Advances in Diagnosis, Epidemiology and Control on Soil-Transmitted Helminth (STH) Infections - Volume II

A special issue of Tropical Medicine and Infectious Disease (ISSN 2414-6366). This special issue belongs to the section "Neglected and Emerging Tropical Diseases".

Deadline for manuscript submissions: closed (15 February 2023) | Viewed by 18460

Special Issue Editor

Section of Pediatric Tropical Medicine, National School of Tropical Medicine, Baylor College of Medicine, Houston, Texas, USA
Interests: helminth; soil-transmitted nematode; vaccine; parasitology; immunology; molecular biology
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue focuses on recent advancements in the diagnosis, epidemiology and control of soil-transmitted helminth (STH) infections.

Soil-transmitted helminth (STH) infections are the most common infections worldwide, and affect more than a billion poor people around the world. The main STH species that infect people are the roundworm (Ascaris lumbricoides), the whipworm (Trichuris trichiura) and hookworms (Necator americanus and Ancylostoma duodenale). STH infections cause significant disease burden primarily in school-aged children totaling 5.2 million disability-adjusted life years (DALYs).

While in some countries, during recent years, the prevalence of STH infections has been on the decline (assisted by economic development, improved sanitary conditions and the application of mass drug administration (MDA)), there are still more than 800 million people with ascariasis, and 450 million people with each of trichuriasis or hookworm infections. This panorama is partly because many questions with respect to the diagnosis, epidemiology and control of these infections remain unresolved.

There is a need to enhance the evidence base for novel strategies for the effective diagnosis and control of STH infections, including intervention studies into the long-term sustainability of MDA and efficacy studies of MDA regimens and delivery platforms; epidemiological investigations into socioeconomic and environmental drivers of transmission; mathematical modelling of competing strategies; epidemiology of STH benzimidazole resistance; new drug discovery; vaccine development; development of effective and accurate diagnostic methods; and finally studies into the pathophysiological mechanisms of morbidity including the immunomodulation of autoimmune diseases.

Dr. Bin Zhan
Guest Editor

Manuscript Submission Information

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Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • Soil-transmitted helminth (STH) infections
  • Diagnosis
  • Intervention trial
  • Water and sanitation
  • Mass drug administration
  • Treatment efficacy
  • MDA resistance
  • Neglected tropical diseases (NTDs)
  • Epidemiology
  • Disease transmission modelling
  • Ascariasis
  • Trichuriasis
  • Hookworm infection

Related Special Issue

Published Papers (6 papers)

