Soil-Transmitted Helminths in the USA: a Review of Five Common Parasites and Future Directions for Avenues of Enhanced Epidemiologic Inquiry

In Vitro Anthelmintic Activities of Khaya anthotheca and Faidherbia albida Extracts Used in Chad by Traditional Healers for the Treatment of Helminthiasis and In Silico Study of Phytoconstituents

Background

Helminthiasis is endemic in Chad and constitutes a public health problem, particularly among school-age children. The aim of this study was to evaluate the anthelmintic activity of extracts of Khaya anthotheca and Faidherbia albida used in Chad by traditional healers for the treatment of helminthiasis.

Methods

The anthelmintic activity was assessed against Heligmosomoides polygyrus and Caenorhabditis elegans larvae using the Worm Microtracker. Embryonated eggs, L1, L2, and L3 larvae of H. polygyrus were obtained after 24 h, 48 h, and 7 days of coproculture and L4 larvae of C. elegans culture using standard procedures. One hundred microliters of extracts at various concentrations, with albendazole and distilled water were, put in contact with 100 µL of H. polygyrus suspension (containing 50 parasites at various developmental stages) in a microplate and incubated for 20 h at 25°C in the Worm Microtracker. The same procedure was adopted for C. elegans, but with 180 µL of OP50. 19 µL of C. elegans suspension (containing 50 larvae) was put in contact with 1 µL of extract at various concentrations and incubated in the Worm Microtracker. Docking studies were carried out using the Schrodinger Maestro software's Glide module. The score function in the software was used to rank and group distinct possible adduct structures generated by molecular docking.

Results

The aqueous and ethanolic extracts of F. albida at a concentration of 2.5 mg/mL showed the same activity as albendazole (100 ± 0.00) on hatching. The IC50s of the aqueous extracts of the two plants (IC50: 0.6212 mg/mL and 0.71 mg/mL, respectively) were comparable on egg hatching of H. polygyrus with no significant difference (p ≥ 0.05) with respect to the ethanol extracts (IC50: 0.70 mg/mL and 0.81 mg/mL, respectively). There was no significant difference between the percentage inhibition of extracts and albendazole on the L1 larvae of H. polygyrus (p ≥ 0.05). The aqueous extracts acted more effectively than the ethanol extracts on the L1 larvae of H. polygyrus with an IC50 of 0.5588 and ∼9.858e - 005 mg/ml, respectively, for K. anthotheca and F. albida. The aqueous extracts of K. anthotheca and F. albida on L3 larvae of H. polygyrus had inhibitory percentages of 92.6 ± 0.62 and 91.37 ± 0.8 at 2.5 mg/mL which were lower than albendazole (100 ± 0.00). The aqueous extracts of K. anthotheca and F. albida on C. elegance showed IC50 of 0.2775 µg/mL and 0.5115 µg/mL, respectively, and were more effective than the ethanol extracts. Examining K. anthotheca and F. albida through the interaction with the protein receptor and its results also confirmed our assumption that the compound used has hydroxyl and carbonyl groups as well as aromatic rings and is exposed to phenolic and flavonoid groups in a more specific way, and it shows a better inhibitory effect.

Conclusions

This study scientifically validates the use of extracts of the two plants in the traditional treatment of helminthiasis. However, it will be necessary to evaluate the in vivo anthelmintic activity and toxicity. Examining the ADME properties of these compounds also supports the potential of these ligands to be transformed into pharmaceutical forms.

Autochthonous Ascariasis, Mississippi, USA

We describe a case of a 2-year-old child who expelled a single adult female Ascaris lumbricoides worm. The patient is from a rural county in Mississippi, USA, with no reported travel outside of the United States. The caregivers in the home practice good sanitation. Exposure to domestic pigs is the likely source of infection.

Dual burden of infectious and chronic disease in low-resource U.S. communities: examining relationships between infection, adiposity, and inflammation

BACKGROUND

Rising global obesity rates are linked with inflammation and associated morbidities. These negative outcomes are generally more common in low-resource communities within high-income countries; however, it is unclear how frequent infectious disease exposures in these settings may influence the relationship between adiposity and inflammation.

AIM

We test associations between adiposity measures and distinct forms of inflammation among adults (n = 80) living in low-resource U.S. communities experiencing high levels of obesity and pathogen exposure.

SUBJECTS AND METHODS

Adiposity measures included BMI and percent body fat. Inflammation measures included systemic inflammation (C-reactive protein [CRP]) and localised intestinal inflammation (faecal calprotectin [FC]). The relationship between a condition characterised by elevated inflammation (Helicobacter pylori infection) and adiposity was also considered.

RESULTS

Adiposity was not significantly related to FC concentration. However, both adiposity measures were positively related with odds of CRP elevation and H. pylori infection was associated with significantly lower adiposity measures (all p < 0.05).

