, and with 70% ethanol (EtOH) as a control. DNA was extracted at timepoints 11, 33, 64, and 94 days and subjected to Ancylostoma spp. quantitative PCR (qPCR). A linear regression model was created to assess the effect of preservative types on the temporal change of qPCR quantification cycle number (Cq) values, accounting for variances among individual animals. Fixation in 70% EtOH least affected Cq values over 94 days. Total-Fix preservation yielded a higher Cq overall, but there was no significant difference compared with 70% EtOH fixation. Fixation in Zn-PVA resulted in significantly (P < 0.001) higher Cq values than 70% EtOH after only 33 days and loss of amplification at 64 days. Consistent with other helminth fixation studies, 70% EtOH performed well in preserving hookworm DNA over 94 days. Total-Fix provided a comparable alternative for qPCR analysis for hookworm. Fixation in Zn-PVA resulted in loss of detectable hookworm DNA at 64 days, as determined by qPCR.
Topics: Animals; Dogs; Ancylostomatoidea; Fixatives; Real-Time Polymerase Chain Reaction; Hookworm Infections; Helminthiasis; Ancylostoma; Helminths; Feces; Polyvinyl Alcohol
PubMed: 36509060
DOI: 10.4269/ajtmh.22-0406