Soil-transmitted helminthiasis in Laos: a community-wide cross-sectional study of humans and dogs in a mass drug administration environment

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.

Zoonotic helminths - why the challenge remains

Helminth zoonoses remain a global problem to public health and the economy of many countries. Polymerase chain reaction-based techniques and sequencing have resolved many taxonomic issues and are now essential to understanding the epidemiology of helminth zoonotic infections and the ecology of the causative agents. This is clearly demonstrated from research on Echinococcus (echinococcosis) and Trichinella (trichinosis). Unfortunately, a variety of anthropogenic factors are worsening the problems caused by helminth zoonoses. These include cultural factors, urbanization and climate change. Wildlife plays an increasingly important role in the maintenance of many helminth zoonoses making surveillance and control increasingly difficult. The emergence or re-emergence of helminth zoonoses such as Ancylostoma ceylanicum, Toxocara, Dracunculus and Thelazia exacerbate an already discouraging scenario compounding the control of a group of long neglected diseases.

Does a school-based intervention to engage parents change opportunity for handwashing with soap at home? Practical experience from the Mikono Safi trial in Northwestern Tanzania

BACKGROUND

School-based de-worming is advocated as a strategy for reducing the burden of soil-transmitted helminth (STH) infections among children. However, re-infection tends to occur rapidly, suggesting that comprehensive water, sanitation, and hygiene (WASH) improvements may be needed to prevent this. We qualitatively assessed the influence of parental engagement activities on parents' motivation to improve WASH infrastructure and hygiene practices at home in the context of a school-based de-worming programme.

METHODOLOGY

We conducted a longitudinal qualitative study nested within the Mikono Safi trial, designed to assess the effect of a WASH intervention on STH infection prevalence in children. Meetings were organized for parents/guardians at schools where they were given information about STH infection, the role of WASH in STH infection prevention, and actionable steps they could take at home. During the meetings, parents/guardians received information about their own child's STH infection status. Twenty purposively selected households were visited and interviewed 3 times over a period of about 8-months. We employed thematic analysis; findings are reported following the Capability-Opportunity-Motivation and Behaviour (COM-B) framework.

PRINCIPAL FINDINGS

The engagement strategy improved parents'/guardians' knowledge and skills about handwashing with soap and its benefits. Parents/guardians reported that the sessions had motivated them to improve WASH infrastructure at home. Of 20 households included in this study, 17 renovated or built new latrines and 18 installed handwashing facilities. However, only 8 households established and maintained handwashing stations with both soap and water at 8 months.

CONCLUSIONS

The engagement of parents/guardians in a school-based WASH education intervention as part of the Mikono Safi trial resulted in increased knowledge and motivation about handwashing and sanitation. This led to improvements in sanitation facilities and handwashing opportunities at home. However, long-term success in provision of water and soap was limited, indicating that sustained engagement may be required to encourage households to ensure these materials are consistently available at home.

Strongyloides hyper-infection in a lung transplant recipient: Case report and review of the literature

CASE PRESENTATION

A 63-year-old man with a left single lung transplant for end-stage combined restrictive and obstructive lung disease developed persistent pulmonary infiltrates and recurrent gram-negative bacteremia post-transplant. Bronchoalveolar lavage fluid revealed a nematode on Papanicolau staining compatible with Strongyloides stercoralis larvae on day 50 post-transplant. Although Strongyloides serology performed post-transplant was negative, a retrospective review of the medical record revealed marked peripheral blood eosinophilia on several occasions before transplantation. Despite reduction in immunosuppression and treatment with albendazole and ivermectin, the patient developed another episode of Escherichia coli bacteremia. He died 3 months post-transplant from pulmonary and neurological complications.

DIAGNOSIS

Strongyloides hyper-infection.

DISCUSSION

Strongyloides hyper-infection syndrome is known to occur in immunocompromised patients, but it has only been reported once in a lung transplant recipient. This case illustrates the importance of screening for parasitic infections before transplantation in patients with marked eosinophilia, especially among immigrants from countries in which Strongyloides is endemic. Hyper-infection syndrome may appear years after infection in the context of immunosuppression or immunodeficiency. This case also highlights the association between Strongyloides hyper-infection and bacteremia with enteric organisms.

Prevalence of hookworm infections among stray dogs and molecular identification of hookworm species for the first time in Bangladesh

Hookworms are the most common and voracious blood-sucking parasites of the small intestines of mammalian hosts such as dogs, cats, ruminants and humans. Canine hookworms are endemic in the Southeast Asian countries including Bangladesh. There is scarcity of information on the prevalence of hookworms of stray dogs in Bangladesh. The present study determined the prevalence of canine hookworms using fecal examination followed by morphometric and molecular identification. Fecal samples were collected from 320 stray dogs living in rural areas of Mymensingh district (Gauripur upazila, Mymensingh sadar upazila and Tarakanda upazila) and hookworm eggs were identified using the flotation techniques. The overall prevalence of hookworm was 79.1% through microscopic examination. Estimated fecal prevalence was higher in Gauripur upazila (89.7%) followed by Mymensingh sadar upazila (84.8%) and Tarakanda upazila (53.2%). Five hookworm species were identified based on the morphometric examination, namely, Ancylostoma caninum, Ancylostoma ceylanicum, Ancylostoma tubaeforme, Ancylostoma braziliense and Ancylostoma duodenale, respectively. Polymerase Chain Reaction (PCR) was performed with the genomic DNA by targeting the 5.8S rRNA (~ 404 bp) and Cytochrome oxidase-1 (Cox 1, ~ 450 bp) and confirmed the identification for the first time in Bangladesh. This study reveals that stray dogs may act as reservoir hosts of human hookworm infection. Further detail molecular study is warranted to explore the genetic diversity of hookworms that infect both dogs and human in Bangladesh.

A Case of Zoonotic Ancylostoma ceylanicum Infection in a Suburban Area of Selangor, Malaysia

INTRODUCTION

The animal hookworm, Ancylostoma ceylanicum, is a dominant hookworm species of dogs and cats. However, it has increasingly been found infecting humans in Southeast Asia.

PURPOSE

We report an autochthonous case of A. ceylanicum in a suburban area of Selangor, Malaysia. A 66-year-old Indian lady who is an avid gardener presented with chronic diarrhea of 4 months' duration.

METHODS

The patient was examined clinically and colonoscopy was performed. Adult parasites obtained via colonoscopy were subjected to microscopy and molecular investigations.

RESULTS

Clinical examinations were unremarkable, and blood investigation revealed normochromic normocytic anemia. Stool occult blood was positive but negative for ova, cyst and adult parasites. Colonoscopy performed showed multiple diverticulae and worm infestation from the terminal ileum to sigmoid colon. Morphological examination on the adult worms showed the specific characteristics of Ancylostoma species. Molecular investigations further confirmed the nematode as Ancylostoma ceylanicum. She was treated with albendazole 400 mg daily for 3 days with symptomatic improvements sustained 3 months later. It is suspected that the patient had ingested or contacted soil contaminated with filariform larvae while gardening.

CONCLUSION

Information on the A. ceylanicum infection in humans, especially in urban and suburban areas, is limited, necessitating further epidemiological and clinical studies.

Zoonotic hookworms of dogs and cats - lessons from the past to inform current knowledge and future directions of research

The early-to-mid 1900s was an era that marked the first published reports of clinical cases and experimental human infections that provided valuable evidence to inform our current knowledge on the zoonotic nature of the canid and felid hookworms. To this day, descriptions of the pathognomonic syndromes produced in humans by these early pioneers provide vital information on the putative geographical distribution of these hookworm species, even before their discovery in dogs and cats. Cases of hookworm-related cutaneous larvae migrans and Ancylostoma caninum-induced eosinophilic enteritis continue to be reported in the medical literature, most commonly in recent migrants or returned travellers who have spent time in regions in which these canine and feline hookworms remain highly endemic. Ancylostoma ceylanicum, now recognised as the second most common hookworm infecting humans in the Asia Pacific region, is also being reported in regions of Africa and South America previously assumed free of this parasite. Despite the substantial technological progress made in the field of parasite diagnostics, our knowledge on the epidemiology and population-level morbidity impacts of these zoonotic hookworms in humans has remained relatively stagnant over the last few decades, with 'covert' infections continuing to remain undetected by currently available forms of routine diagnostics. Improved diagnostic tools that enable accurate and rapid species-specific diagnosis of zoonotic hookworm infections in humans are required to provide the necessary evidence to advocate for future investments in One Health-based intervention strategies.