CONCLUSION

For this disadvantaged U.S. sample, the association between adiposity and inflammation varies by the systemic/localised nature of inflammation and the likely underlying cause of inflammation. Defining these associations will improve understanding of how rising obesity rates shape long-term health inequities, with implications for more effective intervention design.

Antiparasitic activity of ivermectin: Four decades of research into a "wonder drug"

Parasitic diseases still pose a serious threat to human and animal health, particularly for millions of people and their livelihoods in low-income countries. Therefore, research into the development of effective antiparasitic drugs remains a priority. Ivermectin, a sixteen-membered macrocyclic lactone, exhibits a broad spectrum of antiparasitic activities, which, combined with its low toxicity, has allowed the drug to be widely used in the treatment of parasitic diseases affecting humans and animals. In addition to its licensed use against river blindness and strongyloidiasis in humans, and against roundworm and arthropod infestations in animals, ivermectin is also used "off-label" to treat many other worm-related parasitic diseases, particularly in domestic animals. In addition, several experimental studies indicate that ivermectin displays also potent activity against viruses, bacteria, protozoans, trematodes, and insects. This review article summarizes the last 40 years of research on the antiparasitic effects of ivermectin, and the use of the drug in the treatment of parasitic diseases in humans and animals.

The Landscape of Parasitic Infections in the United States

The landscape of parasitic infections in the United States has shifted dramatically over the past century. Although infections such as malaria have been successfully eliminated, others remain endemic and pose a significant public health risk. Numerous parasitic infections are also imported each year. This article focuses on endemic parasitic infections that may be commonly seen in anatomical pathology preparations and discusses their biology, diagnostic histopathological features, and epidemiology.

A Rare Complication of Ascariasis: A Case of Acute Interstitial Nephritis

Acute interstitial nephritis (AIN) due to helminths is a rare cause of acute kidney injury (AKI). Helminthiases often progresses insidiously, making diagnosis difficult. This was the case of a 72-year-old man, who presented with renal failure, itching and diarrhoea. Urinalysis revealed leukocyturia, microhaematuria and mild proteinuria. A full blood count revealed leucocytosis with eosinophilia. A stool parasitological examination revealed fertilised eggs of Ascaris lumbricoides. Tubulointerstitial nephropathy secondary to A. lumbricoides infection was suspected. A percutaneous renal biopsy was not performed since the patient refused the anti-platelet therapy discontinuation. Mebendazole, albendazole and prednisone therapy was administered. After worm eradiation and discharge, recovery from the parasitosis, absence of pruritus and eosinophilia, and progressive improvement of renal function were observed, strongly suggesting a causal relationship between Ascaris infection and AIN. Parasite infection should be considered in the differential diagnosis of unexplained renal failure because early diagnosis and treatment are necessary to avoid irreversible complications.

Using Google Trends to Estimate the Geographic Distribution of Soil-Transmitted Helminthiasis in the United States from 2016 to 2021

Soil-transmitted helminth infections are assumed to be uncommon in the US, despite numerous studies in the past few decades showing high burdens in Appalachia and the southern states. We assessed trends of interest in the Google search engine to gauge spatiotemporal patterns of potential soil-transmitted helminth transmission. We conducted a further ecological study comparing Google search trends to risk factors for soil-transmitted helminth transmission. Google search trends for terms related to soil-transmitted helminths were clustered in Appalachia and the south, with seasonal surges suggestive of endemic transmission for hookworm, roundworm (Ascaris), and threadworm. Furthermore, lower access to plumbing, increased septic tank use, and more rural environments were associated with increased soil-transmitted helminth-related Google search terms. Together, these results suggest that soil-transmitted helminthiasis remains endemic in parts of Appalachia and the south.

Evidence and potential drivers of neglected parasitic helminth and protist infections among a small preliminary sample of children from rural Mississippi

INTRODUCTION

Intestinal infections with helminths (parasitic worms) and protists (single-celled eukaryotes) may be neglected health issues in low-resource communities across the United States. Because they predominantly infect school-aged children and can lead to nutritional deficiencies and developmental delays, these infections can affect lifelong health. More research is needed to understand the prevalence and risk factors of these parasitic infections in the United States.

METHODS

A total of 24 children (ages 0.5-14 years) from a low-resource, rural Mississippi Delta community provided stool samples for 18s rRNA amplification and sequencing to determine infection presence. Parent/guardian interviews provided age, sex, and household size to test for associations with infection.

RESULTS

Infections were found in 38% (n = 9) of the samples. 25% (n = 6) of participants were infected with helminths (platyhelminths [n = 5]; nematodes [n = 2]), while 21% (n = 5) were infected with protists (Blastocystis [n = 4]; Cryptosporidium [n = 1]). There were no associations between infection status and age, sex, or household size. Problematically, analytical methods did not allow for more specific classifications for helminth species.