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Research

11 pages, 855 KiB  
Article
Using Google Trends to Estimate the Geographic Distribution of Soil-Transmitted Helminthiasis in the United States from 2016 to 2021
by Steven H. Adams, Timothy P. Endy and David A. Larsen
Trop. Med. Infect. Dis. 2023, 8(4), 212; https://doi.org/10.3390/tropicalmed8040212 - 1 Apr 2023
Viewed by 1826
Abstract
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 [...] Read more.
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. Full article
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12 pages, 679 KiB  
Article
Seroprevalence of Strongyloides stercoralis in Patients about to Receive Immunosuppressive Treatment in Gran Canaria (Spain)
by Cristina Carranza-Rodríguez, Laura López-Delgado, Álvaro Granados-Magan and José-Luis Pérez-Arellano
Trop. Med. Infect. Dis. 2023, 8(3), 181; https://doi.org/10.3390/tropicalmed8030181 - 20 Mar 2023
Cited by 1 | Viewed by 2116
Abstract
Strongyloides stercoralis infection is generally asymptomatic or mildly symptomatic, but in the immunosuppressed host, it is associated with more severe and complicated forms with a worse prognosis. S. stercoralis seroprevalence was studied in 256 patients before receiving immunosuppressive treatment (before kidney transplantation or [...] Read more.
Strongyloides stercoralis infection is generally asymptomatic or mildly symptomatic, but in the immunosuppressed host, it is associated with more severe and complicated forms with a worse prognosis. S. stercoralis seroprevalence was studied in 256 patients before receiving immunosuppressive treatment (before kidney transplantation or starting biological treatments). As a control group, serum bank data of 642 individuals representative of the population of the Canary Islands were retrospectively analyzed. To avoid false positives due to cross-reactivity with other similar helminth antigens present in the study area, IgG antibodies to Toxocara spp. and Echinococcus spp. were evaluated in cases positive for Strongyloides. The data show this is a prevalent infection: 1.1% of the Canarian population, 2.38% of Canarian individuals awaiting organ transplants and 4.8% of individuals about to start biological agents. On the other hand, strongyloidiasis can remain asymptomatic (as observed in our study population). There are no indirect data, such as country of origin or eosinophilia, to help raise suspicion of the disease. In summary, our study suggests that screening for S. stercoralis infection should be performed in patients who receive immunosuppressive treatment for solid organ transplantation or biological agents, in line with previous publications. Full article
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12 pages, 1230 KiB  
Article
Soil-Transmitted Helminth Infections among Antenatal Women in Primary Care Settings in Southern India: Prevalence, Associated Factors and Effect of Anti-Helminthic Treatment
by Revathi Ulaganeethi, Ganesh Kumar Saya, Nonika Rajkumari, Swetha S. Kumar, Kalaiselvan Ganapathy and Gowri Dorairajan
Trop. Med. Infect. Dis. 2023, 8(1), 48; https://doi.org/10.3390/tropicalmed8010048 - 7 Jan 2023
Cited by 4 | Viewed by 3765
Abstract
Community-based studies from India on prevalence of soil-transmitted helminth (STH) infections have reported estimates as high as 50% in children. However, prevalence estimates during pregnancy in India are lacking. We aimed to describe the burden, associated factors of STH and cure rate after [...] Read more.
Community-based studies from India on prevalence of soil-transmitted helminth (STH) infections have reported estimates as high as 50% in children. However, prevalence estimates during pregnancy in India are lacking. We aimed to describe the burden, associated factors of STH and cure rate after deworming in primary care settings. Pregnant women were recruited from four urban and five rural centers in Puducherry, South India, from December 2019 to April 2022. One stool sample was collected from each participant before deworming and one repeat sample was collected from STH positive woman after three weeks of deworming. The samples were processed with saline; iodine wet mount, and microscopic concentration techniques. Cure rate (CR) was assessed using Kato–Katz thick smear. Of 650 women included, 49 (7.5%, 95% CI 5.6–9.8) had one of the STH infections; the prevalence of Ascaris lumbricoides, hookworm and Strongyloides was 5.4%, 1.8% and 0.3%, respectively. The prevalence of any STH was higher among ages 26–30 years (9.1%), working women (8.3%), multigravida (8.3%), urban setting (8.3%), those who did not wash their hands before food (9%) and anemic women (8.9%), compared to their counterparts, but not statistically significant. The CR for hookworm was 100% and Ascaris lumbricoides was 88.6%. To conclude, the prevalence of STH was low among pregnant women compared to school aged children. Continued deworming activities along with improved sanitation could further reduce the burden. Full article
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14 pages, 1863 KiB  
Article
PD-L2 Blockade Exacerbates Liver Lesion in Mice Infected with Capillaria hepatica through Reducing Alternatively Activated Macrophages
by Minjun Huang, Xiaoli Li, Xiaoyan Zheng, Fei Wang, Yang Zou and Lei Wang
Trop. Med. Infect. Dis. 2023, 8(1), 46; https://doi.org/10.3390/tropicalmed8010046 - 6 Jan 2023
Viewed by 2265
Abstract
Capillaria hepatica is a seriously neglected zoonotic parasite, which infects the liver of mammalian hosts, causing fibrosis or even hepatic failure. At present, the immune responses elicited by C. hepatica are not fully understood, and the role(s) of the programmed death 1 (PD-1) [...] Read more.