Risk profiling and efficacy of albendazole against the hookworms Necator americanus and Ancylostoma ceylanicum in Cambodia to support control programs in Southeast Asia and the Western Pacific

Background: Hookworm disease is endemic throughout many parts of the Asia Pacific, despite targeted control programs of at-risk populations. The success of these programs has been hindered by the limited efficacy of widely-used mebendazole, rapid re-infection rates linked to persistent reservoirs of untreated people and dogs, and the low sensitivity of conventional coprodiagnostic techniques employed. Methods: Here, we used standard faecal flotation (SFF) and a multiplex qPCR (mqPCR) assay to calculate and compare species-specific cure and egg reduction rates of single dose albendazole (400 mg) against hookworm infections at community level. Data from a cross-sectional survey in 1,232 people from Cambodia were used to inform a generalised linear mixed model to identify risk factors linked to hookworm infection(s) at baseline. Furthermore, we calculated risk factors associated to the probability of being cured after albendazole administration. Findings: Overall, 13·5% of all 1,232 people tested by SFF were positive for hookworm infection(s). Most (80·1%) infected people were >12 years of age, hence above the age targeted by the WHO control program. We estimate that as age increases, the odds of being infected increases at a faster rate for females than for males. We revealed a substantial difference in cure rate of hookworm infection(s) following albendazole treatment using the SFF (81·5%) and mqPCR (46·4%) assays, and provide the first data on the efficacy of this drug against the zoonotic hookworm Ancylostoma ceylanicum. We estimated that as age increases by one year, the odds of being cured decreases by 0·4%-3·7%. Similarly, the odds of being cured for people who boiled drinking water was estimated to be between 1·02 and 6·82. Interpretation: These findings show that the adoption of refined diagnostic techniques is central to monitoring hookworm infection(s) and the success of control strategies, which can ultimately aid in reducing associated morbidity in human populations. The approach taken is likely to be directly applicable to other parts of Southeast Asia and the Western Pacific, where specific epidemiological conditions might hamper the success of targeted treatment programs. Funding: Faculty of Veterinary and Agricultural Sciences Strategic Research Funds, The University of Melbourne.

Expression and biological functions of Ancylostoma ceylanicum saposin-like protein

Ancylostoma ceylanicum is a common zoonotic nematode that inhabits the small intestine of humans, dogs, and cats. Saposin-like proteins (SLPs) have hemolytic and antibacterial activities and could be used as diagnostic or vaccine candidates. To explore the biological functions of Ancylostoma ceylanicum SLP (Ace-SLP-1), cDNA-encoding Ace-SLP-1 mature peptide was cloned into prokaryotic expression vector pET-28a and transformed into Escherichia coli BL21 (DE3) to induce expression. After incubation of canine red blood cell suspension with different concentrations of recombinant Ace-SLP-1, the supernatant was separated to measure OD value and calculate the hemolysis rate. The different concentrations of recombinant protein were co-cultured with E. coli and Enterococcus faecalis, and colony-forming units (CFU) were determined by the plate counting method. Peripheral blood mononuclear cells (PBMCs) from healthy dogs were incubated with different concentrations of recombinant Ace-SLP-1, and the cytokine expression was evaluated by relative quantitative PCR. Our results showed that the hemolytic activity of Ace-SLP-1 increased with the increase in protein concentration from 25 to 100 μg/mL. The recombinant protein had no antibacterial activity against the two kinds of bacteria but could stimulate the secretion of cytokines (IL-4, IL-10, IL-12, and IL-13) in canine PBMCs. These data suggest that Ace-SLP-1 is involved in hookworm blood-feeding and survival and has good immunogenicity, supporting its potential as a diagnostic and vaccine target molecule.

Insights into hookworm prevalence in Asia: a systematic review and meta-analysis

INTRODUCTION

Hookworm infections are neglected tropical diseases of humans and animals worldwide. A meta-analysis and systematic review was designed to evaluate the prevalence of hookworm infection in animal and human hosts in Asia until July 2018.

METHODS

The available online articles of five English databases (PubMed, Scopus, Science Direct, Web of Science and Google Scholar) were explored.

RESULTS

The most parasitized carnivores were jackal (48%, CI: 4 to 91%), followed by dog (41%, CI: 29 to 53%), cat (26%, CI: 14 to 38%) and the red fox (19%, CI: 13 to 24%). The weighted prevalence of Ancylostoma braziliensis, A. caninum, A. ceylanicum, A. tubaeforme and Uncinaria stenocephala isolated from different canids were found to be 27% (CI: 21 to 33%), 23% (CI: 7.0 to 53%), 24% (CI: 12 to 35%), 44% (CI: 37 to 51%) and 37% (CI: 18 to 55%), respectively. In total, 98 records were obtained for human hookworms from 3209 760 examined individuals and the calculated weighted prevalence in this population was 19% (CI: 17 to 20%).

CONCLUSIONS

These findings highlight a desirable ecological milieu for parasite survival and transmission in such territories, which implicates revisiting control programs and public health infrastructures in those areas.

A One Health Approach to Defining Animal and Human Helminth Exposure Risks in a Tribal Village in Southern India

The high burden of soil-transmitted helminth infections has been studied in India; however, little data exist on zoonotic helminths, and on animal-associated exposure to soil-transmitted helminths. Our study took place in the Jawadhu Hills, which is a tribal region in Tamil Nadu, India. Using a One Health approach, we included animal and environmental samples and human risk factors to answer questions about the associations among infected household soil, domestic animals, and human risk factors. Helminth eggs were identified by microscopy in animal and soil samples, and a survey about risk factors was administered to the head of the household. Contact with animals was reported in 71% of households. High levels of helminth infections were found across domestic animal species, especially in goats, chickens, and dogs. Helminth eggs were recorded in 44% of household soil (n = 43/97) and separately in 88% of soil near a water source (n = 28/32). Animal contact was associated with 4.05 higher odds of having helminth eggs in the household soil (P = 0.01), and also having a water source at the household was associated with a 0.33 lower odds of having helminth eggs in the household soil (P = 0.04). Soil moisture was a mediator of this association with a significant indirect effect (P < 0.001). The proportion mediated was 0.50. While our work does not examine transmission, these results support consideration of animal-associated exposure to STH and potentially zoonotic helminths in future interventions to reduce helminth burden. Our study provides support for further investigation of the effects of animals and animal fecal matter on human health.

Prevalence and Risk Factors of Intestinal Helminthiasis in Remote Mountainous Villages of Northern Lao PDR: A Cross-Sectional Study

Helminth infections are prevalent in Lao People’s Democratic Republic (Lao PDR). This study aimed at determining the prevalence and risk factors of intestinal helminthiasis in remote mountainous villages of northern Lao PDR. During the dry season in January 2017, a cross-sectional survey was conducted in 3 remote mountainous villages in Oudomxay province, Lao PDR. Villagers older than 18 years of age who agreed to submit stool samples or undergo an interview, were recruited. Stool samples from 198 individuals were examined by the Kato-Katz method, and a questionnaire surveyed 161 individuals among them. Univariable and multivariable logistic regression analyses were used to identify risk factors associated with the intestinal helminthiasis. An overall prevalence of intestinal helminthiasis was 75.8%. Hookworm infection was the most common (63.1%), followed by Opisthorchis viverrini/minute intestinal flukes (17.7%), Taenia spp. (15.2%), Trichuris trichiura (2.0%), Ascaris lumbricoides (1.5%), and Enterobius vermicularis (1.0%). Questionnaire analysis revealed sex (male) and absence of latrine to be significant risk factors for hookworm infection and consumption of raw meat for taeniasis. These results suggest that the mountainous area in northern Lao PDR has a different composition of helminth infections from other studies conducted in Lao PDR; a high prevalence of hookworm infection and taeniasis and low prevalence of T. trichiura and A. lumbricoides infections were observed. Also, liver flukes or intestinal flukes were similarly prevalent in the mountainous area.

Recombinant Paraprobiotics as a New Paradigm for Treating Gastrointestinal Nematode Parasites of Humans

Gastrointestinal nematodes (GINs) of humans, e.g., hookworms, negatively impact childhood growth, cognition, nutrition, educational attainment, income, productivity, and pregnancy. Hundreds of millions of people are targeted with mass drug administration (MDA) of donated benzimidazole anthelmintics.

Gastrointestinal nematodes (GINs) of humans, e.g., hookworms, negatively impact childhood growth, cognition, nutrition, educational attainment, income, productivity, and pregnancy. Hundreds of millions of people are targeted with mass drug administration (MDA) of donated benzimidazole anthelmintics. However, benzimidazole efficacy against GINs is suboptimal, and reduced/low efficacy has been seen. Developing an anthelmintic for human MDA is daunting: it must be safe, effective, inexpensive, stable without a cold chain, and massively scalable. Bacillus thuringiensis crystal protein 5B (Cry5B) has anthelmintic properties that could fill this void. Here, we developed an active pharmaceutical ingredient (API) containing B. thuringiensis Cry5B compatible with MDA. We expressed Cry5B in asporogenous B. thuringiensis during vegetative phase, forming cytosolic crystals. These bacteria with cytosolic crystals (BaCC) were rendered inviable (inactivated BaCC [IBaCC]) with food-grade essential oils. IBaCC potency was validated in vitro against nematodes. IBaCC was also potent in vivo against human hookworm infections in hamsters. IBaCC production was successfully scaled to 350 liters at a contract manufacturing facility. A simple fit-for-purpose formulation to protect against stomach digestion and powdered IBaCC were successfully made and used against GINs in hamsters and mice. A pilot histopathology study and blood chemistry workup showed that five daily consecutive doses of 200 mg/kg body weight Cry5B IBaCC (the curative single dose is 40 mg/kg) was nontoxic to hamsters and completely safe. IBaCC is a safe, inexpensive, highly effective, easy-to-manufacture, and scalable anthelmintic that is practical for MDA and represents a new paradigm for treating human GINs.

Assessment of fecal calprotectin and fecal occult blood as point-of-care markers for soil-transmitted helminth attributable intestinal morbidity in a case-control substudy conducted in Côte d'Ivoire, Lao PDR and Pemba Island, Tanzania

BACKGROUND

Infections with soil-transmitted helminths (STHs) may result in chronic inflammatory disorders affecting the human host. The objective of this study was to evaluate Fecal Calprotectin (FC) and Fecal Occult Blood (FOB) in individuals infected and non-infected with STHs to identify potential intestinal morbidity markers.