CONCLUSIONS

These preliminary findings suggest parasitic infections may be overlooked health issues in the rural Mississippi Delta and emphasize the need for more research on potential health outcomes within the United States.

Rural Embodiment and Community Health: an Anthropological Case Study on Biocultural Determinants of Tropical Disease Infection and Immune System Development in the USA

Purpose of Review

Biocultural methods are critically important for identifying environmental and socioeconomic factors linked with tropical disease risk and outcomes. For example, embodiment theory refers to the process by which lived experiences impact individual biology. Increased exposure to pathogens, chronic psychosocial stress, and unequal resource access are all outcomes linked with discrimination and poverty. Through lived experiences, race and socioeconomic inequality can literally become embodied-get under the skin and affect physiology-impacting immune responses and contributing to lifelong health disparities. Yet, few studies have investigated tropical disease patterns and associated immune function using embodiment theory to understand lasting physiological impacts associated with living in a high-pathogen environment.

Recent Findings

Here, we use preliminary data drawn from the Rural Embodiment and Community Health (REACH) study to assess whether pathogen exposure and immune stimulation within a sample of children from the Mississippi Delta are associated with household income. We also test whether immune marker levels-assessed with enzyme-linked immunosorbent assays using dried blood spot samples-vary between the REACH sample and a similarly aged nationally representative NHANES sample. Immune marker levels did not differ significantly between REACH participants living below vs. above the federal poverty line, yet immunoglobulin E levels-a marker of macroparasite infection-were higher among REACH study participants compared to the NHANES sample.

Summary

These results may suggest community-level pathogenic exposures (i.e., parasitic infections) are embodied by REACH participants with implications for long-term immune function, potentially resulting in immune aspects that differ from nationally representative samples.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40475-023-00282-z.

The accuracy of nucleic acid amplification tests (NAATs) in detecting human intestinal nematode infections: A protocol for a systematic review and meta-analysis

Human intestinal nematode infections are a global public health issue as they can result in considerable morbidity in infected individuals, mainly in developing countries. These infections continue to go undiagnosed, as they tend to be mainly endemic in resource-poor communities where there is a shortage of experienced laboratory staff and relevant diagnostic technologies. This is further exacerbated by the nature of intermittent shedding of eggs and larvae by these parasites. Diagnostic methods range from simple morphological identification to more specialised high-throughput sequencing technologies. Microscopy-based methods, although simple, are labour-intensive and considerably less sensitive than molecular methods which are rapid and have high levels of accuracy. Molecular methods use nucleic acid amplification (NAA) to amplify the deoxyribonucleic acid (DNA) or ribonucleic acid (RNA) fragments of the parasite to detect and determine its presence using different technologies (NAAT). They have increased the sensitivity of detection and quantitation of intestinal nematode infections, especially in low infection intensity settings. The absence of a gold standard test limits current diagnosis and, in turn, restricts intervention measures and effective control efforts. The objective of this review is to determine the accuracy of NAATs in detecting human intestinal nematode infections using Kato-Katz as the reference test for the most common soil-transmitted helminth (STH) infections and the scotch tape test for enterobiasis and Baermann method for strongyloidiasis. Relevant studies will be identified by searches in electronic databases. Two reviewers will independently screen the literature against eligibility criteria. The methodological quality of studies will then be appraised by two reviewers using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS-2) tool. Discrepancies will be addressed by a third reviewer. The true positives, false positives, true negatives and false negatives of all the studies will be extracted into contingency tables. In paired forest plots, study-specific sensitivity and specificity with a 95 per cent confidence interval will be displayed. The systematic review of this protocol will report the diagnostic accuracy of currently available NAATs for the detection of human intestinal nematode infections. This will help healthcare providers and administrators determine the diagnostic method to be used in different clinical and preventive settings. Trial registration: PROSPERO registration number for this protocol is CRD42022315730.

Following the Indian Immigrant: adoption of westernization results in a western gut microbiome and an increased risk of inflammatory bowel diseases

Indians who migrate to westernized countries such as Canada, the USA, and the UK are at an increased risk of developing inflammatory bowel disease (IBD). While the underlying aetiology of IBD remains unclear, a gut microbiome, i.e. no longer symbiotic with its host, is a major player. Increasing IBD incidence in Indian immigrants may be due to the adoption of western practices that result in loss of tolerance of a symbiotic community in the gut and its underlying immune responses. However, little is known about the microbial changes in the Indian gut, including shifts in the microbiome when they migrate to westernized countries. In this Current Opinion, we discuss what is known about the Indian gut microbiome and how living in a westernized environment may be impeding what was once a symbiotic relationship with their gut microbiome and intestinal mucosae, which may be the driving factor in their increased risk of IBD.