Capillaria hepatica is a seriously neglected zoonotic parasite, which infects the liver of mammalian hosts, causing fibrosis or even hepatic failure. At present, the immune responses elicited by C. hepatica are not fully understood, and the role(s) of the programmed death 1 (PD-1) signaling pathway in the context of C. hepatica-induced pathology are not known. In this study, we identify that the late stage of infection with C. hepatica—especially the egg-derived antigens—modulates the host immune responses to promote alternatively activated macrophage (M2) polarization and programmed death ligand 2 (PD-L2) expression. The PD-L2-expressing alternatively activated M2 macrophages play an important role in maintaining Th2-biased regulatory immune responses, which may facilitate the survival of parasitic worms or eggs within the infected liver and reduce the liver pathology caused by the egg granulomas. Treatment with anti-PD-L2 antibody had no effect on the survival of parasitic eggs but deteriorated the pathology of egg granulomas. The obtained results suggest that PD-1/PD-L2 signaling, which is involved in alternative macrophage polarization, determines the immune response pattern and the immunopathology, consequently determining the outcome of the parasitic infection. Full article
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8 pages, 4899 KiB  
Article
Three-Dimensional Models of Soil-Transmitted Helminth Eggs from Light Microscopy Images
by Yan Emygdio Dias, Elisângela Oliveira de Freitas, Dayane Alvarinho de Oliveira, Wendell Girard-Dias, Lúcio Paulo do Amaral Crivano Machado and Eduardo José Lopes-Torres
Trop. Med. Infect. Dis. 2022, 7(9), 216; https://doi.org/10.3390/tropicalmed7090216 - 30 Aug 2022
Viewed by 3538
Abstract
The World Health Organization indicates that more than 1.5 billion people are infected with geohelminths. Soil-transmitted helminths prevail mostly in tropical and subtropical regions, in areas with inadequate hygiene and sanitation conditions, and basic health education problems. Nematode eggs are structures of resistance [...] Read more.
The World Health Organization indicates that more than 1.5 billion people are infected with geohelminths. Soil-transmitted helminths prevail mostly in tropical and subtropical regions, in areas with inadequate hygiene and sanitation conditions, and basic health education problems. Nematode eggs are structures of resistance and infection by fecal–oral transmission. When STH eggs are ingested, they can infect the potential host, causing abdominal pain, diarrhea, anemia, malnutrition, and physical-cognitive impacts in children. Taking advantage of the increasing employment of three-dimensional models of these structured based on light microscopy images to improve the research area and education could be an alternative to improve health education and spread scientific information on transmission and prevention. The objective of this work was to produce 3D printed models from bi-dimensional images of eggs based on their real morphological and morphometric characteristics. The virtual models were reconstructed from the acquisition and selection of images obtained using light microscopy. After selecting referential images, we constructed the models based on the vectorization of the egg structures. After vectorization, 3D modeling was performed and printed in PLA. 3D models have a high potential to contribute to the advanced morphological studies and teaching of parasitological sciences, enriching the teaching-learning process applicable in presential or remote teaching of basic education, undergraduate, and post-graduation classes. Full article
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15 pages, 1714 KiB  
Article
Knowledge, Attitudes, and Practices regarding Soil-Transmitted Helminthiasis among Village Health Volunteers in Nakhon Si Thammarat Province, Thailand: A Cross-Sectional Study
by Udomsak Narkkul, Prasit Na-ek, Jaranit Kaewkungwal and Chuchard Punsawad
Trop. Med. Infect. Dis. 2022, 7(2), 33; https://doi.org/10.3390/tropicalmed7020033 - 19 Feb 2022
Cited by 4 | Viewed by 3937
Abstract
Soil-transmitted helminth infections are most prevalent in rural populations. Village health volunteers (VHVs) are the key individuals for Thai primary healthcare. Therefore, this study aimed to investigate the knowledge, attitudes, and practices regarding soil-transmitted helminthiasis in VHVs. A questionnaire survey was conducted among [...] Read more.
Soil-transmitted helminth infections are most prevalent in rural populations. Village health volunteers (VHVs) are the key individuals for Thai primary healthcare. Therefore, this study aimed to investigate the knowledge, attitudes, and practices regarding soil-transmitted helminthiasis in VHVs. A questionnaire survey was conducted among 552 VHVs randomly selected from four subdistricts in a southern province of Thailand. Sociodemographic variables and information regarding the knowledge, attitudes, and practices related to soil-transmitted helminthiasis were collected using a structured questionnaire. The results demonstrated that VHVs had poor knowledge (70.47%) and practices (66.49%); however, 69.57% had good attitudes. Most VHVs had inadequate knowledge and practices regarding soil-transmitted helminthiasis. VHVs who had been trained in parasitic infection control measures were 2.18 times more likely to have good knowledge. VHVs with a monthly family income of more than 307 USD were 1.58 times more likely to have a good attitude. VHVs with good knowledge were more likely to have good practices. In conclusion, the development of training programs and health promotion should be considered to enhance the knowledge, attitudes, and practices related to soil-transmitted helminthiasis in VHVs, who are the key individuals for providing health education to community members. Full article
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