METHODS

Stool from participants diagnosed positive for Trichuris trichiura and concomitant STH infections from three countries was used to perform FC and FOB point-of-care assays. Simultaneously, identified STH negative participants underwent FC and FOB testing as controls. Potential associations between test results and determinants were analyzed using multivariable logistic regression.

FINDINGS

In total, 1034 T. trichiura infected cases (mostly light infections) and 157 STH negative controls were tested for FC and FOB. Among all participants tested, 18·5% had ≥ 50 µg/g FC concentration, while 14 (1·2%) were positive for FOB. No statistically significant association was found between T. trichiura infection or Ascaris lumbricoides co-infection and FC concentration, while an inverse association (odds ratio (OR): 0·45, 95% credible intervals (CrI): 0·26, 0·75) was found between hookworm co-infection and FC concentration. In Lao PDR, the proportion of participants in the ≥ 50 µg/g FC category was significantly higher in the oldest age category compared to the 5-11 years group (OR: 3·31, 95% CrI: 1·62, 7·24). Too few participants were found positive for FOB to derive any conclusions.

INTERPRETATION

Studies are needed to better understand the relationship between intestinal morbidity and STH infections. Suitable, standardized, low-cost markers of STH attributable morbidity to better monitor the impact of STH control interventions are necessary.

FUNDING

BMGF (OPP1153928).

Morphological and Molecular Diagnosis of Necator americanus and Ancylostoma ceylanicum Recovered from Villagers in Northern Cambodia

Human hookworm infections caused by adult Ancylostoma spp. and Necator americanus are one of the most important tropical diseases. We performed a survey of intestinal helminths using the Kato-Katz fecal examination technique targeting 1,156 villagers residing in 2 northern provinces (Preah Vihear and Stung Treng) of Cambodia in 2018. The results revealed a high overall egg positive rate of intestinal helminths (61.9%), and the egg positive rate of hookworms was 11.6%. Nine of the hookworm egg positive cases in Preah Vihear Province were treated with 5–10 mg/kg pyrantel pamoate followed by purging with magnesium salts, and a total of 65 adult hookworms were expelled in diarrheic stools. The adult hookworms were analyzed morphologically and molecularly to confirm the species. The morphologies of the buccal cavity and dorsal rays on the costa were observed with a light microscope, and the nucleotide sequences of mitochondrial cytochrome c oxidase subunit 1 (cox1) gene were analyzed. The majority of the hookworm adults (90.7%) were N. americanus, whereas the remaining 9.3% were Ancylostoma ceylanicum, a rare hookworm species infecting humans. The results revealed a high prevalence of hookworm infections among people in a northern part of Cambodia, suggesting the necessity of a sustained survey combined with control measures against hookworm infections.

Combating Parasitic Nematode Infections, Newly Discovered Antinematode Compounds from Marine Epiphytic Bacteria

Parasitic nematode infections cause debilitating diseases and impede economic productivity. Antinematode chemotherapies are fundamental to modern medicine and are also important for industries including agriculture, aquaculture and animal health. However, the lack of suitable treatments for some diseases and the rise of nematode resistance to many available therapies necessitates the discovery and development of new drugs. Here, marine epiphytic bacteria represent a promising repository of newly discovered antinematode compounds. Epiphytic bacteria are ubiquitous on marine surfaces where they are under constant pressure of grazing by bacterivorous predators (e.g., protozoans and nematodes). Studies have shown that these bacteria have developed defense strategies to prevent grazers by producing toxic bioactive compounds. Although several active metabolites against nematodes have been identified from marine bacteria, drug discovery from marine microorganisms remains underexplored. In this review, we aim to provide further insight into the need and potential for marine epiphytic bacteria to become a new source of antinematode drugs. We discuss current and emerging strategies, including culture-independent high throughput screening and the utilization of Caenorhabditis elegans as a model target organism, which will be required to advance antinematode drug discovery and development from marine microbial sources.

Ancylostoma ceylanicum: The Neglected Zoonotic Parasite of Community Dogs in Thailand and Its Genetic Diversity among Asian Countries

Ancylostoma ceylanicum is a zoonotic helminth that is commonly found in domestic dogs and cats throughout Asia but is largely neglected in many countries. This study aimed to confirm the species of hookworm in dogs and soil environments and investigate the evolutionary analyses of A. ceylanicum among Thai and Asian populations. In a total of 299 dog fecal samples and 212 soil samples from 53 temples, the prevalence rates of hookworm infection by microscopic examination were 26.4% (79/299) and 10.4% (22/212) in dog and soil samples, respectively. A PCR-RFLP targeting the ITS region was then utilized to identify the hookworm species. In dogs, A. ceylanicum was the main hookworm species, and the rates of A. ceylanicum and A. caninum infections were 96.6% and 3.5%, respectively. The genetic characterization and diversity indices of the A. ceylanicumcox1 gene among Thai and Asian populations were evaluated. Nine haplotypes were identified from Thai A. ceylanicum, in which the haplotype diversity and the nucleotide diversity were 0.4436 and 0.0036, respectively. The highest nucleotide diversity of Chinese A. ceylanicum populations suggested that it could be the ancestor of the populations. Pairwise fixation indices indicated that Thai A. ceylanicum was closely related to the Malaysian population, suggesting a gene flow between these populations. The temples with hookworm-positive dogs were associated with the presence of hookworm-contaminated soil, as these levels showed an approximately four-fold increase compared with those in temples with hookworm-negative dogs (OR = 4.38, 95% CI: 1.55-12.37). Interestingly, the genotypes of A. ceylanicum in the contaminating soil and infecting dogs were identical. Therefore, increased awareness and concern from the wider public communities with regard to the responsibility of temples and municipal offices to provide proper deworming programs to community dogs should be strongly endorsed to reduce the risk of the transmission of this zoonotic disease. In addition, parasitic examination and treatment should be strongly implemented before dogs are imported and exported worldwide.

Strongyloides stercoralis prevalence and diagnostics in Vientiane, Lao People's Democratic Republic

Background

Despite the high prevalence of strongyloidiasis in the Laotian population, Laotian hospitals still lack diagnostic capacity to appropriately diagnose Strongyloides stercoralis infections. This cross-sectional hospital-based study was conducted to assess the prevalence of Strongyloides stercoralis infection among hospitalized patients treated at Mahosot Hospital, the primary reference hospital of Lao People’s Democratic Republic (Lao PDR), and to validate feasible methods for diagnosing S. stercoralis infection at hospital’s laboratory.

Methods

Between September and December 2018, stool samples of 104 inpatients were investigated for S. stercoralis infection by wet smear, Baermann technique, Koga Agar plate culture (KAPC), and real-time detection polymerase chain reaction (RTD-PCR) at the Infectious Diseases Ward of the Mahosot Hospital in Vientiane. The sensitivity, the specificity, the negative predictive value (NPV) of each diagnostic test, as well as their combination(s) was calculated using a composite reference standard (CRS). The correlation of the different test methods was assessed by chi-square or Fisher’s exact test. Cohen’s kappa coefficient was used to assess the diagnostic agreement of the different test methods.

Results

The overall prevalence of S. stercoralis infections among the study population was 33.4%. The cumulative infection prevalence statistically significantly increased from the lowest age group of 40 years and below (22.4%), to the medium (40.0%) and to the oldest age group of 61 year and above (72.7%)(P = 0.003). The cumulative infection prevalence of CRS was considerably higher in male (40.4%) compared to female patients (28.1%), but not statistically different (P = 0.184). The diagnostic sensitivity of Baermann technique, KAPC, RTD-PCR, and the combination of Baermann technique and KAPC were 60.0, 60.0, 74.3, and 77.1%, respectively. Only 13 patients (37.1%) of the total 35 S. stercoralis patients diagnosed with any technique had a simultaneously positive diagnostic test with Baermann, KAPC and RTD-PCR.

Conclusions

We identified Baermann technique and KAPC to be currently the most feasible and implementable standard methods for diagnosing S. stercoralis at a hospital setting such as Mahosot Hospital and provincial and district hospitals in Lao PDR and other low- and middle income countries in Southeast Asia.

Trial registration

This study was approved by the National Ethics Committee for Health Research in Lao PDR (reference no. 083/NECHR) and by the Ethics Committee Northwest and Central Switzerland (reference no. 2018–00594).

Molecular cloning, expression and characterization of aspartyl protease inhibitor from Ancylostoma ceylanicum

Aspartyl protease inhibitors (APIs) from parasitic intestinal nematodes are highly immunogenic and have been suggested as potential vaccine antigens. Ac-API-1 from Ancylostoma caninum showed strong immunogenicity and its polyclonal antibodies could specifically recognize the excretory/secretory products of adult worms. However, little is known about molecular characteristics and biological function of API from Ancylostoma ceylanicum (Ace-API). In this study, the Ace-API mature peptide coding sequence was cloned and expressed, and molecular characteristics of its full length sequence were analyzed. Ace-API cDNA was 684 bp in length, which encoded 228 amino acids. The similarity of the Ace-API amino acid sequence to Ac-API-1 and Adu-API-1 was 96.93% and 96.49%, respectively, and they clustered together in the phylogenetic tree. Escheria coli-expressed recombinant protein was mainly soluble in the supernatant of bacterial cell lysate. Western blot showed that Ace-API protein had good reactivity to the serum of infected dogs. Pepsin inhibition assay revealed that the recombinant protein had inhibitory activity on pepsin. Immunofluorescence results demonstrated that Ace-API was mainly localized to the epidermis, excretory glands, and pseudocoelomic fluid of the adult. Using the quantitative real-time PCR, the expression of Ace-api mRNA in adults was significantly higher than that in the third stage (L3) larvae. Together, these data indicate that Ace-API is secreted extracellularly by the parasite, and might play a role in protecting the parasite against the proteolytic digestion by the host proteases, which stimulate further studies to explore this protein as a potential hookworm vaccine candidate.

Epidemiology and risk factors of Strongyloides stercoralis infection in Papua, Indonesia: a molecular diagnostic study

Strongyloides stercoralis is a parasitic worm that is of considerable clinical relevance. Indeed, it may persist asymptomatically for many years, but can lead to potentially fatal dissemination when the host's immune status is impaired. As commonly employed stool microscopy techniques (e.g. Kato-Katz thick smear) fail to detect S. stercoralis, the epidemiology is poorly understood. In 2013, we conducted a cross-sectional household survey in the district of Mimika in Papua, Indonesia. A total of 331 individuals, aged 1 month to 44 years, had a single stool sample subjected to real-time polymerase chain reaction (PCR) for S. stercoralis diagnosis. The prevalence of S. stercoralis infection was 32.0% (106/331 individuals); higher than any of the three main soil-transmitted helminths (Ascaris lumbricoides, 23.9%; Trichuris trichiura, 18.4%; and hookworm, 17.2%). Amongst the S. stercoralis-infected individuals, 73.6% were concurrently infected with another helminth, with hookworm being the most frequent co-infection (27.4%). Fourteen percent of the S. stercoralis infections had low cycle threshold values on real-time PCR, which may indicate a higher infection intensity. Multivariate logistic regression analysis revealed that age ≥5 years (adjusted odds ratio (OR) 5.8, 95% confidence interval (CI): 3.1-10.8) was significantly associated with S. stercoralis infection. There is a need for in-depth clinical and diagnostic studies to elucidate the public health impact of S. stercoralis infection in Indonesia.

Molecular identification of Ancylostoma ceylanicum in the Philippines

Hookworms are some of the most widespread of the soil-transmitted helminths (STH) with an estimated 438.9 million people infected. Until relatively recently Ancylostoma ceylanicum was regarded as a rare cause of hookworm infection in humans, with little public health relevance. However, recent advances in molecular diagnostics have revealed a much higher prevalence of this zoonotic hookworm than previously thought, particularly in Asia. This study examined the prevalence of STH and A. ceylanicum in the municipalities of Palapag and Laoang in the Philippines utilizing real-time polymerase chain reaction (PCR) on stool samples previously collected as part of a cross-sectional survey of schistosomiasis japonica. Prevalence of hookworm in humans was high with 52.8% (n = 228/432) individuals positive for any hookworm, 34.5% (n = 149/432) infected with Necator americanus, and 29.6% (n = 128/432) with Ancylostoma spp; of these, 34 were PCR-positive for A. ceylanicum. Considering dogs, 12 (n = 33) were PCR-positive for A. ceylanicum. This is the first study to utilize molecular diagnostics to identify A. ceylanicum in the Philippines with both humans and dogs infected. Control and elimination of this zoonotic hookworm will require a multifaceted approach including chemotherapy of humans, identification of animal reservoirs, improvements in health infrastructure, and health education to help prevent infection.

The increased sensitivity of qPCR in comparison to Kato-Katz is required for the accurate assessment of the prevalence of soil-transmitted helminth infection in settings that have received multiple rounds of mass drug administration

Background

The most commonly used diagnostic tool for soil-transmitted helminths (STH) is the Kato-Katz (KK) thick smear technique. However, numerous studies have suggested that the sensitivity of KK can be problematic, especially in low prevalence and low intensity settings. An emerging alternative is quantitative polymerase chain reaction (qPCR).

Methods

In this study, both KK and qPCR were conducted on stool samples from 648 participants in an STH epidemiology study conducted in the delta region of Myanmar in June 2016.

Results

Prevalence of any STH was 20.68% by KK and 45.06% by qPCR. Prevalence of each individual STH was also higher by qPCR than KK, the biggest difference was for hookworm with an approximately 4-fold increase between the two diagnostic techniques. Prevalence of Ancylostoma ceylanicum, a parasite predominately found in dogs, was 4.63%, indicating that there is the possibility of zoonotic transmission in the study setting. In individuals with moderate to high intensity infections there is evidence for a linear relationship between eggs per gram (EPG) of faeces, derived from KK, and DNA copy number, derived from qPCR which is particularly strong for Ascaris lumbricoides.

Conclusions

The use of qPCR in low prevalence settings is important to accurately assess the epidemiological situation and plan control strategies for the ‘end game’. However, more work is required to accurately assess STH intensity from qPCR results and to reduce the cost of qPCR so that is widely accessible in STH endemic countries.

High-throughput multiplex qPCRs for the surveillance of zoonotic species of canine hookworms

The canine hookworms Ancylostoma braziliense, Ancylostoma ceylanicum, Ancylostoma caninum and Uncinaria stenocephala are not only capable of producing morbidity and mortality in dogs but are also neglected tropical zoonoses. Each hookworm species differs considerably in its geographical distribution, life cycle, biology, pathogenic impacts on both canine and human hosts, zoonotic potential, and response to treatment with anthelminthics. Here we describe the development and validation of two Taq-Man based multiplex PCR assays capable of detecting and differentiating all four canine hookworm species in faeces of naturally infected dogs. The analytical sensitivity of both assays was assessed using 10-fold serial dilutions of synthetic gene block fragments containing individual sequence targets of each hookworm species. The sensitivity of the assays and ability to detect mixed species infections were compared to a conventional PCR-Restriction Fragment Length Polymorphism based-approach when applied to laboratory and field samples from endemic areas. The qPCRs detected at least one species of hookworms in 82.4% of PCR-RFLP-negative but microscopy-positive samples. The qPCRs detected an additional 68% mixed infections with different species of canine hookworms, and additional single species infection with A. caninum (47%), U. stenocephala (33%) and A. ceylanicum (0.02%) that were missed by PCR-RFLP. These multiplex qPCR assays will assist field based epidemiological surveillance studies towards an accurate and sensitive monitoring of canine hookworm infections in dogs, to inform their species-specific zoonotic risks to populations living in endemic areas, globally.

Semi-domesticated dogs as a potential reservoir for zoonotic hookworms in Bangkok, Thailand

Background and Aim:

Hookworms are parasitic nematodes that live in the small intestine of their mammalian hosts including humans, dogs, and cats. This study was conducted to determine the prevalence and perform genetic characterization of hookworms using molecular techniques and to elucidate the risk factors associated with hookworm infections among semi-domesticated dogs residing in temples in the Bangkok Metropolitan Area, Thailand.

Materials and Methods:

A total of 500 fecal samples were collected from semi-domesticated dogs from 91 temples in 48 districts of Bangkok. DNA was extracted and screened using internal transcribed spacer polymerase chain reaction-restriction fragment length polymorphism. In addition, samples positive for Ancylostoma ceylanicum were further characterized at the haplotype level based on the analysis of the mitochondrial cytochrome oxidase-1 gene (cox1).

Results:

The prevalence of hookworm infections in semi-domesticated dogs was 6.2% (31/500). Hookworm infections were detected in temple-community dogs in 12 of 48 districts (25.0%), with Bang Khen and Lak Si districts having the highest proportion of infected dogs (22.6%). Regarding molecular characterization of hookworm species, 21 positive samples (67.74%) were infected with A. ceylanicum and 10 (32.26%) with Ancylostoma caninum. Characterization of cox1 in A. ceylanicum isolates revealed the presence of a mixture of human and dog isolates.

Conclusion:

Semi-domesticated dogs act as a potential source of hookworm infections for human and animal populations in Bangkok, Thailand.

The molecular speciation of soil-transmitted helminth eggs collected from school children across six endemic countries

BACKGROUND

The diagnosis of soil-transmitted helminths (STHs; Ascaris, Trichuris and hookworms) is traditionally based on the demonstration of eggs in stool using microscopic techniques. While molecular techniques are more appropriate to speciate STH species they are seldom applied. In this study we speciated STH eggs from stool using molecular techniques to gain insights into the distribution of both human and animal STH species in the human host.

METHODS

We speciated 207 STH egg isolates from stool collected during the baseline survey of six drug efficacy trials conducted in Brazil, Cambodia, Cameroon, Ethiopia, Tanzania and Vietnam applying a PCR - restriction fragment length polymorphisms based approach.

RESULTS

DNA of Ascaris was detected in 71 (34.3%) samples, of which all were identified as the human roundworm Ascaris lumbricoides. In 87 (42.0%) samples, DNA of Trichuris spp. was found and further speciation demonstrated the presence of the human Trichuris trichiura (100%) and the canine Trichuris vulpis (n=7; 8.0%; in Cameroon only). Hookworms were identified in 104 (50.2%) samples, with Necator americanus (n=73; 70.2%) being the predominant species followed by Ancylostoma duodenale (n=40; 38.5%).

CONCLUSIONS

Our study indicates that STH infections in humans are predominantly caused by human STH species. They also suggest that zoonotic transmission occurs on a local scale.

High prevalence of helminth infections in mother-child pairs from three central provinces of Lao People's Democratic Republic

In Southeast Asia, the large majority of the population remains affected by parasitic worms despite longstanding mass treatment and health education campaigns. Soil-transmitted helminths and also the fish-borne liver fluke negatively affect development during early childhood. Here, the prevalence of helminth infections in stool samples of 610 mother-child pairs from Khammouane, Bolikhamxay and Vientiane provinces in Lao People's Democratic Republic was determined by formalin-ethyl acetate concentration technique. Overall, 15.1% of the children and 46.9% of the mothers were positive for at least one helminth species. Helminth detection rates varied significantly by province with the highest prevelance in Khammouane and the lowest in Bolikhamxay province. Mothers that were positive for soil-transmitted helminths were significantly more likely to have children positive for the same helminth species (p < 0.01) but this was not the case for the liver fluke Opisthorchis viverrini. A protective effect of breastfeeding against soil-transmitted helminths was revealed. Our data reconfirm the generally high helminth burden among mother-child pairs who likely share a number of risky lifestyle behaviors also with other family members. To reduce maternal burden of helminths, we propose that anti-helmintic treatment of women of childbearing age and of mothers during postnatal care should be included in the national strategy.

Strongyloidiasis in northern Vietnam: epidemiology, clinical characteristics and molecular diagnosis of the causal agent

Background

Strongyloidiasis is a health problem in Vietnam, but appropriate information is still limited. The aim of this study was to determine the prevalence, geographical distribution, epidemiological aspects, symptoms and other health indicators of Strongyloides stercoralis infections in patients from 27 provinces of northern Vietnam attending the Hanoi Medical University Hospital during 2016 and 2017.

Methods

Blood samples of 2000 patients were analyzed for S. stercoralis infection with an IgG ELISA test. Seroprevalence was analyzed by gender, age group, locality of origin (rural or urban areas) and symptoms. Stools from the seropositive patients were examined for the detection of worms which were subsequently used for species identification by morphology and rDNA ITS1 sequencing.

Results

A seroprevalence of 20% was detected, showing an increasing prevalence from young to older age groups but without significant gender difference. Seroprevalence was higher in rural areas than in urban areas, both in general and individually in all provinces without exception, and lower in the mountainous areas than in the large valley lowlands. The follow-up of the 400 patients showed eosinophilia in 100% of cases, diarrhoea in 64.5%, digestion difficulties in 58.0%, stomachache in 45.5%, stomach and duodenal ulcers in 44.5%, itching in 28.0% and fever in 9.5%. The prevalence of symptoms and signs were also higher in older age groups than in younger age groups. Worms were detected in stools of 10.5% of the patients. Sequencing of a 501-bp nuclear ribosomal DNA ITS1 fragment allowed for the verification of infection by Strongyloides stercoralis.

Conclusions

To our knowledge, this study is the largest survey of human strongyloidiasis in Vietnam so far and the first molecular identification of this nematode species in this country. Long-term chronicity may probably be usual in infected subjects, mainly in the older age groups.

Identification and localization of hookworm platelet inhibitor in Ancylostoma ceylanicum

Ancylostoma ceylanicum is a zoonotic hookworm, which mainly causes iron deficiency anemia (IDA) in humans and animals. Hookworm platelet inhibitor (HPI) has been isolated from adult Ancylostoma caninum and linked to the pathogenesis of hookworm associated intestinal hemorrhage and IDA. However, there is no available data about HPI from A. ceylanicum. To study the molecular characteristics of A. ceylanicum HPI (Ace-HPI), its corresponding cDNA was amplified from adult A. ceylanicum mRNA using the primers designed based on the Ac-HPI gene sequence, and its sequence homology and phylogenetic relationship were analyzed. The differential expression of Ace-hpi mRNA in the adult and third larval (L3) stages was compared using the quantitative real-time PCR. Ace-HPI reactivity and tissue localization were studied by Western blot and immunofluorescence, respectively. Platelet aggregation activity was monitored in a 96-well microplate reader. The results showed that the Ace-HPI encoding gene was 603 bp in length. Ace-HPI showed 91% homology to Ac-HPI, was closely related to Ac-ASP3, and belonged to the CAP superfamily. Ace-hpi transcripts were most abundant in the adult stage, followed by serum-stimulated infective larvae (ssL3), and finally in L3 stage, with a significant difference. Escherichia coli-expressed recombinant protein had good reactivity with the positive serum of A. ceylanicum-infected dogs. Immunolocalization indicated that Ace-HPI was located in the esophagus and cephalic glands of the adult. As well as, recombinant Ace-HPI inhibited the platelet aggregation in-vitro. HPI overexpression, anatomical location in adults, antigenicity and its in-vitro activity indicate its possible role in adult worm blood-feeding and as a valuable target for hookworm vaccine and drug development.

Drug Screening for Discovery of Broad-spectrum Agents for Soil-transmitted Nematodes

Soil-transmitted nematodes (STNs), namely hookworms, whipworms, and ascarids, are extremely common parasites, infecting 1-2 billion of the poorest people worldwide. Two benzimidazoles, albendazole and mebendazole, are currently used in STN mass drug administration, with many instances of low/reduced activity reported. New drugs against STNs are urgently needed. We tested various models for STN drug screening with the aim of identifying the most effective tactics for the discovery of potent, safe and broad-spectrum agents. We screened a 1280-compound library of approved drugs to completion against late larval/adult stages and egg/larval stages of both the human hookworm parasite Ancylostoma ceylanicum and the free-living nematode Caenorhabditis elegans, which is often used as a surrogate for STNs in screens. The quality of positives was further evaluated based on cheminformatics/data mining analyses and activity against evolutionarily distant Trichuris muris whipworm adults. From these data, two pairs of positives, sulconazole/econazole and pararosaniline/cetylpyridinium, predicted to target nematode CYP-450 and HSP-90 respectively, were prioritized for in vivo evaluation against A. ceylanicum infections in hamsters. One of these positives, pararosaniline, showed a significant impact on hookworm fecundity in vivo. Taken together, our results suggest that anthelmintic screening with A. ceylanicum larval stages is superior to C. elegans based on both reduced false negative rate and superior overall quality of actives. Our results also highlight two potentially important targets for the discovery of broad-spectrum human STN drugs.

Prevalence and risk factors of Strongyloides stercoralis infection among Orang Asli schoolchildren: new insights into the epidemiology, transmission and diagnosis of strongyloidiasis in Malaysia

This cross-sectional study aimed to determine the prevalence and risk factors of S. stercoralis infection among 1142 Orang Asli primary schoolchildren in six different states of Peninsular Malaysia. Fecal samples were examined using direct smear, formalin-ether sedimentation (FES), agar plate culture (APC) and PCR techniques. Overall, 15.8% of the children were found to be infected with S. stercoralis. The prevalence was 0.2, 1.3, 15.2 and 13.7% by direct smear, FES, APC and PCR, respectively. Multivariate analysis showed that an age of >10 years, being male, belonging to a Proto-Malay tribe, belonging to the Senoi tribe, indiscriminate defecation, using an unimproved water source for drinking water and not wearing shoes when outside were the significant risk factors of infection among these children. In conclusion, we provide new evidence on the occurrence of S. stercoralis in Malaysia to show that there is a relatively high prevalence of infection among Orang Asli schoolchildren. Therefore, the use of specific methods for detecting S. stercoralis should be considered when screening these children for intestinal parasites. Moreover, prevention and control measures specific to S. stercoralis should be integrated into the intestinal parasitic infections control programme in Malaysia.

Strongyloides stercoralis: Spatial distribution of a highly prevalent and ubiquitous soil-transmitted helminth in Cambodia

Background

Strongyloides stercoralis is a neglected soil-transmitted helminth that occurs worldwide, though it is particularly endemic in tropical and subtropical areas. It can cause long-lasting and potentially fatal infections due to its ability to replicate within its host. S. stercoralis causes gastrointestinal and dermatological morbidity. The objective of this study was to assess the S. stercoralis infection risk and, using geostatistical models, to predict its geographical distribution in Cambodia.

Methodology / Principal findings

A nation-wide, community-based parasitological survey was conducted among the Cambodian population, aged 6 years and older. S. stercoralis was diagnosed using a serological diagnostic test that detects IgG antibodies in urine. Data on demography, hygiene and knowledge about helminth infection were collected. S. stercoralis prevalence among 7,246 participants with a complete data record was 30.5%, ranging from 10.9% to 48.2% across provinces. The parasite was ubiquitous in Cambodia; only five south-eastern provinces had prevalence rates below 20%. Infection risk increased with age for both men and women, although girls under the age of 13 and women aged 50 years and over had lower odds of infection than their male counterparts. Open defecation was associated with higher odds of infection, while having some knowledge of the health problems caused by worms was a protective factor. Infection risk was positively associated with nighttime maximum temperature, minimum rainfall, and distance to water; it was negatively associated with land occupied by rice fields.

Conclusions / Significance

S. stercoralis infection is rampant in Cambodia. Control programs delivering ivermectin are needed to manage the parasite. However, the high cost of this drug in Cambodia currently precludes the implementation of control initiatives. Donations, subsidies or affordable generics are needed so that S. stercoralis, which infects almost a third of the Cambodian population, can be addressed through an adequate control program.

The threadworm, Strongyloides stercoralis, is a highly neglected worm infection, transmitted through infective larvae in the soil. Threadworms occur worldwide, particularly in tropical climates. It may cause long-lasting and potentially fatal infections due to the parasite’s ability to replicate within its host. This study aimed to assess the risk of threadworm infection at national level in Cambodia. We conducted a nation-wide, community-based parasitological survey of the Cambodian population, aged 6 years and over. The threadworm was diagnosed using a serological diagnostic test that detects antibodies in urine. Data on demography, hygiene and knowledge about helminth infection were collected. The purpose of this study was to predict the risk of S. stercoralis infection in unsurveyed locations, assess risk factors for infection, and map its geographical distribution in Cambodia. About one third (30.5%) of the enrolled study participants (n = 7,246) were infected with threadworms. At provincial level, the lowest and highest infection rates were 10.9% and 48.2%, respectively. Prevalence rates below 20% were found in just five south-eastern provinces. The risk of a threadworm infection increased with age for both men and women. Open defecation was associated with higher risk of infection, while having some knowledge of the health problems caused by worms was a protective factor. Infection risk was positively associated with environmental factors, such as nighttime maximum temperature, minimum rainfall, and distance to water; it was negatively associated with land occupied by rice fields. Threadworm infection is highly prevalent in Cambodia and adequate control measures, including access to treatment, are warranted to address the burden of this Neglected Tropical Disease (NTD) in Cambodia.

The extent, nature, and pathogenic consequences of helminth polyparasitism in humans: A meta-analysis

Background

Individual helminth infections are ubiquitous in the tropics; geographical overlaps in endemicity and epidemiological reports suggest areas endemic for multiple helminthiases are also burdened with high prevalences of intestinal protozoan infections, malaria, tuberculosis (TB), and human immunodeficiency virus (HIV). Despite this, pathogens tend to be studied in isolation, and there remains a need for a better understanding of the community ecology and health consequences of helminth polyparasitism to inform the design of effective parasite control programs.

Methodology

We performed meta-analyses to (i) evaluate the commonality of polyparasitism for helminth-helminth, helminth-intestinal protozoa, helminth-malaria, helminth-TB, and helminth-HIV co-infections, (ii) assess the potential for interspecies interactions among helminth-helminth and helminth-intestinal protozoan infections, and (iii) determine the presence and magnitude of association between specific parasite pairs. Additionally, we conducted a review of reported health consequences of multiply-infected individuals compared to singly- or not multiply-infected individuals.

Principal findings

We found that helminth-helminth and helminth-intestinal protozoan multiple infections were significantly more common than single infections, while individuals with malaria, TB, and HIV were more likely to be singly-infected with these infections than co-infected with at least one helminth. Most observed species density distributions significantly differed from the expected distributions, suggesting the potential presence of interspecies interactions. All significant associations between parasite pairs were positive in direction, irrespective of the combination of pathogens. Polyparasitized individuals largely exhibited lower hemoglobin levels and higher anemia prevalence, while the differences in growth-related variables were mostly statistically insignificant.

Conclusions

Our findings confirm that helminth polyparasitism and co-infection with major diseases is common in the tropics. A multitude of factors acting at various hierarchical levels, such as interspecies interactions at the within-host infra-parasite community level and environmental variables at the higher host community level, could explain the observed positive associations between pathogens; there remains a need to develop new frameworks which can consider these multilevel factors to better understand the processes structuring parasite communities to accomplish their control.

Helminth infections are a highly prevalent global health problem. These parasitic worm infections occur in areas also burdened with intestinal protozoan infections, malaria, tuberculosis, and human immunodeficiency virus. While these pathogens tend to be studied in isolation, there remains a need to better understand the nature, extent, and health consequences of helminth polyparasitism and co-infection with major diseases. Here, we reviewed the literature and performed meta-analyses to evaluate the commonality of helminth polyparasitism and co-infection, the potential for interspecies interactions between parasites, the association between parasite pairs, and the health consequences among multiply-infected individuals. We confirmed that polyparasitism and co-infection with major diseases are common in the global South and found that multiply-infected individuals experienced worse health consequences when compared to singly or not-multiply infected individuals. Our analysis suggested the potential presence of interspecies interactions and we identified the existence of positive associations between parasite pairs. These findings support the call for integrating deworming into malaria, TB, and HIV treatment protocols and suggest there remains a need to improve our understanding of the factors influencing co-transmission to achieve sustainable parasite control.

Predictors of hookworm and Opisthorchis viverrini infection among adolescents in urban Laos: a cross-sectional study

Purpose: Infection with hookworm and Opisthorchis viverrini are serious health problems among children and adolescents in Laos. In this study, we demonstrated the factors related to hookworm and O. viverrini infection, including primary school health programs, among secondary school students in Vientiane city of Laos.

Material and methods: A cross-sectional survey and stool examination were conducted among secondary school students in Vientiane. One stool sample from each participant was examined using two Kato-Katz smears. Data of 164 participants were analyzed and the associations among parasitic infections, sociodemographic characteristics, and the school health program in primary school were assessed in a univariate logistic regression analysis. Predictors with p<0.25 were retained in a multivariate logistic regression model. Odds ratios (ORs) and 95% confidence intervals (CIs) were reported. The significance level was set at p<0.05.

Results: The infection rates of O. viverrini and hookworm were 39.0% and 36.0%, respectively. Older students (OR=1.55, 95% CI: 1.01–2.37, p=0.046) and those whose father had irregular income (OR=0.47, 95% CI: 0.13–0.93, p=0.036) had a higher risk for hookworm infection. Students whose mother had irregular income (OR=0.30, 95% CI: 0.13–0.69, p=0.005) had a higher risk for O. viverrini infection. Higher primary school health program scores were associated with a lower risk for hookworm infection in the univariate model but not in the multivariate model.

Conclusion: Sociodemographic factors have a strong influence on infections with both hookworm and O. viverrini. Current school health programs in Laos may be insufficient to reduce O. viverrini infections. Other approaches, such as supporting parents in finding employment with regular income, may be needed.

Cognitive and Microbiome Impacts of Experimental Ancylostoma ceylanicum Hookworm Infections in Hamsters

Hookworms are one of the most prevalent and important parasites, infecting ~500 million people worldwide. Hookworm disease is among the leading causes of iron-deficiency anemia in the developing world and is associated with significant growth stunting and malnutrition. In humans, hookworms appear to impair memory and other forms of cognition, although definitive data are hard to come by. Here we study the impact of a human hookworm parasite, Ancylostoma ceylanicum, on cognition in hamsters in a controlled laboratory setting. We developed tests that measure long-term memory in hamsters. We find that hookworm-infected hamsters were fully capable of detecting a novel object. However, hookworm-infected hamsters were impaired in detecting a displaced object. Defects could be discerned at even at low levels of infection, whereas at higher levels of infection, hamsters were statistically unable to distinguish between displaced and non-displaced objects. These spatial memory deficiencies could not be attributed to defects in infected hamster mobility or to lack of interest. We also found that hookworm infection resulted in reproducible reductions in diversity and changes in specific taxanomic groups in the hamster gut microbiome. These data demonstrate that human hookworm infection in a laboratory mammal results in a specific, rapid, acute, and measurable deficit in spatial memory, and we speculate that gut alterations could play some role in these cognitive deficits. Our findings highlight the importance of hookworm elimination and suggest that finer tuned spatial memory studies be carried out in humans.

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 ofAncylostomaspp. andUncinaria stenocephalawere 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 byA. braziliense(n = 10) andA.cf.duodenale(n = 1). This study reports for the first time the detection ofA.cf.duodenalein 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.

Establishment of a Tm-shift Method for Detection of Cat-Derived Hookworms

Melting temperature shift (T_m-shift) is a new detection method that analyze the melting curve on real-time PCR thermocycler using SYBR Green I fluorescent dye. To establish a T_m-shift method for the detection of Ancylostoma ceylanicum and A. tubaeforme in cats, specific primers, with GC tail of unequal length attached to their 5′ end, were designed based on 2 SNP loci (ITS101 and ITS296) of the internal transcribed spacer 1 (ITS1) sequences. The standard curve of T_m-shift was established using the standard plasmids of A. ceylanicum (AceP) and A. tubaeforme (AtuP). The T_m-shift method stability, sensitivity, and accuracy were tested with reference to the standard curve, and clinical fecal samples were also examined. The results demonstrated that the 2 sets of primers based on the 2 SNPs could accurately distinguish between A. ceylanicum and A. tubaeforme. The coefficient of variation (CV) of T_m-values of AceP and AtuP was 0.07% and 0.06% in ITS101 and was 0.06% and 0.08% in ITS296, respectively. The minimum detectable DNA concentration was 5.22×10⁻⁶ and 5.28×10⁻⁶ ng/μl samples of AceP and AtuP, respectively. The accuracy of T_m-shift method reached 100% based on examination of 10 hookworm DNA samples with known species. In the clinical detection of hookworm in 69 stray cat fecal sample, the T_m-shift detection results were consistent with the microscopic examination and successfully differentiated between the 2-hookworm species. In conclusion, the developed method is a rapid, sensitive and accurate technique and can provide a promising tool for clinical detection and epidemiological investigation of cat-derived hookworms.

Epidemiology of Strongyloides stercoralis infection in Bolivian patients at high risk of complications

Background

Strongyloidiasis can be fatal in immunocompromised patients, but few epidemiological studies investigated the burden of this neglected tropical disease among these populations, particularly in low- and middle-income countries such as Bolivia. This study aimed to fill in this gap by estimating prevalence rate and risk factors associated with strongyloidiasis among patients at high risk of complications

Methods

A cross-sectional study was carried out in Santa Cruz (elevation 400 meters, tropical climate) and Cochabamba (elevation 2,500 meters, temperate climate), among patients with cancer, HIV infection and rheumatic or hematologic disease, using four coproparasitological techniques and one serological (ELISA) test.

Results

In total, 1,151 patients participated in this study, including individuals who were HIV-positive (30%) or with rheumatic (29%), oncologic (32%) or hematologic (9%) diseases. The serological and coproparasitological prevalence was 23.0% (95% confidence interval [CI], 20.7–25.5; n = 265/1151) and 7.6% (95% CI, 6.2–9.3; n = 88/1151), respectively, with an estimated actual prevalence of 20.2% (95% CI, 17.9–22.5). Positive serology and positive coproparasitology were associated with younger age and lower education levels. There was no significant difference in prevalence between Cochabamba and Santa Cruz as defined by coproparasitology (6.4% vs. 8.9%; p = 0.11) or serology (24.0% vs. 22.0%; p = 0.4). Among 64 patients in Cochabamba who had never travelled to the tropical lowlands, 5 (7.8%) had a positive coproparasitology.

Conclusions

Strongyloidiasis is widely prevalent in Bolivia among vulnerable patients at increased risk of life-threatening complications. Transmission of the parasite occurs both in tropical lowlands and temperate elevation (≥ 2,500 m). Control strategies to prevent transmission and complications of this serious parasitic disease should be urgently reinforced.

Strongyloidiasis is an understudied chronic intestinal infection and one of the most overlooked of the neglected tropical diseases, particularly in countries such as Bolivia. The strongyloidiasis usually remains paucisymptomatic for decades in immunocompetent persons, but may lead to severe conditions with high mortality rates in immunocompromised individuals. We carried out a study to explore the epidemiology of strongyloidiasis among Bolivian patients with cancer, HIV infection, and rheumatic or hematologic diseases. Our study highlighted that strongyloidiasis was widely prevalent in tropical and inter-Andean temperate areas of Bolivia among patients at high risk of life-threatening complications. One in five participants was infected. We showed that strongyloidiasis was highly prevalent in both tropical and temperate regions. Improved access to adequate diagnosis, treatment, and preventive measures are therefore urgently required in Bolivia, and most likely elsewhere in the region. Treatment of uncomplicated strongyloidiasis is simple, highly effective, and potentially life-saving.

Improved methods to capture the total societal benefits of zoonotic disease control: Demonstrating the cost-effectiveness of an integrated control programme for Taenia solium, soil transmitted helminths and classical swine fever in northern Lao PDR

BACKGROUND

Control and elimination of zoonotic diseases requires robust information about their effect on both human and livestock health in order to enable policy formulation and the allocation of resources. This study aimed to evaluate the cost-effectiveness of controlling Taenia solium taeniasis/cysticercosis in both humans and pigs, and soil-transmitted helminths (STH) in humans by integrating their control to on-going human and animal health control programmes in northern Lao People's Democratic Republic.

METHOD

A cross-sectional study was carried out in 49 households, focusing on the prevalence of T. solium taenias/cysticercosis and soil transmitted helminths before and after a twelve month intervention. The village data was collected using a semi-structured questionnaire through a door-to-door survey. The village data was then projected to the wider northern Lao PDR population using stochastic modelling and cost-effectiveness ratio (after aggregating the net cost to capture both human and animal health parameters) and GDP per capita as a threshold, to determine the cost-effectiveness of the integrated control of T. solium taeniasis/ cysticercosis and STH, assuming linear scaling out of the intervention. The zoonotic DALY (zDALY) approach was also used as an alternative method of estimating the cost-effectiveness ratio of controlling T. solium taeniasis/cysticercosis in humans and pigs.

FINDINGS

Using cost-effectiveness analysis after aggregating the net cost and control of T. solium taeniasis/cysticercosis alone as the base case, the study found that simultaneous control of T. solium taeniasis/cysticercosis in humans and pigs, STH in humans and Classical Swine Fever (CSF) in pigs was USD 14 per DALY averted and USD 234 per zDALY averted using zDALY method hence considered highly cost-effective whereas controlling T. solium taeniasis/cysticercosis without incorporating STH and CSF was the least cost-effective (USD 3,672 per DALY averted). Additionally, the cost-effectiveness of controlling T. solium taeniasis/cysticercosis in people and pigs using zDALY as an alternative method was USD 3,662 per zDALY averted which was quite close to our findings using the aggregate net cost method.

CONCLUSION

The study showed that control of T. solium taeniasis/cysticercosis alone in humans and pigs is not cost-effective in northern Lao PDR whereas control of STH is. Consequently, integrating T. solium taeniasis/cysticercosis control with other cost-effective programmes such as STH and CSF markedly improved the cost-effectiveness of the intervention. This is especially important in low resource countries where control of zoonotic neglected tropical diseases could be integrated with the human and animal health sectors to optimize use of the limited resources.

TRIAL REGISTRATION

Australia New Zealand Clinical Trials Registry (ANZCTR) ACTRN12614001067662.

Tm-Shift Detection of Dog-Derived Ancylostoma ceylanicum and A. caninum

To develop a T_m-shift method for detection of dog-derived Ancylostoma ceylanicum and A. caninum, three sets of primers were designed based on three SNPs (ITS71, ITS197, and ITS296) of their internal transcribed spacer 1 (ITS1) sequences. The detection effect of the T_m-shift was assessed through the stability, sensitivity, accuracy test, and clinical detection. The results showed that these three sets of primers could distinguish accurately between A. ceylanicum and A. caninum. The coefficient of variation in their T_m values on the three SNPs was 0.09% and 0.15% (ITS71), 0.18% and 0.14% (ITS197), and 0.13% and 0.07% (ITS296), respectively. The lowest detectable concentration of standard plasmids for A. ceylanicum and A. caninum was 5.33 × 10⁻⁶ ng/μL and 5.03 × 10⁻⁶ ng/μL. The T_m-shift results of ten DNA samples from the dog-derived hookworms were consistent with their known species. In the clinical detection of 50 fecal samples from stray dogs, the positive rate of hookworm detected by T_m-shift (42%) was significantly higher than that by microscopic examination (34%), and the former can identify the Ancylostoma species. It is concluded that the T_m-shift method is rapid, specific, sensitive, and suitable for the clinical detection and zoonotic risk assessment of the dog-derived hookworm.

Comparative analysis of Ancylostoma ceylanicum mitochondrial genome with other Ancylostoma species

Ancylostoma ceylanicum may inhabit the small intestine of canids, felids and humans, can pose a potential risk to public health. This study is the first time to amplify complete mitochondrial genome sequence of A. ceylanicum from dog and to compare it with Ancylostoma tubaeforme, Ancylostoma duodenale and Ancylostoma caninum. The results showed that the complete mitochondrial genome of A. ceylanicum was 13,660 bp in length, including 12 protein-coding genes, 2 rRNA genes and 22 tRNA genes and 3 non-coding regions (AT-rich region, SNCR and LNCR). Its mtDNA was the shortest, biased toward A and T at base composition, and higher than other three Ancylostoma species at total AT content. Its nad5 and nad6 genes used TTG and ATT as initiation codons, while other three Ancylostoma species used ATT and GTG or ATG. The 22 tRNA genes were different in length among four Ancylostoma species, but their anticodons were the same. Among 12 protein-coding genes, the cox1 gene was the lowest at AT content and minimum at Ka/Ks while the nad2 gene was the opposite. The phylogenetic tree showed that in the lineage of Ancylostoma, A. ceylanicum occurred on a branch external to other three Ancylostoma species, and A. caninum and A. tubaeforme had closer phylogenetic relationship than A. duodenale. This study not only enhances the mitochondrial genome database of Ancylostomatidae nematodes, but also provides new data for further phylogenetic studies among Ancylostomatidae nematodes.

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.

Ancylostoma ceylanicum, novel etiological agent for traveler's diarrhea-report of four Japanese patients who returned from Southeast Asia and Papua New Guinea

Background

Countries in the Southeast Asia region have a high prevalence of soil-transmitted helminth, such as roundworm, whipworm, and hookworms [Ancylostoma duodenale, Necator americanus, Ancylostoma ceylanicum]. Recent molecular-based surveys have revealed that A. ceylanicum, a zoonotic hookworm, is likely the second most prevalent hookworm species infecting humans in that part of the world, while others have noted that this infection is an emerging public health risk not only for indigenous people but also for visitors from other countries.

Case presentation

We recently encountered four cases of A. ceylanicum infection in Japanese individuals who returned from Southeast Asia and Papua New Guinea. Case 1 was a 25-year-old male who stayed in a rainforest in Malaysia for 4 weeks, where he developed abdominal pain and diarrhea in the third week. Eleven adult worms (five males, six females) were expelled after treatment with pyrantel pamoate and identified as A. ceylanicum based on morphological characteristics and DNA sequences of the mitochondrial cytochrome c oxidase subunit 1 (cox1) gene. Case 2 was a 26-year-old male who spent 2 years as an overseas cooperation volunteer for agriculture in Papua New Guinea. He did not note any symptoms at that time, though eggs were detected in feces samples at a medical check-up examination after returning. Although collection of adult worms was unsuccessful, DNA analysis of the eggs for cox1 and the ribosomal internal transcribed spacer (ITS)-1 and ITS-2 genes demonstrated that they were A. ceylanicum. Case 3 was a 47-year-old male who spent 1 month in a rural village in Lao People's Democratic Republic and began suffering from watery diarrhea from the third week. A total of nine adult worms (three males, six females) were collected by endoscopic procedures and following treatment with pyrantel pamoate. Morphological examination and molecular analyses of the cox1 gene showed that they were A. ceylanicum. Case 4 was a 27-year-old male who participated in group travel to India for 5 days. Three weeks after returning, he developed abdominal pain and diarrhea. Hookworm eggs were found in feces samples and developed into larvae in culture, which were identified as A. ceylanicum based on molecular analysis of the cox1 gene. Eosinophilia was observed in all of the cases prior to treatment.

Conclusions

A. ceylanicum should be recognized as an important etiologic pathogen of hookworm diseases in travelers to countries in the Southeast Asia and West Pacific Ocean regions.

Improving eukaryotic genome annotation using single molecule mRNA sequencing

BACKGROUND

The advantages of Pacific Biosciences (PacBio) single-molecule real-time (SMRT) technology include long reads, low systematic bias, and high consensus read accuracy. Here we use these attributes to improve on the genome annotation of the parasitic hookworm Ancylostoma ceylanicum using PacBio RNA-Seq.

RESULTS

We sequenced 192,888 circular consensus sequences (CCS) derived from cDNAs generated using the CloneTech SMARTer system. These SMARTer-SMRT libraries were normalized and size-selected providing a robust population of expressed structural genes for subsequent genome annotation. We demonstrate PacBio mRNA sequences based genome annotation improvement, compared to genome annotation using conventional sequencing-by-synthesis alone, by identifying 1609 (9.2%) new genes, extended the length of 3965 (26.7%) genes and increased the total genomic exon length by 1.9 Mb (12.4%). Non-coding sequence representation (primarily from UTRs based on dT reverse transcription priming) was particularly improved, increasing in total length by fifteen-fold, by increasing both the length and number of UTR exons. In addition, the UTR data provided by these CCS allowed for the identification of a novel SL2 splice leader sequence for A. ceylanicum and an increase in the number and proportion of functionally annotated genes. RNA-seq data also confirmed some of the newly annotated genes and gene features.

CONCLUSION

Overall, PacBio data has supported a significant improvement in gene annotation in this genome, and is an appealing alternative or complementary technique for genome annotation to the other transcript sequencing technologies.

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.

Strongyloides stercoralis and hookworm co-infection: spatial distribution and determinants in Preah Vihear Province, Cambodia

BACKGROUND

Strongyloides stercoralis and hookworm are two soil-transmitted helminths (STH) that are highly prevalent in Cambodia. Strongyloides stercoralis causes long-lasting infections and significant morbidity but is largely neglected, while hookworm causes the highest public health burden among STH. The two parasites have the same infection route, i.e. skin penetration. The extent of co-distribution, which could result in potential high co-morbidities, is unknown in highly endemic settings like Cambodia. The aim of this study was to predict the spatial distribution of S. stercoralis-hookworm co-infection risk and to investigate determinants of co-infection in Preah Vihear Province, North Cambodia.

METHODS

A cross-sectional survey was conducted in 2010 in 60 villages of Preah Vihear Province. Diagnosis was performed on two stool samples, using combined Baermann technique and Koga agar culture plate for S. stercoralis and Kato-Katz technique for hookworm. Bayesian multinomial geostatistical models were used to assess demographic, socioeconomic, and behavioural determinants of S. stercoralis-hookworm co-infection and to predict co-infection risk at non-surveyed locations.

RESULTS

Of the 2576 participants included in the study, 48.6% and 49.0% were infected with S. stercoralis and hookworm, respectively; 43.8% of the cases were co-infections. Females, preschool aged children, adults aged 19-49 years, and participants who reported regularly defecating in toilets, systematically boiling drinking water and having been treated with anthelmintic drugs had lower odds of co-infection. While S. stercoralis infection risk did not appear to be spatially structured, hookworm mono-infection and co-infection exhibited spatial correlation at about 20 km. Co-infection risk was positively associated with longer walking distances to a health centre and exhibited a small clustering tendency. The association was only partly explained by climatic variables, suggesting a role for underlying factors, such as living conditions and remoteness.

CONCLUSIONS

Both parasites were ubiquitous in the province, with co-infections accounting for almost half of all cases. The high prevalence of S. stercoralis calls for control measures. Despite several years of school-based de-worming programmes, hookworm infection levels remain high. Mebendazole efficacy, as well as coverage of and compliance to STH control programmes should be investigated.

Soil-Transmitted Helminths in Tropical Australia and Asia

Soil-transmitted helminths (STH) infect 2 billion people worldwide including significant numbers in South-East Asia (SEA). In Australia, STH are of less concern; however, indigenous communities are endemic for STH, including Strongyloides stercoralis, as well as for serious clinical infections due to other helminths such as Toxocara spp. The zoonotic hookworm Ancylostoma ceylanicum is also present in Australia and SEA, and may contribute to human infections particularly among pet owners. High human immigration rates to Australia from SEA, which is highly endemic for STH Strongyloides and Toxocara, has resulted in a high prevalence of these helminthic infections in immigrant communities, particularly since such individuals are not screened for worm infections upon entry. In this review, we consider the current state of STH infections in Australia and SEA.

Controlling Taenia solium and soil transmitted helminths in a northern Lao PDR village: Impact of a triple dose albendazole regime

Taenia solium taeniasis-cysticercosis and soil-transmitted helminths (STHs) are parasitic Neglected Tropical Diseases endemic throughout Southeast Asia. Within Lao PDR, a remote northern hill tribe village had previously been identified as a hyper endemic focus for T. solium. To reduce this observed prevalence, a One Health intervention covering both pigs and humans was implemented, which included two Mass drug administrations (MDA1 and MDA2) for village residents using a triple dose albendazole 400mg treatment regime. In addition to the effect on T. solium levels, the dual impact of this anthelmintic regime on STHs within the community was also monitored. Faecal samples were collected pre and post MDA1 and MDA2 and analysed for the presence of Taenia species and the STHs Ascaris lumbricoides, Trichuris trichiura and hookworm species. The McMaster technique was used to measure the changes in both prevalence and intensity of infection. Molecular characterisation of Taenia and hookworm species was conducted to detect zoonotic species. The level of taeniasis within the sampled population decreased by 79.4% after MDA1, remained steady during the five month inter-treatment interval and decreased again by 100% after MDA2. The prevalence of STHs decreased by 65.5% and 62.8% after MDA1 and MDA2 respectively; however an increase to 62.1% of pre MDA1 levels was detected during the inter-treatment interval. Individually, hookworm prevalence decreased by 83.4% (MDA1) and 84.5% (MDA2), A. lumbricoides by 95.6% and 93.5% and T. trichiura by 69.2% and 61%. The intensity of infection within the sampled population also decreased, with egg reduction rates of 94.4% and 97.8% for hookworm, 99.4% and 99.3% for A. lumbricoides and 77.2% and 88.5% for T. trichiura. Molecular characterisation identified a T. solium tapeworm carrier from 21.6% (13/60) of households in the village. T. saginata was identified in 5% (3/60) of households. The zoonotic hookworm A. ceylanicum was detected in the resident dog population. These results suggest that the triple dose albendazole 400mg treatment regime achieved a significant reduction in the level of taeniasis whilst simultaneously reducing the STH burden within the village. The increased STH prevalence detected between MDAs reflects the need for behavioural changes and a sustained chemotherapy programme, which may also need to include the resident dog population.

Hookworm infections among migrant workers in Malaysia: Molecular identification of Necator americanus and Ancylostoma duodenale

Ongoing urbanisation of the working population as well as cross-border migration of workers particularly into large cities has contributed to the development and growth of urban slums. These deprived areas are conducive for the transmission of intestinal pathogens including hookworm. The aim of this study was to determine both the prevalence and species identity of hookworm infections among the migrant worker community in Malaysia. A total of 388 faecal samples were collected from migrant workers between September 2014 and August 2015, representing workers from five employment sectors: construction, manufacturing, agriculture and plantations, food services and domestic services. Faecal samples were examined by microscopy and positive samples were subjected to molecular analysis. A total of 51 samples (13.1%) were positive by microscopy for hookworm infections. A two-step PCR based method amplifying a fragment of the 28S rRNA-ITS2 region was used to identify infections by Necator americanus and Ancylostoma spp. PCR products positive for Ancylostoma spp. were sequenced bidirectionally, and sequences analysed through BLAST and phylogenetic analysis. Samples containing Ancylostoma duodenale were further characterized by amplification and sequencing a fragment of cytochrome c oxidase subunit 1 (cox1) gene. PCR amplicons were successfully obtained from 42 (82.4%) of 51 samples, with 81.0% (34 of 42) identified as Necator americanus, 16.7% (7 of 42) as Ancylostoma spp. and 2.4% (1 of 42) as mixed infections of both species. All eight Ancylostoma spp. were confirmed to be Ancylostoma duodenale and this is the first time A. duodenale was reported in Malaysia. Samples containing A. duodenale from Nepalese and Indonesian workers shared high-similarity and were distinct compared to sequences from other countries. This study highlights the prevalence of hookworm infections among migrant workers living in Malaysia. Our findings underscore the necessity of screening migrant workers for hookworm infections, particularly those working in food-related services and industries.